Citation
Florida's ground water quality monitoring program: background hydrogeochemistry ( FGS: Special publication 34 )

Material Information

Title:
Florida's ground water quality monitoring program: background hydrogeochemistry ( FGS: Special publication 34 )
Series Title:
( FGS: Special publication 34 )
Creator:
Maddox, Gary
Publisher:
Florida Department of Natural Resources
Publication Date:
Language:
English

Subjects

Subjects / Keywords:
City of Ocala ( flgeo )
South Florida ( flgeo )
Water quality ( jstor )
Groundwater ( jstor )
Nitrates ( jstor )
Spatial Coverage:
North America -- United States -- Florida

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Source Institution:
University of Florida
Holding Location:
University of Florida
Rights Management:
The author dedicated the work to the public domain by waiving all of his or her rights to the work worldwide under copyright law and all related or neighboring legal rights he or she had in the work, to the extent allowable by law.
Resource Identifier:
AAA1632 ( notis )
AJG7267 ( notis )

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U FLORIDA GEOLOGICAL SURVEY

STATE OF FLORIDA

DEPARTMENT OF NATURAL RESOURCES DEPARTMENT OF ENVIRONMENTAL REGULATION
Virginia B. Wetherell, Executive Director Carol M. Browner, Secretary
DIVISION OFrm REOUC MANAGEMENT DIVISION OF WATER FACILITIES
Jere y Crft!DiretorRichard M. Harvey, Director FLRIAGEOLOICA o gSURVhE BUREAU OF DRINKING WATER AND GROUND WATER
I ~Charles C Aller, Ghief



FLORIDA GEOLOGICAL SURVEY SPECIAL PUBLICATION NO. 34
FLORIDA'S GROUND WATER QUALITY MONITORING PROGRAM

BACKGROUND HYDROGEOCHEMISTRY



I 9rDEP Ga







1199

ISSN 0085-0640





SPECIAL PUBLICATION NO. 34

DEPARTMENT LETTER OF TRANSMITTALI
OF
NATURAL RESOURCES


oLOG~I










Florida Geological SurveyU TallahasseeI k/qg w'October, 1992



Governor Lawton Chiles, ChairmanI Florida Department of Natural Resources LAWTON CHILES Tallahassee, Florida 32301
GovernorI Dear Governor Chiles:
JIM SMITH BOB BUTTER WORTH
Secretary of State Attorney General The Florida Geological Survey, Division of Resource Management, Department of
Natural Resources, is publishing, as its Special Publication 34, Florida's Ground Water Quality Monitoring Program Background Hydrogeochemistry. This publication is the TOM GALLAGHER GERALD LEWIS second in a series which will present the results of the ground water quality network proState Treasurer State Comptroller gram established by the 1983 Water Quality Assurance Act (Florida Statutes, Chapter
403.063). It is primarily a series of maps which provide the background hydrogeochemical parameters present within the principal aquifer systems of Florida. These BETTY CASTOR BOB CRAWFORD results can be used by state and local governments, planners, and developers for landCommissioner of Education Commissioner of Agriculture use planning, conservation, and protection of Florida's valuable water resources.

Respectfully yours,
VIRGINIA B. WETHERELL
Executive Director

Walter Schmidt, Ph.D., P.G.U State Geologist and Chief
Florida Geological Survey

II






FLORIDA GEOLOGICAL SURVEY

I ACKNOWLEDGEMENTS SUWANNEE RIVER WATER MANAGEMENT DISTRICT:

This publication is the result of contributions by a number of individuals and Nolan Col (Program Administrator)
agencies associated with the Florida's Ground Water Quality Monitoring Program. The Ron Ceryak (Project Manager)
list of contributors below recognizes the many geologists, field technicians, computer Libby Schmidt
3 specialists, draftsmen, secretaries and student assistants who aided in this effort. Willie Ray Hunter
Ben Barber
Much of the work that resulted in the maps found in this volume was performed Martin Gabriel
* by the five water management districts and the county cooperators These agencies
have primary responsibility for maintaining and sampling the Ground Water Quality ST. JOHNS RIVER WATER MANAGEMENT DISTRICT:
Monitoring Program well networks. Ground-water sampling of these networks has been
conducted since 1984. Personnel of these agencies also contributed by providing inter- Don Boniol (Project Manager)
pretation of the hydrogeologic framework within their respective areas Administration of Dr. David Toth
the program has been provided by personnel of the Ground Water Quality Monitoring George Robinson
I Section of the Department of Environmental Regulation (DER) Several individuals from Scott Edwards
Florida's State University System contributed valuable research, training and technical
Advice to the program. The U.S Geological Survey has provided technical assistance SOUTHWEST FLORIDA WATER MANAGEMENT DISTRICT:
U from the early days of the program. The Florida Geological Survey (FGS) has contributed to the program by providing extensive geotechnical assistance and editing, and Gregg Jones (Project Manager)
Sby publication of this report. Lee Clark
I~Eric DeHaven The editors of this volume each provided valuable and necessary expertise. Rick John Gee
Copeland (DER) provided the leadership and central management necessary for the Dave Moore
U development and ultimate completion of this large scale project. Gary Maddox (DER) Tom Rauch
served as a central focal point for the interaction between DER, the water management
districts and the FGS and provided computer expertise in the management of the mas- SOUTH FLORIDA WATER MANAGEMENT DISTRICT: I sive data files generated by this effort Sam Upchurch (University of South Florida) was
the hydrogeochemical guru advising aF the scientists involved in completing this Jeifry W. Herr (Project Manager)
research effort. Jacqueline Lloyd (FGS) and Tom Scott (FGS) edited the maps and text, Roberto L. Sanchez
I supervised map digitization and correction, and compiled the volume for publication. Jonathan E. Shaw
Phillip Fairbank
The following individuals and agencies contributed time, data and valuable exper- Steven D. Anderson
tise in the development of the Background Network and the preparation of this report: Carmen Parada

NORTHWEST FLORIDA WATER MANAGEMENT DISTRICT: Milton P. Switanek

Thomas Pratt (Project Manager) ALACHUA COUNTY:
3 Jeffry P. Wagner
Jay L. Johnson Robin Hallbourg (Project Manager)
Brian E. Caidwell Jim Trifilio
I Ross J Curry John Regan
Libby Schmidt





SPECIAL PUBLICATION NO. 34I

UNIVERSITY OF SOUTH FLORIDA: DEPARTMENT OF ENVIRONMENTAL REGULATION:I

Dr. Sam B. Upchurch Rick Copeland (Program Administrator)
Jian Chen Tim GloverI
Aida Bahtita Gary Maddox
Jackye Bonds
Paul Hansard
FLORIDA STATE UNIVERSITY: Jay Silvanima
Cindy Cosper
Dr. William C. Burnett Mary Geuin
Dr. James B. Cowart Cynthia Humphreys
Dr. William C. Parker Jeff SpicolaI
Dr. William T. Cooper Ill Liang Lin
Donna Burmeister
Peter Grasel3 UNIVERSITY OF FLORIDA: Felix Rizk
David Quellette
Dr. Robedt LindquistU
FLORIDA GEOLOGICAL SURVEY:

U.S. GEOLOGICAL SURVEY: Jacqueline M. Lloyd (Program Manager)U
Dr. Thomas M. Scott (Program Manager)
lrv Kantrowitz Cindy Collier
Walt Aucott Jim Jones
John Vecchioli Ted Kiper
Brian Katz Elizabeth Doll
Marian Berndt Will Evans
Kent Hartong










ivU

I








FLORIDA GEOLOGICAL SURVEY
TABLE OF CONTENTS
PAGE

ACKNOW LEDGE MENTS .......................... ................iii P G

Chapter I INTRODUCTION, by Gary L. Maddox..........................1 Chapter IV QUALITY OF WATER IN FLORIDA'S AQUIFER SYSTEMS, by ....12
Sam B. Upchurch
NHistory and Purpose... .. ............ ...... ...... .... ........ 1
Organization and Establishment of the Ground Water Quality Introduction ........................................12
Background Network 2... ................... .............. .. Chapter Or an zaio ..... .... .. .. ..... ..... .. ... ...........12

Usefulness of Background Network Data...................................... 2 Comparison of Map and Ttle Data -......................12
References Cited. -........................................................... 2 Variable Description Conventions ................................................ 12
Nature of Data Distributions ... .. ........... .......... .12

SChapter I DATA COLLECTION AND MANAGEMENT METHODS, by.......3 Distribution Descriptors .................................12
Gary L. Maddox Aquifer Controls on Ground-water Chemistry .......................12
Factors That Control Ground-water Chemistry................. 12
WellSeecSelectionlin .....an.d.Sam..pl.i.ng...3..Precipitation............emirstptaronCh..sty................................................11


Ana ta a eytemds ...........................................4 Soil Typd Aqife rgine r agy..............................13

A vailabiltity D ta ... .. ...o.f. ..D.a..a. .4..N.atu.re.. .. .. ... .. ..q. .i.fe.. .S4NsurtemAq iProystositsyt a danrdtu e .. ....c.. .. ... .. ..11

References e Cited................5....Cav.e......o...........u..g.y.., aarn usdVgg ,rndFrctuurersiyP......o....t.....151
Aquifer System Flow Path and Residence Time............... 15
IChapter III HYDROSTRATIGRAPHY, by Thomas M. Scott..................6 Mixing with Other Waters in the Aquifer system................15
Aquifer Microbiology..................................................... 15

Geologic Structures in Relation to Hydrostratigraphy ................. 6 Previous Works ........... .............................. 16
Aquifer Systems and Confining Units Surficial Aquifer System...................................16
Surficiaulersy te .....a.quif.er.........y............. Int merm ediuateS st m ..............i.........................1
Northwest Florida Water Management District .....6 Floridan Aquifer System.................................. 16
Suwannee River Water Management District.......6 General Descriptors .......... ................................16
St. Johns River Water Management District .......7 Temperature ........ ..................................16
Southwest Florida Water Management District..... 7 Importance...................... ................16
South Florida Water Management District ............. 7 Standard or Guidance Criterion ...................... 17
Intermediate aquifer system and intermediate confining unit 7 Distribution in Ground Water.........................17
Northwest Florida Water Management District .....8 Surficial Aquifer System.... ................... 17
Suwannee River Water Management District...... 8 Intermediate Aquifer System. ........................... 17
St. Johns River Water Management District....... 8 Floridan Aquifer System... .......................... ..17
Southwest Florida Water Management District..... 8 Acid-Base Relationships (pH)...............................17
ISouth Florida Water Management District ............. 9 Importance.. .................................... 17
Flonidan aquifer system ............................................ 9 Standard or Guidance Criterion................................ .17

SNorthwest Florida Water Management District..... 9 Distribution in Ground Water ............................ ........ 18
ISuwannee River Water Management District......... 10 Surf icial Aquifer System....... ...................... .. 18
St. Johns River Water Management District ....... 10 Intermediate Aquifer System........................... 18

SSouthwest Florida Water Management District..... 10 Flonidan Aquifer System.... .....................18
ISouth Florida Water Management District............. 11
References Cited ............ ... ... .... ............ ........11







SPECIAL PUBLICATION NO 34


PAGE PAGE




Major Cations... ................ .................19 Intermediate Aquifer System ................... 26
MM i rCnors........a.....o.n..... ..1....F........r....a..n9F Adn quuirfysem ......S......t....m...2.6....2

CTrum.a...c...e.... ........e....tals.............19 Lmeandnd o r e .................. .. ........26

Importance and Sources ........................... 19 Standard or Guidance Criterion ............ ..........26
Standard or Guidance Criterion .......................20 Distribution in Ground Water..........................26I
Distribution in Ground W ater..........................20 Surficial Aquifer System ........................27
Surficial Aquifer System ....... ................ 20 Intermediate Aquifer System ................ 27
Intermediate Aquifer System... ...............20 Floridan Aquifer System.... .................27U
Floridan Aquifer System ...... ...............20 Anions ............. - ...................27



Standard or Guidance Criterion ..................... 21 Minor Anions........... .. .......................27
DDi rbstribuGtndWior ..n.......i.n... G..........d2 TWatnenr ..2.1 ........T.....c..........i.o..........2
Surficial Aquifer System ............. .........21 Bicarbonate, Carbonate and Alkalinity .......... ... ........27I
Intermediate Aquifer System....................21 Importance and Controls........-................ 27
Floridan Aquifer System ....... ................22 Data Interpretation........... .....................27
Sodium.......... .............. ................ 22 Standard or Guidance Criterion .... ............. 28I
Importance and Sources ............................22 Distribution in Ground W ater..................... . 28
Standard or Guidance Criterion................... .. 22 Surficial Aquifer System ............ ....... 28
Distribution in Ground Water....- ............... .23 Intermediate Aquifer System............ .......28I
Surficial Aquifer System ... ..............- .23 Floridan Aquifer System ........... ...........28
Interm ediate Aquifer System ............. .....23 Sulfate ........ . ................ ..........29
Floridan Aquifer System............................... 23 Importance and Controls............ ............. 29
Potassium ..... ......................................... ............. 23 Sources and Sinks of Sulfur ........--.. .......... 29
Importance and Sources........................................ 23 Standard or Guidance Criterion .... .............-30
Standard or Guidance Criterion...... .............. 24 Distribution in Ground Water... .............--. 303
Distribution in Ground W ater..........................24 Surficial Aquifer System. .. ............. ......30
Surficial Aquifer System .................... ..24 Intermediate Aquifer System........ .... ......30
Intermediate Aquifer System ........................ 24 Floridan Aquifer System.. .................. 303
Floridan Aquifer System...................................24 Chloride ......................... ................31
Iron... ... .......... .............................................. 24 Importance and Controls....... ........ --...31
Importance and Sources........... ........... .... 24 Standard or Guidance Criterion........... -... 31
Standard or Guidance Criterion..... ............- .....24 Distribution in Ground Water........... ....... 31I
Distribution in Ground Water .... ... ......... .25 Surf icial Aquifer System ...- -. .......-..32
Surficial Aquifer System ....... ... .. ..... 25 Intermediate Aquifer System... .. ........... 32
Intermediate Aquifer System..... ---....... 25 Floridan Aquifer System. ....... 32I
Floridan Aquifer System ... ... .25 Phosphate ......... .- .. ........ 32
Mercury....-......-...........-....-............................ 25 Importance and Controls.. -.. ..... 32
Importance and Sources .................. 25 Standard or Guidance Criterion ...-......-. .... 33I
Standard or Guidance Criterion .-.......- .. 25 Distribution in Ground Water..... -.............. 33

Surf icial Aquifer System -.......-- .. 33
Intermediate Aquifer System...-.- ..- 34I
Floridan Aquifer System. ....- --... 34



VII









FLORIDA GEOLOGICAL SURVEY


3 PAGE PAGE



Importance and Controls.......... ............ ....34 Chloroform... .............................. 4
Standard or Guidance Criterion .... ...............35 Chloromethane...................... ..........44

SDistribution in Ground Water ..... .. ...............35 Dibromochloromethane .... .. ..... ... .......44
Surficial Aquifer System .... ...................35 1,2 Dibromoethane............................ 44
Intermediate Aquifer System .. ............. 35 1,2 Dichlorobenzene ..... ........... ..... .4

SFloridan Aquifer System .... ...................35 1,3 Dichlorobenzene ................... .......4

Importance and Controls........ .....................3 Dc lrdiloo hane. .......................4
Sta dar orGuidance Criterion ... ............. ...71, Dih r et ne...........................4
Distribution in Ground Water.. .-.......... ........ 37 1,2 Dichloroethane...............................4
Surficial Aquifer System.. .................. 37 trans-i1,2 Dichloroethene.................... ..45

SIntermediate Aquifer System....................37 1,2 Dichloropropane......................... 45
IFloridan Aquifer System ...................... 37 Ethylbenzene......... .......... ......... .45


T otal D iss olv e d.. .. .. .. .. .. . . . .. .. .. ...s. .. 3.8.. 3MM tthnyle nr d .. .. ..e.. ...h..l.o.. .. .. .. .. ..4.4

Standard or Guidance Criterion ......................38 1,1,2,2 Tetrachloroethane....... ............46
Distribution in Ground W ater........................ 38 1,1,1 Trichloroethane .. ......................46
3Surficial Aquifer System ...................... 38 Tetrachloroethene ............................46
Intermediate Aquifer System ................... 39 Toluene.....................................4
Floridan Aquifer System ............ ...... 39 Trichloroethene ............................. 46
SppeciCfduicce ......C.....n...u...........e.......9.........3cTn hlrorormfhael............etha..............4

Im tan cd e ud n eC ie on............ ......... 39 Vinyld s ... Chloride....... ......................-- 46

Distribution in Ground Water................ ................... 39 Importance............ ........ ...........-....47
Surficial Aquifer System................................. 39 Standard or Guidance Criterion ...... ......... ...... 47
Intermediate Aquifer System...... .................... 40 Distribution in Ground Water.......................... 47

E loridan Aquifer System ........................40 Aldrin..................... ..47

Total O r an c e ............a.r............o.n. ........ ..40 A rsenc .................................... 47

SStandard or Guidance Criterion .......................41 BBHC..................... ................48
Distribution in Ground W ater..........................41 2,4-D.....................................48
Surf icial Aquifer System ....... .. ............41 4,4'-DDE .............. .. ......... .........48

SIntermediate Aquifer System ....... ............42 4,4'-DDT ...................................48
Floridan Aquifer System ........... ..........42 Dieldrin.....................................48

Sy t ei iOrg anslt s .. ............... .......... 42 E thxdr......................n..........48

Imotnc n C..ntr................. .................... 4.Mrx............................ ................. 4
Standard or Guidance Criterion ..................... 43 Hydrochemical Facies and Predominant Water Types ................ 48
Distribution in Ground Water................................ 44 Introduction ................................................. .............. 48

Acrylonitnile................... ............. 44 Predominant Water Types..............................................49
Benzene....... ............................ 4Uses of Predominant Water Type and Hydrochemical Facies Maps 49







VII





SPECIAL PUBLICATION NO. 34

PAEPAGEI

Water Types in Florida Aquifer Systems ......................50 Total Dissolved Solids.................................................... 57
Surficial Aquifer System....- .-.......................... 50 Synthetic Organios....... .............................. 57
Intermediate Aquifer System ....._..-................... 50 Pesticides ................ ................... .... 57
Floridan Aquifer System ...-_........................... 50 Total Organic Carbon... ...... ....... ............. 57
Endnotes .... ........ .._............ .. 51 Need for Additional Work......... ................... 57a
Management Implications......................57
Chapter V CONCLUSIONS AND RECOMMENDATIONS, by ................ 53 Comparison to Backgroud........... ......57
Sam B. Upchurch Sensitivity to Contamination ..... ..................... 57
Effects of Consumptive Use.._......................_.......57
Introduction.................................53 Long-Term Resource Evaluation .... ........ ___......57
Goals...........................53 Need to Continue the Program and the Future..........58I
Evaluation of Health and Use Risks..............53 References Cited Chapters IV and V....................59
Data Interpretation and Use...................53
Recharge Areas......................54U
Discharge Areas.......................54
Flow Systems......................54
Surface-Water Features..................54U
Land Uses.......................54
General Summary of the Quality of Florida Ground Water.........54
General Quality of Florida's Ground Water...........54
Siliciclastic Aquifers...__ ...........4....
Carbonate-Rich Siliciclastic Aquifers.............54
Limestone and Dolostone Aquifers..............54
Definition of Background Water Quality...............55
Pristine Water.....................
Background Water....................55
High Salinity Water....................55I
Coastal Intrusion.....................55
Connate Water.....................553
Deep-Flow-System Water.................55
Interaquifer Transfer...................55
Nature of Anthropogenic Contamination...............55
Point-Source Contamination................56
Non-Point Source Contamination...............56
Statewide Levels of Contamination.................56
pH..........................56U
Sodium.................... ......56
Iron..................... ......56
Mercury........................56
Lead.........................56
Sulfate........................56
Chloride........................563
Fluoride........................56
Nitrate.................... ...56




ilX






U FLORIDA GEOLOGICAL SURVEY


I LIST OF FIGURES
PAGE PG

U1. Background Network Wells Sampled as of March, 1990 .............. 86 14. Distribution of calcium (Ca2n, mg/L) in the Floridan aquifer system.........131
A. NWFWMD, B. SRWMD, C. SJRWMD, D.SWFWMD, E. SFWMD.
2. Data Collection and Editing Flowchart........... .............. .. 87
15. Distribution of magnesium (Mg2, mg/L) in the surficial aquifer.... ......136
3. Hydrostratigraphic nomenclature........ .. ............. .... 88 system. A. NWFWMD, B. SRWMD, C. SJRWMD, D.SWFWMD, E
SFWMD.
U4. Structural features of Florida: a) mid-Cenozoic b) pre-Cenozoic......... 89
16. Distribution of magnesium (Mg", mg/L) in the intermediate aquifer.......... 141
5. Comparison of the sodium to chloride mole ratio of precipitation at.......... 90 system. A. NWFWMD, B. SRWMD, C. SJRWMD, D.SWFWMD, E.
the Kennedy Space Center, Brevard County, to the mole ratio of sea SFWMD.
water. Data from the National Atmospheric Depositions Program,
National Trends Network. 17. Distribution of magnesium (Mgt, mg/L) in the Floridan aquifer................ 146
system. A. NWFWMD, B. SRWMD, C.SJRWMD, D. SWFWMD, E.
6. Distribution of temperature in the surficial aquifer system. Data are.......... 91 SFWMD.
3 in degrees Celsius. A. NWFWMD, B. SRWMD, C. SJRWMD, 0.
SWFWMD, E. SFWMD. 18. Distribution of sodium (Na+, mg/L) in the surficial aquifer system..........151
A. NWFWMD, B. SRWMD, C.SJRWMD, D. SWFWMD, E. SFWMD. 37. Distribution of temperature in the intermediate aquifer system. Data ...... 96
are in degrees Celsius. A. NWFWMD, B. SRWMD, C. SJRWMD, D. 19. Distribution of sodium (Na+, mg/L) in the intermediate aquifer......... ...156
SSWFWMD, E. SFWMD. system. A. NWFWMD, B. SRWMD, C.SJRWMD, D. SWFWMD, E.
U SFWMD.
8 Distribution of temperature in the Floridan aquifer system. Data are........101
Sin degrees Celsius. A. NWFWMD, B. SRWMD, C. SJRWMD, D. 20. Distrbution of sodium (Na+, mg/L) in the Floridan aquifer system. .. ....161
ISWFWMD, E. SFWMD. A. NWFWMD, B. SRWMD, C.SJRWMD, D. SWFWMD, E. SWD

S9. Distribution of water pH in the surficial aquifer system. Data are in........... 106 21. Distribution of potassium (K+, mg/L) in the surficial aquifer system..........166
standard pH units (s.u.). A. NWFWMD, B. SRWMD, C. SJRWMD, D. A NWFWMD, B. SRWMD, C.SJRWMD, 0. SWFWMD, E. SFWMD.
SWFWMD, E. SFWMD.
22. Distribution of potassium (K+, mg/L) in the intermediate aquifer .. ..........171
10. Distribution of water pH in the intermediate aquifer system, Data are ... ... 111 system. A. NWFWMD, B. SRWMD, C.SJRWMD, Da SWFWMD, E.
in standard pH units (s.u.). A. NWFWMD, B. SRWMD, C. SJRWMD, SFWMD.
D.SWFWMD, E. SFWMD.
U23. Distribution of potassium (K-, mg!L) in the Floridan aquifer system. .......176 11. Distribution of water pH in the Floridan aquifer system. Data are in. ........ 116 A. NWFWMD, B. SRWMD, C.SJRWMD, 0. SWFWMD, E. SFWMD.
standard pH units (s.u.). A. NWFWMD, B. SRWMD, C. SJRWMD, D
SWFWMD, E. SFWMD. 24 Eh-pH diagram showing iron stability fields and water samples from...... .181
the surficial and Floridan aquifer systems of central Florida at 2500. 312. Distribution of calcium (Cat, mg/L) in the surficial aquifer system. ........... 121 Modified from Upchurch et a! (1991).
A. NWFWMD, B. SRWMD, C. SJRWMD, D.SWFWMD, E. SFWMD.
25. Distribution of total iron (Few and Fe3, mg/L) in the surficial aquifer .......182 313. Distribution of calcium (Ca2, mg/L) in the intermediate aquifer.. ........... 126 system. A. NWFWMD, B. SRWMD, C.SJRWMD, D. SWFWMD, E.
system. A. NWFWMD, B SRWMD, C. SJRWMD, D.SWFWMD, E. SFWMD.
SFWMD.


II





SPECIAL PUBLICATION NO 341



PAGE PAGE

26. Distribution of total iron (F&n and Fe>, mg/L) in the intermediate .......... 187 39 Distribution of phosphate (P03-; mg/L) in the intermediate aquifer ........248I
aquifer system. A. NWFWMD, B. SRWMD, C.SJRWMD, D. system. .A. NWFWMD, B. SRWMD, C. SJRWMD, D. SWFWMD, E.
SWFWMD, E.SFWMD. SFWMD.

27. Distribution of total iron (Fe2n and Fe3, mg/L) in the Floridan aquifer ........ 192 40. Distribution of phosphate (POP-; mg/L) in the Floridan aquifer ..........253
system. A. NWFWMD, B. SRWMD, C.SJRWMD, D. SWFWMD, E. SFWMD. system. .A. NWFWMD, B SRWMD, C. SJRWMD, D. SWFWMD, E.
SFWMD.
28. Distribution of bicarbonate (HC03; mg/L) and total alkalinity in the .......197
surficial aquifer system. A. NWFWMD, B. SRWMD, C. SJRWMD, 41. Distribution of fluoride (F-; mg/L) in the surficial aquifer system. ............. 258
D. SWFWMD, E. SFWMD. NWFWMD, B. SRWMD, C. SJRWMD, 0. SWFWMD, E. SFWMD.

29. Distribution of bicarbonate (HCO;; mg/L) and total alkalinity in the........202 42. Distribution of fluoride (F-; mg/L) in the intermediate aquifer system......... 263
intermediate aquifer system. A. NWFWMD, B. SRWMD, C. SJRWMD, A. NWFWMD, B. SRWMD, C. SJRWMD, D. SWFWMD, E. SFWMD.
D.SWWDE.SWM.43. Distribution of fluoride (F-; mg/L) in the Floridan aquifer system. A.... .. 2681

30. Distribution of bicarbonate (H-CC;; mg/L) and total alkalinity in the........207 NWFWMD, B. SRWMD, C. SJRWMD, D. SWFWMD, E. SFWMD.
Floridan aquifer system. A. NWFWMD, B. SPWMD, C.SJRWMD, D.
SWFWMD, E. SFWMD. 44. Distribution of nitrate (NO,; mg/L) in the surficial aquifer system. A.......... 273U
NWFWMD, B. SRWMD, C. SJRWMD, D. SWFWMD, E. SFWMD
31. Eh-pH diagram showing sulfur stability fields and water samples............ 212
from the surficial and Floridan aquifer systems of central Florida at 45. Distribution of nitrate (NO;, mg/L) in the intermediate aquifer system.......278
250G. Modified from Upchurch et al. (1991) A. NWFWMD, B. SRWMD, C. SJPWMD, D. SWFWMD, E. SFWMD.

32. Distribution of sulfate (SOt-; mg/L) in the surficial aquifer system............ 213 46. Distribution of nitrate (NO,; mg!L) in theFloridan aquifer system.............. 283U
A. NWFWMD, B. SRWMD, C. SJRWMD, D. SWFWMD, E. SFWMD. A. NWFWMD, B. SRWMD, C. SJRWMD, 0. SWFWMD, E. SFWMD.

33. Distribution of sulfate (SOP-; mg/L) in the intermediate aquifer.... .......218 47. Distribution of total dissolved solids (TDS; mg/L) in the surficial .............. 288I
system. A. NWFWMD, B. SRWMD, C. SJRWMD, 0. SWFWMD, E. aquifer system. A. NWFWMD, B. SRWMD, C. SJRWMD, D.
SFWMD. SWFWMD, E. SFWMD.3

34. Distribution of sulfate (SOP-; mg/L) in the Floridan aquifer system ....... 223 48. Distribution of total dissolved solids (TDS; mg/L) in the intermediate........ 293
A. NWFWMD, B. SRWMD, C. SJRWMD, D. SWFWMD, E. SFWMD aquifer system. A. NWFWMD, B. SRWMD, C. SJRWMD, D.
SWFWMD, E. SFWMD.
35 Distribution of chloride (C1-; mg/L) in the surficial aquifer system. A......... 228
NWFWMD, B. SRWMD, C. SJRWMD, D. SWFWMD, E. SFWMD. 49. Distribution of total dissolved solids (TDS; mg/L) in the Floridan...........2983
aquifer system. A. NWVFWMD, B. SRWMD, C. SJRWMD, D.
36. Distribution of chloride (Cl-; mg/L) in the intermediate aquifer system........ 233 SWFWMD, E. SFWMD.
A. NWFWMD, B. SRWMD, C. SJRWMD, D. SWFWMD, E. SFWMD.I
50. Distribution of specific conductance (j mhos/cm) in the surficial............. 303
37. Distribution of chloride (Cl-; mg/L) in the Floridan aquifer system. A. ......... 238 aquifer system. A. NWFWMD, B. SRWMD, C. SJRWMD, D.
NWFWMD, B. SRWMD, C. SJRWMD, D. SWFWMD, E. SFWMD. SWFWMD, E. SFWMD.
38. Distribution of phosphate (POP-; mg/L) in the surficial aquifer ............243 51. Distribution of specific conductance (pmhos/cm) in the........,. ......308
system.A. NWFWMD, B. SRWMD, C. SJRWMD, D. SWFWMD, F. intermediate aquifer system. A NWFWMD, B SRWMD, CI
SFWMD. x SJRWMD, D. SWFWMD, E. SFWMD.






U FLORIDA GEOLOGICAL SURVEY



PAGE PAGE

U52. Distribution of specific conductance (pmhos/cm) in the Floridan.. ........ 313 8. Concentrations of selected constituents in average sea water,.......... 69
aquifer system. A. NWFWMD, B. SPWMD, C. SJRWMD, D. ranked by abundance.
3 SWFWMD, E. SFWMD. 6
9. Classification of water hardness....................................... 6
S53. Distribution of total organic carbon (TOC, mg/L) in the surficial ............. 318
aquifer system. A. NWFWMD, B. SRWMD, C. SJRWMD, D. 10. Summary of total calcium distribution (Ca2 mg/L), by region and ...... 70
SWFWMD, E. SFWMD. aquifer system

54. Distribution of total organic carbon (TOG, mg/L) in the intermediate ......... 323 11. Summary of total magnesium distribution (Mg2m mg/L), by region .. .... 70
aquifer system. A. NWFWMD, B. SRWMD, C. SJRWMD, D. and aquifer system.
SWFWMD, E. SFWMD.
12. Summary of total sodium distribution (Na;, mg/L), by region and ......... 71 55. Distribution of total organic carbon (TOG, mg/L) in the Floridan............. 328 aquifer system.
aquifer system. A. NWFWMD, B. SRWMD, C. SJRWMD, D.
3SWFWMD, E. SFWMD. 13. Summary of total potassium distribution (K', mg/L), by region and.......... 71
aquifer system.
56. Predominant water types in the surficial aquifer system. A.............. 333
INWFWMD, B. SRWMD, C. SJRWMD, D. SWFWMD, E. SFWMD 14. Summary of total iron distribution (Fet, Fe3*, mg!L), by region............ 72
and aquifer system.
S57. Predominant water types in the intermediate aquifer system. A........... 338
NWFWMD, B. SRWMD, C. SJRWMD, 0. SWFWMD, E. SFWMD. 15. Summary of total mercury distribution (Hg", mg/L), by region ...... ... 72
and aquifer system.
S58. Predominant water types in the Floridan aquifer system. A............. 343
INWFWMD, B. SRWMD, C. SJRWMD, 0. SWFWMD, E. SFWMD. 16. Summary of total lead distribution (Pb2, mg/L), by region and........... 73
aquifer system.
LIST OF TABLES
17. Summary of total bicarbonate distribution (HC0;, mg/L), by ............. 73
1. Ground Water Quality Network Monitoring Parameters................... 64 region and aquifer system.

I2. Florida Primary and Secondary Drinking Water Standards for................. 65 18. Summary of total carbonate distribution (COn-, mg/L), by region.......... 74
Selected Parameters and aquifer system.

U3. Summary of the composition of precipitation from selected sites............. 66 19. Summary of total bicarbonate alkalinity distribution (mg/L), by region..... 74
in Florida. and aquifer system.

U4. Common minerals in Florida aquifer systems and confining beds ............ 67 20. Summary of total sulfate distribution (304-, mg/L), by region and............. 75
and their dissolved weathering products. aquifer system

35. Common minerals in Florida aquifer systems ............... . ... 67 21. Summary of total chloride distribution (Cl-, mg/L), by region and.......... 75
aquifer system.
36. Summary of temperature distribution (*C), by region and aquifer...... .. 68
system. 22. Summary of total ortho-phosphate distribution (POt-, mg/L), by region .. 76

7. Summary of water pH distribution, by region and aquifer system............. 68an uirsytm

IX





SPECIAL PUBLICATION NO 34U



PAGE PAGE

23. Summary of total fluoride distribution (F-, mg/L), by region and ............... 76 APPENDICESI
aquifer system.

24. Summary of total nitrate distribution (NO;, mg/L), by region and............. 77 APPENDIX 1 Additional Sources of Information.................................... 348I
aquifer system.
APPENDIX 2 Ground Water Quality Monitoring Program references:..........349
25. Summary of total dissolved solids distribution (TDS, mg/L), by ......... 77 List of related reports and publications
region and aquifer system.
APPENDIX 3 Geomorphic features maps and maps showing major .............. 352
26. Summary of specific conductance distribution (gmhos/cm), by.............. 78 rivers.
region and aquifer system.

27. Summary of total organic carbon distribution (TOG, mg/L), by ................ 78
region and aquifer system.

28. List of synthetic organics analyzed in the Background Network, ............ 79
with guidance concentrations or standards.5 29. Summary of total synthetic organic compound concentrations ( tg/L), by.... 81
region and aquifer system.3 30. Classification of anthropogenic organics according to volatility.............. 81
in water.U 31. Classification of synthetic organic mobility in water............................ 81

32. List of pesticides analyzed in the Background Network, with................. 82I
'guidance concentrations or standards.

33. Summary of total pesticide concentrations (pg/L), by region and ....... 83I
aquifer system.

34. Some arsenic-based pesticides and their uses................................ 84I

35. Proportions of major ions within the trilinear-diagram fields on............... 84
the Predominant Water Type Maps.
36. Some possible criteria for identification of aquifer system.................... 853
flow system components.

37. Percent of samples that exceeded water quality standards in................. 85I
Florida aquifer systems.


xii








FLORIDA GEOLOGICAL SURVEY


Chapter I from leaking fuel storage tanks Past waste Fhorida's water management districts require potential sources of contamination;
disposal practices, coupled with the increasingly permits for the installation of certain types of wells INTRODUCTION high volumes of waste generated, have resulted in In many areas! increased demand for potable 3) To disseminate water quality data
movement of significant quantities of pollutants ground water has resulted in water shortages and generated by the network to local
Gary L. Maddox into portions of the state's aquifer systems In subsequent restrictions on water use. gvrmnsadt h ulc
many areas, Florida's ground-water resources are gvrmnsadt h ulc
Flornda Department of Environmental Regulation not well protected from surface infiltration of
TalhaseFonapotential contaminants. Most of the state's In some areas of Florida, the amount of
ground-water supplies are derived from shallow meteoric water entering the aquifer systems greatly aquifers, which begin at the top of the water table exceeds the amount locally discharged, these The purpose of this report is to present the Over the past several decades, Florida has and extend downward, Often there is no protective areas are referred to as recharge zones. These results of the initial quantification of background experienced phenomenal population growth, with overlying aquitard or aquiclude to attenuate the areas are particularly sensitive to land uses which water quality in each of the state's major potable approximately 300,000 new residents annually downward migration of potential contaminants contribute contaminants to soil or surface waters, aquifer systems. Results are presented and
Joining the 13 million who, in 1992, already call the Where present, these protective low permeability or restrict downward percolation of meteoric interpreted in light of the influencing factors which
"Sunshine State" their home. This trend will likely formations are often locally breached by karstwaesPteinthearsfrmag-saelalyndrgnlyafctmbntrud-ar
continue into the foreseeable future. The rapid features, such as sinkholes and solution pipes, human development preserves the quality and locally. Tan s reintaly daftabien groundwatbern
Influx of people, in addition to exerting acute which allow surficial waters to rapidly infiltrate amount of water entering the aquifer, and thus theqult.TiiniadtaiJsevasabeie
I ~ pressures on existing social services and the downward, carrying with them any pollutants ground-water supply. Currently, Florida counties from which future sampling results can be
infrastructural framework of many communities, picked up along the way. This provides little time and municipalities are required to address the compared. Future sampling of the Network will has stressed the water resources of the state in for natural chemical and biological processes to issue of protecting areas of high recharge through indicate the extent to which Florida's regional
Stwo ways a sharp increase n the demand for break down potential contaminants before they the state's Growth Management Act, particularly ground-water resources are improving or declining
potable water supplies, and a corresponding reach the water table and enter aquifer systems. within the Natural Ground Water Recharge element in quality
generated. dfcutdecisions regarding growth management
Unlike visible contamination in surface waters, and land use, everyone ultimately benefits from ORGANIZATION AND
the effects of contaminant transport in under- the continued availability of abundant, safe ESTABLISHMENT OF THE GROUND
Florida is blessed with the most abundant fresh ground aquifers are not easily observed drinking water. WATER QUALITY MONITORING
ground-water resources of any state {McGuinness, Delineation of subsurface contamination areas can NETWORK
S1963) Plentiful potable water is perhaps Florida's involve the use of expensive technology, such as
I most important and vulnerable natural resource geophysical detection methods and the installation HISTORY AND PURPOSE
As of 1980, approximately 87% of Florida's public of monitoring wells. Cleanup of a contaminated The Florida Department of Environmental
~~~~drinking water supply came from underground site can easily cost millions of dollars Even so,RelznthnedtthruhysdyteRgatn(E)isheedagnyn
sources (Fernald and Patton, 1984). The remaining once contaminated, it is virtually impossible to Rfealizimn'g thevneed ton toraughly suyte egltiohmn (DR)i the leaud Waenc uin
13% came from surface sources, such as rivers remove all pollutants from the subsurfaceantoptetndmrwilyaagouwtrMntrngNwrkdtriiggasad
and rakes. In order to achieve potability, these environment using current technology, making res orceste Floid Loegislyan urI93 pased Mstrgeting prworitie derdinaigas the
3 surface sources generally require more extensive restoration of an aquifer to completely natural thes WatesQuality Assuria re At i s legisto ovrallg se tThng p armnt wor c losnawi the
treatment than most ground-water sources This conditions unlikely. It is much easier (and cost- required the Department of Environmental th veaer maneDprment disrics (WDs)l wt
is due in large part to pollutants introduced into effective) to prevent, rather than clean up, ground- Regulation to "establish a ground water qualitythfvewermngm tdircs(W 's

Surface waters by human activities Without water contamination monitorng network designed to detect or predict (WMD boundary lines are shown in Appendix 3,
abungdantegrounds water, ther u ld not bure contamination of the state's ground water figure 1), and several counties, which carry out
population, especially in the high growth areas of Floridians use more water per capita than any resources" (Florida Statutes, Section 403.063) To most of the necessary field work and provide local southern and central FLorida other state As a result of this use, coupled with facilitate this effort, the Act required the technical expertise. The Florida Geological Survey
increasing population growth and development, Department to work cooperatively with other (FGS) and the Water Resources Division of the
~the state's ground-water supplies are threatened federal and state agencies, including Florida's five U.S. Geological Survey (USGS) provide additional
Since all fresh ground water ultimately has a by excessive overdraft and contamination water management districts, in the establishment technical support, as have several studies funded
surface source, any pollution contained in rainfall, Increased demand means Increased drawdown in of the network. through the State University System. The Ground
I ri~~ver or lake water can eventually turn up in our the aquifer systems, and this can also cause waterWaeQultMoirngNwrksacalymd
underground drinking water supplies. In Florida quality degradation. When withdrawal exceeds ThWheaai ol fth ttwd rudu ftee praityMnipaln eetrs: tu madb
these two sources, ground and surface water, are recharge, the aquifer systems are essentially being Wte re ali Moiog Pogrtam satre netwdupotrs ana elreymeas: wofmhichrsb
I ~ ~~~intimately connected- most lakes and rvers in the mined for water Excessive withdrawal of freshWteQulyMntngPrrmar.ewrkadonsrvechfwhhha
state are fed at least partially from ground-water water within some areas causes the upwelling of unique monitoring priorities and goals. These aredischarge through springs and seeps, and surface underlying denser connate water, or lateral 1) To establish the background and
water bodies recharge aquifers. Changes in land intrusion of seawater. This is particularly baseline ground-water quality of major -Bogon ewrdsge ohl
I use activity can supply potential contaminants- problematic in high volume withdrawal areas along aquifer systems in the state;-BkgudNewrdsndtohp
rainfall percolating into the subsurface can carry the coast, such as in the vicinity of urban wellfields. define background water quality
with pesticides and herbicides from agricultural In these and other susceptible areas, ground-water 2) To detect and predict changes in through a network of over 1600 wells
areas, metals and synthetic organic compounds withdrawals must be carefully managed in order to ground-water quality resulting from the that tap all major potable aquifers within
from urban stormwater runoff, and hydrocarbons preserve water quality, this is one reason why effects of various land uses and the state,
1







SPECIAL PUBLICATION NO. 34


VISA (Very Intense Study Area) sources) may be present. being able to identify appropriate water supply REFERENCES CITED
Network, designed to monitor the sources based on water quality.
effects of various land uses on ground- USEFULNESS OF BACKGROUND Femald, E A. and Patton, D. J ,1984, W a t e r
wtrqatywtn pcfcqufr nNETWORK DATA The well and water quality data is available to resources atlas of Florida: Florida State
selected areas. The VISA Network the public via access to a computer bulletin board, University Institute of Science and Public
became operational In 1990, and o ycnatn:Afis alhseFoia 9
results will be published in a Data generated by the Ground Water Quality o ycnatn:Afis alhseFoia 9
subsequent volume, Monitoring Program can be used to evaluate
regional ground-water quality This has numerous Florida, State of, 1983, Florida Statutes, S e ct ion
Private Well Survey, designed to practical applications in both the public and private 403.063 Water Quality Assurance Act,
analyze, on a one-time basis, ground- sectors. Florida Department Of Environmental Chapter 174 2455 Ground water qualityI
water quality from 50 private drinking Reuainmonitoring: 1983 Florida Legislature,
water wells in each of Florida's RegulationFlnda
counties This data will supplement the Local water quality can be compared to regional Bureau Of Drinking Water & Ground WaterTalaseFoi.
Background Network by providing over background water quality, where changes in Resources
indicating the general quality of water upgradient information, against which the effects 2600 Blair Stone Road in the nationaL water situation: U.S. Geological
consumed by private well owners This of a potential contamination source can be Survey Water-Supply Paper 1800,I
survey is a joint effort between the compared. It can also aid in quantifying temporal Tallahassee, Florida 32399-2400 Washington, D C., p 244-255.
Florida Department of Health and changes in ground-water quality brought on by
Rehabilitative Services (HRS) and sweeping land use changes, such as urbanization Staff-(904) 488-3601 or Scott, Thomas M., Lloyd, Jacqueline M. and
the DER This long-term project Until background is defined, it'is difficult to SUNCOM 278-3601 Madx ayL(d.,19,Florida's Ground
began in 1986 and is ongoing. determine whether an unusual parameter FAX (904) 487-3618 or Maddor Quariy L.n(eds.)g 1 rogr, -Iydo
concentration measured at a welt is the result ofSUCM2-31gelga FmwrkFlnaG lgca
natural or anthropogenic influences SNO 7-68gooia rmwr:FoiaGooia
This publication is a compilation of water quality GWIS BBS (Computer Bulletin Board) Survey Special Publication No. 32,U
data generated by the Background Network of (904) 487-3592 or Tallahassee, Florida, 97 p
Flornda's Ground Water Quality Monitoring Background data will be useful for determining SUNCOM 277-3592
Program. The data used in this report were potential health risks to the public resulting from
generated between 1984 and 1988 Future data ground-water consumption. State and local generated by both the Background and VISA agencies wilt find the data useful in land use
Networks will be compared to information planning and zoning decisions, the protection of
contained ini this report in an effort to quantify public drinking water supplies, and in theU changes in ground-water quality over time. development of state-mandated comprehensive
growth planning. Water management districts can
use the data to evaluate permit applications
BACKGROUND NETWORK regarding water withdrawal and use. RegulatoryU
agencies will find the data invaluable in

deteced a bangeinfromon wc tocompare fuur strategies, such as weihead protection, delineation changes must be determined. Baseline refers to o ehreaddshreaes n ufc
current regional ground-water quality, determined water/ground water co-management Mapping of from statewide sampling from 1984-1988 This may physical aquifer extents and distribution (Scott et or may not be synonymous with the pristine ground- al, 1991), coupLed with knowledge of chemicalI water quality that existed before measurable human aquifer characteristics (this volume) helps to better imatto the aquifer. A well in the Background define available resources Future efforts involving Network is designed to monitor an area of the aquifer treinmeppn of hydotrtiaphqice unsabdthe which is representative of the general ground-water development of ydaotarvationi unetosw all Ih quality of the region (for the purposes of thisdvepmnofdteautinmtdswlal program, a region generally incorporates an area contribute to the body of information which will aid greater than or equal to the size of a county, and is in the wise use of the state's ground-water defined by aquifer extent and, if possible, ground- resources. water basin boundaries) It is not intended to indicate
changes in aquifer chemistry associated with specific The private sector will find the data particularly contamination sources; however, widespread useful when preparing reports on such issues asI
changes in water quality associated with regional contamination assessments, risk evaluations, land use patterns (the accumulated effects of many water supply studies and waste disposal designs.
Industry and agricultural interests will benefit by


2








FLORIDA GEOLOGICAL SURVEY


Chapter II c) Well diameter known, are resampled approximately every three to five many difficulties encountered in collecting and
d) Lithologic and geophysical logs years for all network parameters A subset of analyzing a representative ground-water sample.
available; Background Network webls, the Temporal Potential variability introduced by the use of
I ~DATA COLLECTION AND e) Hydrogeologic information available Varnability Subnetwork ("TV Net"), is sampled more different sampling personnel, techniques arnd
MANAGEMENT METHODS frequently (monthly or quarterly), in order to detect equipment, sample transport from the field to the
variations in ground-water quality over time. laboratory, environmental and laboratory
Over 1200 existing wells were initially selected Samples collected on a quarterly basis are contamination, concurrent use of several analytical Gary L Maddox through this process Although optimal quality analyzed for major ions and field parameters, while laboratories, and varying methods of reporting
assurance and quality control could be more fully monthly data collection consists of the results have all had an effect on the analyses
Florida Department of realized by drilling all monitoring wells expressly for measurement of field parameters only (see Table discussed here By working closely with personnel
Environmental Regulation use in the network, the associated costs prohibited 1) Wells sampled monthly are a subset of the in the field and in the laboratory, and by developing
Tallahassee, Florida such an approach It was determined that useful wells which are sampled quarterly. In addition, a standardized CA/CC procedures, sampling and
data could be obtained using wells already in pilot project is currently underway to define analytical methods have steadily improved over

WELL SELECTION AND SAMPLING existence, if the selection criteria were strictly temporal variability on an even finer scale. Using the history of the program, with the goal of
adhered to, dedicated probes and automatic sampling devices minimizing the potential variability introduced
installed in a few wells, the goal of this "optima throughout the entire process.
Prior to selecting monitoring sites for inclusion Subsequent to locating existing wells, frequency study" s to observe variations in
I in the Background Network, hydrogeologic data correlating well depth with site hydrogeology and ground-water quality on a weekly, daily, or hourly
were evaluated in conjunction with land use in- considering land use patterns, locations for basis Results from the Temporal Variability Sampling of the Background Network began in
formation Most of this information was of a additional monitoring wells were determined Over Subnetwork will be published in afuture volume mid-1985. A portion of the existing wells were
general nature and was compiled by the state's 600 new wells were drilled in areas where no sampled using permanently installed pumps The
U ~five water management districts (Appendix 3, suitable existing wells could be found, Depending DvlpetothBakrudNwrkremaining existing wells and all new wells were
figure 1). The first volume of this series (Scott et al. on the hydrostratigraphy at each new site, a single occurre pmin f the phakrendNswksampled using teflon bailers, dedicated bladder
1991) contains a wealth of hydrogeological data well or cluster of wells was installed, allowing each rrdnthfolwgpasspumps or submersible pumps. Some monitoring
collected during the initial phase of the program major water-bearing zone to be separately wells have been fitted with semi-permanent
I This information was used to develop regional monitored Geological information was obtained at Phase I: Data collection, compilation, internal standpipes, to facilitate purging and water
monitoring strategies, and aided in the selection of each site during drilling At many sites, a core from and location of existing wells which could sample collection. Sample collection protocol potential well sites These wells were selected or the uppermost significant confining bed was be incorporated into the Background currently follows that established by the U.S.
drilled in order to achieve optimum areal and obandfrlbrtr eemnto fNetwork, Environmental Protection Agency (EPA) (EPA,
aquifer distribution, permeability. Initial well placement was biased 1982, 1991) The initial sampling episode included
toward preferential monitoring of the most Phase II: Selection and during of initia the collection of a comprehensive set of physical,
The second phase of the program entailed important potable aquifer within a region: current monitoring wells; chemical, biological and radiometric parameters
locating existing wells suitable for inclusion in the strategy emphasizes the uppermost aquifer system (Table 1)
monitoring network An initial inventory of existing in an area This latter philosophy is based on the Phase III: Initial sampling of the Backwells meeting these criteria was conducted by the notion that surface-introduced chemical changes ground Network to determine ground- Initial sampling of the Background Network
U U.S. Geological Survey and the water management (due to land use or meteorological considerations) water quality spatial trends and define was overseen or performed by each water
districts, The following criteria were used to would first be detected in the uppermost water- baseline, mngmn itc l apigi urnl
determine eligibility: bearing unit Figure 1 shows the general location conducted or supervised by a trained professional.
of currently sampled wells by aquifer system in the Phase IV: Hesamping of wells found to Annual training of sampling personnel is funded by Background Network contain abnormal concentrations of one or DER and provided by the staff of the USGS Ocala
a) Depth of well and cased interval more parameters, Quality of Water (OW) Service Unit A rigorous

I )Opnhoeitevl as nyon qufrThe first sampling of each weI in the network _-Phase V: Refinement of the network quality control program has been established (see
bOpe hle-bea taonlyoeqie involved the measurement of a comprehensive set through removal of redundant wells and trpadlbrtr lnsaesbitdoo ae-ern oeANALYTICAL METHODS section below). Field,
c) Precise site location known; of field, chemical, microbiological, and naturally- those found not to monitor representative rtin baIntialy alaln aenies were
d) Well owner cooperative; occurring radioactive parameters (Table 1) These background ground-water quality, as well requirthae n indivduallapprovaed aityer
e) Future accessibility for sampling analyses, combined with historical data, can be as drilling of additional wells where assurane/qlty c nto (ndAvCdulyanrone quaith
Granted; used to estimate baseline ground-water quality nee suac/ult oto Q/C lno iewt
)Hstr ftest(piranusOnce current baseline has been determined, data nedthe Department, and to submit periodic CA/C
preHioryoft smpite (ires l ndn e from future monitoring of the network will be _-Phase VI: Ongoing periodic resampling saplingts. nowerormnded urndersngl
U continually evaluated to determine changes in to define variations in ground-water quality "umbrlla' Cs nCw plarftored bder a nd
water quality over time This information is overtime "mrla AQ ln uhrdb E n
Other non-mandatory, but desirable criteria particularly useful for implementation of wellfield signed by each sampling agency (DER, 1991)
included: prtcinmauewtrqaiymntngadAgreement by each agency to use standardized
land use planning SAMPLING PROTOCOL sample collection methodology further minimizes
a) Site ownership by local, state or federal sampling variability
Agency; After the initial samples are collected and The history of sampling of the Background

b) Prior water quality data available, analyzed, Background Network monitoring wells Network reflects an increasing awareness of the The determination of sampling frequency and

3







SPECIAL PUBLICATION NO. 34

the parameters to be monitored at each site were methods described by EPA, USGS or DER DATA BASE SYSTEMS popular off-the-shelf computer-aided drafting
based on several factors, such as network (American Public Health Association, 1980; (CAD) package allows the user to plot well
designation, land use activity and the Fishman et al., 1989; DER, 1981). Avreyodaabsansftreytmslocations and data on a map, or define a region of
hydrogeologic sensitivity of the site. After initial Avrtyodaabsansfwreysmsinterest graphically, for subsequent data retrievalI
sampling, several wells were dropped from the have been developed to store, manipulate and
Background Network, based on analytical sample To assess laboratory accuracy and precision, display information related to the Ground Water
results which indicated that data from the wells duplicate samples and reference samples are Quality Monitoring Program. All water quality AVAILABILITY OF DATA
were not representative of regional background anonymously submitted, along with trip, ifraincletdb h rga sulae
water quality. In some instances, existing equipment and field blanks. These GA/GO to DER's mainframe "Central Repository', anThGWSrrmandtaflscnb
monitoring wel~~~~~~~~~~ls did nthav god hydraulic samples currently constitute over 20% of the total archive of statewide environmental data available TeSI rga n aaflscnb
connectiong wihe aqienot e oiored In number of samples analyzed. As a QA/QC check to DER and other state agencies. In the near obtained from DER by contacting our Tallahassee
conetin it te qufr o e ontoed I n roedre ad ffcinyth lboatne aefuture, Background Network data will also be office at the address or telephone numbersI
other instances, the quality of water from the well onproedure adficincythie abortoies aren written into an ORACLE database, for use with previously listed. The programs and data are also Adioal wmael may beo adefll iontrustin. meetings are held among the Ground Water DERs ARC/Info geographic information system available via a computer bulletin board (BBS)
Adiinlwlsmyb de ofl ngp nQuality Monitoring Program staff and laboratory (GIS). Contact DER's Bureau of Information running 24 hours a day, seven days a week, forI
aenmt or aquirspecgiic coverages. This pesonnel to discuss procedural problems as they Systems for details on availability of these data anyoer with anm IBM-compatible personal
Network database and GWIS programs are
Residual well construction materials and available for remote use or for down-loading. TheI
casing corrosion can significantly increase the Table 1 references the standard EPA Currently the most widespread system in use bulletin board system can handle 300, 1200 and
volume of suspended solid material present within laboratory methods initially used to analyze is the Generalized Well Information System (GWIS), 2400 baud calls using industry standard a well. Turbidity analysis can be used to evaluate samples from the Background Network. These a micro-computer database and retrieval system communications parameters of no parity, 8 data webl construction integrty for many wells methods have and will change as heifer equipment which houses all well and analytical water quality bits, and 1 stop bit (n-8-1). These are the default
Redevelopment is often required in problem wells and procedures become available. Major ions, information generated by the program. It was settings for most major communications software
whih wre mimprope nsrlye, r instamlledgancsmetalsn organicsolg radiomeptrincnsBMPC omptibeandtormicropbkios.Tlognicalus ydevemplortpedl
tendency to accumulate residual solids, due to parameters were all included in the analyses. Field consists of two separate data bases, one (904)487-3592 or SUNCOM 277-3592.I local hydrogeologic conditions (Aller et a 1989). parameters were measured in the field at the time containing physical well information and one Prior to 1989, almost all samples were unfiltered in of sample collection. Table 2 lists the Primary and containing analytical results The two are linked by DT AIAINPOEUE the field prior to laboratory analysis. Thus, the Secondary Drinking Water Standards for a USGS-format (latitude/longitude/sequenceDAA LDAINPOEU S
combined contribution of particulate matter, parameters sampled in the Background Network number) common well identifier The data fileI suspended (colloidal) solids, and the soluble' format is currently fixed-field length ASCII, but will Before network data is released to the public,
fraction in each sample were measured with each To assess methodology protocol and the be changed to dBase format in the near future, raw laboratory and field data is converted into
anaysi Tis s rprsenatie f wll atr prfomace f smpingperonelpendi fildThe system was written in-house, to quickly and dBase format and then run through an extensive analyis bThi n is eresativeqf well wuater performane ofrnsampuing pesnelberodicthed efficiently handle the large volume of data series of automated and manual screening proce-U quity, t wnot ntelfcsarly aqusife wte squlityasaf.Ths audits are are uymmsppfmted DEy generated b the network, and is available to the dures (Figure 2). Error checking programs detect for many of the particulates present in the samples program staf. Theseutsa supledmeuted by public.,~l water quality data retrievals run in parameter values outside allowable ranges. Data (Nielsen, 1991). Since data on both aquifer and require sapCn rgeport, suitalreald uateyby three main steps: entry mistakes are often the cause for these errors.
well water quality was desired, filtered and problems encountered during sample collection.Chreblnehckarrusalyn unfiltered samples are now coLlected for affected All agencies performing sampling or analytical ser- 1) Select wells of interest (from physical indication of the integrity of laboratory analyses. parameters at each site and separately analyzed vices for the program are required to have an well information database, using almost Outlier programs use non-parametric estimation to
approved OA/QC plan on file with the Department, any combination of constraints); flag values which, while within allowable ranges,
ANALYTICAL METHODS or to comply with the 'umbrella' plan written by seem not to fit regional trends. When outliers are
DER. 2) Select parameters of interest (from found, sampling procedures are first checked. In
sampe daabae, idivdualy o by re-addition to these automated checks, the data are
The initial chemical analyses of Background defined group); isetdmnal ysaft suecm
Network samples were performed by private All water quality results are submitted to DER pleteness of each data set and to remove GA data
laboratories, with some parameters analyzed by in both paper and electronic formats, In addition 3) Retrieve data. to another database. GA data includes field, trip
the water management district laboratories, Due to the actual results, these data also include and laboratory blanks submitted at regularI
to the magnitude of the program and the large information on analytical method used, STORET intervals in the sampling process. After in-house
initial number of samples, several different code' (EPA, 1984), well, field and laboratory The program also allows the user to constrain editing and review, provisional data sets are
analytical laboratories were used. This caused identification numbers, units, parameter name, retrievals by sampling dates, or to only retrieve released to sampling agencies for their review. concern about consistency and relative project name, exceedances of existing standards, results above or below a given threshold value Outliers are flagged, and sarnplers are asked toI
comparability of data from one lab to another. As and data submitted by field personnel, such as (these can correlate with exceedances of assigned provide any data which may explain the a result, all inorganic analyses are currently sampling date and time, and remarks. This standards). Output formats allow for row-and- anomalous values. Results are compared to trip
performed by one lab, the USGS Ocala OW information is for the most part incorporated into column or tabular report generation and the and equipment blanks taken during sampling. In
SrceUtndrgmsrenaydbyhethe data bases discussed below. calculation of summary statistics on multiple some instances, the well may be re-sampled, or
DER Central Laboratory or its designated overflow samples. Various utility programs allow the laboratory procedures may be investigated. If
lab. Sample analysis protocol generally follows calculation of frequency distributions, water types, circumstances surrounding the collection or
and statistical outliers A direct interface with a analysis of the sample are suspect, the data may

4U







FLORIDA GEOLOGICAL SURVEY


be left in the database but flagged with conditional Florida Department of Environmental Regulation,
~provisions, or removed altogether Other para- 1991. Chapter 17-160, Quality Assurance:
meter analyses from the same sample may or may Tallahassee, Florida; 40 p.
I not be affected, If no disqualifying problems are

included in the release database
guidance concentrations: Florida Department I ~of Environmental Regulation, UIC, Criteria &
Ground-water quality data are constantly Standards Section, Tallahassee, Flornda, 14 p.
I being received as ongoing sampling projects
continue. The main GWIS distribution databases Nielsen, David M. (ed), 1991, practical handbook are updated three or more times a year of ground-water monitoring: Lewis Publishers,

Inc., 717 p.
ENDNOTES
Scott, Thomas M., Lloyd, Jacqueline M. and STORET is a water quaLity database Maddox, Gary L (eds.), 1991, Flornda's Ground
management system established by the U.S. Water Quality Monitoring Program HydrogeoEnvironmental Protection Agency. Five-digit logical Framework. Florida Geological Survey
STORET codes are assigned for each parameter Special Publication No. 32, Tallahassee,
based on methods used during sample collection Flornda, 97 p
United States Environrmental Protection Agency, REFERENCES CITED 1982, Handbook for sampling and sample
I preservation of water and wastewater. United
Alle, LndaBenettTruan W, Hcket, GenStates Environmental Protection Agency EPAPetty, Rebecca J., Lehr, Jay H Sedoris,60/-22,CicnaOho42p I Helen, Nielsen, David M., and Denne, Jane E.,
1989, Handbook of suggested practices for United States Environmental Protection Agency, the design and installation of ground-water 1984, Overview of STORET. United States
I monitong wells: EPA 600/4-89/034, National Environmental Protection Agency, Water Well Association, Dublin, Ohio, 398 p Washington, D.C 26 p.
American public Health Association, 1980, United States Environmental Protection Agency,
I Standard methods for the examination of 1991, Standard operating procedures and
water and wastewater, 15th edition American quality assurance manual. United States Public Health Association, Washington, D.C Environmental Protection Agency, Region IV,
1134 p Athens, Georgia, 203 p.

~Fishman, Marvin J and Linda C. Friedman (eds),
1989, Technkques of water-resources I investigations of the U S. Geological Survey,
Rook 5, Chapter Al Methods for
~determination of inorganic substances in water
and fluvial sediments, third edition: U S.
Geological Survey; 545 p

i Flonda Department of Environmental Regulation, U 1981, Supplement "A" to standard operating
procedures and quality assurance manual.
I Florida Department of Environmental I Regulation, Solid Waste Section, Tallahassee,
Florida, 110 p.



5






SPECIAL PUBLICATION NO 34I

Chapter III Geologic Structures in Relation AOUIFER SYSTEMS AND In many areas of the state, the surficial aquifer
to Hydrostratigraphy CONFINING UNITS system lies on a karstified erosional surface
HYDRSTRTIGRPHYdeveloped on Eocene to Miocene carbonates ThHYDuROSTRATknssadtoIGRAPHYia aufe sstmKarst processes have also affected the surficial xTnhe occurece hircknests adet soelyca aufe yse aquifer system by forming collapse features which
Thomas M. Scoff rextedt the aqifrucara tes risnti ar dietl filled with surficial aquifer system sediments and
relate tohe stjrupctural feature resafent inagitven The SEGS (1986) defines the surficial aquifer may be in direct hydrologic contact with the
Florida Geological Survey various aquifer systems include the Ocala system as the pefordatetesunca aquifer system evuelopisg
Florida Department of Natural Resources Platform, Chattahoochee AnticlineSanford High open sinkholes onth presentrln suys e. eelpn
Tallahassee, Florida and the St. Johns and Brevard Platforms (Figure "permeable hydrologic unit contiguous
4a) The major negative features include the Gulf with the land surface that is comprisedI INRDCINBasin, Apalachicola Embayment, Gulf Trough, pnincipaliy of unconsolidated to poorly NORTHWEST FLORIDA WATER
INTRODCTIONJacksonville Basin, Osceola Low and the indurated, (silici)clastic deposits It also MANAGEMENT DISTRICT
Okeechobee Basin (Figure 4a). These structures includes well-indurated carbonate rocks,
Florida's ground-water resources occur in a affected the deposition and erosion of the later other than those of the Fioridan aquifer The surficial aquifer system in the Northwest
complex Fateral and vertical sequence of Cenozoic Cenozoic sediments. Older structures, including system where the Floridan is at or near Florida Water Management District (NWFWMD)
sediments comprised of both siliciclastics and the Peninsular Arch and the South Florida Basin land surface. Rocks making up the occurs over most of the district, It is absent only in
carbonates which underlie the entire state. (Figure 4b), affected the lower portions of the surficial aquifer system belong to all or a limited portion of Wakulla, Leon and Jefferson
Hydrostratigraphically, the section consists of Cenozoic section (see Scott (1991) for a discussion part of the Upper Miocene to Holocene Counties at the eastern edge of the district along
several major aquifer systems defined on lateral of the structural features in Florida) Series It contains the water table, and the the western flank of the Ocala Platform. It is thin to
extent, degree of confinement, and hydrologic water within it is under mainly unconfined absent on part of the Chattahoochee Anticline in
parameters of the sediments. The Southeastern conditions, but beds of low permeability Jackson and Holmes Counties Where the surficialI
Geological Society's ad hoc Committee on Florida The surficial aquifer system is thin to absent on may cause semi-confined or locally is present it ranges in thickness from less than 10
Hydrostratigraphic Unit Definition (Southeastern the positive features, Its thickness increases off confined conditions to prevail in its deeper feet in the east to more than 500 feet in the northGeological Society (SEGS), 1986), in an attempt to the positive structures reaching maximum thick- parts. The lower limit of the surf cial western corner of the area (Scoff et al., 1991)
alleviate many of the nomenclatural problems nesses in the Okeechobee, Jacksonville and Gulf aquifer system coincides with the top ofU
surrounding Florida's hydrostratigraphic units, Basins and the Apalachicola Embayment the laterally extensive and vertically
defined the framework of the various aquifer persistent beds of much lower The siliciclastic sediments comprising the
systems occurring in the state. Most of the The intermediate aquifer system and/or permeability." thea C itrer sysnd MicnoskNW Fo rm atos
geologic community have accepted these intermediate confining unit also thins onto the "Cae C lasnics and th sunderentatedns
dfnto n ndaare A ufrsing hes sugestanedv positive features Sediments forming these units The surficial aquifer system occurs throughout sediments of Pleistocene-Holocene age (Marsh, nomenclre.ne Anquieres of imotace have are erosionally absent from much of the most of the state In many areas, it is used for 1966; Scott, 1991). These sediments are primaily
berecgizcsed in sme eaurea of theci sae and Chattahoochee Anticline, Ocala Platform and the small yield domestic and agricultural water quartz sands with varying percentages of clayU arehiscsex d dfin te andteratre ony eii ars Sanford High. These units thicken off the highs, supplies. However, in the western panhandle the Where the clay content becomes great enough to Thi ytext msl deieussnd chrcerbny the m aj1or) reaching the maximum thicknesses in the basinal surficial aquifer system, referred to as the Sand inhibit the transmission of ground water, localized aquier systems icusd b the S qiES (1986). areas. As the sediments of the intermediate and Gravel Aquifer, supplies important amounts of impermeable beds may confine water creating the intermediate aquifer system or intermediate aquifer system and confining unit thicken, water for municipal and industrial supplies. In the artesian conditions within the surficial aquifer
confining unit, and the Florndan aquifer system permeable beds become more commonly southeastern pard of the state, the surficial aquifer system The surficral aquifer system yields greater
including the Claiborne aquifer and the sub- interbedded with the impermeable strata, resulting system is called the Biscayne Aquifer and provides quantities of water in the western panhandle where Flordan confining unit. Figure 3 indicates which in a more fully developed intermediate aquifer enormous quantities of water for the coastal the Citronelle contains less clay and is thicker than foratonsfom prtonsofthevaiou auifr ystm.communities in this area. The surficial aquifer in those areas where the clayey Miccosukee
systems throughout the state. Miller (1986) system is utilized for public water supply in occursI
provides an excellent, in-depth discussion of the EcnadOlgen rbntsdmnsofsouthern Brevard, Indian River and St. Johns
Floridan aquifer system and the associated EcnadOigeecrbatsdmnsofCounties. Elsewhere in the state, the surficial SWNE IE AE
shallower strata It is recommended that the the Floridan aquifer system are exposed to thinly aquifer system is of limited importance. MUANGEMEN ISRIAT
reader review Miller's volume for a more detailed covered on the Ocala Platform and the Throughout the extent of the surficial aquiferMA GE NTDTRC
description of the ground-water system in Florida. Chattahoochee Anticline. These sediments are system, the thickness varies significantly from a Appendix 3, figure 2 delineates the distribution of covered by a thin intermediate confining unit on feather edge to more than 350 feet in southeastern The surficial aquifer system in the Suwannee
aqie ysesi Fodthe flanks of the positive features. In these areas, Florida and 500 feet in the western-most River Water Management District (SRWMD) is
aquier sstes inFlorda.the carbonates have been exposed to aggressive panhandle (Scott et al., 1991) The top of the present in several areas of the district According
ground water, developing an extensive karstic surficial aquifer system is the natural land surface, to Ceryak (SRWMD, personal communication, References to Florida's geomorphic features terrain In the basinal areas, the carbonate sedi- The base occurs where impermeable beds of the 1991), the surficial aquifer system is present irn are made in this and succeeding chapters ments have not undergone such extensive intermediate confining unit and aquifer system adjoining portions of southern Madison, eastern
Appendix 3, figures 3 to 7 delineate these features dissolution due to the thick protective cover begin or, in those areas where the intermediate is Taylor and western Lafayette Counties, eastern inch di1)trict For further discussion refer to provided by the intermediate aquifer system and absent, at the top of the Flondan aquifer system Suwannee County, much of Columbia, Hamilton

ntredae ofiiguntcabnae.and Union Counties, along the eastern edge ofI 63








FLORIDA GEOLOGICAL SURVEY


Bradford County under Trail Ridge and under Formation consist of quartz sands with varying The base of the surficial aquifer system occurs limestones with varying admixtures of shell and
Waccasassa Flats in central Giichrist County percentages of clay The Nashua Formation and at the top of the impermeable sediments overlying clay As a result of the variability, the quality of the
SSediments equivalent to the surficial aquifer Caloosahatchee Formation-equivalent beds are the carbonates of the Florndan aquifer system in surficial aquifer system in SFWMD changes
system are present throughout much of the district composed of varying admixtures of quartz sand, the northern part of the district When dramatically from place to place Numerous
but are not utilized for water resources clay, shells and shell debris. The Anastasia impermeable sediments of the Hawthorn Group investigations of these sediments have discussed
Thicknesses of the surficial aquifer system range Formation is composed of sand and coqumna, are subjacent to the undifferentiated sediments the variable nature of the aquifer characteristics
I ~ from 10 to 30 feet but may reach 50 to 60 feet Quartz sands and varying amounts of clay make they form the base of the surficial. The Hawthorn (for example, Causaras, 1985; Weddemburn et al.,
under Trail Ridge (see Scoff (1991) for discussion up the Coosawhatchie Formation with limestone Group lies subjacent to the Cypresshead 1982, Shaw and Trost, 1984, Knapp et al., 1986,
of the geomorphology of Florida). becoming prominent in portions of Duval and Formation under the Lake Wales Ridge and forms Smith and Adams, 1988)
Nassau Counties Locally, the sediments contain the base of the system The Hawthorn Group
sufficient clay to form impermeable beds creating sediments also form the base of the surficial
Theurthea quifferenytimasedmns nartesian conditions in the surficial aquifer system aquifer system in southern SWFWMD where the nemdaeAufrysmad
SRWMD rep of th nifrnitdsdmnsHawthorn underlhes the Tamiami, Caloosahatchee Intermediate Confining Unit
and in some areas, the upper Hawthorn Group and Fort Thompson Formations,
sediments. These sediments are quartz sands The base of the surficial aquifer system in the TeSG 18)dfnsteitreit
with varying amounts of clay and carbonate In SJRWMD occurs at or near the top of the TeSG 18)dfnsteitreit
localized areas the clay content of the sediments Hawthorn Group or in the undifferentiated post- SOUTH FLORIDA WATER aquifer system or intermediate confining system as
Smay form confining beds within the surficial Hawthorn sediments when those sediments are MANAGEMENT DISTRICT including
system. relatively impermeable.
The surficial aquifer system is widespread in "all rocks that lie between and collectively
SThe base of the sur-ficial aquifer system In the SOUTHWEST FLORIDA WATER the South Florida Water Management District retard the exchange of water between the
U SRWMD occurs at the top of the impermeable MANAGEMENT DISTRICT (SFWMD) constituting an important water overlying surticial aquifer system and the
sediments of the Hawthorn Group throughout resource Although the surficial aquifer system is underlying Floridan aquifer system. These
much of the district. However, in the eastern present over much of the district, it is the most rocks in general consist of fine grained
Sportion of the district, the base may occur within The surficial aquifer system occurs over much important source of ground water in the (silici~clastic deposits interlayered with
the sediments of the upper Hawthorn Group. In of the Southwest Florida Water Management southeastern portion of SFWMD, in Dade, Broward carbonate strata belonging to all or parts
other areas, the intermediate confining unit may be Distrnct (SWFWMD). It is of generally limited value and Palm Beach Counties In Lee, Hendry and of the Miocene and younger Series In
Absent and the surficial aquifer system may lie in the northern portions of the district and Coller Counties, the surficial provides significant places poorly-yielding to non-waterdirectly on the carbonates of the Flonidan aquifer increases in importance to the south. SWFWMD quantities of potable water for domestic and yielding strata mainly occur and there the
syte o b aset at idiats ha te uricalaqifr ysem5 agricultural uses. Throughout the district, the term intermediate confining unit applies.
systm orbe asentthin over much of the district (Scott et al 1991) surficial aquifer system varies in thickness from a In other places, one or more low to
Thicknesses range from less than 25 feet in much few feet to more than 400 feet thick moderate-yielding aquifers may be
I ST JOHNS RIVER WATER of the northern part of the district on the Ocala interlayered with relatively impermeable
MANAGEMENT DISTRICT Platform to 25 to 50 feet in the southern area and confining beds, there the term intermore than 250 feet under the Lake Wales Ridge The sediments comprising the surficial aquifer mediate aquifer system applies The
The urfcia aqife sysem n te S. Jhnssystem are from several lithostratigraphic units In aquifers within this system contain water
Thesufiia auiersyte i te t.Jonsthe north-central SFWMD area, the surficial occurs under confined conditions."
River Water Management District (SJRWMD) is an Surficial aquifer system sediments in in the undifferentiated sediments, Cypresshead
important source of potable water in Duval, Clay, SWFWMD belong to the undifferentiated Formation and shell beds of the CaloosaI St. Johns, Putnam, Brevard and Indian River sediments in the northern half of the district In the hatachee/Fort Thompson Formations, In the "The top of the intermediate aquifer I Counties, The coastal counties utilize the surficial southern half of SWFWMD the sediments include western part of SFWMD, sediments of the system or intermediate confining unit
to varying degrees with St. Johns, southern the Tamiami, Caloosahatchee and Fort Thompson Tamniamni, Caloosahatchee/Fort Thompson Forma- coincides with the base of the surficial
Brevard and Indian River Counties, using it for Formations. Along the Lake Wales Ridge, the tions and the undifferentiated sediments make up aquifer system. The base of the inter3 public supply. Eastern Orange and eastern surficial aquifer system iscmne fsdmnsthe system In the eastern area of SFWMD, the mdaeaufri ttetpo h
Alachua Counties also utilize the surficial aquifer belonging to the Cypresshead Formation and the surficial aquifer system, in part referred to as the vertically persistent permeable carbonate system In other areas of the district, the surficial undifferentiated sediments In a limited area in Biscayne Aquifer, consists of sediments from the section that comprises the Florndan aquifer aquifer system may be used for limited domestic central SWFWMD, the Bone Valley Member of the Anastasia Formation, Miami and Key Largo system, or, in other words, that place in
I ~ supplies. The surficial aquifer system thickness is Peace River Formation, Hawthorn Group forms Limestones, Fort Thompson Formation, and the section where (silici)clastic layers of
highly vanable, ranging from a few feet to in excess part of the surficia aquifer system. The sediments Caloosahatchee and Tamiami-equivalent sig nificant thickness are absent and of 100 feet. in these units generally consist of quartz sand with sediments In SFWMD, the base of the surficial permeable carbonate rocks are dominant"
varying percentages of clay and shell except in the system occurs at the first impermeable sediments
U ~ ~~~~~~~~~~~~~~~Bone Valley Member where phosphate forms ainteHwhrGru OcainlythupeTeitrmdteqifrstmorneSediments forming the surficial aquifer system significant proportion of the sediment Vacher et ntHathhorn Group mensiayr the basal Th nemediate nqui cursfer much of nte in SJRWMD are lithostratagraphically assigned to al (1990) characterize the sediments as quartz porton o u simials satom h asmate ining nt o cr oser wuh t was
~~~~the undifferentiated sediments, Gypresshead and sand with less than 10 percent clay over much ofprtn fhesfca-stt.t sbsnfrmtseraswretws
Nashua Formations, Caloosahatchee Formation- th itc.They also show shell content of the removed by erosion and the surfacial aquifer
equivalent shell beds and the Coosawhatchie surfacial aquifer system increasing toward the The lithostratigraphac units forming the suricial system sediments, if present, lie immediately
Formation of the Hawthorn Group The coast and to the south in the southern halt of the aquifer system consist of a complex array of suprajacent to the carbonates of the Floridan
undifferentiated sediments and the Cypresshead district facies The sediments range from quartz sands to aquifer system Springs are a common feature of






SPECIAL PUBLICATION NO. 34


these areas Surrounding the areas where these Walton, Leon and Wakulla Counties (Sinclair and The intermediate aquifer system is interbedded public water supply source in Flagler and eastern sediments are missing, the intermediate aquifer Stewart, 1985) with the impermeable beds of the intermediate Indian River Counties Elsewhere it is utilized for
system or intermediate confining unit is often confining unit. The intermediate aquifer system is limited domestic and agricultural supplies.
perforated by karst features, Where this condition developed in the sands and carbonates of the Permeable strata in the Hawthorn Group and the
exists, the intermediate aquifer system and the Siliciclastic sediments predominate in the Hawthorn Group (Ceryak et al., 1983). In the post-Hawthorn undifferentiated sediments often
intermediate confining unit allow water to pass intermediate confining unit in NWFWMD northeastern portion of the District, four discrete exhibit rapid lateral and vertical variability resulting
through into the Floridan aquifer system or into the Carbonate sediments are present in the sediments carbonate units have been identified, each of in a limited areal distribution of water-producingU surficial aquifer system of the Apalachicola Embayment and east of the which is a separate intermediate aquifer. These units. The intermediate aquifer system is most
Apalachicola River. In western NWFWMD, the aquifers are up to 40 feet thick, and are all often utiized in Nassau, Duva, Baker, St. Johns
confining unit is the Pensacola Clay which grades confined, with the possible exception of the basal and Clay Counties where the Hawthorn Group or The regional significance of the intermediate eastward into the Alum Bluff Group. Further east, Hawthorn carbonate unit, which may be in post-Hawthorn undifferentiated sediments areI aquifer system is quite limited. Statewide, this generally east of the Apalachicola River, the hdalccnatwt h pems lrdntiksifligteJcsnil ai
section is referred to as the intermediate confining Hawthorn Group forms the intermediate confining hauic cntac ihteuprmsm.rdntiket niln h Jcsnil ai
unit It serves to confine the Floridan aquifer unit. Within the Apalachicola Embayment, portionsaqiesytmSOTW TFLRDWAE
system and forms the base of the surficial aquifer of the Intracoastal Formation form the inter-SUTW TFLRDWAE
system. The sediments comprising this section mediate confining unit. ST. JOHNS RIVER WATER MANAGEMENT DISTRICT
are predominantly siliciclastic (quartz sand, silt and MANAGEMENT DISTRICT
clay) with varying proportions of carbonates Th nemdaeaufrsse sgnrlyThe intermediate confining unit and inter(inemeite conngnite wprsite duringth not an important water-bearing unit in NWFWMD. The intermediate confining unit and inter- mediate aquifer system are present throughout
nterMiocene afnErPincunet Itas doiteresting Permeable beds of limited extent are present mediate aquifer system occur throughout the most of SWFWMD (Buono et al., 1979). Although nte thin sme anareas iller (186 as eticlde l ocally and may provide limited amounts of water SJRWMD except along the western district the sediments comprising this section are absentI lowtera nsme ait Miocer9) ad Ecued to small, domestic wells. The intermediate aquifer boundary in parts of Marion and Alachua Counties to very thin in the northern half of SWFWMD, they caonaesmenacwith the Mocene edimoents system/confining unit acts as an aquifer system on the Ocala Platform. The combined confining thicken to more than 650 feet in the southern end asarofte inctmatwthe oniin diet primarily east of the Choctawhatohee River unit and aquifer system ranges In thickness from of the district (Buono et al., 1979). In the northern
aspr fteitreit ofnn nt(agner, 1988). The permeable zones utilized for less than ten feet to more than 500 feet. It is half of the district, the section is generally theU
ground water are siliciclastic and carbonate beds thickest in the Jacksonville Basin in northeastern intermediate confining unit and is thin to absent on The top of the intermediate aquifer system or in the Intracoastal Formation (Barr and Wagner, SJRWMD It thins over the St. Johns Platform, the southern end of the Ocala Platform. In the intermediate confining unit ranges from more than 1981), the Alum Bluff Group and, to a very limited Sanford High and Brevard Platform in the central southern half of SWFWMD, approximately from 350 feet below National Geodetic Vertical Datum extent, the Hawthorn Group portion of the district then thickens into the northern Polk and Hilisborough Counties south,I
(NGVD) to greater than 225 feet above NGVD Osceola Low and the Okeechobee Basin in the intermediate confining unit also contains
Miller (1986) cites thicknesses of the intermediate RVRWTRsouthern SJRWMD. In the SJRWMD the permeable sediments forming the intermediate
confining unvt (his upper confining unit) ranging SUWANNEE ISRIAT Hawthorn Group or undifferentiated post- aquifer system. In this area, the sediments thickenU
from very thin or absent to greater than 1000 feet. MNG ETDSRCTHawthorn sediments, where present, are to the south into the Okeechobee Basin (Buono et
considered to form the top of the intermediate aL, 1979; Scoff, 1988).
NORTHWEST FLORIDA WATER The intermediate confining unit is present in aquifer system
MANAGEMENT DISTRICT SRWMD under the Northern Highlands This Siliciclastic and carbonate sediments of theU
includes portions or all of Jefferson, Madison, The intermediate confining unit and Hawthorn Group comprise the majority of the
Hamilton, Suwannee, Columbia, Baker, Bradford, intermediate aquifer system consist primarily of intermediate confining unit and intermediate The intermediate confining unit occurs over Union and Alachua Counties. Within this area, the interbedded siliciclastic and carbonate sediments aquifer system in SWFWMD In addition, someU much of the NWFWMD serving to effectively thickness of the intermediate confining unit may of the Hawthorn Group and sand, clay and post-Hawthorn siliciclastics may form a limited
confine the Floridan aquifer system It is thin to exceed 300 feet (Scott, 1988) and confined to limestone of the undifferentiated post-Hawthorn portion of the intermediate confining unit in the absent over the Chattahoochee Anticline in semiconfined conditions exist. It is thin to absent sediments The Hawthorn Group sediments are northern half of the district. In the northern portion
portions of Jackson and Holmes Counties. The on the Ocala Platform and thickens on its flanks absent over much of the Sanford High and limited of the district, clayey sediments lying on theI
intermediate confining unit is also thin to absent in reaching the greatest thickness in the Jacksonville portions of the St. Johns and Brevard Platforms in Florndan aquifer system carbonates belong in part eastern Wakulla, southeastern Leon and southern Basin to the east of SRWMD. Karst features are southern Flagler County, much of Volusia County in the Hawthorn Group and in part may be reJefferson Counties The intermediate confining unit common throughout this area except in the and northern Brevard County. worked Hawthorn sediments along with residuum
thickens dramatically under the western end of northeastern part of SRWMD (parts of Baker, from dissolution of carbonates.U
NWFWMD in Escambia County and in the Bradford, Columbia, Hamilton and Union
Apalachicola Embayment under Gulf and Franklin Counties). Outliers and sinkhole fill consisting of Karst conduits breaching the intermediate Becigo h nemdaecniigui
Counties. Thicknesses range from less than 10 the sediments of the intermediate confining unit aquifer system and intermediate confining unit are rahn fte intermediate er yntm ng karstU
feet to greater than 1000 feet. are common in the areas where the unit is absent, common in much of the SJRWMD. Only in Baker, and the itreit qie ytmb as
Nassau, Duval and parts of Clay and St Johns features is common in the northern half of the
Counties are karst features very few in number and district and along the Lake Wales Ridge in Polk
The ability of the intermediate confining unit to Siliciclastic sediments dominate the inter- the intermediate confining unit is not often County (Sinclair and Stewart, 1985). The southernI effectively confine the subjacent Floridan aquifer mediate confining unit in SRWMD. These breached (Sinclair and Stewart, 1985) portion of SWFWMD has limited karst
system is impaired in those areas where it has sediments most often are part of the Hawthorn development (Sinclair and Stewart, 1985) and few
been breached by karst development. These areas Group or materials that are resid ual from it karst conduits penetrate the intermediate confining
include portions of Jackson, Holmes, Washington, ("Alachua Formation") The intermediate aquifer system is utilized as a unit and intermediate aquifer system.
83








FLORIDA GEOLOGICAL SURVEY


U ~The intermediate aquifer system is utilized in Floridan Aquifer System Floridan aquifer system from carbonate sediments The elevation of the top of the Floridan aquifer
the southern half of SWFWMD and becomes most deposited during the Paleocene through Early system varies significantly throughout the state
Important at the southern end of the district where Miocene The top occurs at elevations in excess of 100 feet
the Floridan aquifer system is deeply buried and Th ES(1986) defines the Floridan aquifer above NGVD on the Ocala Platform and
highly mineralized. The permeable strata of the system as a Chattahoochee Anticline to depths greater than
Hawthorn Group and portions of the Tamiami The thickness and lithology of the sediments 1100 feet below NGVD in southern Florida and
Formation form the water-producing horizons "thick carbonate sequence which includes suprajacent to the Floridan determine the surficial 1500 feet below NGVD in the western-most
providing variable quantities of ground water all or part of the Paleocene to Early [sic] expression of the karst processes On the Ocala panhandle (Miller, 1986) The thickness of the
(Sutcliffe, 1975) Micn eisadfntosrgoal sPlatform from Hillsborough and Polk Counties Floridan varies from Foss than 100 feet in the
aMwaer-eldng hydruicnein Wher north to the state line, then westward into Leon western half of the panhandle to in excess of 3500
a wte-yelin hdrali uitWhreand Wakulla Counties and on the Chattahoochee feet in southwestern peninsular Florida (Miller,
3SOUTH FLORIDA WATER ovranby either the intermediate aquifer Anticlino in Jackson and Washington Counties, 1986)
MANAGEMENT DISTRICT system or the intermediate confining unit, carbonate sediments of the Floridan aquifer
the Floridan contains water under confined system crop out or are covered by a thin Layer of
conditions. Where overlain directly by the unconsolidated siliciclastics (Sinclair and Stewart, The base of the Floridan aquifer system, the I ~The intermediate confining unit and the inter- surficial aquifer system, the Floridan may 1985) In these areas, the carbonates have been sub-Floridan confining unit, varies stratigraphically
mediate aquifer system occur throughout SFWMD or may not contain water under confined exposed to extensive dissolution by aggressive throughout the state. The SEGS (1986) indicates
However, the intermediate aquifer system is conditions "ground waters percolating downward from land that the base of the Florndan in the panhandle
utilized in a limited number of counties along the surface. Often the karst geomorphology has occurs in the Middle Eocene approximately at the
western edge of the district. This section ranges in "The top of the aquifer system generally reached a relatively mature stage of development top of the Claiborne Group The base of the
thickness from approximately 500 feet in the coincides with the absence of significant rsligi ueossraedpesoswihsse ntepnnuagnrlyi osdrdt
norher SWMDara t moe han90 fet i te ticneses f silciclatic fom heoften coaLesce. The Floridan aquifer system occur within or rear the top of the Paleocene
sothrnos prtonofth dstic (cot,198)setin ndwih heto o tevertically exhibits well developed cavernous porosity and Cedar Keys Formation (SEGS, 1986). Miller (1986)
Much of the SFWMD area lies in the Okeechobee persistent permeable carbonate section conduit flow paths. Most of Florida's major provides a more detailed picture of the variability of
Basin. For the most part, the top of the aquifer springs occur in this zone including Wakulla and the stratigraphic positioning of the Floridan aquifer
system coincides with the top of the Silver Springs. system base but indicates the same general
Suwannee Limestone, where present, or reia treds
Interbedded siliciclastic and carbonate the top of the Ocala Group (Limestone) rgo rns
sediments from the Hawthorn Group form the The carbonates of the Floridan aquifer system
intermediate confining unit and intermediate lie beneath a variable thickness of post-Floridan NORTHWEST FLORIDA WATER
Aquifer system in SFWMD. Previously, some of In limited areas the Avon Park Formation formsslicatc ndarntsofhentmdatMA GE NTDTRC
the sediments currently included in the inter- the top of the aquifer system. Sediments of the confining unit, intermediate aquifer system and the Mediate confining unit and intermediate aquifer Arcadia Formation (Hawthorn Group), the Bruce surficial aquifer system on the flanks of the Ocala
U system along the west coast were placed in the Creek Limnestone, the St. Marks Formation or the Platform and the Chattahoochee Anticline The Floridan aquifer system in NWFWMD
Tamiami Formation but are now considered part of Tampa Member of the Arcadia Formation may Although karst processes have affected the supplies more than 90 percent of the water
the Hawthorn Group (Missimer, 1978; Wedderburn form the top of the Floridan aquifer system (SEGS, sediments of the Floridan in these areas, forming demand and is utilized in all the counties in the

Set al ,1982; Scott,1988). In the eastern part of the 1986)- dissolutional conduits and caverns, the karst district except Escambia and part of Santa Rosa
district, Tamiami-equivalent sediments may form topography is not as well developed as in the Counties (Wagner. 1988). It underlies the entire
the top of the intermediate confining unit "The base of the aquifer system in areas of thin cover However, in these areas the district but is too saline for potable water in the
(Causaras, 1985) panhandle Florida is at the gradational karst features are often of large diameter and western end of the panhandle. The water quality
contact with the fine-grained (silici)clastic depth due to overburden thickness (Sinclair and over a ba aret crespong to tuhen The importance of the intermediate confining rocks belonging to the Middle Eocene Stewart, 1985). the coastal zone may be affected by the upconing
unit and intermediate aquifer system in the western Series. In peninsular Florida, the base of mineralized waters (Scoff et al ,1991).
part of SFWMD has led to a number of studies in coincides with the appearance of the The Floridan aquifer system lies subjacent to a
U ~Charlotte, Lee, Hendry and Collier Counties regionally persistent sequence of anhydrite thick sequence of post-Floridan sediments in the
(Sutoliffe, 1975; Wedderburn et al., 1982, Knapp et beds that lies near the top of the Cedar Okeechobee Basin, Jacksonville Basin, Gulf The top of the Floridan aquifer system in
al 1986; Smith and Adams, 1988). There are Keys Limestone (Formation)." (SEGS, Trough, Apalachicola Embayment and the Gulf NWFWMD varies in elevation from 150 feet above
three principle producing zones within the 1986). Basin of the western panhandle. In these areas, NGVD in Jackson and Holmes Counties to greater
intermediate aquifer system in this area, the the carbonates of the Floridan have apparently not than 1500 feet below NGVD in Escambia County
"Minssinaurer(95,te" nmdwtor aquifer" ofTeFoiaandfrsse ehbtxrm been subjected to extensive karstification. (Miller, 1986; Scoff et al., 1991). The thickness of
Weddierr et197 (982),n the owe-Hawthorn vauriraoftiondin pqierebiiym reulingt fxrma However, subsurface investigations of the the aquifer system ranges from approximately 100
Wederbrnet l (98) ad te lowr-Hwtornvaiatonsinpereabliy rsulin ro alimestones indicate some karstic modification of feet thick in portions of Jackson and Holmes
que" fKppet al. (1984). These producing cobnt o ri ginal depositional conditions, tCounties on the Chattahoochee Anticline to more
zones have been very important to the diagenesis, structural features and dissolution of the sediments during subaeria ensure priotr ton20 ettiki Faki onyi h

I dveopen sutsysstFendmc hnas ben extensivelyM altered9 bykarst mediate confining unit and intermediate aquifer Apalachicola Embayment (Scott et al., 1991).
processes in some areas of the state. Disso-- system (U Hamms and 0 Budd, University of
lutional and diagenetic processes have been Colorado, personal communication, 1991). In the western part of the district, the Floridan
3 extremely important in the development of the aquifer system is subdivided into an upper and


9






SPECIAL PUBLICATION NO 34


lower aquifer separated by a confining unit, the the SRWMD providing the vast majority of the throughout the SJRWMD containing potable water district, dissolution of the carbonate fraction of the Bucatunna Clay. The confining unit thins and water supplies The top of the Floridan ranges supplies in most areas Salt water intrusion or Plio-Pleistocene sediments is responsible for the
pinches out towards the east in Okaloosa County, from greater than 100 feet above NGVD in upwelling is a concern in many of the coastal areas development of some of the karst features
where the Floridan becomes a single aquifer Jefferson County to more than 300 feet below and along the St Johns River Valley (Scott et al ,
(Marsh, 1966; Scott et al., 1991) NGVD in Bradford County (Scott et al., 1991). The 1991)SOTW TFLRDWAE
thickness ranges from approximately 1100 feet inSUTW TFLRAWTE
northern Jefferson County to 2200 feet in southern MANAGEMENT DISTRICT
Carbonate sediments dominate the Floridan Jefferson County (Miller, 1986). The thicknesses of The top of the Floridan aquifer system inU aquifer system with minor occurrences of the Flonidan aquifer system sediments in SRWMD SJRWMD occurs at the highest elevations on the T
siliciclastics The siliciclastics generally Occur show the effects of the Apalachicola Embayment flank of the Ocala Platform in Alachua and Marion Te Floridan aquifer system underlies the intimately mixed with the carbonates and are more and Gulf Trough in Jefferson County These Counties. In this area, the uppermost Floridan entire SWFWMD area and contains plentiful,
common in the upper portion of the aquifer sediments also exhibit the thicker carbonate sediments range from 50 to more than 100 feet potable water supplies throughout most of theI
system. Within the district, the Florndan aquifer seunedpstdi h eislraeabove NGVD The upper surface of the system district Areas of mineralized water along the coast
system is composed of the Ocala, Marianna, seunedpstdi h eislrae.dips into the Jacksonville Basin, in the northern and in portions of Charlotte and Sarasota Counties
Suwannee, Chickasawhay, and Bruce Creek part of SJRWMD, where it may be more than -550 limit the availability of fresh water from the Florndan
Limestones and the St Marks and Chattahoochee Carbonate sediments deposited during the feet NGVD. To the south, the top of the Florndan in these areas (Scoff et al., 1991)
Formations Paleocene through the Early Miocene comprise the reaches more than -350 feet NGVD (Scott et al
Floridan aquifer system in SRWMD The base of 1991). The thickness of the system ranges from The top of the Floridan aquifer system in the
Stratigraphically, the base of the Floridan the system occurs near the top of the Paleocene approximately 1500 feet in Baker County SWFWMD displays two distinct elevational trendsI
aquifer system varies significantly throughout Cedar Keys Formation (Miller, 1986) Carbonates (northwestern SJRWMD) to 2900 feet in southern The northern two thirds of the district (from central NWFWMD In the Pensacola area, the base of the Oldsmar and Avon Park Formations, the Brevard County (Miller, 1986). Polk and Hillsborough Counties northward) is
ocuswti h pe oeeOaaLmsoeOcala and Suwannee Limestones and the St. relatively flat with elevations varying from sea level
(Miller, 1986) Under the eastern end of the syrste inrmthendi prict se SuwFian Liestn Carbonate sediments dominate the Floridan t ewe 0 n 5 etaoeNV h
district, the base falls within the Paleocene Cedar formsem pion o the ForiT d uanne aproimely aquifer system within the district Siliciclastic top of the Foridan in the southern one third of the Keys Formation The depth to the base of the one halfrt of the strict w i therStMatrky sediments, when present, occur mixed in with district dips distinctly to the south dropping from
Floridan varies from -100 NGVD on the netoteds c hl h tMrscarbonate lithologies and predominantly in the salvlt oeta 5 etblwNV ln
Chattahoochee Anticline to -3100 feet NGVD in the Suanne Limnestone an thed StMarks Formaton uppermost portion of the Floridan. The Ocala the southern district boundary (Scoff et al., 1991) Apalachicola Embayment (Miller, 1986) are absent, the Ocala Limestone forms the top f Limestone forms the top of the aquifer system over These trends are related to the positions of the
th sstmInth suhen orin fph d otnt the majonty of the district. In very limited areas of Ocl Plaorm sand the northern edge of the
The Claiborne aquifer has been recognized the Ocala Limestone is absent due to erosion and VlsaadOag onis h vnPr
within the sub-Floridan confining unit. The totai the Avon Park Formation forms the top of the Formation occurs at the top of the Floridan.
extnt f hisaqufe isno knwn ndit s nt ystm.Sediments of Oligocene age occur at the top of the The thickness of the aquifer system also
extento utis (auier, is7) not now anmd i otfytm aquifer system along the east coast in displays distinct trends The Floridan is more thanI
oftenutlized sAlcl as8) ticmpose ofh southernmost Brevard County and in Indian River 1400 feet thick in the northern-most portion of the
clarbornae anriccatc eietsouh The top of the sub-Floridan confining unit County. Miller (1986) shows small outliers of district and thins southward across the northern
Claibrne roupgenerally occurs within the Cedar Keys Formation Suwannee Limestone at the top of the Floridan in one third of SWFWMD to approximately 600 feet
throughout SRWMD (Miller, 1986) The positioning the northern portion of the district The majority of thick (Wolansky and Garbode, 1981) From theI The effects of karstification are most intense of the permeabliity barrier shifts locally within the the aquifer system is comprised of the Avon Park thinnest point of the Floridan aquifer system, it on and surrounding the Chattahoochee Anticline in upper part of the Cedar Keys Formation from the and Oldsmar Formations thickens into the Okeechobee Basin southward,
Jackson, Holmes and Washington Counties and top of the unit to some distance below the top. reaching more than 2400 feet thick in theI
on the flank of the Ocala Platform in Leon and The depth to the sub-Floridan confining unit varies.. ,SW MDar fHgansCuy(Wask
Wakulla Counties In these areas, the aquifer from -1200 feet NGVD on the Ocala Platform to The sub-Flonidan confining unit occurs within SWFd art ofHghadsCuty(1)nk
sytmhs enetnsvl ltrdb isouin-2100 feet on the flank of the Gulf Trough (Milier, the Cedar Keys Formation throughout the district n abd,18)
sys te has entney ltred bynduis oluton9 The positioning of the base of the Floridan varies
andrfte nt h mandrectn conuitsensmte 18)from the top of the Cedar Keys Formation to within As in the rest of the peninsula, carbonateI
sundrfaer into duhe mopinan prAnextensive' the upper portion of the formation (Miller, 1986) sediments dominate the Floridan aquifer systern in
Wundears condith Wadping rojt of the The sediments of the Flonidan aquifer system The top of the sub-Floridan confining unit varies SWFWMD Siliciclastic-beaning carbonates and
Woodvilt (Parr Plainebyth F odvitae Unavrsliny throughout SRWMD have been greatly affected by from -1600 feet NGVD on the flank of the Ocala siliciclastic units in the basal Hawthorn Group mayI pront(arkermmurnera, oid91)t ivrsnty karstification Sinkholes ale very common in most Platform to -3200 feet NGVD in the Jacksonville form the upper portion of the Floridan in part of the dpeumonln tcommunctiond91)i cmp etlyh areas and numerous springs are scattered across Basin and the Okeechobee Basin (Miller, 1986). southern portion of SWFWMD. In much of the
documetingl ftueslnt ncmlxt of the ae the district. The only area of minor karstification 's district, the Suwannee Limestone forms the top of
disslutonalfeauresof he aea.in northern-most Columbia and Baker Counties. Karst processes have significantly altered the the Floridan In the northern most portion ofU
carbonates of the Floridan aquifer system in much SWFWMD, the Ocala Limestone and, in limited
SUWANNEE RIVER WATER ST. JOHNS RIVER WATER of the SJRWMD. Karst features are common in areas, the Avon Park Formation comprise the top
MANAGEMENT DISTRICT MANAGEMENT DiSTRICT much of the central and western portions of the of the aquifer system The Avon Park and Oldsmar
district (Sinclair and Stewart, 1985). The Formations form the main body of the Flonidan in
The Flonidan aquifer system occurs throughout Th lrdnaufrsse speetkarstification in these areas is related to dissolution the district The sub-Floridan confining unit occurs
TheFlrianaqufe sstm i pesntof the Ocala Limestone In the southern half of the in the upper Cedar Keys Formation and varies from


10U








FLORIDA GEOLOGICAL SURVEY


U -1900 feet NGVD on the Ocala Platform to -4100 the Cedar Keys Formation (Miller, 1986) The top Knapp, M 3 Burns, W S., Sharp, T S ,and Shih, Sinclair, W. C and Stewart, J. W ,1985, Sinkhole
feet NGVD in the Okeechobee Basin (Miller, 1986). of the sub-Floridan confining unit ranges from G 1984, Preliminary water resource type, development and distribution In Flornda
-3000 feet NGVD on the northern edge of the assessment of the mid and lower Hawthorn Flornda Geological Survey Map Series 110,
altraton f te Forian quierOkeechobee Basin to -4400 feet NGVD in the aquifers in western Lee County, Florida South scale 50 km to 1 inch.
Kasi atrtono h Foia aufrdeeper portion of the Okeechobee Basin Florda Water Management District Technical
sytmhsoccurred truhtmuhof the Publication 84-10, 106p
Sdistrict In the southern portion of SWFWMD. PSmith, K. R., and Adams, K. M 1988, Ground
I where the Hawthorn Group thickens in the The development of karst features in the water resource assessment of Hendry County,
Okeechobee Basin, karst features are not as sediments of the Floridan aquifer system in Knapp M S ,Burns, W S ,and Sharp, T 1986, Flornda South Florida Water Management
abundant (Sinclair and Stewart, 1985) In the SFWMD has not been extensive, Throughout Preliminary assessment of the groundwater District Technical Publication 88-12, 109 p
northern two-thirds of the district and along the much of the district, the Floridan contains saline resources of western Collier County, Florida plus appendices
Lake Wales Ridge, karst features are quite waters and has not been flushed by fresh water South Florida Water Management District,
common Surficial karst features in much of The Florndan aquifer system is also buried by as Technical Publication 86-1,142 p Southeastern Geological Society (SEGS) Ad Hoc
southern SWFWMD are the result of dissolution of much as 1100 feet of confining beds and other Committee on FloridaHyrsrtgphcUt
Bicarbonate sediments and shell material in the aquifer systems under much of SFWMD. Mrh 96 elg fEcmi n Definition, 1986, Hydrostratgric Unitf
Miocene through Pleistocene units Santa Rosa Counties, western Florida Florida: Florida Geological Survey Special
REFERENCES CITED panhandle. Florida Geological Survey Bulletin Publication 28, 8 p
I SOUTH FLORIDA WATER 46, 140 p.
MANAGEMENT DISTRICT Allen, T A, 1987, HydrogeoLogy of the Holmes, Sutcliffe, H., Jr 1975, Appraisal of the water
Jackson and Washington Counties area, Miller, J A., 1986, Hydrogeologic framework of the resources of Charlotte County, Florida: Florida
Potable water supplies within the Floridan Florida Florida State University (MS thesis), Flondan aquifer system in Florida and parts of Bureau of Geology Report of Investigations 78,
aquifer system In SFWMD are limited to the 13pGeorgia Alabama and South Carolina United 53 p
northern part of the district. The sediments of the States Geological Survey Professional Paper
Floridan occur throughout the district but in many Barr, 0 E and Wagner, J R 1981, Recon- 1403-B, 91 p. plus maps. Vacher, H L., Jones, G W., and Stebnisky, R. J.,
areas do not contain acceptable quality water naissance of the ground-water resources of 1990, The reed for lithostratigraphy: How
southwestern Bay County. Northwest Florida Msmr.T M 1978, The Tamiami Formation- heterogenous is the surficial aquifer?. in

SThe top of the Floridan aquifer system occurs Water Management District Technical Missimernomto otatiotws Allmon, W and Scott, T (compilers), PliOU ~at elevations ranging from sea level in the northern Publication 81-8, 47 p Haworn Foraticontct, 1, southwest Plitocene stratigraph andpaleontolog of
most edge of the district (Orange County) to Society, Guidebook 31, Annual Field trip 1990.
Greater than 1100 feet below NGVD in south- Boggess, 0 H,, and Missimer, T M 1975, A re-SctTM,18,heihortgapyfte
I ~~western SFWMD (Miller, 1986). Most of this area connaissance of the hydrogeologic conditions HwthornM Group TMioene ofthlorigrah Forid WanrtRh198 udmnalgon ae
lies in the Okeechobee Basin The thickness of the in the Lehigh Acres and adjacent areas of Lee Geologirn Srve up(llen) 59, F14nd p.condWions within the FNorthetlriud Water
Floridan ranges from less than 2300 feet in Orange CutFod ntdSae elgclGooia uvyBlei 9 4 .cniin ihnteNrhetFod ae
~~~County to more than 3400 feet under parts of Palm CuntyOe Floida Uiedpttes5 Geologimncaslc NrtwstFonaWa
Beach and Martin Counties and more than 3500 SurveyM, LoypJMnanFMidl, GMRngponrt tr7t,-ub5c n8rmaip
feet under western Lee County (Miller, 1986). (Sdot s, 99 Lloda'sMGround Maddox Gult Mangeent DititPbicIfrmto
Buono, A Spechler, R M Barr, G. L and (dtr) 91 lrd' rudWtrQaiyBlei 82
Wolansky, R. M., 1979, Generalized thickness Monitoring Program-Hydrogeological
Thick sequence of carbonate sediments of the confining bed overlying the Floridan framework Florida Geological Survey Special Wedderburn, L. A Knapp, M S., Waltz, D P., and
contain ing some beds of siliciclastics and aquifer, Southwest Florida Water Management Publication 32, 97 p Burns, W. S 1982, Hydrogeologic reconsiliciclastic-rich carbonates form the Floridan District United States Geological Survey naissance of Lee County, Florida- South
aquifer system in SFWMD The majority of the Open File Report 79-1171, map plus text Sct 91Agooia vriwo lnaFlorida Water Management District Technical
sediments comprising the Floridan are carbonates In Scott, T. M., Lloyd, J M and Maddox, G Publication 82-1, 192 p plus appendices.
with little to no siliciclastics However, in
southwestern Florida, sand beds have been noted Causaras, C R 1985, Geology of the surficial (editors), 1991, Florida's Ground Water Quality
Sin the Ocala Limestone (Missimer, personal aquifer system, Broward County, Florida, Monitoring Program Hydrogeological White, W A, 1970. Geomorphology of the Florida
communication, 1991) Siticiclastic-bearing United States Geological Survey Water- framework: Flornda Geological Survey Special peninsula Florida Bureau of Geology Bulletin
carbonates and a few siliciclastic beds from the Resources Investigations Report 84-4068, Publication 52, p 5-14. 51, 464 p.
Sbasal Hawthorn Group may form the upper beds of map plus text
the Floridan aquifer system in some areas of the Shaw, J E and Trost, S M., 1984, Hydrogeology Wolansky, R M., and Garbode, J. M,, 1981,
dsrc general, the Suwannee Limestone Ceryak, R., Knapp, M S and Burnson, T., 1983, of the Kissimmee planning area, South Florida Generalized thickness of the Floridan aquifer,
forms the upper unit of the aquifer system with the The geology and water resources of the upper Water Management District: South Flornda Southwest Flornda Water Management District:
SOcala Limestone and the Avon Park, Oldsmar and Suwannee River Basin, Florida. Florida Bureau Water Management District Technical United States Geological Survey Open File
pprCedar Keys Formations comprising the main of Geology Report of Investigation 81, 165pPulatn84,pa1,25.Rprt8-2,mppustx
mass of the system The base of the Floridan
~aquifer system, the top of the sub-Floridan
confining unit, occurs within the upper portion of

11






SPECIAL PUBLICATION NO. 34


Chapter IV between 1985 and 1988, and for monitoring water- result of the dual goals of the Background asymmetrica, with a long tail that extends towards
quality changes in the future, which is part of the Network. The maps represent the program's best the high concentrations. If mean and standard
intent of the 1983 Flonda Water Quality Assurance interpretations of analyte distribution, while the deviation were used to describe a skewed QUALITY OF WATER IN FLORIDA'S Act. While there is not sufficient data for site tables reflect GWIS database and an uncritical distribution, the mean would be high relative to theU
AGUIFER SYSTEMS specific determinations, the data can also be used review of the data contained therein. most abundant concentrations, thus giving a false
to assess general background conditions for impression of the quality of water in the aquifer
Sam B Upchurch permitting, risk assessment, and contamination sytm
evaluation. Finally, the data can be used to The maps were prepared from the bestsstm
evaluate ground-water flow systems, ability of the available data. Outliers and data that failed the Department of Geology aquifer systems to tolerate contamination, and nearest-neighbor criteria were excluded from the Distribution Descriptors
University of South Florida potential best uses of the waters. These last uses maps. As a result, many of the 'bulls eye" contour
Tampa, Florida require some understanding of how ground-water lnstypical of representations on unevaluated
chemical systems behave. To this end, the data are avoided. The map contours represent the In order to better represent the distributions of
following discussions summarize some of the best assessment of data distributions, although variables, the median, quartiles, minima, and
INTRODUCTION chemical behaviors of the aquifer systems, and it some of the maxima and minima represented in mis the u entle wHale a pes are bedlon
discusses some ways that the aquifer systems the tables are not displayed. The maps, therefore, i h 0hpretl.Hl h ape r eo
Adjust chemically to contamination and mixing of represent conservative assessments of the the median in concentration, the other half above
Scope waters with different compositions, distributions of analytes. The median is used in this report to compare water
quality between aquifer systems and regionally.
Thidas chapter dscustes the qualtybaere in Throughout this chapter, references to various The tables reflect the distribution of data mn the Flria' Baqufrn sysems.r Tepdtbas used 5n geomorphic features and surface-water basins are GWIS database at the time of report preparation. The quartiles represent 25 and 75 percent of
theewhBackgussroundn-wNetworkiy. devmmeldomedmu byuesErR epndedthe samples. The 25th percentile (Qower quartile orU the water management districts, Some data have adependisussing 1 grodwter lity. Mfrardimus and wminrh imu vales nare r-epgor 4 rtile in the tables) represents the value below
bece Ie omite fothet map uan aay-a shes Apendx f gures 3t 2so helctoso and outlier criteria. Unreasonable maxima and which 25 percent of the samples occur. Constadads n ers o ln blace [Nte ennoesminima are evaluated in the text in the context of versely, the 75th percentile (upper quartile or 'I
how valid they are. In most cases, they can be Ortile on the tables) represents the value above are located at the end of each chapter] or they are Chapter Organization shown to represent well-construction problems or which only 25 percent of the samples occur The
raically different ro anab roete tneab values that cannot be considered until confirmed maximum and minimum are also given in the
bwekgrond tero, quanot bepoeorfetThe discussions of individual anlyt' inti by re-sampling and analysis. The tables give the tables, so a complete representation of theI
background waterpquality.organized into four majoranaop i n thi reader a "feel" for the range of data in the GWIS distribution is available Where a standard or
repot ar topcs:database guidance concentration is available, the number of
Three aquifer systems2 are included in the sIpe hteceedta au sas
report- (1) surficiaf aquifer system, (2) intermediate 0 General Descriptors the variables that represented in the tables.
aquifer system and intermediate confining unit describe the conditions under which the Use of median and quartile population
(hreftr eredth itemeiae qufe sstm)chemicals occur, specifically temperature descriptors avoids problems with inclusion of the
(hafter3 Ftermdteineeit aquifer system), snuto and PH; outliers and represents the best possible indi- AQUIFER CONTROLS ON
of these aquifer systems in Florida are discussed in e Cations including calcium, magnesium, catmons of water quality. Users are cautioned to GROUNDWATER CH4EMISTRY
Chate Il f hi vlue ndinScttetal (99).sodium, potassium, iron, mercury, and examine the GWIS database and be selective in
Chptr IIofths olmead n cof t l.(191.lead; use of these data until confirmations are made with Factors That Control
0 Anions including bicarbonate and the second round of sampling. Ground-Water Chemistry
The discussion and maps are arranged by carbonate, chloride, sulfate, fluoride,
water management districtK Alachua County nitrate, and phosphate; and VARIABLE DESCRIPTION Bfr icsigtewtrceityo
participated as aseparate entity during parts of the 0 Other Constituents including total CONVETION dIcsigtewtrceityo
data collection and analysis phases of the data, dissolved solids, conductivity, total organicCNETONFordaufrsytm tsiprantobfy
For convenience, the Alachua County data are carbon, and synthetic (man-made) discuss the factors that affect ground-water
included with the SRWMD. The tables contain data organics Nature of Data Distributions chemistry. These factors include:
on the number of samples collected, not numberU of wells. Surficial aquifer system results are divided
into (1) Sand and Gravel Aquifer, (2) Biscayne The discussions for each analyte are broken Environmental, geochemical data are seldom 0 Precipitation chemistry,
Aquifer, and 'Other", which includes all of the down into aquifer system and then into regions normally distributed (Ahrens, 1954a,b). That is, 0 Surface conditions at the site samples not classified as coming from either the (water management districts), as needed they normally do not reflect the classic "bell- of recharge,U
Sand and Gravel or Biscayne Aquifers shaped" curve for which the standard distribution 0 Soil type in the recharge area,
Comparison of Map and Table Data descriptors (mean, standard deviation, variance, 0 Mineralogy and composition of the
etc ) are intended. Geochemical data are typically aquifer system,
The data presented below can be used in a chrcezdby a large number of samples with Ntuefaqfrsyemprsy
number of ways. They can be used as a baseline Comparison of the analyte-distibutmon low concentration values and a few samples with and structure,
for evaluation of the condition of water quality in maps and tables in the following text will indicate high concentrations. This leads to a distribution S Flow path In the aquifer system
the aquifer systems of the state as they existed some discrepancies. These discrepancies are a that is skewed. That is, the distribution Is

123







FLORIDA GEOLOGICAL SURVEY

U 0@ Residence time of water in the of the intermediate and Floridan aquifer systems from the land surface and vadose zone5 soils or is acids lower the water pH to values that are
aquifer system, have been locally affected by acid rain where transpired by plants, the chemicals dissolved in the commonly loss than four If the soils are wet and
Mixing with other waters in the recharge is rapid and buffering capacities are water are concentrated Evaporation also occurs chemically reducing, the microbes produce
I aquifer system, and minimal The effects of acid rain on aquifer water from the water table, especially where it is shallow organic acids and methane gas (CH4), rather than
Aquifer microbiology quality cannot yet be evaluated because no and in porous and permeable aquifers As will be carbon dioxide. Under wet, reducing conditions,
suitable background water-quality database for shown below, the increase in dissolved solids microbial destruction of humus is retarded, and comparison has existed until this time content by evapotranspiration is an important peats and mucks form as sol components
Precipitation Chemistry starting point in the evolution of aquifer waters.
Florida's climate can be classified as a Therefore, recharge through wet, lowland or
The first major factor that affects the chemical "maritime climate", The proximity of all padts of the Surface Conditions dry, upland soils will affect local ground-water
U composition of ground water is the chemical state to the sea has a profound affect on rainfall chemistry differently. The nature of plant cover,
composition of precipitation. Precipitation, which chemistry. Sea spray is generated by the wind and supply of humus, moisture content, and soil
recharges the aquifer systems, is important as a transported inland as an aerosol This aerosol is Surface conditions have a pronounced effect temperature affect both the availability, quantity,
source of dissolved chemical species and as an mixed with precipitation so that Florida rainfalF is a on ground-water chemistry, especially in the and chemistry of humic substances and the acid that induces chemical reactions in the aquifer very dilute mixture that has the ionic proportions of surficial aquifer system and in unconfined portions microbial populations that teed upon these
systems. sea water (FigureS') of the Flonidan aquifer system. Land use, for substances.
example, can have a dramatic effect, including
I introduction of waste heat and contaminants. The
Natural rainfall is affected by reactions with Table 3 summarizes the chemical quality of effects of human activities have been avoided, Soil and Aquifer Mineralogy
atmospheric gases and particulates and by rainfall in Florida (National Atmospheric Deposition where possible, in design of the Background
Proximity to the sea Natural rainfall is slightly Program (IR-7)/National Trends Network, 1990) Network. However, natural conditions can also
acidic. It gains acidity by the reaction of water Note that there is a small amount of all of the major affect ground-water quality. Once water has passed through the humus
(H20) with carbon dioxide (CO2) to form carbonic grudwtrchemicals in average rainfall, These zone, it is characteristically acidic, and it can react
acid (H2C03) according to the reactions, aaas hwta hr ssm irt n with minerals in the soil or rock. The reaction
sulfate presently being introduced as acid rain. Natural surface features that can have (modified from Goldich [1938] and assuming that
significant effects on ground water include' (1) the reaction is with carbonic acid) can be lakes, swamps, and marshes, (2) sinkholes and generalized as
002 +1 H20 = H2C03 (1) The last column in Table 3 is the deviation sinking streams, and (3) proximity to the sea and
(difference) of the sodium to chloride mole ratio tidal influences Lakes, swamps, and marshes can I H2CO, = H + HCO- from that of average sea water. The coastal and serve as sources of natural organics, metals, and
near-coastal stations (Quincy, Kennedy Space low pH water. Sinkholes, sinking streams, and Center, Verna Well Field, and Everglades National other karst features can introduce surface waters Mineral + H2CO3 (2)
As shown in reaction 1, carbonic acid Park) have average deviations from sea-water into deeper portions of the aquifer system (Ceryak, = Cations + HO;-+ Residue
dissociates into hydrogen ion (Hj), which is the composition of five percent or less. More inland 1977). The sea is a source of sodium, chloride and source of acidity, and bicarbonate (HCO). If sites (Austin-Gary Forest, Bradford Forest) have other constituents, which can enter the ground
rainwater is fully equilibrated with atmospheric average deviations from sea water compositions of water through canals, river mouths, and other Cations6 are the metals found in the sol or
I carbon dioxide, the resulting pH4 is approximately 54 and 20 percent, respectively. The significance regions where the fresh-water potential is aquifer minerals, and bicarbonate is the dominant
5.6 to 5 7 at 25*C. If atmospheric moisture has not of these larger deviations should not be exag- insufficient to prevent intrusion. Saline water can anion The residue forms if the mineral contains completely equilibrated with atmospheric carbon gerated, however, as the individual data points also intrude laterafly and vertically when fresh- aluminum or oxidized iron (Fe-i), which are often
~dioxide, pH wil be somewhat greater than 5 5 show a significant grouping near the sea-water water potential is reduced by human activity, relatively immobile in ground and sol waters. I This is the same levei of acidity as soda pop, and ratio The means are skewed because of a few
this moderately acidic precipitation has been data points that may reflect anomalous conditions
responsible for rock weathering over geologic time. or analyses. Soil Type in Recharge Area To illustrate these reactions, we can compare
the reaction of acidic sol water with calcite, the
U~primary mineral in limestone, to a reaction with "Acid rain" is a problem caused by intro- Therefore, as a general rule, newly fallen pre- As precipitation percolates into the soil and potassium feldspar, a common, aluminum-beaing
duction of sulfur and nitrogen gases into the cipitation, uncontaminated surface runoff, and aquifer environment, the weak acids react with the mineral that is present in small amounts in Florida
I atmosphere as fossil fuels are consurned. These uncontaminated soil waters in Florida have the minerals of the soil or rock and with organics. The quartzose sands. The reaction with calcite is U gases react with water in reactions similar to initial compositions of dilute sea water, Based on uppermost sol zone, where plant growth is active,
reaction 1 to form nitric acid (HNO3) and sulfuric the differences in chloride concentrations, these is characterized by an accumulation of plant debris

Said (H2S4) and further lower the pH of rainfall waters average about 0.009 percent (1.66 mg/L in (humus), which is decomposed by sol microbes. If
I (Table 3). Acid rain has been produced in the U.S precipitation, 19,350 mg/kg in sea water) sea the soils are aerated, these rmicrobes produce
for Jess than 200 years. Because of the long times water. While the total dissolved solids contents carbon dioxide (C02), which combines with water CaC03s + HC0O (3)
involved with ground-water transport and the high are low, the ratios of dissolved metals to chloride, according to reaction 1 to form additional carbonic n Ca + 2HC0buffering capacities of limestone- and dolostone- especially sodium to chloride, are nearly constant acid and further lower pH. In addition, the partly S
U ~ rich aquifers, only a small amount of Florida's and reveal an origin as marine aerosols, decomposed organic material often includes
ground water has been affected by acid rain. The water-soluble fractions, including fulvic acids. In this reaction, dissolved calcium and bidata presented in this report suggest that the These organics contain abundant hydrogen as carbonate are produced There is no residue
surficial aquifer system and near-surface portions As this dilute sea-water solution evaporates acid radicals. The added carbonic and organic because neither aluminum nor iron is present in the


13






SPECIAL PUBLICATION NO 34


mineral. In reality, natural limestones usually constituents that were derived by weathering of very high sorption capacities and can effectively significant Calcite predominates in the Suwannee contain other minerals that may leave residues Hawthorn minerals (Lawrence and Upchurch, bind most metals As a result of chemical and Ocala Limestones elsewhere. Water which
upon rock weathering. 1976) weathering, the Hawthorn Group introduces has equilibrated with the Floridan aquifer system,
numerous constituents into the ground-water therefore, includes calcium! magnesium, andI
system. bicarbonate as dominant chemical species The
Potassium feldspar (KAISi3O8) reacts with Table 4 lists the compositions of common pH of Floridan aquifer system water is buffered by
carbonic acid according to minerals found in Florida aquifer systems and dissolution of carbonate minerals and generally
confining beds, and their dissolved weathering Dolostone and limestone contain the minerals ragsfIm7t
products according to the weathering reaction dolomite and calcite (Table 4). Reactions withragsfot8 (reaction 2). Most of these minerals are weathered these carbonate minerals (e g reaction 3) buffer 2KAISi,08+22C3~ slowly, so an important factor in determining how the acidity of ground water and release calcium The base of potabLe water in the Floridan is
+ 9H20 = A12Si2C,(OH)4 (4) much of the weathering product enters the ground and magnesium into the system (Table 4) variable, The base of the aquifer system, whichI
**"water is the length of time the water is in contact varies from the lower Avon Park Formation,
+ 2K + + 4H4SlO4a with a particular rock type (e g the residence Th rmr hshrt eoisaethrough the Oldsmar Formation, to the top of the
+ 2HCQ b'fl time). copoed of arbpoat-florptoit, whie Cedar Keys Formation (Scottetal., 1991)is usuallyU
+ 2H~n- ompsedof arboatefluraptit, wiledolomitic. The base of the aquifer system is
weathered and reprecipitated deposits contain characterized by reduced permeability, partly as a
In this reaction, aluminum and some silica remain Table 5 lists the most common minerals found carbonate-hydroxylapatite (Table 4). These apatite result of the presence of intergranular gypsum and to form the common soil clay mineral kaolinite in Florida aquifer systems and confining beds. The minerals contain fluoride, phosphate, and small anhydrite (Tables 4, 5) Therefore, water that hasI (A12Si2O5(OH)4). Silica is also mobilized as silicic surficial aquifer system is composed amounts of uranium (Altschuler et al., 1958), which come in contact with the base of the aquifer acid (H-tSiO4), and potassium (K+) is a dissolved lon predominantly of sand from the south-central part are released upon weathering, system contains sulfate as a major constituent
cation. The H' in reaction 4 comes from carbonic of the peninsula to the western end of the acid through reaction 1, so bicarbonate is also panhandle. This sand is primarily composed of the Fnly h atoncnan ubro
prdcdI rpclt sbrpclciaemineral quartz, which is essentially chemically inert inally nthent Hathorn c otans ra ne of Nature of Aquifer System
proucd n roicl o ubroicl liats,(Table 4) The surfictal aquifer system in coastal trc osiunsta ay belcly impotn Itoiyad tutr
kaointe anbe urhe wethredacordngtoareas contains varying amounts of shell and sand- contains widespread but small quantities of pyrite to silt-sized calcite and aragon ite. The (Table 4), which release iron and sulfur as sulfate or calcite/aragonite content of the aquifer system sulfide to ground water The sulfate may be in the Porosity, the nature and amount of pore space increases to the south, and the Biscayne Aquifer of form of sulfuric acid (H2SOj), and the sulfide may in an aquifer system, and structure, the distribution southeastern Florida is predominantly carbonate be as hydrogen sulfide (H12S), which imparts a of large-scale fractures, joints, faults and karst A12Si2Q5(OHx~s, + 5H2O (5) The surficial aquifer system contains highly 'rotten egg" odor to water. Pyrite, and possibly features affect the ability of water to react with
-A1 2O, .3H20 +st 2HMSiU variable amounts of clay, oxyhydroxides, and other sulfide minerals, can release small quantities rock materials. This is because the size and
ibie a whumic material (Table 5), all of which are reactive of trace metals and arsenic (which is present in geometry of the pore space controls the amount of
and have the ability to sorb metals and some some metal sulfides) upon weathering. The reactive mineral surface area with which the waterU
with release of additional silica as silicic acid anions. Iron oxide coatings, which have some Hawthorn also contains gypsum, a source of comes in contact Where faults, fractures, and
Gibbsite (A120,.3H20) is one of several common sorption capacity, are common on the sands In sulfate (Table 4), at scattered localities7. This large caverns exist, contact of water with rock is aluminum oxyhydroxides found in Florida soils all, the sand-rich surficial aquifer system has the gypsum has not been previously described, nor minirmized and water can travel through an aquifer Both kaolinite and gibbsite are residues in the ability to sorb moderate amounts of metals and has its origin been determined. Rosette-shaped system without significant changes in compositionU Goldich weathering reaction (reaction 2). Aluminum anions. In addition, the carbonate-rich portions of clusters of gypsum, especially those which have can also be mobilized in ground water if the waters the aquifer system have the ability to consume been replaced by chalcedonic quartz, are probably INTERGRANULAR POROSITY are acidic or organic rich, (buffer) acidity by reactions similar to reaction 3. a primary deposit indicative of playa lake orI
occurrences do not have diagnostic crystal forms, All of Florida's aquifer systems contain
Iron and aluminum oxyhydroxides, sulfide and The intermediate aquifer system and confining but the nature of their occurrence suggests that significant intergranular porosity. lntergranular sulfate minerals, and a few other minerals are beds comprise a complex array of materials (Table the gypsum may have formed as a result of pyrite porosity dominates in coarse siliciclastic0 aquifers, weathered by different processes, which are dis- 5) with important consequences for ground-water oxidation such as occur in the sands and gravels of the
cussed with the individual analytes below. Clay quality. Strata of the Hawthorn Group include surficial and parts of the intermediate aquifer
minerals and some of the oxyhydroxides are also interfingering beds of clay, sand, dolostone, systems. With intergranular porosity, the pores
important as sites for ion exchange, which may limestone, and phosphorite (Scott, 1988). The mineral assemblage of the Floridan aquifer through which water passes are the spacesU
also affect ground-water quality. system is less complex than the other aquifer between sand grains. The passages (pore throats)
systems (Table 5). The predominant minerals are between adjacent pores are often small, and sandy
The clays include a predominance of calcite in limestone and dolomite in dolostone aquifers can be excellent mechanical filters for
When water sequentially passes through rocks magnesium- and iron-rich smectite, palygorskite, (Table 4) Dolomite is widespread. Significant microbes, and small particles of humic material,U with different mineral compositions, the chemistry and sepiolite (Weaver and Beck, 1977; Reik, 1982; portions of the Floridan in the SRWMD and oxyhydroxides, and clays When the pore throats of the resulting water reflects the compositions of Scott, 1988). Weathering of these minerals SFWMD are dolomitic Also, large sections of become plugged, permeability is reduced Fine to
all previous contact, not just the rock type from releases iron, magnesium, and silica, and Middle Eocene to Paleocene strata (particularly the medium sand aquifers have moderate areas of which the water was sampled. For example, water produces kaolinite as a residue (Table 4) Clay-rich Avon Park and Oldsmar Formations) of the mineral surface in contact with the water, and,I from the Floridan aquifer system that has passed horizons often contain opaline material (opal-A and Floridan aquifer system are dolomitic. Where the while quartz is inert, coated sand grains, interstitial through the confining beds of the Hawthorn Group opal-CT; Jones and Segnit, 1971), which also lower Hawthorn Group carbonates are part of the clays, or interstitial oxyhydroxides can chemically contains fluoride, magnesium, silica, and other releases silica upon weathering. The clays have Floridan (Scott et al., 1991) dolostone is likely to be interact with the water.

14







FLORIDA GEOLOGICAL SURVEY


Where the surficial aquifer system is porosity at two different scales. Intergranular Floridan aquifer system in central Florida are however, the mixing is between waters that differ
composed of quartz sand and gravel, porosity is porosity is present in most areas, but the characteristically long, and changes in composition significantly in chemistry, important changes in
intergranular White, loose, "sugar sands" have permeability associated with intergranular porosity along the flow paths reflect chemical maturation9 composition and reactivity of the mixture may U ~ little interstitial material or grain coatings, so they is significantly less than that characteristic of as reactions occur, result (Runnels, 1969). There are two situations in
have little ability to sorb and bind dissolved larger, interconnected cavities, such as caverns, Florida where natural mixing (as opposed to mixing
chemicals. Brown, coated sands and clayey sands vugs, fossil molds, and fractures. Therefore, unless Residence time is, therefore, the length of time of contaminated water with native water) is known
have moderate sorption capacities which can a well is located in the middle of a block of rock the water has been in contact with a particular rock to be important These are (1) mixing along the
improve water quality to a limited extent. As the that is affected only by intergranular porosity or in type. Residence time is a function of hydraulic fresh-water/sea-water transition zone0 in coastal clay and carbonate contents of the surficial aquifer which the larger pores are unconnected, water head, bulk permeability, and flow path length areas and (2) mixing of fresh and saline waters system increase, porosity remains intergranular, quality in the well reflects the more productive, Residence time decreases if either head or near the base of the upper Florndan aquifer system. I ~ but permeability is reduced The clays and larger interconnected pore space. When water permeability increases. If water passes through
carbonates are reactive and the low water/mineral passes through larger cavities, the water may not rock rapidly, there may not be sufficient time for In both of these settings the mixtures have
surface area ratio suggests that chemical come in contact with rock, or it may have a short the rock to interact with the water. On the other been shown to have increased ability to react with
interactions are increased in comparison to pure time in contact with the rock The water has little hand, a long residence time mnay allow sufficient the host limestones and dolostones Hanshaw Islands. opportunity for chemical interactions with the rock time for full chemical equilibration of the water and and Back (1971a,b), Badiozomani (1913), and
and it retains its chemical character inherited from rock In the first instance, the rook will have rifle Plummer (1975), for example, showed that mixing precipitation, soils and human impacts, or earlier effect on the water; in the second, the effect may in the transition zone can cause dissolution of The siliciciastic beds of the Hawthorn Group rock contacts For example, Upchurch and be considerable. calcite and, under certain circumstances,
I ~ constitute part of the intermediate aquifer system Lawrence (1984) were able to identify a plume of precipitation of dolomite. The dissolution of calcite
These sands contain significant intergranular clay surface water within the Florndan aquifer system Typical residence times range from days to can lead to development of karstic features

Sand phosphatic sediments that range from gravel that orginated from Algator Lake in Lake City, thousands of years depending on the nature of the (caverns, enlarged fractures, etc.) and formation of
to clray sies The phspat mineral (arbonate- Columbia County The plume extended several flow system. Residence times in the surficial collapse breccias. Precipitation of dolomite in the
fsorap atitenng carboaedroxypaite4)h ae kilometers south of the lake along a prominent aquifer system range from days to perhaps space created by dissolution of calcite is thought disorce o speaten prod Te 4),yuc ars fracture trace hundreds of years The flow systems are short by many (Hanshaw and Rack, 1971a,b;
also subject to weathering, and they also have high (T6th, 1962, 1963), with primary discharge to local Badiozoman i, 1913) to be an im portant
sorption capacities, which assist in retarding the Structure of the clay-rich confining beds of the wtadlks temadcnl.I sntdlmtzto ehns
mvmn certain metals in ground water Hawthorn Group is also important Vertical possible to predict residence times in the
(Upchurch et al, 1991). The clays yield magnesium leakage through the confining beds is most intermediate aquifer system because of the Aquifer Microbiology
I ~ and silica upon weathering efficient where these beds are breached by complexity of pathways through the lithologically
sinkholes or where the clays have developed diverse Hawthorn Group. Water that passes All aquifers contain microbes (bacteria, fungi,
blck facursthrough sinkholes, fractures, and karst conduits and other organisms) that play important roles in
lntergranular porosity in the carbonate- blcyfatrsthat penetrate the Hawthorn may have brief teceityo h ae osrie hs
mineral-rich Biscayne Aquifer and the Floridan residence times. Conversely, water that passes miecemsrquirte oure o uricarbos,
aquifer system is between carbonate grains, which Aquifer System Flow Path and along the tortuous pathways in the clay-rich nitrogeps porur slur on, and otrb,
are chemically reactive. These aquifer systems are Residence Time horizons may have residence times of thousands nutriens Becasehese utfrirnts aendotrma
doubly porous, with both primary, intergranular to tens of thousands of years. Residence times in introduced intoathe aquier systems near th land
I porosity and secondary, fracture- or karst-related The length, depth, and tortuosity of the flow the Floridan aquifer system also cover a wide surface, the microbes are most abundant there,

Sporosity Due to the presence of secondary path a body of water follows In an aquifer system range of time Short times have been recorded for and they decline in abundance with depth
dissolution features and fractures, the intergranular profoundly affect the quality of water In general, some sinking streams and resurgences in north Microbial utilization of these nutrients results in a porosity of these aquifer systems may be sign'- shallow, short flow paths, which are characteristic and central Florida (e g., Ceryak, 1977). These number of changes in aquifer chemistry. These ficantly less important in terms of water flow than of the surficial aquifer system, result in low short residence times are associated with conduit changes are discussed in detail with the individual
the larger openings. As a result, these aquifer residence times for chemical reactions to go to flow over distances of a few kilometers In analytes (below). The most important roles
systems may contain blocks of rook where water completion Also, short flow paths result in contrast, Hanshaw et al (1965) used C dating mcoe lyi anann qie hmsr
quality is dominated by the reactions associated contact with a limited number of different aquifer methods to approximate residence times in the mires pay irnfmrrnaiing aquniereisryn with the high grain-surface areas characteristic of minerals and less opportunity for chemical regional flow system of the Floridan aquifer system sulfur species For example, sulfate-reducing
intergranular flow systems These blocks are composition to be altered Consequently, total in the west-central part of the state They foundbatrarnsrmufte(O-toydgn
separated by zones of cavernous or fracture dissolved solids contents are less than those residence times in excess of 30,000 years for flow bactida tr)asformdulaengC' to hdoe
U ~ ~~porosity that have distinctly different water anticipated for longer flow-path systems By the from northern Polk County to coastal Sarasota slie(2)acrigt
compositions same reasoning, short flow-path systems are more County This long residence time is associated
vulnerable to contamination because of lack of (1) with ground-water velocities as high as 2 to 8 so; + 2Cra +2H20
I ~~CAVERNOUS, VUGGY, contact with reactive aquifer minerals or (2) meters per year (Hanshaw et al, 1965).mirba
AND FRACTURE POROSITY sufficient time for chemical reactions to occur.mcrba
Mixing with Other Waters in the-(6
If the flow path is long (on the order of tens of Aquifer System()
U The Biscayne Aquifer, carbonate aquifers of kilometers), reactions between rock and water activity
the intermediate aquifer system and limestone and become more probable and the total dissolved Mixing of waters in aquifers is common Most
dolostone of the Floridan aquifer system are solids content of the water increases as a result of of the time mixing is of little consequence. When, Its +i 2HC03,
doubly porous That is, they contain two types of continued rock weathering Flow paths of the

15






SPECIAL PUBLICATION NO. 34


By this reaction, organic carbon and sulfate aquifer system, which is one of the most Aquifer water quality include Klean and Hull (1978) GENERAL DESCRIPTORSU
are consumed and hydrogen sulfide and productive aquifer systems in the world and the and Radell and Katz (1991) The latter report
bicarbonate produced Since bicarbonate is also a major source of public supply for much of the includes some of the Background Network data. A eprt,
product of weathering of calcite! addition of state, has been widely studied major U.S. Geological Survey report on the TeprIr
bicarbonate through sulfate reduction will tend to chemistry of surficial aquifer system water in
drive reaction 3 to the left and may induce calcite southwest Florida is in review (Berndt and Katz, IMPORTANCE
precipitation Thus, microbial activity may result in Surficial Aquifer System pers comm ,1991). Salt-water intrusion in the
a complex array of "spin off" reactions that affectMamar hsbnamarcoensneth
major and minor element compositions of ground The surficial aquifer system is not a major 1950's. Several landmark papers on the salt-water Temperature of ground water is controlled by
water. source of water in most of the state. This report is transition zone were written on the transition zone climatic conditions, cultural activities, heat flow
the fist sttewid syntesis o its roundwaterin theMiamiarea hesefromudtKhe ea(19h'sb)intertiorrt'andnenhricdalhm reactiontsnsin thefist taewde ynhess f ts rond-atrand ther iam ae Ths1 icud9ohu4)90ab the aquifer system. Water temperature affects the
DEFINITION OF HYDROCHEMICAL qrualt gMano the rindidalr-ount and wae adCoeeta.(96)nature and rate of chernical reactions and
FACIES maaeetdsrc ae-upyrprsmicrobial activity in aquifers. It can also be used to
published by the Florida Geological Survey, U.S Intermediate Aquifer System evaluate the residence time of water in aquifer
The net result of the factors discussed above districts contain minor amounts of chemical datasytmandehtowihgudwtrhs
is that the composition of ground water reflects its on the surficial aquifer system. Southwestern Flonida (portions of Charlotte, moved.
recharge and flow history. Shortly after recharge Lee, and Collier Counties) and portions of FlaglerI
the chemistry may be highly variable, but with and Indian River Counties in east-central Florida In shallow aquifers, water temperature is
chemical maturation, as a result of increasing The sand and sand-and-shell portions of the are the only areas where the intermediate aquifer usually controlled by climatic conditions, as
reidnc tme hecopoitos ecmemoesurficial aquifer system in northern and system is a major water-supply aquifer. The opposed to other possible causes. Water that has
reincftim.e, thea compositions befecom motrein northeastern F orida are used for public water quality of water in the intermediate aquifer system rUetyetrdteaqie ytmnral
wit te ajr ocktyesalngtheflw ats.suply ntalyin St. Johns County. Elsewhere in in this area has received some attention, relently eter tempuierau t syte m ormll
SFWMD scatterd, doWmesti lsW suppl Elsewhere, little interest has been shown in water recharge. Therefore, temperature can often be
Partof his ompex hdrohemcalistryWoFpoabl w attermted sumrficia aqie systelyu quality of the system. Duerr and Enos (1991) used to identify recently recharged ground waterI Par ofths cmplx ydrcheicl hstoy f ptabe ate frm he urfcil auifr ystm, discussed the hydrogeology of the intermediate If the temperature of the water source is modified ground water can, therefore, be determined by otherwise its main use has been for irrigation, aquifer system in Hardee and DeSoto Counties. by human activity, including such activities as examining the regional composition and variability waste disposal, and maintenance of surface-water Duerr and Wolansky (1986) described the industrial processing, power generation, and some of the water. Broad regions of an aquifer system features There are a few studies that characterize intermediate aquifer system in central Sarasota forms of waste-water disposal, temperature can beI that can be shown to contain water with relatively water quality in the surficial aquifer system of north County, and Duerr et al. (1988) described the an excellent parameter to identify affected water in uniform major-element compositions are repre- and central Florida. These include Hutchinson intermediate aquifer system in southwest Flonda. the aquifer system In karst systems, actively sented by a particular hydrochemical "fadies"" (1978), Causey and Phelps (1978), Hayes (1981), Wedderburn et al (1982) described the geologic recharging sinkholes can sometimes be identified Methods of identification and wrapping of Duerr and Wolansky (1986), Duerr et al. (1988), and framework of the intermediate aquifer system in because the water they introduce is at a differentI
hydrochemical faces have been described by Upchurch et at. (1991). In general, the emphasis of Lee County, and they included some water quality temperature from the ambient ground water. As
Back (1961, 1966). As an example, waters of the these papers has been to simply describe water data Upchurch (1986) used uranium-series the water moves away from local recharge areas
Flonidan aquifer system which have been in con- quality in the surficial aquifer system. Upchurch et isotopes and major element chemistry to establish and enters local flow, water temperature in shallow tact with limestones are likely to belong to the al. (1991) included reduction-oxidation potentials interaquifer connections between the surficiat, aquifer systems approaches mean annualU calcium-bicarbonate facies as a result of limestone and radionuclides in their study of surficial aquifer intermediate and Flonidan aquifer systems in Lee atmospheric temperature Because of the local weathering Water in a quartzose portion of the system waters in, and near, interaquifer recharge County. nature of shallow aquifer systems, it may be
surficial aquifer system may belong to a sodium- wells in Polk County. dfiutt orlt eprtrsfo n elt
chloride faces dernved from the marine aerosols dfiutt orlt eprtrsfo n elt
that give precipitation its chemical character. TeSnadGrvlAufroEsmbaFloridan Aquifer System aohr
County is a major source of public and private In deeper aquifer systems, temperature can be
PREVIOUS WORKS supply for western NWFWMD. It had been Because of its importance as a water-supply affected by recharge from shallow environments,
somewhat neglected until recent years, when the aquifer, the Floridan aquifer system has been earth heat flow, and chemical reactions. Of these U.S. Geological Survey began a comprehensive extensively studied. Important papers that discuss
The aquifer systems of Florida have been study of the aquifer, including water quality, water-quality data include Stringfield (1966), heat flow has received the most attention in Florida
intensely studied for over 50 years. Previous Significant papers on the chemistry of the Sand Stningfield and LeGrand (1966), Rack et al (1966), (Smith and Griffin, 1977). Rock is an excellent studies have largely been directed toward aquifer and Gravel Aquifer include Katz and Choquette Kaufman and Dion (1967), Back and Hanshaw thermal insulator, so water temperatures change
systems that are heavily used. As a result, large (1991) and Roaza et al. (1991) (1970, 1971), Plummer (1977), Wilson (1977), Hull slowly. As water passes downward into deeper
areas of the state that are characterized by low and Irwin (1979), Ceryak et al (1983), Crane (1986), parts of an aquifer system, itis warmed by heatU
populations and aquifer systems with little use Sprinkle (1989). Duerr and Enos (1991), and I generated nearer the earth's interior. In Floridathis
have been neglected. With the exception of the The Biscayne Aquifer has been extensively Jones (1991). A major review of the hydro- warming is slight because of the dynamic
Biscayne Aquifer and, to some extent, the Sand- studied because it is the major source of potable chemistry of the Floridan by Katz (pers. comm., circulation within the deeper aquifer systems and-Gravel Aquifer, very few studies have been water for southeast Florida. Early work on the 1991) using data from the Background Network is (Smith and Griffin, 1977).U directed toward the surficial aquifer system. The physical aspects of the aquifer includes Parker in review by the U.S. Geological Survey intermediate aquifer system has also been (1951) and Parkeret al (1955). More recent papers If deep-flow-system water moves upward
somewhat neglected. In contrast, the Floridan that include important summaries of Biscayne


16








FLORIDA GEOLOGICAL SURVEY

3 ~without sufficient time to cool, such as might occur Figure 6 shows the distribution of temperature Acid-Base Relationships (pH-) The acids may then react with aquifer
in large conduits near the coastal salt-water in the surficial aquifer system, by distrnct With the minerals, during which acidity is consumed and
transition zone, warm springs may result. Few exception of the surficial aquifer system in the IMOTNEalkalinity is produced. Quartz is inert (Table 5) and
warm springs exist in Florida. The most notable SFWMD, the data are not contoured due to the IMOTNEhas no affect on pH. Carbonate minerals are
are Warm Mineral Springs and Little Salt Springs in lack of continuity between data points. The highly reactive, and buffer the pH through
Sarasota County (Rosenau et al., 1977). Warm inability to contour these data reflects the localized The variable pH reflects the potential for acid- consumption of acidity and production of HCO3.
Mineral Springs has waters ranging from 23 to nature of the flow systems and temperature base reactions in water. As such, it is often treated For example, the major mineral in the Eloridan
I 3700 (Clausen et al., 1975; Rosenau et al., 1977) variations over the time of sampling. The variability as a variable that determines the reactions in the aquifer system is the carbonate mineral calcite
Ishgeral thereonarm fwaste adrelatiuey oa thedatahereforeti, recsarge ofesalngecin h Ho qie ae s nfca ecin3 h eutn Hicesst prx
i scageer o the re io nal flow sstes a re lat i e ly o ca e at ,her econd ti re c hargi e events, ng, aquifer system rather than as the product of those (CaCO ). It reacts w ith carbonic acid according to
U cold waters to recharge. Deviations from this depth in the aquifer system result of past chemical reactions, and it is also a imately 7.0-7.5, depending on temperature and
large-scale regional pattern are generally caused measure of the potental for reactions, if chemical CO; concentrations.
by rapid lcal recharge, conduit flow, or Intermediate Aquifer System equilibrium between the water and surrounding
contminaion.rock has not been established. It as included in this In recharge areas, waters that have not
I section because of its importance in predicting equilibrated with carbonate minerals tend to be
STANDARD OR GUIDANCE In many areas of the state the intermediate reactions that affect both cationic and anionic more acidic due to the presence of carbonic and
CRITERION aquifer system is more isolated from surficial constituents discussed below organic acids. In Florida, water from mid-flow and
I ~~~~~~~~~~~conditions than the surficia! aquifer system. dshreaeshscm ncnatwt
However, there is still considerable variability in the dshreaeshscm ncnatwt
There is no standard or guidance criterion for data (Table 6; Figure 7). Median temperature in the The hydrogen-ion concentration in water is carbonates and other minerals, so pH values tend

Temperature in ground water (Flo rda Department intermediate aquifer system is 24.60C statewide, indidcsp ,ahc i ein d a te n gaitor o the i tohry ofrdsctis of ex aern
of Environmental Regulation, 1989) with a quartile range of about two degrees (Table' logarithm of the hydrogen-ion activity. Waters with idctro h itr fratoso h ae
6) As with the surficial aquifer system, there is an a pH of 7 are neutral, while values less than 7 are with aquifer minerals. increase in water temperature to the south, which acidic and those greater than 7 are basic, or
DISTRIBUTION IN GROUND WATER reflects an increase rn mean annual atmospheric alkaline. Hydrogen ion (He) is generally the cause STANDARD OR GUIDANCE
temperatures. of acidity, and bicarbonate (HC0; ) is the most CRITERION
Tempratre dta rom halow auifr sytemabundant source of alkalinity in natural waters e r nm e at ur(e at ah r s hallowa aquifer system A cidity can also be generated by other proton
enviownenied pr.n, the sufca qientemdt Flordan Aquifer System donors, notably organic acids, and alkalinity can The guidance crteron for pH in Florda ground
I sadlloncnfqiedrytions) ofrte intermedate. be created by proton receptors, such as waters is established by the Secondary Drinking
Water from local recharge areas is ikely to reflect Temperature data for the Floridan aquifer phosphate (P043) and nitrate (NO;). Wttand eayerd(cabtner -5 Florida stautes
conditions at the time of sampling Temperature of system are summarized in Table 6 and Figure 8 (Flrid Dseartyent freb Enroa Reguation,
U ~ recently recharged water and of very shallow water The regional data clearly illustrate flow-system- The pH in aquifer systems is normally 1989nd. ThepHrm of ter mtalti teuratne
varies with seasons, so these data do not related patterns. Water temperatures are cooler controlled by chemical reactions with the of65o8).5 accpHoftrd utf w the stangrd

I ~~represent long-term conditions Temperatures in inland, where recharge is likely, and warmer near atmosphere and rock framework For example, o o85acrigt h tnad
deeper portions of the aquifer systems do not vary the coasts, where discharge after passing along a ground water becomes acidic by dissolving carbon
U significantly with time, and the data are better deep flow path occurs. Cooler waters are often dioxide gas (COJ). The carbon dioxide is produced Water less than 6.5 is likely to be corrosive,
indicators of long-term conditions. present near drainage divides. Note that water by equilibration with the atmosphere and with have high iron and high phosphate, and cause
temperatures in excess of 280C occur along the carbon dioxide produced by microbial decay of transport of undesirable metals, such as lead Surficial Aquifer System Peace River lineament (G Jones, 1991) and in humus in the soil. The reaction forms carbonic Above 8.5, the waters may also be corrosive to
coastal Sarasota County (Figure 8d). The wells acid (H2CO2) by the reactions given in reaction 1 certain alloys and boiler scale and turbidity may along the Peace Rrver tap the lower portions of the result from precipitation of carbonate minerals
Since the surficial aquifer system is, by aquifer system in an area characterized by Eulbaino ae ihamshrcC2
Definition, unconfined or poorly confined, water upwelling (Healy, 1975; Kaufman and Dion, 1967,Eqibrtnofwtrwhamspn C,
temperature often reflects the most-recent Lehrnan, 1978) The coastal wells are in the which has an average partial pressure (gas It is unlikely that natural pH values greater than
Recharge and seasonal temperatures. Conse- coastal upwelling zone in the vicinity of Floida's concentration) of 10" results in a pH in rainfall of 8 5 will occur in most Florida aquifer systems.
quently, water temperatures within a region vary warm springs (Warm Mineral Springs, Little Salt about 5 5 Once the precipitation infiltrates, the Where pH values of aquifer water are this high, well Iosdrby nadtotmeaue aywthSrns lue ta. 95 oea ta. water reacts with the CO. in the sol atmosphere, construction problems are usually indicated. This
coniuderb Ind aditiosytem per(atures var weith Spig; luene l 95 ).nu ta. and the pH drops even more, The partial pressure is because driling fluids and poorly cured cements
latit em ra rs andaf rystem ty (les 6) ein 1977).rnof CO:, in the sol can be as high as 10-", which is and grouts are highly alkaline. Natural, aqufer
watrnsf teeate a slighess in othernut 10 to 50 times the CO, in the open atmosphere water in siliciclastic aquifers is likely to fall below
Wportins theufr statemssd and ereabout Median ground-water temperature in the The high C02 partial pressure in soil atmosphere is the minimum of 6 5 due to the carbonic and
Where tepaur systemld stady wand prehable, Florndan aquifer system is 24.00C There is an a result of CO, production by sol microbes as they organic acid contents.
Cater tepratursfe aufr sholfucutem wtchae.s increase in temperature toward the south, and the metabolize humus. Dissolved organic acids are Clayy prtios o th aqufersysem hve essmedian temperatures by district reflect atmos- also a by-product of the microbil decay of humus U ~ exchange with the surface and respond to phenic temperatures. Therefore, the pH's of soil waters and shallow, Table 7 lists the number of samples in which
recharge events less rapidly surficial aquifer system waters are commonly in the' the standard was not met. Note that 93 percent of
range of 3-5 from the carbonic and organic acids, the surficial aquifer system samples in the


17






SPECIAL PUBLICATION NO. 34


NWFWMD failed to meet the standard, whdle only surficial aquifer system waters, by district. Note buried and individual water-producing horizons These are from shallow wells that are near swampsI 27 percent failed in SFWMD Statewide, water that there is considerable local variability, which become more continuous With more isolation in unconfined, or poorly confined, areas In these samples from the surficial aquifer system failed to reflects variations in well depth, aquifer mineralogy, from the land surface and more lateral continuity, areas, high concentrations of dissolved organic meet the standard 37 percent of the time. Some of and local production of carbonic and organic pH data are less variable and more continuous As acids lower pH. Comparnson of these areas withI these failures represent the high alkalinities shown acids, In the SJRWMD (Figure 9c) the effect of a result the data can be contoured, the distribution of total organic carbon suggests a
in Table 1 and are a result of well construction coastward increase in shell content of the surficial close correspondence.
problems Most, however, fail the standard aquifer system on pH is particularly well Floridan Aquifer System
because they are low, which is a result of natural demonstrated. Inland, pH values are 6.0 or less, There is an area of high pH that extends from
causes Failure to meet the standard in the and near the coast the water may exceed 1.5. In southeast to northwest through Alachua and
intermediate aquifer system averages 16 percent south Florida (Figure 9e), pH is usually in excess of Table 1 depicts the distribution parameters for southern Columbia Counties in the SRWMD of the samples, while 14 percent failed in the 6.5 due to the high carbonate mineral content of pH in the Floridan aquifer system. Median pH's (Figure 11b). This high pH water may reflect some-U Florndan aquifer system. The lower failure rates in the Biscayne Aquifer and related rocks. All pH are uniformly near 7.4 with the exception of a 7.1 in what 'stagnant" flow under the Northern Highlands the intermediate and Floridan aquifer systems values above 8.8 in the SFWMD came from newly the SRWMD. ph values range from 4.9 to 12 5 in physiographic province (Lawrence and Upchurch, result from buffering with host-rock carbonates, constructed welLs These samples may reflect the SRWMD. The high range in Floridan aquifer 1976, 1982;Upchurch and Lawrence, 1984), which
aquifer system in the SRWMD results from high (grout, drilling mud) prior to sampling construction problems and high recharge of acidic This is a common phenomenon where the Floridan
organic acid content of waters from the poorly waters, is highly confined and the hydraulic gradient is low
confined Coastal Rivers Basin (Taylor, Dixie, and Intermediate Aquifer SystemI
below and in the Total Organic Carbon section The high values (12.5 in SRWMD, 12.2 in Regional flow in the Floridan is such that
The high range in pH values in the intermediate SJRWMD, 10 1 in SWFWMD, Table 7) reflect waters from coastal discharge regions are likely to
DISTIBUTON I GROND WTERaquifer system (Table 7) reflects the mixed alkalinities that are aresult of residual drilling fluids have somewhat higher pH's due to the multiplicityI
DITIBTONI RONlWTRithology of the Hawthorn Group and related or well cements or grouts that have cured impro- of reactions that have affected the water along the
sediments. Both siliciclastic and limestone and perly. pH values within the upper and lower quar- flow path. This is illustrated in scattered coastal Table 1 summarizes the distribution of pH dolostone horizons serve as aquifers in the tiles (Table 7) are natural and represent equi- zones through the state. However, there is a
measurements. The aquifer systems that are Hawthorn Carbonate units have higher water pH vibration with the carbonates of the Floridan. surprising amount of low pH water in coastal
characterized by high carbonate-mineral contents values, while siliciclastic units may have low pH's, aesSm fti o Hwtri osa ra
have median water pH values that are slightly over if the water has not come in contact with The minimum pH of 4.9 in the SRWMD reflects reflects local recharge, which may be acidic due to
1, while siliciclastic aquifer waters have pH values carbonate minerals. Median pH of waters from the water that contains carbonic and/or organic acids organic acids or carbonic acidI of 5 to 6, depending on the amount of admixed intermediate aquifer system is 7.3, which reflects that have not yet reacted with the Floridan carbonate mineral material. buffenng by reactions with carbonate materials in carbonate minerals (Lawrence and Upchurch, Water from areas where the Floridan is
many portions of the aquifer system. 1976). This is locally common in recharge areas unconfined and near the mouths of rivers, such as
Surficial Aquifer System characterized by conduit flow. Because of the near the mouth of the Suwannee River (Figure
Figure 10 illustrates the distributions of pH large amount of rock surface area to which non- 11 b), shows low pH values, which appears within the intermediate aquifer system Note that conduit (intergranular) flow water is exposed, inconsistent with the regional discharge pattern. The surficial aquifer system in the panhandle there is considerable variability in pH at a local equilibration of water and rock is much faster in These low pH waters may reflect local rechargeI and north-central Florida is predominantly quartz scale This reflects the nature of the aquifer intergranular-flow than in conduit-flow water and from the rivers or flux of lower pH- waters on the sand, which is not reactive with carbonic or horizons within the intermediate aquifer system. low pH values are not expected. Low pH values salt-water transition zone.
organic acids, As a result, pH values are generally Carbonate aquifers near the base of the system are widespread in the Coastal Rivers Basin (Taylor, low (Table 7), and the median pH values of surficial aetemsprdtvanthswtrsavpHDixie, and Lafayette Counties) of the SRWMD,
aqiersstmwte n WWD n SWDvalues near 7 as a result of reactions with where the Floridan is poorly confined and the Finally, there are minor indications (isolated
are less than 6.0. Elsewhere, median pH values are limestone and dolostone. The upper and middle surface is predominantly swampy and poorly wells with low pH water) near some urban areas
somewhat higher because of equilibration of the parts of the system include siliciclastic horizons drained, that may reflect use of drainage wells. Drainage
waters with carbonate materials, especially calcite that yield somewhat acidic ground waters, wells are utilized in many areas of the state whereI
and aragonite, in the aquifer system. Carbonates Fgriilusatshedtibio ofurban and suburban development is in karst
are found in the surficial aquifer system near the measure pH ilsr the dstribufr ytem.In terrain Drainage wells are installed to carry stormcoast in all districts, and throughout the south half The amount of carbonate material and lateral mesrdp nteFoia qie ytm water runoff into the host aquifer. The effects of
of SWFWMD and all of SFWMD. These result in continuity of aquifer horizons increase southward general, there is little variation in pH data, which is these wells have been studied by Hull and
higher median pH values in these districts. For within the Hawthorn. This can be seen by com- a common occurrence in carbonate-rock aquifers Yurewicz (1979), Kimrey and Fayard (1982), example, compare the median pH of the Sand and paring Figures 10a and 10b with 1be. The pH data due to buffering The patterns of pH in each of the Schiner and German (1983), and Bradner (1991). Gravel Aquifer of NWFWMD with the pH of the from the intermediate aquifer system in NWFWMD maps appear to be characterized by closed areas The sampling plan for the Background NetworkI
Biscayne aquifer of SFWMD. Minimum pH values and SRWMD (Figures 1 Oa,1 Ob) cannot be of high or low pH within an overall distnbution of was established to avoid urban areas with similar,
are in the 3 to 4 range, which reflects waters from contoured due to high local variability and lack of little or no variation. For the most part, these known sources of contamination, but suburban sandy aquifers in which no equilibration with stratigraphic continuity between production zones, closed areas reflect differences in depth of well and rural drainage wells were not avoided. Low carbonate minerals has occurred. The pH values vary by as much as one unit (one penetration and sampling. Shallow wells usually pH water near Orlando (Orange County, FiguresU
order of magnitude in hydrogen ion activity) have somewhat lower pH values and deeper wells lice), Live Oak (Suwannee County, Figure 11b),
between adjacent wells. In SFWMD, the have somewhat elevated pH values Several local and elsewhere may reflect this storm-water
Figure 9 illustrates the distribution of pH of intermediate aquifer system becomes more deeply areas show data with pH values hess than 6 5 disposal practice.

18







FLORIDA GEOLOGICAL SURVEY


U CATIONS are not included because they are rare in natural Sea water contributes calcium to the aquifer Floridan aquifer system water can be used to
Florida ground waters, systems in two ways Precipitation that contains identify local recharge areas.
marine aerosols introduces minor amounts of
Clasifictioncalciunm to the land surface. Average precipitation The chemical controls on cations are throughout Florida contains approximately 01-03 Precipitation of calcite as a result of
Cations are positively charged ions that are discussed under the individual constituents mg/L Ca2' (Table 3). Calcium is also important evaporative concentration is common in the generated by loss of electrons. Cations can be Common processes that affect cation abundances where mixing with sea-water-deived ground water surficial aquifer system Calcite 'sand crystals"
U grouped into three categories according to their iclu mxng of wrpatenr masses m airal along the salt-water transition zone occurs (TableS)- have been found growing in the quartzose, barrnerabundance in the natural environment ratns tinxhng nly, island sands of Dade County and in dolomitic silts
hydroxides and organics, and chemical corn- Weathering of silicates in siliciclastic aquifer in Citrus and Levy Counties. Calcitic nodules are
I MAJOR CATIONS plexing. zones is generally an insignificant source of widespread in the surficial aquifer system and
calcium in Florida ground waters Calcium-rich barrier islands throughout the state Vadose silicates are rare in Florida sands and carbonate pisolites occur in soil-filled caverns at the top of Major cations are the dominant elemental Calcium rocks An important exception results from the Floridan aquifer system in Hernando, Citrus,
present in concentrations in excess of 1.0 mg/L. system Smeotite (Tables 4, 5) is a major and Alachua Counties Evaporative precipitation
The major cations in Florida waters are calcium IMPORTANCE AND SOURCES component in the Hawthorn Group and although it has also been shown to form calcrete crusts on
I (Ca"), magnesium (Mg"), sodium (Na'), potassium contains more magnesium than calcium, rocks of the Biscayne Aquifer in south Florida and
K),ndstrontium (Sr2") With the exception of In many aquifer systems, calcium is the weathering can be shown to contribute some the Keys (Multer and Hoffmeister, 1968)
strontium, which is often less than 1 mg/L in dominant cation It is dominant because of calcium to intermediate and Floridan aquifer
Florida, all of the major cations are discussed weathering of the calcite (or aragonite) and system waters (Lawrence and Upchurch, 1982)
below dolomite (Table 4), the minerals that constitute Ion exchange is a widespread phenomenon in
limestone and dolostone, respectively Calcite and Calcium is removed from the aquifer systems aquifer systems deposited in coastal plain

MINOR CATIONS aragonite are abundant in shelly portions of the by mineral precipitation and ion exchange Calcite environments (Foster, 1950) Clays, particularly
surficiat aquifer system Dolomite and calcite cements and void fillings are common in smectites, have high ion-exchange capacities. The
constitute the carbonate-rock horizons and are sandstones and carbonate rocks throughout the ion-exchange reactions of sodium and calcium Minor elemental cations occur in concen- abundant as clasts in the siliciclastic horizons of state (see for example, Vernon (1951) and Pun and with a clay sorption (ion exchange) site can be trations of 0 001 to 1.0 mg/L Important minor the intermediate aquifer system The Floridan Vernon (1964) for descriptions of calcite-cemented characterized as follows
I cations include iron (Fe2-, Fe"), barium (Ba"), and aquifer system is composed of calcite and strata). These cements are a result of evaporation
manganese (Mn', Mn"). Iron is included in this dolomite. of calcium-bicarbonate-rich waters or by N
report because of its importance as a regulated degassing of carbon dioxide. However, Jones et N
water-quality constituent. Barium and manganese Th ecinfrwahngo ietn sal (in press) have argued that there is little regional Ioa + Ca2a
have not been included Ammonium (NH4) is a Teratofrwahrigflmsoniscementation in the Floridan aquifer system from -a
trace cation. However, for convenience it is given in reaction 3 Dolomite is weathered mass-balance calculations
Discussed in the Anion section with its negatively according to Na (9)
U charged counterpart nitrate (NO3) CaMg (CQ) 2 + 2H Calcite precipitates as a result of carbon r Ca-clay + 2Na

TRACEMETAL dioxidee degassing according to the reaction
TRCUETL 7
Ca i M"+2HO~ Ca2 +I2HCOk If deposited in sea water, these clays are initially
Ca + M 2HC saturated with sorbed sodium, which is loosely Trace metals include elemental cations that (8) held on clay-mineral surfaces. Calcium and
are characteristically present at concentrations In both reactions, calcium is released as a +CaCOd + COg + HO. magnesium have a higher affinity than does
less than 0 001 mg/L. Trace metals are usually dissolved cation. Therefore, calcium is expected sodium for clay surfaces, so when calcium- or
present in very low concentrations In natural to be a widespread and important cation in magnesium-rich ground waters bathe the Naground water due to (1) low abundance in aquifer carbonate-rich aquifers Weathering of limestones Carbon dioxide degassing is the common process
rock materials, (2) low mineral solubilities, (3) high and dolostones consumes acidity (reactions 3Sand for calcite cementation in caves (White, 1988) and clays, ion exchange is likely to occur Calcium or
I probability of adsorption on mineral surfaces and 7), so calcium concentrations are highest in shallow ground-water systems. Little work has magnesium exchange for sodium, and the clay
particulate organics, and (4) precipitation as a alkaline waters that are fully equilibrated with the been done on carbon dioxide mobility in Florida becomes a Ca-and/or Mg-saturated clay, while the metal oxide or sulfide If present, trace metals are host rock ground waters Starks (1986) has shown that water is enriched in sodium The reverse reaction
usually In the pg/L concentration range Some of degassing of carbon dioxide occurs on the occurs upon salt-water intrusion into Ca- or Mgthe important trace metals that occur in aqueous upward-flow portion of the Floridan aquifer system rich clays. Even though the sorption potential of
systems are lead (Pb2'), mercury (Hg"), cadrmium Calcium is also released upon weathering of near springs on the middle Gulf Coast This sodium is low relative to calcium or magnesium,
S(Cdj), chromium (Cr), and cobalt (Con). In gypsum and anhydrite (Table 4) Gypsum is degassing provides potential for calcite tehg ocnrtoso oimi e ae
UFlorida, lead and mercury are of concern due to occasionally found in the Hawthorn Group, and precipitation in coastal environments On-going tehg ocnrtoso oimi e ae
the widespread occurrences of these metals in both gypsum and anhydrnte are common at the research at the SWFWMD (Upchurch, Jones, and cause exchange with a release of calcium and
aquatic organisms For this reason, lead and base of the Floridan aquifer system, in the Avon DeHaven, 1992, pers. comm.) indicates that magnesium and a loss of sodium in the ground
mercury are discussed below, The other metals Park and Oldsmar Formations carbon dioxide partial pressures in shallow water

19






SPECIAL PUBLICATION NO. 34


STANDARD OR GUIDANCE surficial aquifer system in the SJRWMD and limestone and dolostone that have been reworked equilibration thereby enhanced. Upchurch and
CRITERION SWFWMD includes carbonate minerals In coastal by waves and currents into and mixed with the Lawrence (1976) also suggested that high calcium
environments and in the southern half of the quartz sand and clays. As a result, calcium in the Flondan aquifer system in the vicinity of the
SWFWMD The surficial aquifer system in SFWMD content of the water is uniformly high relative to the Cody Escarpment, a zone of high recharge at the
There is no standard or guidance criterion for is predominantly carbonate. surfial aquifer system (cf Table 10 and Figures transition between the unconfined Flordan of the
calcium in ground water (Florida Department of 12 and 13) Coastal Lowlands and the highly confined Floridan
Environmental Regulation, 1989). Calcium is not o h otenHglnsi ot lrdi
considered a hazardous component in potable The distribution of calcium in the surficial result of complexing with natural organics. BrownI
water. aquifer system is shown in Figure 12 It is difficult Calcium concentrations are highly variable (1989) confirmed that organic complexing ento reconcile some of the calcium concentrations in because of the heterogeneous nature of hances transport of calcium, but failed to show a
The calcium plus magnesium content of water the surficial aquifer system with known composition in the Hawthorn Group and wide strong spatial correlation with all of the high
called "hardness", Durfor and Becker (1964) compositions of aquifer materials. For example, range of contact times between rock and water calcium regions in the escarpment environment.
IS the surficial aquifer system in the interior of the (Figure 13ab, and c). There is a minor increase in The location of these studies is within the >200
classified waters according to their hardness state n north Florida is predominantly a siliciclastic calcium content towards the coast in the SJRWMD (fable 9). Hardness is of concern because calcium aquifer system. As such, calcium concentrations (Figure 13c), which reflects salt-water intrusion and mg/L zone in southern Columbia County (Figure and magnesiurm interfere with the function of should be relatively low. Most analyses in increased carbonate content and water residence 4b).I
soaps and certain detergents Hard waters are also NWFWMD and SRWMD are low (<10 mg/L, Figure times. a problem because they form calcium- and 12a,b), however a few of the analyses are in Back and Hanshaw (1971) studied the
magnesiurm-carbonate mineral residues ("scales") excess of 20 mg/L These may reflect calcium distribution of calcium and degree of saturation ofI
in hot-water heaters, boilers, and humidifiers, derived from (1) cements used in well construction, In southwestern SWFWMD (Figure 13d) and aquifer water with respect to calcite and dolomite Evaporation of hard waters leads to scale on (2) weathering of carbonate minerals or rock western SFWMD (Figure 13e) there is a second in central Florida.Thyfudta acm
firswmn olwalbtr and dihs.Frttsceaos halren fragments reworked into the surficial sands and process operating. Upwelling along the salt- -concentration and saturation state of the water
fitrs n ihs o hs esnalregravels from the underlying Hawthorn Group or water/fresh-water transition zone brings deep with respect to the minerals increase along theI
industry selling and supporting water softeners has residual from the original shell content, (3) fugitive Flondan aquifer system water into the intermediate flow paths radiating from the vicinity of the Green evolved. Care should be taken, however, in dust from unpaved roads, quarries, or nearby aquifer system (Upchurch et al., 1991). This water Swamp in northern Polk County (Figure 14d).
consumption of softened water due to increased construction sites, or (4) application of calcium-rich has some of the longest and deepest flow paths of sodium content. Additionally, calcium-rich waters soil amendments, such as gypsum, calcite, or any aquifer system water En Florida. As a result ofI provide dietary calcium. Hardness of waters in the dolomite. All of these sources can locally affect having traveled along the base of the Floridan, The data from SJRWMD (Figure 1 4c) and Floridan aquifer system has been described by the chemistry of the surficial aquifer system. Also, where it picked up calcium from the dissolution of SWFWMD (Figure 14d) support this conclusion, Shampine (1965) and Sprinkle (1982a). since the samples were not filtered, the presence gypsum, calcium is present in excess of 100 mg/L although the pattern is not as apparent asI
of suspended particles may affect some analytical inoicase i alcium tans d 19.ther i th
DISTRIBUTION IN GROUND WATER results- Flondan Aquifer System SJRWMDabutn mostof thwer hger caliumh
concentrations appear to be a result of saline-I
Calcium concentrations in ground water in In coastal areas and the southern half of the The Flordan aquifer system is almost entirely water upconing in central Flagler and Volusia
Florida are a direct result of aquifer contact, Florida peninsula, the surf icial aquifer system limestone or dolostone. Waters that are in equl- Counties (Figure 14c). Sea water, which averages residence time, and flow path. Table 10 compares contains shell, marl, and limestone. In these areas, irum with the host aquifer rock, therefore, have 411 mg/kg (Table 8), locally a potential source of the calcium contents of aquifer systems, by calcium will naturally be relatively high and local high calcium content, Much of the variability shown calcium at the transition zone throughout the state.
district. Comparison of the surficial, intermediate, influences, such as discussed above, will be in Figure 14 is a result of well depth or position of and Flonidan aquifer systems illustrates the role of masked. Calcium increases toward the coast in highly productive zones in long open-hole wells. Climi oeti ehreaesi eta calcite and dolomite dissolution in aquifer the SJRWMD (Figure 12c) indicating the increased Water from deeper wells often has higher calcium Pasco Cunty adwinsth uppr Wthlacooche anU
chemistry, ~~~~~~importance of calcite and aragonite in the surficial and sulfate concentrations due to contact withHlsb r ghRvrwtrh d n he WF M
cheisty.aquifer system near the coast A similar pattern is gypsum and anhydrite at the base of the Flordan, THilsbrugh Rsoie wtrshe Withace FW D
present in northern and central SWFWMD, but long flow paths, and long residence times. Wells Tergo soitdwt h ihaoce n
Calcium concentrations are generally higher in there is also a net southerly increase in calcium that have long reaches of open hole cannot be Hillsborough Rivers coincides with the margin andI the intermediate and Floridan aquifer systems than along the southern district boundary (Figure 1 2d) untfdasodphofhewtrspe.t western half of the Green Swamp and suggests
in the surficial aquifer system (Table 10). This is a This increase in calcium is continued in western qunfedr tato deyptodfte wtrisame It bs that recharge is most effective on the margin of the result of interaction of the water with limestone and SFWMD (Figure 12e), and reflects increased of the aquifer system in central and south Florida clsiomp a po os bera ntr y swancarn dolostone horizons in both aquifer systems and importance of shell to the south. (the 'boulder zones" of Purn and Winston, 1974)) are Hcinson (1992) frown istoi da.nce nwith carbonate clasts in siliciclastic horizons of the often characterized by htgh calcium and sulfate. Htratonsoincrese9 ad2)l from thesedta reonsn
ineredat qufe sstm Due to the high transmissivities of these Zones, according to the Back and Hanshaw (1971) model.
wells that tap them are characteristically donated The high calcium in the vicinity of the Peace RiverI Surficial Aquifer System ItreieAqfrSyemby these deeper waters (southern Hardee, Desoto, western Sarasota, and
Intemedite quifr Sytemnorthern Charlotte Counties; Figure 14d) coincides
Calcium concentrations are least in the Lawrence and Upchurch (1976; 1982) found with upwelling of calcium-sulfate-rich waters at the
surficial aquifer system, especially in NWFWMD The intermediate aquifer system includes somewhat elevated calcium concentrations in the salt-water transition zone. G. Jones (1991) has
and SRWMD, where the aquifer system is abundant beds of limestone and dolostone, and highly confined Floridan in north-central Florida, suggested that this upwelling is enhanced by the
predominantly siliciclastic in composition. The the siliciclastic horizons include fragmental where flow systems are apparently sluggish and presence of a fracture system along the axis of the

203







FLORIDA GEOLOGICAL SURVEY


H ~Peace River and also along the Myakka River, (Randazzo and Saroop, 1976; Randazzo et al., dolomite in the Avon Park Formation and system or horizons where Hawthorn sediments
which coincides with a re-entrant in the transition 1977, Randazzo and Hickey, 1978; Randazzo et Suwannee Limestone can be at ributed to depo- have been reworked into the surficial aquifer zone in coastal Sarasota County Culbreth (1988) al., 1983). The dolomite in the intermediate and sitional conditions at! or shortly following, the time system. The highest magnesium concentrations in I ~ has documented some of these fracture systems. Floridan aquifer systems may be either a source or of deposition. Prasad (1986) concluded that SJRWMD are in an area of coastal intrusion in
The width of the re-entrant, which occupies a zone sink for magnesium. Finally, particulate dolomite dolostones and dolomitic clays and silts in the Flagler County and upconing in Seminole and a few kilometers in width along the Peace River, is mn the unfiltered samples may cause a strong Hawthorn resulted from replacement of aragonitic southeast Orange Counties. In SWFWMD, high too wide to correspond to a single fracture These correlation of magnesium with dolostone. or calcitic muds at the transition zone. However, magnesium concentrations are also coastal (Figure
fracture traces must reflect a concentration of Randazzo and Bloom (1985) and Randazzo and 15d), with minor highs in the interior. Highest
multiple fractures or extensive modification of a Cook (1 987) found dolomites in the Flonidan magnesium concentrations in SFWMD are in Lee,
fracture zone by rock dissolution. The width of the One of the most important models for dolomite aquifer system that can be attributed to Highlands, and Glades Counties Much of this
Sre-entrant in the water-quality data is most likely an formation in Florida is based on chemical dolomitization in the transition zone While modern region is characterized by clay-rnch, shelly sands,
artifact of u pconing along the fracture-trace equilibrium conditions that exist in the salt-water dolomitization cannot be documented, they found which contain reworked material from the system and lateral transport of deep, calcium- transition zone. Back and Hanshaw (1970), that modern, transition-zone ground waters are Hawthorn The Biscayne Aquifer is low in
Sulfate waters in the "boulder zones" in response Hanshaw and Back (1971 ab), and Hanshaw et al. thermodynamically saturated with respect to magnesium, but a few wells on the western margin
I to heavy pumpage (1971) first postulated that dolomites may be dolomite and dolomite precipitation is predicted. of the aquifer show minor increases in magnesium
forming in coastal portions of the Florndan aquifer One of the problems with correlation of existing (Figure 15e). system at the present time. Runnels (1969) offered dolostone horizons to modern ground-water
SFinally, since the samples were not filtered, an explanation for this phenomenon His argument chemistry is that Cenozoic sea-level fluctuationsMansucoetrinsnmrneeool
High calcium mnay be a result of particulate calcite is that mixing of two water masses that are have been sufficiently rapid to prevent formation of Mgeimcnetain nmnearsl
or dolomite in the samples. Unusually high saturated with respect to calcite will result In a new well-defined dolostone horizons or transition-zone (Table 3) are less than 0.4 mg/L magnesium, while
calcium concentrations most likely represent water mass that is out of equilibrium with respect karst at the present positions of the transition magnesium in the surficial aquifer system in much
drilling-fluid or particulate contamination in poorly to calcite, In coastal mixing zones, the mixture is zones (Fanning et al, 1981). of the northern part of the state is less than 1 mg/L
I developed wells, under-saturated with respect to calcite and (Figure 15). These concentrations are on the same
limestone dissolution is predicted. Badiozomani order of magnitude as precipitation with minor
(1913), PHummer (1975), and Wigley and Plummer STANDARD OR GUIDANCE evaporative concentration In the southern part of
Magnesium (1976) expanded the concept and showed that CRITERION the state magnesium concentrations are higher
mixtures of calcium-bicarbonate-rich Floridan indicating more evaporative concentration,
IMPORTANCE AND SOURCES aquifer system water and sea water, both of which additions of irrngation waters from deeper aquifer
may be saturated with respect to calcite and There is no standard or guidance criterion for systems, and possible mixing with residual marine
dolomite before mixing, become undersaturated magnesium (Florida Department of Environmental waters trapped within the Plio-Pleistocene Due to chemical similarities, many of the with respect to calcite in the approximate range of Regulation, 1989). The problems with hardness sediments.
factors that govern the distribution of calcium in 4 to 45 percent sea water. The water is over that were discussed under Calcium (above) are
Florida aquifer systems may also be applied to saturated with respect to dolomite in this same valid for magnesium. nrmdteAufrysm
I ~ ~~magnesium. Magnesium has several sources and salinity range. Thus, in the landward "half" of theIneedaeAufrSsm
sorne possible sinks (pathways by which it is salt-water transition zone, the equilibrium models DISTRIBUTION IN GROUND WATER
removed from the water). predict that calcite would be either dissolved, Intermediate aquifer system water characthereby producing karstic porosity, or replaced by teristically has higher magnesium concentrations
Mea manesum oncntrtio inprei-dolomite. Hanshaw and Back (1980) have Surficial Aquifer System (Table 11) than the surficial or Floridan aquifer
Menmgeimcnetaini rc-documented calcite dissolution in the mixing zone systems due to the presence of magnesium-rich

0 2 mrL in the south (Tableg 3) Enapothrapirao rins Ycotntersiasibard ty (187 has reviewed The median magnesium concentrations in the minerals (clays, dolomite, Table 5). There is an
may raise the concentration in surface and soil themxing oneoel Handned pos7hsbleflws. surficial aquifer system (Table 11) are low (<10 increase in median and maximum magnesium to waters by a factor of ten Sea water averages temxnznemdlndntdpsbefaw.mg/L) throughout the state. Maximum values in the south, indicating a southward increase in clay
1,290 mg/kg magnesium (Table 8), so the waters in If the model is possible, dolomitization of SJ RWMD, SWFWMD, and SFWMD probably and dolomite content and in aquifer system thickthe transition zone may be magnesium rich limestones within transition zones along the coast reflect either intermediate or Florndan aquifer ness, water residence times, and permeabilities.
and at the base of the Floridan may constitute a system water that has been introduced through
signficnt snk or mgneiumirrigation or upward discharge or weathering of In the NWFWMD, the magnesium increases to
The Hawthorn Group contains significant magnesium-rich minerals reworked into the the east (Figure 16a), where the Hawthorn Group
U sources of magnesium (Table 5), including Dolomite precipitation within the intermediate sediments of the surficial aquifer system from magnesian clay deposits occur (Scoff, 1988). The
magnesium-rich clays (Weaver and Beck, 1977' and Flonidan aquifer systems is a highly debated underlying strata. trend continues into the SRWMD and western
Miller, 1978, Reik, 1982; Strom and Upchurch, topic. Dolomite is less soluble than calcite or S.JRWMD (Figure 16b,c). Concentrations in the

S1977: 1Pras 198Scf, 1988) dWeamtern W on' aragonite, and the mixing-zone dolomitization Mgeimcnntaosarchacri-intenor of the SWFWMD (Figure 16d) are similar to
aquife systs (Lawrcett 1and) Wthenng of model is a possible mechanism for magnesium Mag:nesmg/incenrthFloriar (Fhgreacrs- those of north Florida. However, magnesium
any of these minerals adds to th Oadf removal frmaquifer water. Randazzo and Saroop tc.l mestanesiumg/ nnrhFod Fgr increases to concentrations in excess of 50 mg/L
magnesium in the intermediate and Floridan (1976), Randazzo et al. (1977), Randazzo and c) ihmgeimconcentrations nNW MDin the coastal transition zone and lower Peace
aquifersystem (Lawrece andUpchurch, 1976, Hickey (1978) and Randazzo et al.(1983) have ndRWDare in areas where the Hawthorn isRvebsnThcnetrtnsnLeHghnd
1982). The Florndan aquifer system also contains extensively studied the origins of dolomite in present beneath the surficial aquifer system. Rive GbadsTh contrt igos in LeereHinhlxns, abundant dolomite, especially within the Fndaufr ytsfrmorptrgpy.These high magnesium values may reflect wells and mGlas Counesiur lextns e in stcns ofa
SuaneLmsoeadAo akFrainThese studies concluded that much of the thtiavretytptememdaeaufrconstitute major aquifers in the area.

21






SPECIAL PUBLICATION NO. 34

Floridan Aquifer System (Figure 17e). There is a re-entrant near Daytona Connate, saline waters that are residual from Taylor County the prevalent ratio is approximately
Beach (Volusia County) that reflects intrusion as a the Plio-Pleistocene marine transgressions also 1 3, indicating that there is approximately fifty Meia a eiu cnenrtinsi teresuit of well pumpage. There is a similar area with constitute a signficant source of sodium inland. percent more sodium as a result of exchange for
Media mgeimcnetaininhehigh magnesium concentrations near Hastings (St Connate waters may be present in isolated pores calcium,.
Floridan aquifer system fall between those of the Johns County). Highs in northern Lake County, within the fresh-water portions of the aquifer surficial and intermediate aquifer systems (Table near Lake George, and in southern Seminole systems. They may also occur at the base of the
11).chs of the warinath oridan aifroc sy. stm County underlie the St Johns River Leve (1983) Floridan aquifer system in northern and central suchaly feathpars o asdiun e mnorreaof,
muchof he wterin te Foridn auife sytemhas shown that upwelling from the Floridan aquifer Florida and throughout much of the Floridan sc sflsaso lycnb oreo
has passed through the intermediate aquifer system along faults occurs elsewhere on the St. aquifer system in southern Florida, where deep sodium in ground water. Sodium feldspars (sodic
system and has inherited magnesium from that Johns River. circulation has not been able to sweep the water plagioclase, (Na,Ca)AI(AI,Si)Si2O8) and sodiumsystem (Lawrence and Upchurch, 1976, 1982). out of the system. Minor sea water is also present rich clays (montmorillonite and nontronite; table 4)
This magnesium is diluted by directly recharged as 'bubbles" trapped in unconnected primary are found in siliciclastic horizons of the surficialU
waters that are low in magnesium. Second, some There is a trend of increasing magnesium porosity that ranges in size from cavities up to a and intermediate aquifer systems Minor amounts
portions of the Floridan aquifer system (notably towards the coast in SWFWMD (Figure l7d) The few centimeters between grains to cavities less occur in the Floridan aquifer system. The near the base of the aquifer system in the Avon transition zone is well delineated by the 10 mg/L than a millimeter within marine shells and weathering reaction is similar to reaction 4, withI Park Forrmation and Oldsmar Limestone, near the isoline in the northern part of the district The 10 authigenic minerals, however, the volume of this release of sodium, other cations, silicic acid, and top in the Arcadia Formation (Hawthorn Group), rmg/L isoline crosses the District from west to east water is likely to be low, bicarbonate (Table 4).
and in the Suwannee Limestone in central where the Hawthorn Group ceases to be an
SRWMD) contain dolomite. Maximum magnesium effective confining unit. That is, south of the 10I
contents are in coastal transition-zone mg/L isoline the Flondan is confined, and north it is Sorption sites on clays deposited in a marine STANDARD OR GUIDANCE
environments where sea water (mean magnesium semi- to unconfined. Therefore, confinement, long environment are usually saturated with sodium. CRITERION
concentration = 1,290 mg/kg: Tables8) intrudes the flow paths, and proximity of the overlying When bathed in calcium- or magnesium-rich aquifer system Hawthorn result in higher magnesium concent- waters, the calcium and magnesium is exchanged Sodium is regulated under the PrimaryI
rations. There are significant re-entrants that for the sodium in a form of natural 'water Drinking Water Standard (Ch 17-550 310-320,

The distribution of magnesium in the Fioridan paralle both the Peace and Myakka River axes, softening" (reaction 9; Foster, 1950) This sodium F A C ;Florida Department of Environmental
aqifr ysem(igre17 rflcs evra o teThese re-entrants were attributed to upwelling is not from connate water, although it is left Over Regulation, 1989). The standard is 160 mg/L The
aqfrssem (Fnigured 17bfetsve alnfsthe along major lineaments by G. Jones (1991). from previous marine transgressions Sodium standard is based on the possibility of adverse
prcesses mtinaerd aboe. MneFWmD released from clays by ion exchange can be health effects, including heart disease and
(icre ase hs in cr ear drefcti inNMatrtD aafo FM Fiue1e r i n recognized by comparison of sodium and calcium hypertension Table 12 includes the number of
along the direction of regional flow and interaction cannot be used to draw many conclusions. Thehaeadu to chloride cocn ratio simila m to thatersTh samples that exceed the standard arsne with dolostones within the aquifer system. absence of data in the central and south portions seav watsedumo l rde ratio s 7,increase i thfe haamersta ine the staiinner irn
Magnesium concentrations are in excess of 20 of the District reflect poor water quality in the sra which aroe acoaied by a5 crease in the creionst alcyningo dee watrns.to on r mg/L in the Apalachicola River delta as a result of Floridan aquifer system. Magnesium concen- calmto hchlrid ratio cnan be atteriute to ionon Ifucnn fdee aes
coastal upwelling. The corrdor of low magnesium trations are high here as reflected by the 100 mg/Lexhg.Telrgamutf dualong the lower Ocklockonee River reflects isoline that skirts the northern shore of Lake becabne.Te argte amount sodums-seSaeie orprcn ftesmlsf
displacement of the transition zone by riverine Okeechobee Hydrochemical Facies section) indicates that ion the surficial aquifer system exceeded the 160 mg/L
waters, while the complex pattern in Wakulla exchange is an important process in Florida criterion The proportion of samples that
County reflects the complex flow patterns Sodium exceeded the standard ranged from zero in
associated with the large springs there SRWMD to 16 percent in SJRWMD. The samples
The reverse exchange reaction occurs where from the SJRWMD are coastal and reflect the
The region of high magnesiurm in the IMPORTANCE AND SOURCES sea water intrudes into an aquifer system that transition zone.
norteasern artof he SWMD(Fiure 7b) contains potable, calcium- or magnesium-rich ntheasothern p ands off RM H Figure C7bumbin waters Here, calcium- or magnesium-saturated
theNorher Hihad fHmloClmiThe primary sources of sodium in Florida clays are bathed in sodium-rich solution and the Twenty-three percent of the samples from the
Union, Bradford, and Alachua Counties, represents aquifer systems are marine aerosols and mixing exchange reaction (reaction 9) goes to the left, intermediate aquifer system exceeded the the influence of weathering of the magnesium-rich with sea water in the transition zone This results in a calcium- or magnesium-chloride standard The range in proportion of samples that
minerals in the Hawthorn, through which Floridan Concentrations of sodium in rainfall average from facies, which has been documented in this report exceeded the standard ranged from zero to 45 aquifer system waters pass during recharge. The 0.44 in north Florida to 1.58 mg/L in south Florida along the inner margin of the transition zone. percent The proportion that exceeded theI large area of high magnesium concentrations in (Table 3). The range of sodium concentrations standard was low in all districts except the
Taylor, Lafayette, and Madison Counties measured in precipitation is 0.02 to 293 mg/L. SFWMD, where connate waters are common in the
corresponds to an area of dolomitic Suwannee Evapotranspiration of meteoric water can cause An excellent example of widespread 'on intermediate aquifer system.
Lirmestone. High values in coastal environments increases in sodium concentrations above those of exchange occurs in Taylor County, where a near-I reflect the transition zone, which exhibits large re- the rainfall itself. The mole ratio of sodium to surface, Plio-Pleistocene clay (the "San Pedro entrants up several rivers chloride in sea water is 0.851, and in Florida rainfall clay") appears to be releasing sodium to the Seventeen percent of the samples from the

it ranges from 0.85 to 0 92. These ratios persist ground water The mole ratio of sodium to Floridan aquifer system exceeded the standard.U
Floridan aquifer system water in the SJRWMD throughout the surficial aquifer system in Florida chloride in adjacent counties, where the clay is not The proportion ranged from one percent in is generally low in magnesium, with highest and reflect the importance of precipitation as a present, is essentially the same as sea water NWFWMD to 59 percent in SFWMD Again,
concentrations near the coastal transition zone source of sodium. (0.857) due to the influence of rine aerosols In connate waters in the Florndan in southern Florida


22








FLORIDA GEOLOGICAL SURVEY


H and in coastal regions elsewhere, and the coastal inland. There is a weak coastal influence in the system (Figure 18e) The high is located near the attributed similar features to upwelling along faulttransition zone account for these high Sand and Gravel Aquifer (Figure 1 8a) in the Caloosahatchee River and coincides with a re- controlled regions of high permeability in the St.
concentrations NWFWMD, but highest sodium values near the entrant in the Ploridan aquifer system Johns River The upwellings are in some areas,
I coast appear to reflect upconing of saline water potentiometric surface (Healy, 1962) This area apparently natural and associated with springs. In
under pumping stresses. The influence of the appears to be characterized by both natural other areas the upwellings are associated with
DISTRIBUTION IN GROUND WATER coastal transition zone and, possibly, incomplete upwelling and heavy pumpage, and coincides with pumpage
flushing is well displayed in the SJRWMD (Figure the location of improperly abandoned wells that
The distribution of sodium in Florida's aquifer 18c). Here, large re-entrants from the coast have were initially instalLed for petroleum exploration The coastal transition zone is apparent in the
systems is summarized in Table 12. Care should developed where pumpage has induced intrusion purposes SFM Fgr 0) ihr-nrnsi
btknininterpreting ths aaa h eino h aafo h otenhl fSFM loManatee County and along the axes of severaL of
teBackground Network includes coastal, sea ndatawe-dvlpdrnstnzneFgueFloridan Aquifer System the major rivers. These features have been
water intruded zones, regions affected by connate lad). Note that well-developed re-entrants of previously discussed
water, and areas of upconing of deeper waters. In sodium-rich water extend inland along the axes of
Addition, there are no wells in the central the Peace, Myakka, and Little Manatee Rivers In Sodium in the Floridan aquifer system is
I ~ Everglades region of SFWMD. The distribution of SFWMD (Fig ure 18Se) the Biscayne Aquifer greatest along the coast, where the salt- Most of central and south SFWMD (Figure 20e)
wells is not in proportion to the areal extents of ilLustrates the coastward increase in sodium, This water/fresh-water transition zone is clearly has no data This region is characterized by low these regions of the aquifer systems, so neither the is one of the classic and most studied transition delineated (Figure 20). Elsewhere, minor sodium potentiometrnc heads and ittle flushing action Sdistributions nor the number of samples exceeding zones in the world (Kohout, 1960ab; Cooper et al highs appear to be a result of ion exchange in the Consequently, Floridan aquifer system water in
the 160 mg/L standard can be taken to literally 1964) A major management effort of the SFWMD overlying Hawthorn clays, connate water, and the District is saline and unfit for most uses If
characterize the aquifer systems. The maps is to minimize landward intrusion and restore water sampling of deeper, more mature waters TabLe 12 there were data in this region, sodium contours
S(Figures 18-20) provide a better synthesis of the quality in the Biscayne Aquifer. High sodium summarizes the sodium-distribution data for the would indicate high concentrations, with most
conditions present in the aquifer systems. concentrations inland, especially in southwestern Floridan throughout the state. The median sodium areas in excess of the standard. The contoured
Glades County, are probably a result of interaquifer concentration for the state is 11 0 mg/L, and the data delineate this region of poor quality with transfer through irrngation and remnant connate range in concentrations is from a minimum of 0 2 increasing sodium to the south. Note that Table 12 suggests that there is a water. mg/L to a maximum of 7043 mg/L.
I ~ ~~general increase In median and maximum sodiumPoasu
contents of aquifer system waters to the south.Ptssm
These increases are, in part, a result of the Intermediate Aquifer System In the NWFWMD (Figure 20a) the transition
increased importance of marine aerosols in zone is well defined, although few of the samples IPRAC N ORE
U ~ ~~precipitation in the peninsula as opposed to the Sodium in the intermediate aquifer system exceeded the standard A major re-entrant occurs IPRAC N ORE
northern part of the state, especially with respect statewide ranges upward from 1.0 mg/L (Table in Walton County, which reflects major withdrawals
to the surficial aquifer system and shallow wells in 12), with a median concentration of 41.0 mg/L. The in Okaloosa and Walton Counties (Wagner et al, Potassium is primarily derived from sea water, I the unconfined parts of the Floridan aquifer wide range in sodium concentration reflects a 1984) Wagner et al. (1984) attributed the large re- which averages 399 mg/kg (Table 8) Therefore,
system. The large increases in SFWMD are a diversity of processes, including marine aerosols, entrant in southern Bay and Gulf Counties to coastal regions, where the fresh-water/salt-water
result of low hydraulic gradients, which have not connate water, coastal, saline waters, and pumpage. The re-entrant in Wakulla County is a transition zone is present, are expected to contain
Caused complete flushing of the aquifer systems, weathering of Hawthorn Group minerals The result of discharge from the large sprng complex the highest potassium concentrations Elsewhere,
especially near the coast, and to human-induced influence of Hawthorn Group weathering has beer surrounding Wakulla Springs and by pumpage. potassium is derived in trace concentrations
salt-water intrusion- discussed by Lawrence and Upchurch (1976, (usually less than 0.2 mg/L) from marine aerosols
1982) Re-entrants in the SRWMD (Figure 20b) reflect in precipitation and from minor weathering of clays
Surfcia AqiferSysem ntruiontowrds oasal itie an inustres.Re-and feldspars. Weathering of potassium feldspars
Surfcia AqiferSysem ntrsiontowrdscoasal itis ad inustes.Re-and clays (see reaction 4) is not considered a
The majority of the inland samples (Figure 19), entrants on the transition zone include one in dominant process in Flornda due to the scarcity of The edin sdiumconentatio intheparticularly in the NWFWMD and SRWMD, are Taylor County that is a result of high pumpage near these minerals in aquifer sediments and slow
The meian sdium cncentation n theequivalent to the sodium contents of the surficial Perry and a large re-entrant in Levy County thatwetngratonrtsnadptsums surficial aquifer system statewide is 17.0 mg/L- corresponds with the Waccasassa River and wahrn ecinrtsIlnptsimi
UThe range of values is 017 to 3,730 mg/Lf(Table 12) aquifer system, and marine aerosols: so they sap io oimhgsi aitnadrrl rsn nqatte vrafwmlirm
The majority (samples within the upper quartile) of reflect simple recharge. Near the coast, upwelling Alachua Counties correspond with areas of per Liter This is because there is not a great the sodium concentrations are within the range of along the transition zone results in higher sodium withdrawal near White Springs and Alachua. The quantity of potassium-rich sediment in the aquifer marine-aerosol enriched precipitation that has concentrations, especially where pumping or the high sodium in Bradford County corresponds to system and because potassium is immo-biliized as
been concentrated by evapotranspiration The prsneo age iescuetelwng withdrawals near Starke. a nutrient by plants and sorbed onto clays.
higher concentrations reflect wells that are near the hydraulic heads
coastal transition zone or that are inland and are Ptsimi necletidctro h
influenced by connate water or introduction of There is a high sodium area at the south- Data from the SJRWMD (Figure 20c) indicate otasiumfne is nsxcllentdiscauste
deeper aquifer system water through irrngation Or western corner of Glades and northeastern corner that the coastal transition zone is well-developed integrity of nel iaorcnstllen welln becus other interaquifer transfer, of Lee Counties (Figure 1 9e). This is the only area throughout the District, A major re-entrant exists in padsiumens as major consttorilling flids
Iin the intermediate aquifer system sample set St. Johns County, and smaller, inland features padscemein use inbewa well ottin ighae
whee te sdiu stndrd s sgniicatexiNst along the St. Johns River. Much of this high ptassiuthin at oabwae well ceeti often inrdiathes Examination of Figure 18 reveals the influence weedhd Tsdim csta nd s sithificantgy sodium water is believed to be connate in origin that eternh eleti poorly dec nddlifured, the l
of the coast and these "pockets" of high sodium noted In the same area in the surficial aquifer (Boniol, 1992, pers. comm ). Leve (1983) hashabenpoldvlpdaddrligfusae


23






SPECIAL PUBLICATION NO 34

still present, or the well cements are deteriorating, origin- Iron Iron is closely associated with bacterial activityI
*n ground waters In oxidizing environments,
STANDARD OR GUIDANCE The data from SJRWMD and SWFWMD IMPORTANCEANDSOURCES bacteria induce colloidal ferric hydroxide
CRITERION (Figures 21 cd) illustrate the influence of the precipitation. These iron colloids and the
transition zone on potassium. Note that many ofasoitdbtn cuelgggofwlsres the coastal re-entrants mentioned above are Iron has two valence states, Fen and Fe3, and and aquifer pore throats. They also result in
There is no standard or guidance criterion for represented in the potassium data. The high in is highly susceptible to reduction/oxidation (redox) violations of color and turbidity standards. For potassium. Potassium iS an essential nutrient, and central Hardee County (Figure 21d) coincides with reactions. Hem (1976) summarized the stability example, in a water quality survey of the central is considered beneficial in low to moderate a zone of upooning saline water in the underlying relationships of iron in sulfur-rnch systems. In Florida phosphate district, Gordon Palm and
quantities. Floridan (Dalton! 1978; Lehman! 1978). Dalton general, the sources of iron in ground waters Associates (1983) found that 16 percent of the
(1978) documented the flux of Floridan aquifer include (1) oxidation of pyrite (FeSJ, (2) oxidation of shallow-well samples from mine areas violated theI DISRIBTIN I GOUN WAERsysemwatr itothesufical qufersyteminorganic compounds, and (3) dissolution of iron water-quality standards for color and 20 percent
H-ardee County and showed that it is a result of oxide and silicate minerals (Table 4).pecn violated tcor standard rn nd e percent
irrigation practices. Other highs in the surficialprn violated olo standards.Rc arge well utlierdny
Median potassium content in all distncts and aquifer system, therefore, may reflect irrigation phrh ta.(19)chrceizdteted hostandutare riclarly susstibleb
aquifer systems is low indicating minor contri- waters pumped from the underlying Floridan sUchudridant aquifer sysrtesinzedntral tohironspolorandurdtry eproblemsly h suseibI
butions from aerosols and weathering. The values aquifer system. The high potassium on the east uria ndFloridanso reducion/oxidtmsin (rentrx) screens plug with trial mates. and fe that fall below the upper quartile (Table 13) are well side of the SWFWMD roughly coincides with the Fpotenial i grerm 24) Teyfu n/dxtdat the suridia) hydroxids;pu ihb clm and dildigehs nrusa ion within the expected concentrations from Lake Wales Ridge. Similar highs are not present In aqie ystem angu esTe froundhloizn tofro the suwcahdoiell bore duroding tsamln cusstcoor
eaatve.Vryg concentrations cptto and0 rock the SFuMDeta Fgr 1) oSFM datpraet.slightly reducing. The Floridan aquifer system is and iron standards to be violated (Upchurch et al.,
weahrng. Very ighi conctraos(10mI are suspectatpen. generally reducing, although areas of rapid 1991)
inland >4r0b mbL i coarsta el rea s r usct recharge are likely to be oxidizing. The waters ofI
prhe s probabmyepresent wellfcon tructionthe interm ediate aquifer system are sim ilar to the
probems.Intemedate quifr SytemFloridan in redox potentials. Data from surficial Ferrous iron (Fe") Is a minor, but prevalent,
and Floridan aquifer system water samples from constituent in organic- (humic-substance) rich
Surficial Aquifer System Tearguments that were given for potassium in Polk County were plotted on Eh-pH diagrams forwarsBeus gni-chwtsinuda
tesurf cial aquifer system hold for the intermediate iron species, and they indicate that Fe2 is generally source of carbon, microbial activity tends to cause aquifer system Median potassium concentration the stable form of iron in central Florida ground strongly reducing conditions, which encourage The median potassium concentration for the statewide is 4.4 mg/L Most of the data are well waters (Figure 24). reduction of ferrc iron (Fej) to the ferrous state
surficial aquifer system statewide is 1 2 mg/L within expected concentrations for meteoric water, and transport with the water. Ferrous iron is
(Table 13). There is no significant difference in but high potassium concentrations that result from known to move moderate to long distances in
potassium concentration medians or quartiles weathering of the Hawthorn and possible well In general, Fen is the stable iron phase in reducing, karstic aquifers Given the presence of3
within the state Maxima do vary significantly, but constriction problems exist (Figure 22). acidic, reducing waters (Figure 24) Iron should sulfide or phosphate, ferrous iron may precipitate
the highest values represent either sea water or remain in solution in acidic, oxidizing waters. In as pyrite (FeS3), vivianite (Fe3(P04)2.8H20), or other
well-construction problems. basic, reducing waters, pyrite (FeS2) and siderite mineral species.
Floridan Aquifer System (FeCO3) are stable solids that may precipitate
depending on the sulfide and bicarbonate contentsI
mg/L iand may c nronsed natfactso wel The distribution of potassium in the Floridan of the water; whereas, in basic, oxidizing waters, Filtration, mode of sampling, and well
amorphous ferric hydroxide (Fe(OH),) should environment may greatly affect reported Iron
construction, These highs are found In several aquifer system (Table IS; Figure 23) clearly precipitate concentrations. Iron analyses reported in this
districts (Table 13, Figure 21) and their distribution illustrates the influence of the transition zone, study are total iron, and no attempt is made to
appears to be random and uncorrelated to There is a coastward increase in potassium in the differentiate the two oxidation states Since Fe'
adjacent wells. Floridan aquifer system in the districts (Figure 23) Ferric hydroxides form colloidal and larger tends to precipitate as ferric hydroxide, it is
Re-entrants along the coast were previously particles that generally do not travel long distances probable that iron concentrations in well-I
Ptdiscussed under Sodium. Scattered occurrences in intergranular aquifers. Travel distances depend developed wells are predominantly Ft. Samples
Poassium concentration in sea water is of high potassium concentrations inland probably on sizes of the colloids and of pore throats. These from poorly developed wells probably contain both
approxirmately three percent of the sodium reflect residual potassium in newly constructed colloids have been documented to travel distances iron species, especially since the metals samples

coctation. u Therefore, potassium in meteoric wells. Large areas characterized by minor highs in up to a few meters, but not kilometers The parti- were not filtered. Also, iron-bearing well casing waers sud b nfh range 0.-0. mg/L, potassium concentration in the regions where the dles are more likely to travel as suspended matenal may "rust" or otherwise prejudice iron
drved frrom marine aerosols and not Hawthorn Group overlies the Florndan aquifer sediment in karst conduits. Femc hydroxide is the concentrations. For this study, only data from
concentraed by evapotranspiration Most system reflect rock weathering in the siliciclastic reddish to yellowish scale or stain that is so non-metal cased wells were used, so the sample
samples should remain near three percent of the section of the Hawthorn (Lawrence and Upchurch, commonly found where iron-rich waters are density is much reduced over other analytes.
sodium concentration unless weathering, plant 1976, 1982). Elsewhere, the data are consistent utilized. Ferrnc hydroxide forms rapidly when water uptake, or sorption change the partitioning of with marine aerosols accompanied by minor is heated in hot water heaters or aerated in the
sodium and potassium. Most of the samples from concentration as a result of evaporation in the near vicinity of well pumps, sinks, toilets, and other STANDARD OR GUIDANCE the surficial aquifer system are within or near this surface environment. environments where oxidation of Fe2n to Fe3 is CRITERION
concentration range, or they are in proper possible In soils and rocks ferric hydroxide slowly
proportions with sodium to indicate meteoric crystallizes as the mineral goethite (Table 4). Io ssbett h lrd eodr

Iro i sbjet o he loid Seonar
24







FLORIDA GEOLOGICAL SURVEY

Drinking Water Standards, arnd the maximum Lack of physical continuity between sample Mercury for release into surface waters and the surficial
allowed concentration is 0 30 mg/L (300 pg/L, sites prevents contouring of data (Figure 25). The aufrsse.Amshrcfloti nte
Flria Department of Environmental Regulation, high degree of variability reflects local well IMPORTANCE AND SOURCES possible source of mercury. Burning of fossil fueje
1989) This is because of the potential for conditions and surface conditions. caol n uiia n nutilwse a
islr ato n uniiyi.w tr ih x esa dMercury is incuded in this report because of the potential of introducing variabe amounts of
iron, aeAqierSstmrecent cocrsaotmercury in surface waters mercury into the atmosphere and, ultimately, onto
Intermdiate quiferSystemaquatic biota. There is considerable debate as the land surface as either dry fallout or
Tabre 14 summarizes the proportions of to the source of mercury in surface waters, and precipitation (Hem, 1985). Finally, many pesticides
samples that exceeded the standard Because of The statewide median iron concentration is discovery of mercury in the ground-water data that have been widely used contain mercury
possible contamination from iron and steel casing, 0.07 mg/L in the intermediate aquifer system. would have been of great assistance in compounds (Crier, 1968) Organomercuric
only samples taken from wells with non-metallic There is a high range in median iron concentrations determining the origin of the mercury in surface compounds were used as seed grain treatments
casing are listed in the table. Statewide, 75 percent (<0.05-1.17 mg/L, Table 14) due to the diversity ofwtrsTegun-ardtadno ditenyportth16'.Peymruysatadotr
of the surficial aquifer system samples exceeded environments in the Hawthorn Group. Iron is sources of mercury in the surface waters, mercury compounds have been widely distributed
the standard. The range in the proportion that abundant in the Hawthorn Group as a constituent frbcecdsadfniie.Teepsiie
xcddthstnrdwsrm70t90prntin clays, pyrite, goethite, and related iron may also constitute a source of mercury in surface
The proportion that exceeded the standard in the oxyhydroxides. Figure 26 illustrates the distri- Elmna ecr ssal ne at ufc onions h eaiiporances 0f the
Intrmdiae quiersysemwas42pecen btios f ionin hedisncsconditions It is slightly soluble in water (~ 25 pg/L, sources are unknown for Florida ground waters at
sintermedit aqufrangystem14 aso4 percent buTheorninteditcs Hem, 1985), but if the water is open to the atmos- the present time.
stapteie, wtha rex ofd1d toe standrden The phere, the mercury is sufficiently volatile that much
Floridan aquifer system was 49 percent, statewide. Floridan Aquifer System o twl saea a.Mruyfrsceia
Th poprtonrage ro zroto70pecetcomplexes with chloride and hydroxide in high ionic Due to the small natural amounts of mercury in
Clearly, there is a high probability that any aquifer The distribution of iron in the Floridan aquifer merncuryuiosFlnd' ufr sption and chemia togplxingt
system water sample from Flornda will violate the system (Figure 27) suggests that high iron watersmruyfrsrponndr hmc opexg
standard for iron, especialy if it is an unfiltered may occur near the coast. In SRWMD and Metallic mercury (Hgo) can be oxidized to either wuld be nature npresent in dtectabletamoruts
sample. northern SWFWMD this reflects swampy Hg2 (mercurous) or Hg2' (mercuric) valence states Any mercury detected in the aquifer systems as
conditions overlying the unconfined Floridan Both ions can form strong chemical complexes part of the Background Network is most lIkejy a
DISTRIBUTION IN GROUND WATER Elsewhere, high iron near the coast and along the with humic substances (Jenne, 1970; Jonasson, result of human activity, including atmospheric
re-entrants previously discussed indicates 1970; Cline and Upchurch, 1973). In addition, fallout or agricultural use of mercury-containing
U mobilization of iron in the aquifer systems Median methanogenic bacteria have the capability of pesticides
Iron distribution data are summarized in Table concentration of iron, statewide, is 0 21 mg/L forming methyl mercury (HgCHg) frorn metallic
14. Note that median iron concentrations are Comparison of this median with average sea mercury in organic-nch environments (Wood et al.,
characteristically highest in the surficial aquifer water, which has an average concentration of 2 1968). Methylated mercury is readily soluble in SADR RGlAC
system. This is a result of proximity to sources of mg/kg (Table 8) indicates that iron concentrations body tissues resulting in bioaccumulation of CRITERION
iron in the siliciclastic portion of this aquifer are increased in the wells by a factor of over 50. mercury and its entrance into the food chain.
system, including iron minerals, ferrnc iron- and Mercury is subject to the Florida Primary
organic-rich soil horizons, and dissolved humic Iron is present in waters directly affected by Mercury minerals are unknown in Florida's Envirnme tanaRegu lond98) D apdrte
substances Median iron concentrations are low in the Hawthorn Group. There is also a strong sediments. Sea water, which averages 0.03 g/kg maximumneale coenation is9) 0.00 mg/h(
all of the aquifer systems. High values correspondence of iron and total organic carbon in Hg, is an important natural source of mercury. gL.Ti mixsuaboecaueto the potetia for (

S(concentrations > 5 mg/L) are probably a result of many areas of the state as a result of iron co r- Assuming that the average chlo rde in precipitatio n ac ultion in the fchan and she io st xicty
using unfiltered samples. These high con- plexing by humic substances (Young and is 1.66 mg/L (cf. Table 3), the equivalent mercury problmslto in hmn Merdcurinake Ien umansii
centrations represent particulate ferrc hydroxides Comstock, 1986) (compare Figure 27 and the concentration in rainfall is estimated to be prhas n astdwh Mecrniand auten
ttwrewashed from the aquifer system under distribution of TOG in Figure 55). approximately 0.05 parts per trillion, which is not toicty beeasciadmenthJirlness andati andt
Sth e tu rb u le n t c o n d itio n s c h a ra c te ris tic o f w e ll d e e t b e a i e a r s l a t e e o e e rtoy isressia (m e rta 1 9 6 8).n g s t c n
pumpingtransport very small amounts of mercury inland.
a:It is important to note that small iron anomalies Quaternary marine transgressions may constitute

I ufca q ie ytmaeevidet n the aufe system ner areas e r an additional source of natural mercury in Florida. Table IS summarizes the samples that were
SuricalAqufer Sytem rier Fdcarg water tough Esallown hoe iRWMo Mercury forms strong chemical complexes with found to exceed the 2 ~g/L standard Many of
F~ordan t te Coy EcarpentIn SWMDsedimentary organics and clays. Marine trans- these detections have not yet been confirmed by
Median iron concentrations reported by district (Figure 27b). These anomalies suggest that areas gressions place sea water in juxtaposition with resampling. As might be expected, mercury in
from the surficial aquifer system range from 0 88 to where rivers flow directly into karst conduits in the these sorption media, and sorbed or complexed excess of the standard is most common in the
2 14 mg/L (Table 14). The statewide median is Floridan aquifer system should be closely mercury may remain as the sea retreats. surficial aquifer system. Statewide two percent of
I 08 mg/L Normally, the surficial aquifer system is monitored because of their sensitivity to rapid the samples exceeded the standard. The
high in iron because of the presence of organics ground-water quality deterioration, if water quality proportion of samples that exceeded the standard
and reduction-oxidation reactions that can in the rivers deteriorates. Human activity has undoubtedly contributed to ranged from zero to ten percent.
I mobilize iron. the availability of mercury in the environment
Draining peat- and muck-rich sediments may allow
oxidation of the organics, and any sorbed or It is somewhat surprising that three percent of
chemically complexed mercury has the potential the samples from the intermediate aquifer system

25






SPECIAL PUBLICATION NO. 34


exceeded the standard. Given the reducing con- Floridan aquifer system with mercury in excess of or complexing suggest that ground-water samples While the widespread nature of lead is a matterI ditions and clay and organic content of the the standard from Flornda's aquifer systems should not contain of concern at this time, it is important to recall that
intermediate aquifer system, one would expect detectable Lead. Lead concentrations in natural the samples were not filtered, many of the wells
mercury to be immobile The range in proportions systems are expected to be in the order of 2 pg/L have had lead weights on water-level recorders in
of samples within the districts is zero to 13 Ledor less (Hem, 1985). the past. Also, most of the analytical results have
percnt.The istict ith13 prcet ofitsnot been confirmed by subsequent sampling If
ineredtTe aqifrcsamples3 pxcednthe IMOTNEiNtsRCSd onrbt the high proportion of wells with detectable lead
stndrdisthe SqJfRWM lseceigteIPRAC N ORE Human influences, alternatively, docnnuecontinues after the second round of sampling andI
stndrdisth SRWDlead to the land surface Fallout from fossil fuel analysis of the Background Network data, which
Lead minerals are very rare, but trace combustion (e.g., leaded gasoline, coal and fuel will include filtered and unfiltered samples, has
As might be expected, few samples from the quantities of lead are present in feldspars and oil), disposal of lead-containing wastes (e.g., been completed, then it will be necessary to Florndan aquifer system exceeded the mercury other minerals. Average sea water contains 0 03 batteries, paints), widespread use of lead solders, determine the cause of lead mobilization in
standard. Statewide, the proportion was 0 9 pg/kg lead (Table 8), so Plio-Pleistocene marinefasngpnsuefledwghsndsdr nFnd'aqfrsytm
percent, with a range of zero to two percent. transgressions may have resulted in deposition of wel or wer ytems; pausu nusesry; ad pint
DISTRBUTIO IN GOUND ATER es an ther faorble ites Asndt mru, a bullets are among the many potential sources of Samples from the surficial aquifer system that
DITRBUINmNariNnWTE e anerl caribe expeted to wtraspr eadry lead in Florida environments. Many of the wells exceeded the standard made up eight percent of
minote terorsa bt onlxpncte tratnspofa that were used in this study have had lead weights the samples statewide. This is a high number, but Theconentatin dta ndiatetha thre sfion s ofha panrbt pney tilin concentration on water-level recorders installed at one time. This the range of proportions of wells in which lead was minimal opportunity for mercury to enter surface Because of the lack of an obvious source, any rmayin belaonwo oeo h dtcin fla dtecevredfmzr percent in SFM. the rWMDtono
waters from the ground-water system and that the occurrence of lead in Florida ground water is mentionedexcedth sbedlownth risk of exposure to humans from state ground probably a result of human activities. samplmesdtat exuceer sytem sandrdg ighe
waters is minimal A few wells in each aquifer STANDARD OR GUIDANCE pretsaeie iharneo w o2
Sincte smlsta i have detectable umut fmruy issolved 'ead is uivalen[ (Pb2; Garrels anu RTRO percent by district Again, this proportion is high
quantite ofamper tae widel cateedabnd Christ, 1964; Hem, 1985) in most natural waters, If and suspect. Finally, the proportion in the Floridan
beusemans of hec rideeyo dctiornd have carbonate is present, lead carbonate (cerussite, Lead is subject to the Florida Primary Drinking aquifer system is nine percent statewide. nbeue n ofrme by r espig map shwionghv PbCO3) is relatively insoluble and precipitation of Water Standards (Florida Department of NWFWMD had zero percent above the standard,
no bencofrmd y eamligmpsshwigcerussite may control the solubiliity of lead in Environmental Regulation, 1989), and the and SJRWMD and SWFWMD had 19 and 20
the locations of these detections are not included carbonate aquifers. Lead sulfate (anglesite, PbSO4) maximum allowed concentration is 0050 mg/L (50 percent, respectively.
1ntisrpotand lead sulfide (galena, PbS) are also relatively g/L). Lead compounds are highly toxic to animals
insoluble and are likely to precipitate in sulfur-rich, and humans Accumulation in the food chain has DISTRIBUTION IN GROUND WATER Surficial Aquifer System oxidizing and reducing environments, respectively been documented. Lead intake in humans has
None of these minerals have been found in Florida, been associated with chronic and acute toxicity, Mercury concentrations are generally quite low al (1991) indicate that trace amounts of cerussite Hem, 1985) systems is summarized in Table 16. Several rather
in the surficial aquifer system (Table 15). Median should precipitate where lead-rich waters en- startling trends are apparent in the lead data.
concentrations are below detection limits in the counter Florida carbonate rocks
surficial aquifer system. With the exception of data Table 16 summarizes the samples found to
from the NWFWMD, at least 75 percent of all exceed the standard in Flornda's aquifer systems. First, lead appears to be widespread, alsarmples were below detection limits The Lead is also strongly bound to organics, Many of these exceedances have not been though usually in quantities less than the standard.I
SJRWMD had a sample with 52 pg/L colloidal oxyhydroxides, and clay surfaces by confirmed by resampling There is a large number The widespread nature of the metal, combined
sorption and/or chemical complexing mechanisms of samples that exceed the standard. The very with the large number of samples that exceeded (Hem, 1976, Moore and Ramamoorthy, 1984; high values (>500 pg/L) almost certainly represent the standard, suggest the need for additiona study
Intermediate Aquifer System Upchurch el at., 1991) Sorption isotherms some contamination problem All samples with and a potential problem.I
(Upchurch et al., 1991) of lead on surficial aquifer concentrations above detection limits probably Similar results exist in the intermediate aquifer system quartz sand (a ferrc hydroxide-coated reflect local contamination. Given that local Second, it is somewhat surprising that
systems. The medians are below detection limits, sand), Hawthorn Group clay (montmorillonite, contamination as a result of land use cannot be detectable lead is present in the carbonate- and
and only SJRWMD had more than 25 percent of palygorskite), and Floridan aquifer system documented for these wells from which the clay-rich aquifer systems. The intermediate aquifer
the samples with detectable concentrations, limestone indicate that all three media are able to samples came, a probable source for the lead is sse src ncasadla hudb
fix lead, but the limestone and sand have less the use of lead weights in the wells, According to sse src ncasadla hudb
sorption capacity than the Hawthorn clays. In this SFWMD staff (J. Herr, 1991, pers. cornm) many of adsorbed, rather than mobile Lack of sample filFindan Aquifer System experiment, 99.6 percent of the lead was removed the high lead concentrations in that district are a tration is likely to result in analysis of the sorbedon theclaywhileboth te san and he ilestoneresul of ue of ead sygttsms w(Fr-oridaneadqruiter, swystrmInand c prbn tionsu of
The median concentration in the Floridan were responsible for removal of 97.8 percent recorders in thwls Asima situation appa t intermediate and surficia aquifer systems)
aquier yste isalsobintedrmetdniamte Atlead is likely to precipitate as cerussite. least 15 percent of the sample sets from all The absence of a strong source and the affinity ave reported lad n aqie ytmsm sComparison of filtered t nltrdsmlsi h
districts were below detection limits, as well, of lead for both mineral precipitation and sorption hvrprtdld.second Background Network sampling will Statewide, there were only six samples from the
26







FLORIDA GEOLOGICAL SURVEY


indicate the presence of sorbed or precipitated Floridan Aquifer System convenience in well construction are highly alkaline If the
lead cements are not properly cured and if wells are not
Lead concentrations from the Floridan aquifer Bicarbonate, Carbonate, and properlmy deeoed thklie pnd one reulin we
USince the samples that did have detectable system are roughly equivalent to those in the Alkalinity warsmny Tberalkraine alnd' cabonae mytes
quantities of lead are widely scattered, and intermediate aquifer system The statewide phret herefore aain Floria'nmietre stes
because many of the incidences of detection have median concentration is below detection limits, butIPOTNEADC TRLcosdrdnmaabnteaneuedsa
not been confirmed by resampling, maps showing two districts had upper quartile samples above M RTNEADC TRLcnsdrdnmaabnteanbusdsa
the locations of these detections are not included detection limits, and two are near the standard possi be check on well development and
in this report The importance of the carbonate system as an

ANIONS agent in weathering reactions has been previously
SufcilAqierSstmdiscussed. Bicarbonate and carbonate are dis- Alkalinity Total alkalinity is determined by
sociation products of the reactions between titrating all of the anions in a solution with strong
Classification carbon dioxide and water. Carbon dioxide and acid. The variable is, therefore, a measure of the
Median lead content of samples from the water react to produce carbonic acid (reaction 1) ability of a water to consume, or buffer, acid, and it
surficial aquifer system statewide was 2 gg/L. This Carbonic acid dissociates to bicarbonate and is a measure of the total anionic concentration in the
is a high value, which is subject to concern. The Anions are negatively charged species in hydrogen Ions (reaction 1), which are represented wtrta a ettae iha cdTeain
medians ranged from less than <2 gg/L In SFWMD aqueous solutions They form by taking on by pH The hydrogen reacts with rock materials in that are neutralized by titration with strong acid
Ito below 10 pg/L in the NWFWMD and SRWMD to electrons given up by cations Unlike the cations, the weathering reaction (reaction 2), and include HCOJ COf-, B(OH);, H3SiO4 HS-, POt-,
36 pg/L in the SWFWMD The upper quartiles many of the naturally occurring anions are not ele' bicarbonate remains as the anionic constituent in and some organic ligands. Total alkalinity
(75th percentiles) for lead concentration in the mental (e g., Cl-), they are compound radicals (e g the water. Bicarbonate can further dissociate to includes all of these acid-neutralizable anions. In SJRWMD exceeded the standard, Maximum P043) Anions can be classified according to their carbonate according to the reaction most natural systems, bicarbonate Is the major
concentrations exceed 1,000 pg/L lead in two abundances in the natural environment anion, and concentrations of the other anions are
districts, The three wells in SFWMD with the minor. As such, bicarbonate is the dominant
highest measured lead concentrations had once MAJOR ANIONS HCO; a H- + CO '-. (10) constituent of alkalinity of the water If the analysis
contained either water-level recorders with lead of alkalinity includes only bicarbonate and carboweights or had casings perforated by bullet holes nate, then the alkalinity is called the carbonate
Anions that are present in aqueous systems in Ths H iabntadcarbonate are closely alkalinity The other components can, however,
concentrations greater than 1.0 mg/L are said to Ths H iabntadsignificantly contribute to total alkalinity in some One would expect that the surficial aquifer be major anions. Major anions in ground-water ratdwaters. Non-carbonate alkalinity is the total
system mgtbe the most susceptible to lead systems usually include bicarbonate (HCO3), amount of the non-carbonate species that can be
contamination through fallout or local land uses sulfate (SO4S), and chloride (Cl-). These anions are Bicarbonate Bicarbonate (HCOJ) is the dominant titrated. Of the non-carbonate components listed The low clay content, low carbonate content, high used to classify hydrochemical facies and are carbonate species in the pH range of 6.4 to 10 3 at above, H23SiO4, HS-, and P043- are likely to be I ~ acidity, and high organic content of surficial aquifer discussed in the following section 25DC Bicarbonate Is the primary an ionic significant in Florida waters.
system waters can lead to lead mobility. However, wahngpout(ecin n ) oi sa
the large proportion of samples with detectable weoantin rdctreaonsf andm),smituy is an
Lead, and the high concentrations detected in MINOR ANIONS iportan inca tor of ctsrhemica mh atr inga The districts varied in how alkalinity and
many wells, seems too great, even with these rauier, Beausnae ofis roulely the wmeatherin concentrations of carbonate and bicarbonate were
potetialtraspor coditins.Minor anions range in concentration from in potable ground waters. carbonate, others carbonate alkalinity, and yet
0.001 to 1 0 mig/L. The important minor anions in others total alkalinity In some cases the districts
Intermediate Aquifer System Florida ground waters include fluoride (F-), nitrate Carbonate Carbonate (CQ~2) does not becorne an measured more than One analyte. Consequently,
(NO3), sulfide (SS- and HS), and orthophosphate important anion in water unless pH values are in the tables and maps that follow indicate the nature

SMedian lead concentrations in the intermediate nP ) With th usexdcepton of sulie,nthe ior excess of 8 to 8.5. In most natural systems, car- of the varable reported
aquifer system vary from below detection limits in data are limited, so the anion is discussed in concentrist arempmrllntomnarndctonstatunte DAAINEPETTO
three districts (Table 1 6) to <43 pg/L in the conjunction with sulfate. Depending ons the smetho ofpanalsis tbcarbonateDAANEPETTN
SWFWMD. Maximum and upper quartile concen_-eedn ntemtodo nlss abnt
Stations are not as high as in the surficial aquifer concentrations are unlikely to be reported.
system, but they are still high. Given that the TRACE ANIONS Three tables are used to indicate the variety of
intermediate aquifer system includes the clay- and In order for carbonate to be a dominant anion Talent 1 nd rptscarbonatepc eamntto s.l
organic-rich sediments, as well as carbonate-rock TrcTnosnralyocriaocnrtinbnwtrlxroriaycniin haas ih1 ies 7roate bcronceat onstatns Table
horizons, the incidence of lead should be lower. pHc nosnral ccri ocnrtosi mutr exitaSruncr conditions ohcu hig 1glinree cetatosan abe1
The SWF WMD samples show the highest lead less than 0.001 mg/L Carbonate (C0)), nitritepH usexs Suhcnton cuinsln'rprsta aklnyNtehtthmthdf
concentrations, which reflects, in part, use of lead (NO2), and organic nitrogen (total Kjeldahl nitrogen adevrnetlksweep sgetrta 'rprigttlaklnt nldsbt acu
weights on water-level recorders in some wells [TKNI) are included in this group and discussed Buffering of the pH through rock-water interactions carbonate alkalinity and alkalinity in milliequivalents below Carbonate is discussed with bicarbonate. limits natural carbonate activities in ground-water per liter
Nitrite and TKN are discussed in conjunction with systems in Florida,
nitrate. While ammonium (NH;) is a positively
charged cation, it is included with nitrate for Cements, grouts. and some drilling fluids used Wide ranges in bicarbonate content (Table 17)


27






SPECIAL PUBLICATION NO. 34

reflect different levels of "chemical maturity" of the STANDARD OR GUIDANCE rock weathering becomes more important and Figures 28 and 29).I
ground waters. In general, high bicarbonate CRITERION bicarbonate content increases. The southward
concentrations indicate that the waters have gradient is well illustrated in the SWFWMD (FigureBcrbatcntn ntentrdataufr
undergone significant equilibration with the rock The carbonate species do not constitute a 28c). The increase in bicarbonate content toward Bicarbonas cohlvnte dun t he eeteaqieru matrix. [ow values indicate that little equilibration health hazard per so; therefore, there are no the coast and along the Peace River axis is an systue ishglyvraledet the hetrnGeu adrenaeu has occurred standards or guidance crfteria for the carbonates. artifact of a general increase coastward in ionic nae oten apwith Growur andrbelate
To an extent, carbonate concentrations are strengthof te w ater associated wit increase sednents. amlest wrmith loe bicrfoat
The bicarbonate concentration ranges repor- rpeetdn trifrpHThrisamxmmsediments. siliciclastic horizons. Samples with higher
ted in Table 17 are indicative of some of the pH criterion of 8.5, which is about the pH where -bicarbonate concentrations are from carbonateproblems associated with bicarbonate analyses in H-CO, concentration begins to decline and CO2 rich beds, including the dolostones, limestones, or
aquifer systems For example, in the surficial begins to grow in importance. A similar coastward increase in total alkalinity dolosilts.I
aquifer system, zero bicarbonate concentrations is weakly shown in the data from the northern
are possible due to the acidity of waters in DISTRIBUTION IN GROUND WATER portion of the SFWMD (iure 28d) anteprs ogabnt Tal 8,cnvre om/
siliciclastic aquifer materials, especially those the kisie Riversvaidgy and adjacn pat ofCarbonate (Tae s1m)l cone rtonsg.
characterized by organic acids. High bicarbonate Most Florida ground-water samples have low thC akhte Walexs idge and aante carbonate gvs setdimilarWM cneains.fe
concentrations reflect shelly siliciclastic or to non-detectable carbonate contents (Table 18). while waters elsewhere have high alkalinities. SWFWMD wells, where well development problems Limestone aquifers in which equilibration with a Wells with detectable carbonate, especially those There are no wells in the surficial aquifer system in have been reported. carbonate mineral& has occurred The same wells with carbonate contents in excess of 1 mg/L' Ih aot fteEegae n i yrs
relationships are possible, but less likely, in the are likely to be newer wells that have not been therajority Aofitbe dEvergnde a B ignypes intermediate aquifer system. Here, carbonate thoroughly developed or in which cements and driage. Avaiablednt Andcatfthr aSystntim
clasts are mixed with the siliciclastios and there are grouts have not yet cured, are low in these regions, which are characterizedFordnAufrSse
widespread horizons of limestone and dolostone. by organic-rich waters and direct interconnectionI
between the surficial aquifer system and surface The Floridan is almost entirely limestone or
Avalable alkalinity data for the aquifer systems water. The SFWMD well with the 2,260 mg/L dolostone, so bicarbonate concentrations are Significant aqueous carbonate concentrations (Table 19) are inconsistent. Some of the districts concentration probably represents contamination characteristically high and variability is less than in
are unusual in natural systems. They are usually reported alkalinities in milligrams per liter as by grout or drilling mud. Subsequent samples from the other aquifer systems. Statewide, the medianI caused by improper well installation or devek CaCO3, others reported it in milliequivalents per this well have produced much lower alkalinity concentration is 146 mg/L, and the quartile range opment. Low bicarbonate concentrations (fable liter, others did not report it at all In spite of the concentrations is96 mg/L.
11) associated with high pH (Table 7) values may inconsistent data, alkalinity is included in this
reflect high alkalinity in the form of carbonate ion report because it is a common analyte in ground- Carbonate was nydteedIwlIn the I
(CO2). Obvious problem data have been omitted water contamination studies. Note that, where onMl(ybl1) weetedl ionwstrcin es A weak coastward increase in bicarbonate is
from this analysis, yet some data remain that available, the alkalinity data closely follow the knRWMD Tabe 18),whprebell cnsructio ind present in the Floridan aquifer system throughout suggest influences from well construction, bicarbonate concentrations, indicating that the knwWM tohe bein an robemIesR andeo the state (Figure 30a, b, and d) This increase is a Carbonate concentrations are summarized in Table primary source of alkalinity is bicarbonate, detection limitsrs. fceiclmtrto loggon-ae
18. Comparison of the bicarbonate and carbonate n .flow lines. Chemical maturation within the Florndan
concentrations in the database, or the bicarbonate Surficial Aquifer System aquifer system is characterized by increases in
and pH values on the maps in this report, should Intermediate Aquifer System ionic strength accompanied by dissolution ofI
suffice to differentiate between natural carbonate carbonate minerals (Punnels, 1969; Drever, 1988).
and well-related carbonate. In the Floridan aquifer Median bi car bon ate (Table 1 7) and total Where deeper waters rise to the surface at springs,
system, zero bicarbonate concentrations should alkalinity (Table 19) in the surficial aquifer system The Hawthorn Group and associated strata this increase in bicarbonate is pronounced. For not occur Newly recharged water located in a increase to the south in response to increasing contain abundant carbonate material. Dolostone example, the large re-entrant in Liberty, Wakulla,I
large, karst conduit and, therefore, not in contact calcium-carbonate content of the aquifer system. and limestone beds are widespread and often and Franklin Counties (NWFWMD, Figure S0a) is a with the host carbonate rock may still be acidic Statewide, the median bicarbonate concentration constitute major water-producing zones. Silici-rsutfuweinofdprwtrsnth nr
and have low bicarbonate. Mixing and partial is 138 mg/L., no carbonate is present, and total elastic horizons contain carbonate clasts reworked mresul of thweltiin ofe. wateso the iner equilibration with the host rock should occur in alkalinity is approximately 111 mg/L. as CaCO, from these beds Also, the Hawthorn contains sea water contains about 142 mg/L. bicarbonateI motcssbeds of silt-sized, unconsolidated dolomite (Scott, (Table 8), so bicarbonate concentrations higher
mostoat onasresnsar enra lw1988). These fine-grained "dolosilts' are highly ta 0 gLaearsl fmtrto ln h
Bntesiciaaqrsytemntaionr nerall Flowd reactive with ground water. Water in contact with flptha20 notL sareaeul-owatert uraionaogh The bicarbonate content of the aquifer water (igh urficalb aqufe sste in noter Forbina either source of carbonate gains bicarbonateflwptntst-aeitrioI can be used as a very rough indicator of the abiliy (Figuea ) asth aqufr sse.Tesullc o bcarat alkalinity as a result of weathering Consequently, of the aquifer system to tolerate acidic wastes, mineals iontentauifner ss. Tee t low cr ground waters in the intermediate aquifer system The pattern of bicarbonate in SRWMD (Figure
Lo bcaboat wtes chasocurbopHnae concentrathions tare ssoaed withbow generally have higher bicarbonate alkalinities than 3Db) is complicated because of the presence of
iLow icarbo ate aers, suchito as toccrne pH'spando ofFur2 with toaFissoled calsrbons do waters in the surficial aquifer system. The flow systems east and west of the SuwanneeI wilcicgastic rnt aquifersiteo nov tolece Compaisonsofhigur b 28 w pHur an lwubtraes median bicarbonate concentration in the River. The highest bicarbonate values are near
whlehgnabnteaufrcaesoeterltoshpbtenlwpHadlwbcr intermediate aquifer system, for example, is 143 springs and areas of regional discharge. High
tolernce.bonate content. mg/L as compared to 138 mg/I. in the surficial bicarbonate concentrations also exist along the
aquifer system. This difference is particularly Cody Escarpment, in Columbia and Ahachua
Shell and limestone content of the surficial distinct in north Florida, where the surficial aquifer Counties, and In the Northern Highlands, where aquifer system increases to the south. As a result, system waters contain little bicarbonate compared3

28







FLORIDA GEOLOGICAL SURVEY


flow is thought to be relatively stagnant and introduced to the system by marine aerosols Sulfur is a necessary element for life. Plants Sulfide Given prevaling reducing conditions,
recharge is limited due to the presence of thick (Table 8) and by acidic precipitation from airborne contain sulfur in amino acids and other organic sulfide is the thermodynamically favored species confining strata (Lawrence and LUpchurch, 1976) sulfur oxides Deposition of significant quantities components They obtain this sulfur by reducing (Figure 31) in most Florida aquifer system I of airborne sulfur oxides is a recent phenomenon dissolved sulfate, and they pass the sulfur on to environments. Upchurch et al. (1991) studied the
related to the acid-rain problem. Waters that heterotrophs, including humans and other animals. Eh-pH conditions of surficial and shallow Floridan Total alkalinity in the Floridan aquifer system in recharged Florida's aquifer systems prior to the Because sulfur is stored in tissues, decomposition aquifer systems in Polk County. They found that
the SJRWMD (Figure 30c) suggests a weak re- late 1800's should contain little or no of organic materials constitutes another possible surficial aquifer system water'is reducing (-300 toO0
entrant that follows the St Johns River Many of the anthropogenic sulfur. Recently recharged waters source of sulfur as sulfide. Sulfur constitutes mV) and, given a pH range of 4 to 6, H2S is the higher alkalinity concentrations reflect deeper wells may contain significant amounts of this sulfur about one percent dry weight in organisms most probable sulfur species Water samples from
Modern precipitation contains an average of 1 75 Decomposition of humic substances by microbes the Floridan aquifer system were influenced I Bicarbonate concentrations in the SWFWMD mg/L sulfate statewide (Table 3). The highest involves chemical reduction, so the released sulfur somewhat in their study by interaquifer recharge.
(Figure 30d) reveal two significant patterns The sulfate concentration recorded in the precipitation is usually in the form of sulfide Oxidation may Eh ranged from -250 to O my, and the pH was near data from the northern half of the district show an data (Table 3) was almost 23 mg/L, which is well follow rapidly 7 (Figure Si) Under those Eh and pH conditions,
irregular distribution of bicarbonate Part of this within the range of concentrations recorded from the Florndan aquifer system water samples fell near
I ~irregular pattern is a result of variations in well Florida's various aquifer systems. Se ae sa ~o uft nthe intersection of the SO: H25, and HS stability
depth, but much of it reflects the unconfined to coaa wenvronns A vrtagse sulfate nn fields. It appears that, outside of regions of
poorly confned nature of the Floridan aquifer Rock weathering is the most important natural train inewrtnrns 27A10rmgkg (Tale 8) soth immds redcadgH -isdth sabl sulfr secies.
syein the d area. d Lscal rfslw sytem ruad source of sulfur in aquifers Most rocks contain at transition zone should contain a concentration Hydrogen-sulfide odor (the familiar "rotten egg' pren Tof detdicrge tesoulthn the irregua least trace quantities of pyrite (FeS2) and other gradient that increases toward the coast regard- odor) is detectable in many wells in all aquifer dpsttent hew da fom her southern aluo te metal sulfides. These sulftde minerals can be less of any contributions from the deep flow systems of the state, supporting the conclusion of
disrit ho asiplr isriutonpaten uetooxidized according to the reaction sse
the confined nature of the aquifer system. sytmUpchurch et al. (1991).
Rl-S. + 3 50 + H20
Daa rm heSWM Fiur 0e ae(1)Finally, a number of agricultural, waste Much of the H2S in aquifer systems is a
Daufit from thve SFWMD (ingretO. Toae( disposal, and industrial activities release sulfur result of sulfate reduction The conversion of
I ainficientt r ovindte muhinfrmat ion. Taly R +2S + H, compounds to ground water. Gypsum (Table 4) is sulfate to sulfide is usually accomplished by
alknLktaes dg area. h Kisime River valleys S~+ used as a soil amendment to acidify soils. Landfill aquifer or sol microbes, and follows a reaction
andgLe aes idge r area. he Luggest Wa leachate can be high in sulfates and/or sulfides. such as shown in reaction 6. Note that a source of
the low alkalinities are a result of a low level of where Rl-S2 is a metal-sulfide compound, such as platng pnutns, eese slfate, sall y andfui organic carbon must be present for sulfate Chemical maturation In contrast, Flordan aquifer pyrite, containing reduced sulfur, and RNis a pton co antbut ae sulfate s grundl wae in thei reduction Rightmire et al (1974) and Rye et al.
system waters near the coast contain higher rnetal, such as iron, that is simultaneously involved acid. Phosphogypsum disposal at agrichemical (1981) used isotopic analysis of sulfur to determine
aklntswchrfetmurtn.As indicated in the oxidation reaction plants in central and north Florida has been shown the origins of sulfate and sulfide in Flordan aquifer
below, there is an abundance of sulfate in Flordan R 25 2Htocnrbtsufetogonwtrinhesystem waters Sulfide in shallow portions of the
FqieVytm ae ncasa n h cnrlad+ 0.25O + -2.2 immediate vicinity of the gypsum disposal areas Floridan near recharge areas was shown to be a

Southern parts of the SFWMD This sulfate (12) Mier n u ie ,98 194ucinqun result of sulfate reduction.
I replaces bicarbonate as a major anion, and there- R' (OH)+ 2H. system water samples in the Alafia River basin. He
by reduces akalinities. -- + 'found calcium-sulfate water in two wells that areUnruntysfdewsntdtmnd
distant from the phosphochemical plants. There- throughout the Background Network, so only the
I sulfate If the reaction involves pyrte, Ra is Fe>, which is fore, high sulfate concentrations in the general area role of sulfate can be documented in this report.
oxidized to Fe>. Thus, oxidation of metal sulfide of phosphochemical plants may not be a direct There are some sulfide data from the SWFWMD minerals results in the production of sulfate and product of those fertilizer plants. that allow a partial understanding of sulfide
IMPORTANCE AND CONTROLS hydrogen ion, which reduces the pH. Reactions 11 concentrations in Florida's aquifer systems.
and 12 are the 'acid-mine drainage" reactions. Sulfide in the surficial aquifer system averages 0.55
Pyrte is found in all of Florida's aquifer systems Sulfate is removed from surficial aquifers by mg/L (&* 1.09 mg/L, range = 0.00-5.50, n = 82).

SSulfur occurs in several oxidation states, and aquitards. It is especially abundant in clay-ch plant metabolism It can also be removed by There are no data for the intermediate aquifer
depending upon the reduction/oxidation potential horizons of the Hawthorn Group (Table 5). aquifer rmicrobe metabolism, including reduction to system. In the Floridan aquifer system, sulfide
of the water. Two are of major importance in sulfide Precipitation of sulfate as gypsum can avrgs0.44 mg/L (&* = 0 63, range = 0.00-2 43,
aquifer systems These are the oxidized form, occur at high ionic strengths, such as occur in n = 136). These concentrations are consistent with
sulfate (SO:), in which sulfur has a valence of +6, Dissolution of gypsum and anhydrite at the evaporative lakes and desert soils. Although there concentrations in equilibrium with H2S at the Eh
and the reduced form, sulfide (S2- or HS-), which base of the Flondan is also an important source of is no evidence of sulfate mineral precipitation in and pH ranges found by Upchurch et a! (1991).
has a valence of -2 sulfur as sulfate. The dissolution of gypsum has FHonda today, sulfate-rich evaporite minerals are
been documented by Rightmire et al. (1974) and common at the base of the Floridan aquifer system Slae-I h ae soiiig(iueS)

SOURCES AND SINKS OF SULFUR Rye et at (1981) This sulfate is brought upward and locally in the Hawthorn Group Sulfides are sulfide may beh oxdie to sulfaes. Thi reaction
I ~along the coastal transition zone, so that much of removed from ground water by oxidation to can be driven either inorganically or microbially.
the coastal Flordan aquifer system can contain sulfate, metal-sulfide mineral precipitation, The reactions can be characterized by reactions 11 There are many potential sources of sulfur in high sulfate concentrations. degassing of HsSga, and microbial fixation. and 12. Note that the product is SO2 plus H-, in
5 ~Florida's aquifer systems Sulfate is directly other words a dilute sulfuric acid solution.


29






SPECIAL PUBLICATION NO. 34


While sulfide oxidation is a widespread deposition of high sulfate water on plant foliage Median sulfate concentrations (Table 20) are soils, such as the surficial aquifer system. They
reaction in Florida's aquifer systems, the dominant may cause crop losses. Sulfate-rich water has a low in NWFWMD and SRWMD for three reasons: found that microbial sulfate reduction is inhibited source of sulfate is dissolution of gypsum and laxative effect on humans and may produce (1) the surficial aquifer system, especially the Sand and sulfide formation is minimized at redox
anhydrite near the base of the Floridan aquifer adverse taste mn drinking water, as well As a result and Gravel Aquifer of Escambia County, is well potentials above -150 my and at pH's outside theI system. These minerals! which are interstitial in of the latter effects, the Secondary Drinking Water flushed, (2) there is limited upward flux of deeper, range of 6 5 to 8.5 Since optimal conditions for the Eocene Avon Park Formation and lower standard for sulfate has been set at 250 mg/L sulfate-rich waters, and (3) few wells in the sample microbial sulfate reduction may not be present in
horizons, are dissolved into deep flow systems in (Florida Department of Environmental Regulation, set are coastal. The maps of sulfate distribution the surficial aquifer system (low pH values and Eh the Flondan. The result is that Floridan aquifer 1989). (Figure 32a,b) in these districts show minor coastal values that tend to be above -150 my), sulfate, not
system water that upwells near the coastal increases in sulfate concentrations. The causes of sulfide, may predominate as a metastable species.
transition zone has an inner 'belt" of sulfate-rich high sulfate concentration inland are unknown, but
water Rightmire et al. (1974) and Rye et al. (1981) Sulfides are much more undesirable than oxidation of pyrite-containing peats, upwardI
showed that dissolution of the sulfate minerals, sulfates in ground water. Hydrogen sulfide gas transfer of intermediate or Floridan aquifer system Intermediate Aquifer System rather than oxidation of sulfides, is the dominant (H2Sga) is a persistent problem in ground water, water by pumpage, and evaporative concentration cause of the deeper and coastal sulfate-rich although Florida suffer less than some regions of sulfate-rich precipitation are possible causes. The intermediate aquifer system contains
waters' ~~~~~~~~~which can be detected in water at dissolved a ud n ytadg p u a e nf udi
concentrations of just a few milligrams per Itter. Median sulfate concentrations in the other number of regions of the state. Low permeabilities Microbial Activity Microbial processes and While some persons treat H2S and sulfate-rich three districts (Table 20) are relatively high because in the clays and the presence of particulate humic
chemical kinetics determine the rates of water ("sulfur water" in the vernacular) as a health- the surficial aquifer system includes regions of substances limit oxidation of the pyrite, but theI
conversion from one species to the other (Connell giving resource which one drinks to "clean out" the natural and irrigation-related upward flux of potential for oxidation and aqueous sulfate and Patrick, 1968, Rye et aJ., 1981) The ability of alimentary system or in which one bathes for deeper, sulfate-rich waters and of mixing with sea production exists Red, orange, and yellow tints the microbes to function in an aquifer system is therapeutic reasons, most consider this common water in the coastal transition zone. Atlantic from ferric hydroxides and goethite in exposures of dependent upon a complex array of conditions phenomenon as a liability. In high concentrations, Coastal Ridge portions of the surficial aquifer the Hawthom Group and in immediately underlying and, if these are not met, the sulfur may not be hydrogen sulfide is irritating to the eyes and lungs. system often contain sulfide-rich organics and limestones along the flanks of the Ocala Platform altered regardless of Eh and pH. For example, if It is highly toxic as an atmospheric gas There is no pyrite. These are locally important aquifers in the document oxidation of pyrnte in the past. there isn't a source of organic carbon (reaction 6), standard or guidance criterion for sulfide in ground SJPWMD and SWFWMD, and they are wellI aquifer microbes may not be able to reduce sulfate or drinking water for two reasons: (1) the odor can represented in the data set. Zones of local With the exception of Flagler and Indian River to sulfide. Therefore, metastable sulfur species be eliminated by degassing and is unpleasant upconing are evident in western Indian River Counties (SJRWMD), the intermediate aquifer may be present in the water samples. enough to serve as its own limitation, and (2) there County, Volusia County, and Orange County and system is neither widespread nor widely used in
Is usually sufficient aeration and oxidation in public the coastal interface is well demonstrated in the northern districts (NWFWMD, SRWMD, andI water supplies that any sulfide is converted to SJRWMD (Figure 32c). Sulfate upconing is also SJRWMD; Table 20); consequently, few data are The abundance of sulfate in the deep Floridan sulfate, for which there is a standard. present in Hardee and DeSoto Counties, and there available. Where data are present, it appears that
aquifer system is an example of a potentially is a large re-entrant along the Peace River axis flow systems are restricted and sulfide oxidation is
metastable sulfur species. The deep Florndan 's (Figure 32d; Kaufman and Dion, 1967) In SFWMD, limited. Sulfate concentrations are characteris-I
chemically reducing, and sulfide is generally the DISTRIBUTION IN GROUND WATER the sulfate concentrations in the Atlantic coastal tically low and variable (Figure 33a,b, and c).
stable species. While there'is some sulfide in deep ridge portions of the surficial aquifer system are
Floridan aquifer systern waters, microbes appear It is interesting to note that, while maps and low due to the dynamic circulation in the aquiferU td eual oefcivedlyyrdiusolutio of gysmonyte nelare spatial studies of the distribution of sulfate clearly systems. Few sulfate data exist from the In contrast, the intermediate aquifer system is theri b dofeauinfe sysm Trhne lt nfter show an increase with depth and towards the Everglades portion of the SFWMD (Figure 32e) highly utilized in southwestern SWFWMD and In microbs ordc the ulftemay Te arbslt of ah coast, Table 20 suggests that there is little Andrejko and Upchurch (1978) have shown that western SFWMD. Here, the circulation system is miroestoreuc te ufae aybea esltofad feene n ulat cnenraios etee tethe peats of the Everglades contain sulfur that is better developed, and connection with theI
lack of an organic carbon source (WNatrous and diffree qine sulftems concentrart bewe the converted to anhydrite during peat fires. This underlying Floridan aquifer system is present in Upor h ny yeran.)an ionseerlong fte flowst sea water affects all systems equally, (2) there is anhydrite is then dissolved in surface waters, many coastal areas (Upchurch, 1986) As a result, po any yer n ayklmtr ln h significant interaquifer transfer of water in both which, in turn, recharge the surficial aquifer sulfate is widespread and abundant (Table 20). Rept upward and downward directions, and (3) the system. One can conclude, therefore, that sulfate entrants along the Peace and Myakka River axesI
sample set is somewhat biased toward the more concentrations in the surficial aquifer system (Figure 33d) reflect upconing and intrusion along STANDARD OR GUIDANCE potable, low sulfate waters, Maximum concen- should be moderately high lineaments that extend through the Hawthorn
CRITERION trations do suggest that the deep Floridan aquifer Group (G. Jones, 1991). These regions are a resultI
s tmis prone to higher sulfate concentrations CmaiooftehpHcntosofheof natural discharge, exacerbated by pumping.
syse Cm rsn fteE-Honton fteThere is a region of high sulfate that apparently
Even though sulfur is necessary for life, than are the other aquifer systems. surficial aquifer system (Figure 31) indicates that, reflects upconing in northeast Lee County, as well
adverse effects arise if it is present in hazardous at 25C, the water falls at or below the boundary (Figure 33e).U
forms or concentrations, Formation of sulfate Surficial Aquifer Systerm between SOf and H2S, with the majority of the
through aqueous sulfide oxidation (reactions 11 samples well within the H2S stability field The
and 12) or equilibration of sulfur oxides with water kinetics of equilibrium reactions between the two Florndan Aquifer System
in the atmosphere both result in acidic, sulfate-rich The distribution of sulfate in the surficial sulfur species are dominated by bacteria, andI waters that have the potential of being corrosive aquifer system (Table 20) reflects local geology metastable species can exist if bacterial action is Sulfate concentrations increase with depth in and hazardous to aquatic organisms. Sulfate-rich and flow system dynamics inhibited. Connell and Patrick (1968) investigated the Floridan aquifer system throughout the state.
waters are potentially toxic to plants and the stability of sulfate and sulfide in waterlogged

30







FLORIDA GEOLOGICAL SURVEY


H The data set summarized in Table 20 and Figure Floridan aquifer system. Low concentrations of Connate waer can be a minor source of transgressions.
34 has not been stratified by depth, so some of the sulfate in much of the upper Florndan aquifer chloride The potentiometry of the Florndan aquifer
higher sulfate concentrations represent deeper system in the center of the state indicate that system in south Florida is insufficient to flush the SADR RGIAC
wells. Lowest sulfate concentrations are in sulfate reduction, sorption/precipitation reactions, Floridan aquifer system completely. As a result! CTNDRITERINC
recharge regions where meteoric waters have not and dilution reduce sulfate in comparison with the connate waters remain in much of the aquiferCRTRN
accumulated sulfate This lack of sulfate results surficial aquifer system. The Eh-pH range in the system, where they render the water non-potable
from (1) residence times that are too brief for pyrnte deep Florndan is suitable for microbial sulfate Connate waters also occur in southern St Johns, Chloride is associated with taste and electrooxidation, (2) pyrite or other sulfate sources have reduction according to the criteria of Connell and north-central Flagler, Brevard, and Indian River lytic corrosion problems As a result, the either been depleted or were never present, or (3) Patrick (1968). Limitations of available organic Counties Elsewhere, minor connate waters may Secondary Drinking Water standard for chloride
pyrite oxidation is not thermodynamically favored, carbon apparently inhibits sulfate reduction and be present in 'dead" spaces in the aquifer system. has been set at 250 mg/L
Highest concentrations are in deep wells where accounts for the persistence of sulfate Dead spaces may include portions of the aquifer
contact with the underlying gypsum and/or system with poor to nonexistent circulation Or low
anhydrite has enriched the water with sulfate Choiepermeability. Exploration of the Eocene and older DISTRIBUTION IN GROUND WATER
Chloridestrata below the lower confining beds of the
I ~ ~~~~~~~~~~~Floridan aquifer system for deep-well disposal ofThditbuonfclrdesawdeelcs
nFM g nd sRWMD. Lannrgtae, oast ren IMPORTANCE AND CONTROLS wastes and oil and gas exploration indicates theThdsnbtn fhldetawderfet
NWFMDan SWM. arecostl e-widespread presence of connate water and brnnes. proximity to connate waters and recharge by
entrants occur in Walton County and along the These high chloride waters may upwell locally into meteoric waters. The surficial aquifer system
I Apalachicola River in NWFWMD (Figure 34a) Chloride (Cl-) is a conservative lon. That is, it is the potable portion of the Floridan if the confining contains waters with low median chloride
These are a result of natural discharge along the not reactive in most ground-water chemical sequence is inadequate or where withdrawal is too concentrations (Table 21). Median concentrations nvyer and to pumpage The pattern in SRWMD is systems. It does not participate in sorption, great. in the intermediate aquifer system are high, largely
more complicated due to the local flow system mineral precipitation, microbial metabolism, or as a result of low permeability zones in the
I between the Suwannee River and the coast other processes The only processes that lower Hawthorn Group. Median concentration in the
Coastal re-entrants exist along many of the coastal chloride concentrations in Florida ground water are Once chloride enters the aquifer systems, it is Floridan is low, but this reflects the bias En

rnvers and in the vicinity of the Suwannee River- dilution and dispersion. The only common subject to several factors that can cause increases sampling towards potable water masses The
High sulfates are also present in the confined, circumstance in which chloride ,s chemically in chloride concentrations Near the land surface, maximum chloride content recorded is in the sluggish flow system under the Northern Highlands removed from an aquifer is mineral precipitation evaporation and transpiration may increase Floridan and, at 20,500 mg/L, this concentration is in the northeast part of the SRWMD (Figure 34b; under intense evaporation, which occurs only in chloride content. Evaporation occurs both at the slightly greater than average sea water (19,350 Lawrence and Upchurch, 1976) desert environments, not in Florida. Because it is land surface, in lakes, streams, and other water mg/kg, Table 8). Thus, the Floridan aquifer system
I ~not reactive, chloride travels at the rate of the bodies, and within permeable and porous aquifers contains the highest concentrations of chlorndes
H1 hsulateconentatios i SJWMDandgrond wter soit s a exellet tace ofgrondPlant roots extract moisture from the vadose, Hig slaecnetaininJRM angruwter, oi sa eclettacro rud capillary, and phreatic zones, as well. The net
SWFWMD (Table 20) reflect longer flow paths in wate fow, result is that chloride content increases in near- Surficial Aquifer System
the Floridan that contact the gypsum and anhydrite sraeevrnet.Cmaio fTbe n
at the base of the aquifer system and bring that Chloride can be added to aquifer environ- surac eviowsnhtments. Cmariso ofnaenrts nTedsrbto fclnei h ufca
water near the surface along the inner, coastal- ments in three ways. The most widespread surficial aquifer system waters range from four to aquifer system (Table 21) closely mirrors
transition zone. Characteristically, sulfate process is addition of chloride in marine aerosols over 30 times the chloride concentrations in preci- precipitation (Table 3). Median chlornde concenI concentrations increase towards the coast There that enter the ground water through rainfall. pitation within the respective water management trations are lowest in north Florida (NWFWMD,
is a region of high sulfate along the St Johns River Florida precipitation averages 1 66 mg/L. chloride districts In the same data, the mole ratio of SRWMD) where continental influences on (Figure 34c), which has been attributed to (Table 3). Mean chloride concentrations in sodium to chloride remains relatively constant and precipitation are greatest Peninsular Florida has
upconing along a fracture or fault by Leve (1983). precipitation range from 0.75 mg/L In north Florida near that of sea water (0.87 to 1.25 in preci- highest median concentrations of chloride in both Similar re-entrants along the Peace and Myakka to 2.81 mg/L in the south. Lawrence and pitation; 0.71 to 1.42 in ground water), so it precipitation and ground water. The difference in
Rivers (Figure 34d) have also been attributed to Upchurch (1982) documented the origin of sodium appears that much of this increase in chloride concentration between precipitation and surficial
upconing along lineaments by G. Jones (1991). and chloride in the Floridan aquifer system in an concentration is a result of evaporation or aquifer system water can be attributed to evaTecswrdnras nsLcai ed alusrasof unconfined, high recharge area of north Florida as transpiration. poration and transpiration.
in the SWFWMD (Figure 34d). Lczdars having been derived from rainfall
upconing of sulfate-rich water are found
throughout both districts The observed increases in chlornde concoen- Charactenistically, chloride concentrations are
I ~Chloride is the dominant anion in sea water tration with depth can be explained by three lowest inland (Figure 35) Monitor wells in
(Table 8). Sea water averages 19,350 mg/kg hypotheses One explanation is that connate NWFWMD and SRWMD are generally inland, so
The Floridan aquifer system in the SFWMD is (Table 8), so chloride content of water on the water trapped in sealed pore spaces or below the the median and maximum chloride concentrations
Very poorly flushed and sulfate-rch. The data given coastal transition zone can be quite high Because sub-Flordan confining sequence is added to the are low. The coastal transition zone is reflected in
U ~ in Table 20 are somewhat biased in that no wells of the water quality standard for chloride, the aquifer system water by rock dissolution and/or a few wells in NWFWMD (Figure 35a)
are represented from the southern portion of the coastal transition zone is often defined as the 250 opening of pore throats Another explanation is district (Figure 34e), where sulfate concentrations mg/L isochior. While the transition zone is actually that hydration of minerals removes water from the
are the highest. a broad belt, the position of this isochlor, which aquifer system, thus increasing the residual SJRWMD data include a number of wells near
defines a surface, has incorrectly led to the chloride content. The most plausible explanation the transition zone, hence the higher median Eh-pH- relationships (Figure 31) indicate that concept of the transition zone as being an is that the chloride is a result of incomplete concentration (Table 21). As Figure 35c indicates,
either sulfate or sulfide can be stable in the interface, the "salt-water interface". flushing subsequent to the Plio-PReistocene marine coastal re-entrants with high chloride concen31






SPECIAL PUBLICATION NO 34


trations exist in Flagler and, to some degree, St The medians and ranges of chlonde in the surficial The transition zone is relatively narrow in most Pollution Control Administration, and its successor Johns Counties, A high chloride zone centered on and intermediate aquifer systems are generally not of the SRWMD (Figure 37b). Re-entrants exist the U.S. Environmental Protection Agency, western Brevard and Indian River Counties significantly different in the northern part of the along some coastal rivers (Steinhatchee, Aucilla, because it was felt that phosphate was the limiting
coincides with the upper St. Johns River and state. However, the central and southern portions, Waccasassa), and re-entrants in Taylor and Dixie nutrient' in most waters of the nation It isI wetlands to the south. Intense evapotranspiration where the Hawthorn is thick, are characterized by Counties can be attributed to pumpage associated questionable whether phosphate is a limiting accompanied with possible upconing or upward high chloride concentrations One should not be with small towns and industry Inland highs nutrient in surface water in many areas of the state transfer of water from deeper aquifer systems surpnsed, therefore, if somewhat elevated chloride include an upconing at the Ichetucknee Springs due to the abundance of apatite-group minerals in along fractures and through imgation can account concentrations are encountered in the intermediate group (the high at the Suwannee-Columbia County late Tertiary and Cuaternary sediments.I for this area of high chloride concentration aquifer system inland, boundary and the Santa Fe River).

The most important sources of phosphate in
The coastal transition zone and associated Distributions of chlornde in the intermediate The data from SJRWMD (Figure 37c) illustrate Florida are the phosphate-bearing sediments
salt-water intrusion are well represented in the aquifer system in NWFWMD, SRWMD, and the coastal transition zone, with a re-entrant in found throughout the Hawthorn Group Two
SWFWMD (Figure 35d). The high in Hardee SJRWMD (Figure 36a-c) reflect evaporative Volusia County Other high chloride areas in St. apatite group minerals predominate in the
County has been attributed by Dalton (1978) to up- concentration. There is considerable local Johns and central Flagler Counties; along the St. phosphatic sediments carbonate-fluorapatiteI ward transfer from the Florndan aquifer system by variability, and increases toward the coast can be Johns River in Putnam, Volusia, and Seminole [Ca5(PO4,CO)3F, or "francolite""] and carbonateirrgation. The re-entrant along the Peace River seen. The causes of the local variability cannot be Counties; and in Brevard and Indian River Counties hydroxylapatite [Ca5(P04,C03)3(OH), or "dahlite"j. has been attributed by G. Jones (1991) to identified from the data set, but interaquifer are thought to be connate water (Stringfield, 1966; Weathering of both minerals introduces phosupconing and intrusion along a major lineament. transfer through irrgation is likely. Boniol, 1981, pers. com.). The re-entrant that phate into ground and surface waters (LawrenceI
extends from the coast in St. Johns County, and Upchurch, 1982). The widespread occurrence
throgh utna Conty andint Maon Cunt isof these phosphate minerals (see the discussion of
Chloride concentrations in the Biscayne The coastal transition zone is well documented through Puna oundin toMrinCunyi the distribution of the Hawthorn Group in Scott
Aquifer (Table 21, Figure 35e) are generally low, in SWFWMD (Figure 36d). Local re-entrants reflect poaldutopcng.[1988]) suggests that phosphate is locally, naturallyI with a small, intrusion-related re-entrant in the salt-water intrusion due to pumpage and lowering available throughout much of the state.
Miami (Dade County) area. Chloride concentrations of potentials by other medians The large re- Comparison of the potentiometric map of the in the northern part of the district are also generally entrant along the Peace River axis is also well Floridan aquifer system (Figures 35 and 36 in Scoff low, but irrngation with deeper, more saline waters documented. et al., 4991) with chloride data from SWFWMD Carbonate-fluorapatite is the primary phos-I
has resulted in a few high chlornde zones. Data (Figure 37d) and SFWMD (Figure 37e) clearly phate mineral in the Hawthorn Group. It was
from the SFWMD indicate an increase in chloride illustrates the effects of poor flushing and intrusion precipitated from the Miocene sea throughout the
toward the Everglades, which reflects the presence The transition zone appears as a broad surface where the hydraulic potentials are low5 The eastern and southern sides of the Ocala Platform. of connate water and upooning of poorer quality with a relatively shallow dip in the SFWMD (Figure southern third of SWFWMD and the southern two Subsequent erosion of the Hawthorn on the crest water from underlying aquifer systems Reduced 36e) Highs in northern Collier and eastern Lee thirds of SFWMD have lower potentials. As a of the Ocala Platform and elsewhere, led to permeability of the surfictal aquifer system has Counties are a result of upooning caused by result, chloride content of the aquifer system is transport of dissolved and particulate phosphate prevented thorough flushing of connate water natural upward discharge and by pumpage higher and the transition zone is broader and into contemporary sediments, where theI
beneath the Everglades. In addition, drainage of flatter In the central and northern thirds of phosphate accumulated as extremely rich ore
wetlands for agriculture has significantly lowered Floridan Aquifer System SWFWMD, hydraulic potentials are high, chloride deposits These deposits are mined in central
the water table and induced upconing. concentrations are how, and the transition zone is Florida (Polk, Hillsborough, Hardee, DeSoto, and
steep and narrow. Scattered areas with chlornde Manatee Counties) and in north Florida (HamiltonI With the exception of the data from SFWMD, concentrations in excess of 10 mg/L in the County) Ore-quality deposits occur at depth in St.
Intermediate Aquifer System the Florndan aquifer system is similar in chloride northern third of the SWFWMD reflect somewhat Johns and Brevard Counties and other areas. The
distribution to the other aquifer systems of the deeper wells. In general, this area is characterized deposits that contain these phosphate-rich Median chloride concentrations in the inter- state (Table 21). Chloride concentrations are by recharge, and chloride contents are near those horizons constitute portions of the intermediate mediate aquifer system show the same pattern as generally low in shallow wells, inland, and in of precipitation. aquifer system. Carbonate-fluorapatite was also
in the surficial aquifer system (Table 21). Chloride recharge areas. They are highest near the coast, in reworked during subsequent marine transgresconcentrations are low in the continental-climate- deeper wells, and in areas of pumpage-induced sions and regressions into younger, Quaternary
dominated northern part of the state and high in intrusion, hsht deposits that constitute the surficial aquifer
the more maritime climate of the south, system.
The transition zone is well defined in the IMPORTANCE AND CONTROLS
The intermediate aquifer system, which NWFWMD (Figure 37a). Areas of intrusion include Carbonate-fluorapatite is a source of several
includes the Hawthorn Group, contains significant Escambia County, southern Walton County, Phosphate, as reported here, is ortho- other environmentally important constituents in
clay deposits (Scott, 1988), which have high southern Bay County, and isolated spots in phosphate (P02-). Phosphate is of concern Florida ground water. Carbonate-fluorapatite is
porosity and low permeability These clays Franklin and Wakulla Counties. All of the re- because it is an essential nutrient of all living the primary source of fluoride in the aquiferI
apparently contain some connate water As a entrants west of the Apalachicola River are things. Because is it an essential nutrient, excess systems (see Fluoride below). Carbonateresult, one would intuitively expect that chloride associated with well fields and pumpage. The phosphate can cause run-away plant growth and fluorapatite also contains trace quantities of concentrations would be somewhat more variable isolated highs in Franklin and Wakulla Counties are eutrophication6 of surface waters. Therefore, uranium (Cathcart, 1956, Altschuler et al., 1958).I and the median would be higher than surficial near small communities and a large spring com~ control of phosphate in surface water has been a The uranium undergoes a series of decay events aquifer system waters. This pattern is supported plex, both of which can lead to intrusion, national priority since the late 1960's. Control was that result in radium, radon, and polonium, all of by data from the Background Network (Table 21). established as a priority of the Federal Water which have been shown to be problems in3

32







FLORIDA GEOLOGICAL SURVEY


SFlorida's aquifer systems (e.g., Kaufmann and document an area in Columbia County where this Phosphate is removed from ground water by phosphate in unfiltered samples. NWFWMD and
Bliss, 1977; Cowart et at., 1978, Burnett et a!., process is taking place today. several processes in carbonate-rich aquifers, the SJRWMD measured total phosphorus, which
1988; Upchurch eta!., 1991) removal is by precipitation of carbonate-bydroxy- includes minor amounts of condensed and orlapatite (reaction 14) This reaction is effective as a ganic phosphorus, as well as orthophosphate Deposition of carbonate-hydroxylapatite in mechanism for orthophosphate precipitation, and SWFWMD analyzed for total phosphate (orthoCarbonate-hydroxylapatite is a result of re- significant ore bodies occurred in a belt along the alkaline waters seldom have detectable phos- phosphate, condensed phosphates, and other
precipitation of phosphate following weathering of eastern flank of the Brooksville Ridge (Hernando, phate as a result. Should phosphate be detected phosphate compounds), and SFWMD measured I ~ carbonate-fluorapatite. The phosphate ion (P043) Citrus, Marion, Levy Counties) and elsewhere. The in ground water, it is safe to conclude that (1) the dissolved (filtered) orthophosphate. Differences in
is soluble in acidic waters, such as occur in deposits are commonly preserved in paleo- popaehsntytecutrdsfrin hs esrmnsaentcniee
siliciclastic horizons of the surficiah aquifer system sinkholes, where the carbonate-hydroxylapatite phosalnte h ausno preptatenacotere sufhcent- thse meiasueetnrntcniee
The ion is insoluble in alkaline aquifers, such as lines the sinkholes and partially replaces the alnknliniyt case preciitaind( slcommosni phueornfcn
occur in the Floridan aquifer system. The reactions adjacent limestone. Economically important horizons) or (2) the phosphate is either complexed
are as follows. In the acidic surficial and inter- deposits are termed "hard-rock" phosphate. Hard- with a metal or present as some form other than The distribution of orthophosphate in Florida mediate aquifer system waters, carbonate- rock phosphate was mined in Citrus, Gilchrnst, quusrhphpatground waters is summarized in Table 22. In
Sfluorapatite is dissolved according to Marion, and Levy Counties from the 1890's to the auosrtphpae.general, median phosphate concentrations follow
U ~mid-1 960's The process of carbonate- chemical controls rather than the distribution of
hydroxylapatite precipitation continues today in the Phosphate is strongly adsorbed by ferric sources That is, highest median and maximum Cas (PO4, CC3) 2Fs + 7.5H+ Floridan aquifer system, and dissolution of the hydroxides and certain other colloids in soils and concentrations are in the surficial aquifer system,
resulting hard-rock deposits may constitute an aquifers. This sorption is an important mechanism where the water is acidic and reaction 13 pre-SCa2' + 1 .SH3PO4 (13) additional source of phosphate in ground water for phosphate removal from ground water, dominates. Water from the intermediate aquifer
especially where on-site and land-application system, which contains the majority of the sewage treatment release phosphate to the phosphate mineralization, contains Jess phosphate
U + 15[H2C0O + FMarine aerosols constitute a small, but environment Childs et al. (1974) documented because of buffering with alkalinity derived from
significant, source of phosphate Based on an orthophosphate sorption reactions on ferric the associated carbonates (reaction 14). Water
average chloride concentration of 1.66 mg/L in hdoiecae adgan n ncasblwfo h lrdnaufrsse scaatr
where the phosphate and carbonate are wriften as precipitation (Table 3), and chloride and phosphate thydiecoate sa nd ainlsti anduonclay Tbe frothe loin spatudfer sytem hracterg
phosphoric and carbonic acids for simplicity and concentrations in sea water of 19,350 mg/kg and showed that phosphate fixation in septic-tank alkalinities.
phosphate and carbonate are present in equal 0 05 mg/L (50 pg/kg, Table 8), respectively, the drain fields is very nearly quantitative, with mole proportions in the apatite. Upon encoun- concentration of phosphate in precipitation should concentration factors on the host soils in excess of
tering an alkaline environment, the phosphoric and be 1 6 pg/mI Measurements of phosphate in 1000 times Rea and Upchurch (1980) studied Surficial Aquifer System
I carbonic acids are neutralized and carbonate- precipitation (Table 3) average 0 03 mg/L orthophosphate fixation on a ferric hydroxidehydroxylapatite precipitates according to statewide, and suggest that the atmosphere is coated fine sand in the surficial aquifer system. Phosphate in the surficial aquifer system can

I ~ +15 O 1)perche for orders oft magnsitude o0verathe They found that minor amounts of ferric hydroxide come from several sources, including natural
5Ca~+ IsPOaq (4) pected ahermoolyr coetrat Thi atly (< 3 weight percent) removed large quantities of weathering of phosphate minerals reworked into
becauseHteOmonolayrpofeseawater attat thesuref amos-i)i phosphate. the aquifer sediments from the underlying
a 2 ~~~~~enriched in phosphate, and partly a result of Hwhr rulahn fntrlpopae
organics and particulates in the atmosphere. At STANDARD OR GUIDANCE from organic sediments and decomposing plant
-Ga6 (PC4, COB) (OH)0.- any rate, precipitation is an important source of CRITERION materials, use of agricultural fertilizers, and septic
phosphate for plants. The concentration of tank systems and other waste-disposal practices.
S+ SSH- phosphate in precipitation is similar to that in the The widespread occurrence of phosphate in the
U ~surficial aquifer system There is no standard or criterion for phosphate surficial aquifer system suggests that geologic
in ground water (Florida Department of conditions produce a strong "overprint' on the
The hydrogen released by the precipitation reac- Environmental Regulation, 1989). The U S. aquifer system and that local sources (swamps,
tin s onumd y lkliit ad/r isoltin fOther sources of phosphate include inorganic Environmental Protection Agency and the state human activities) build on that background overcact ration 3)Ift is consumed byallityndo dissolution o and organic fertilizers, organic tissues, animal both have standards for total phosphorus in print Because the human sources are local, they
of calcite, carbonate-hydroxylapatite is likely to wastes, human waste effluent, and industrial surface waters. These standards vary with cannot be identified on the maps, and the main
replace limestone, effluent. Phosphate is an abundant constituent of classification of the surface water body. The use of thrust of the following discussion is the geologic
household waste. In the areas of the state a standard for surface water, but not for ground overprint.
Represented in the Background Network, this wtr sarsl frcgiino aua ore
The crest of the Ocala Platform was stripped waste is usually released to the environment by waer ihspaoreult ofrgiin ofae atura smorace
of Hawthorn sediments in Late Miocene, Pliocene, means of on-site treatment systems (septic-tanks) of phosphorus as a limiting nutrient in surface Statewide, the median orthophosphate
and Ouaternary times, While most of the and small, land-application treatment facilities water, concentration is 0.06 mg/L and the maximum
weathering products of this erosion were swept Should such systems fail to properly function, recorded is 4.00 mg/L (Table 22). Maxima are
into adjacent rivers, estuaries, and the sea, some phosphate may enter the aquifer system. Since generally lower, however, and indicate that
of the dissolved phosphate (H3PO4in reaction 13) septic-tank systems, fertilizer use, and animal DISTRIBUTION IN GROUND WATER phosphate mobility is not a widespread problem in
I ~ migrated downward into the underlying Floridan wastes are common in rural areas, especially in the state
aquifer system Upon contact with the limestones agricultural areas, phosphate is a likely constituent
of the Floridan, phosphate precipitated according in near-surface aquifers in the Background The districts measured phosphate in several
to reaction 14. Upchurch and Lawrence (1984) Network ways (Table 22) SRWMD measured ortho- Phosphate concentrations are highly variable

33






SPECIAL PUBLICATION NO. 34


and generally low In NWFWMD and SRWMD or the sample, which is unfiltered, contained charge of phosphate-rich, intermediate and aquifer system. Upward hydraulic potentials and
(Figure 38a,b). Higher concentrations are found in particulate apatite The median concentration in surficial aquifer system water, and surface water, the high alkalinities of the Floridan aquifer system siliciclastic portions of the aquifer system where the Floridan aquifer system is 0.04 mg/L into the Florndan. Their studies show that high also result in precipitation of any significant frmntrlaaierwre noaufrrpeetlclrcag n odi lwpH's are low The sources of the phosphate range phosphate waters in the Floridan aquifer system phosphate introduced to the aquifer systemU
sediments, especially in eastern SRWMD, to Maximum phosphate concentrations in the similar high occurs in southeastern Madison
animal and human wastes and fertilizers. In Floridan aquifer system are somewhat higher than CuyHgh nLyadGihrsCutesreFluoride
SJRWMD (Figure 38c) the phosphatic portion of expected (Table 22). This is an artifact of the onty Highks in thewBrndksilchriRtdgountdes are the Hawthorn Group, especially in St. Johns "plumbing" of the karstic and fractured aquifer Ridge. Both represent similar situations to the IMPORTANCE AND CONTROLS
County, is accompanied by higher phosphate system. Dissolved phosphate requires alkaline Cody Escarpment It is interesting to note that
concentrations in ground water waters in order to precipitate. In recharge areas, there is high phosphate in the Floridan aquifer
much of the water moves in conduits (fractures or system along the coast in Levy and Dixie Counties. Like chlonde, fluonde (F-) is a halogen anion. ItI caverns) under laminar flow conditions. Under The concentrations reported here are too high for is somewhat more reactive than chloride, and it The data from SWFWMD (Figure 38d) indicate these conditions, equilibration is slow and phos- sea water (Table 8), and most probably reflect the forms dissolved chemical complexes. These comregion of moderately high phosphate concen- phate can persist for some distance within the influence of organic-rich surface water from the plexes remain soluble in Florida ground water, soI trations (>0.5 mg/L) in southern Polk and Hardee Floridan aquifer system. Lawrence and Upchurch coastal swamps. fluoride essentially behaves as a conservative ion.
Counties, where phosphate mining of the (1976) illustrated an example of dissolved
underlying Hawthorn Group is underway. There is phosphate persistence in cavernous flow near also a belt of moderate phosphate concentrations Lake City, Columbia County. There, phosphate Phosphate concentrations in the Floridan Marine aerosols can contribute small amountsI
(>0 1 mg/L) that parallels the coast and reflects the enters the Floridan through karst features. Upon aquifer system in the SJRWMD are generally near of fluonde to ground water. Assuming that the coninner margin of the transition zone recharge, the dissolved phosphate persists as a detection limits (Figure 40c). Highs exist in north- centration of chloride in precipitation is 1.66 mg/L
well organized "plume" for several kilometers with western Volusia and in Flagler Counties. The Flagler (Table 3) and that the ratio of fluoride to chloride is The Biscayne Aquifer (Table 22; Figure 38e) is near Bunnell, an area characterized by extensive aerosols, precipitation should contain approximately
generally low in phosphate due to the absence of fern cultivation. This higher phosphate water is 0.00022 mg/L F-, which is three orders of magniphosphate-bearing minerals (apatite) and to the The pattern of dissolved phosphate in the probably a result of induced recharge from the tude less than median concentrations in Florida's
high alkalinity of the water. Where present, Floridan aquifer system in the NWFWMD (Figure overlying intermediate aquifer system The Volusia aquifer systems (Table 23).
phosphate can be attributed to land uses. In 40a) shows several regions of modest phosphate County high is less easily explained. It is associated western SFWMD (Figure 38e), the Hawthorn is concentrations. Phosphate is elevated along the with a minor recharge area (Figure 74, Scoff eta! Moto halordlnFoiarudwtri
present near land surface, and phosphatic rock inner transition zone in Okaloosa and Gulf 1991) and may reflect downward movement of derive fom wthernin ofconate-rapatiwter I
has been reworked into the surficial aquifer system Counties. Phosphate is also slightly elevated in a intermediate aquifer system water as well. tend Hramwathn g oup (ectrbonaIe-fluonpse sediments This reworked phosphate is accom- broad belt that originates near the coast in Franklin in teHwhr ru rato 3.Cne
panied by organics, which may also be a source of and Wakulla Counties and extends westward, quently, the presence of fluoride is an excellent
phosphorus. through the center of the district, into Okaloosa Phosphate in the Floridan aquifer system in the indicator of waters that have come in contact withI
County. This belt roughly coincides with the SWFWMD (Figure 40d) is associated with local the Hawthorn Group at some time in the past.
Intemedite quifr SytemBeacon Slope, New Hope Ridge, and southern recharge through the Hawthorn Group The belt
IntrmditeAqifr ysemWestern Highlands, and with the edge of the that extends from southeast to northwest in
Hawthorn Group and equivalent units to the west Sumter and Citrus Counties cannot be readily Cook eta. (1985) described fluorite (CaF3 inI
Th dstbtin fphspat n atr o te(Scott et al., 1991). Lawrence and Upchurch explained. This belt is in roughly the same area as gypsum nodules at the base of the Flonidan aquifer
nTedistribquionr posphaein aberso thgue) (1976, 1982) and Upchurch and Lawrence (1984) the hard-rock phosphate district, but the belt of system (Eocene Avon Park Formation) in Hernando Phosphate tends to be below detection limits in have shown that phosphate is introduced with high phosphate and the mining district do notCunyThsrrndgwtrwsfudtob carbonate-rich portions of the system. In rechargein asimilar context to the east, in the coincide. Additional works needed to explain this fundrstsrutewith rspoet thypuas ndftI
siliciclastic horizons the phosphate ranges up to SRWMD. An area of low phosphate concen- distribution, Many of the local highs in fluite, soysltiomn ofnfuite at ten bsue ofh
2 28 mg/L (Table 22). It is not possible to discern trations occurs along the northern boundary of the Hillsborough County coincide with karst terrains fluoride for the deep flow system. To date only large patterns in the distribution maps due to the district. This region includes recharge areas where (Upchurch and Littlefield, 1988) that are urbanized In oehsbe on ocnanfune oi localized nature of dissolution/precipitation reac- confinement is limited and flow along karst or agricultural in use, These phosphate concen- onece has beenhfounr tho clont florites it tions and the sparsity of data. conduits occurs. All of the data from the tration highs, therefore, may reflect the influencesmaosurefflri.
NWFWMD are near the detection limit (0 04 mg/L) of local use of on-site waste treatment, animalmjr ureffurd.
wastes, and/or crop and lawn fertilization. The re-I
Floridan Aquifer System entrant that extends up the Hillsborough River Intrusion of sea water can also be a minor
A similar pattern is present in the SRWMD reflects an unconfined part of the aquifer system source of fluoride (Table 8) With the exception of
Phspat cncntat(Figuudre t r n0b)t wherera centerth Cofg posphate that is immediately overlain by swamps and the coastal transition zone, sea water is an unimbelow detection limits in the Floridan aquifer Union Counties. This center is situated on themdrteutuadvlpmnptntsue system due to high water alkalinity. As Table 22 Cody Escarpment, which is characterized by large indicates, median concentrations are near detec- sinkholes and sinkhole lakes that drain into the Phosphate is generally low in the Floridan The Florida phosphate industry is one of the
tion imits, and they are generally low. The sample Floridan aquifer system. It is within this center that aquifer system in SFWMD (Figure 40e). The nation's most important producers of fluoride andI from the SRWMD that has 21.00 mg/L is suspect Lawrence and Upchurch (1976, 1982) and Floridan is confined by the Hawthorn Group, and fluorine products. The fluoride is extracted from
The value is either an incorrect chemicaL analysis Upchurch and Lawrence (1984) documented re- there appears to be little recharge to the Floridan the carbonate-fluorapatite as hydrofluoric acidI



34I







FLORIDA GEOLOGICAL SURVEY

(H)Some of this fluoride is lost to ground water In most areas of the state, ground water does (Figure 38) is also represented in the fluoride data High fluoride concentrations are evident in nerthe phosphochemical plants, where it may not contain concentrations sufficient to serve as a This suggests that the chemistry of the plume is SWFWMD and northwest SFWMD (Figure 42d,e)
present a problem. Upchurch et at (1982) preventative for caries, so many public water somehow influenced by the weathering of near the coastal transition zone Note especially
I characterized the effects of fluoride-rich effluent supplies have opted to augment natural fluoride for carbonate-fluorapatites in the Hawthorn Group. the well-defined re-entrant along the Peace River
that had been introduced from a phospho- the sake of public health lineament (Figure 42d).
chemical plant into sea water in Tampa Bay The
minerals fluorite (CaF2) and pachnolite Two regions of high fluoride can be seen in
(NaCaAFg.H2O) were found precipitated in a delta DISTRIBUTION IN GROUND WATER SWFWMD (Figure 41d) One is in central and Floridan Aquifer System
H ~at the ouffall Srmnlar processes may be occurmng stes2)hesouthern Polk County, a phosphate mining area
in calcium- and sodium-rich ground water near Th eincnetain ffurd nteHigh fluoride probably occurs in this area because
I ohe agchmial latsAt hepreen tme hemeiancocenraios o fuode n heit is associated with waters derived from within the While there are no known significant sources
threislpla eid nthts prcesent wde aquifer ssm (Table reflect resource. phosphatic deposits, not because of mining The of fluoride in the Floridan aquifer system, water
thered is littleevdnctha hspoes wd-Fluoride is lowest in the surficial aquifer system, Hawthorn Group, especially the Bone Valley that has passed through the Hawthorn Group
spred orimpotantwith a median of 0 17 mg/L The intermediate and Member of the Peace River Formation, in central contains fluoride (Lawrence and Upchurch, 1982),
Floridan aquifer systems contain median and southern Polk County is characterized by as does water in the coastal transition zone. The
There is little indication that any natural concentrations of 0.39 and 0 20 mg/L respectively enriched deposits of carbonate-fluorapatite. Some median concentration in the Floridan aquifer
process is responsible for actively removing The intermediate aquifer system is highest in of this apatite has been reworked into the surficial system is 0 2 mg/L (Table 23). The maximum
fluoride from ground water in Florida. Most of the fluoride concentration because the source aquifer system here, and the uppermost part of the concentration found was 6.9 mg/L in the I reduction in concentration is aresult of dilution and carbonate-fluorapatite is present in the aquifer Bone Valley Member is in direct hydraulic NWFWMD The location of this high is near the
dispersion. system. Concentrations are somewhat lower in connection with the sands of the surficial aquifer coast in Gulf County. The concentration is higher
the Floridan because of dilution and dispersion of system Thus, this region of high fluoride directly than expected for sea water (Table 8). waters that have passed through the Hawthorn reflects mineralization and hydraulics of the aquifer
I ~ ~~~STANDARD OR GUIDANCE sediments, and because the data set includessytmThcotahihfurdzneinheitibinofloieinNF D
CRITERION waters that have not come in contact with these ytmTh asahghfurdzneinTedtrbtnoffurd nNFM
sediments, Hillsborough County and in the southwestern part (Figure 43a) shows a strong coastward gradient. A
of the district reflect the transition zone. The outer large re-entrant in Gulf and Bay Counties can be
In small amounts (< 1 mg/L), fluoride is con- part of the transition zone is directly influenced by attributed to pumpage and discharge along the
sidered beneficial as a preventative for dental Surficial Aquifer System sea water, the inner part reflects fluoride-rich Apalachicola River. To the east, the pattern in
caries. The fluoride reacts with the apatite in teeth waters upwelling after following long, deep flow Wakulla and Liberty, and Franklin Counties is
to form a fluorapatite that is resistant to cavity- paths and mixing with the sea water. irregular, probably in response to local flow
causing microbes In excess of 2 mg/L, fluornde As Table 23 indicates, fluoride concentrations systems associated with the extensive conduit
begnsto cause unsightly darkening and mottling in the surficial aquifer system are generally lower tmt
of the teeth, a condition termed dental fluorosis. than in the other two aquifer systems. The low Fluoride is somewhat high in coastal areas in fow system tere. SSevere mottling requires concentrations in excess concentrations are a result of limitations on the the surficial aquifer system in SFWMD (Figure 41 e).
Uf1-4mgLEtee oe a induce toxicity, sources of fluoride While the relative importances The coastal parts of the Biscayne Aquifer containHghfunecnnrtos cralgth
inluin xcsscacfiatono bne, tffesof the following sources have not been quantified, over 0.2 mg/L, as do coastal parts of the aquifer Hoighfluorie conctraton ou alon the bonesndrsmstirfmstnnesdththe data presented in this report clearly indicate system in Lee and northern Charlotte Counties. Cody Escarpment and in the Northern Highlands in
I ~that some of the fluoride is from precipitation, with Fluornde slow in the central part of the district the SRWMD (Figure 43b). These reflect recharge
the concentrations enhanced by evapo- of intermediate and surficial aquifer system waters
Standards for fluornde have been set to control transpiration. Most of the fluoride in the surficial Intermediate Aquifer System in the large sinkhole complexes that characterize
toxicity and fluorosis. The Primary Drinking Water aquifer system, however, is derived either from the escarpment. Other areas of elevated fluoride
I ~ Standard, which addresses toxicity, is 4 mg/L The weathering of reworked carbonate-fluorapatite or concentration exist in Hamilton County. The
Secondary Drinking Water Standard, which from deeper waters that are introduced to the Given that the intermediate aquifer system in eastern area is near a phosphate-mining and
addresses fluorosis, is2 mg/t aquifer system by natural discharge and by the eastern panhandle and the peninsula generally agrichemical complex. The western one is
pumpage (Dalton, 1978) coincides with the phosphatic Hawthorn Group, associated with the recharge of intermediate

Duetowethengofcabontefloraatteinone would expect that fluoride concentrations aquifer system waters near the Alapaha River
the Hauhorn sysoums floridentidreainsta syTem patn noft florid ig urfiia 4aub)rs systems. This is the case (Table 23), but con- Taylor and Lafayette Counties appear to be Fxorida' aquifrk g systes Coetrna tis thocat haatnt a afowsystem in nrhalrda (i u e at centration differences are not significant. Fluoride associated with the San Pedro clays which overlie exceedlty Driknd, Wcathe Sandard are ca-aractetco an oncnalosse aquifeer. ata w is highest in SWFWMD and SFWMD, where the the partly confined Floridan aquifer system.
sFWMon a bl found eseiy inly SWF.1 acnd ar aibe n cnetainfregnrlylw intermediate aquifer system is thick and used as a Coastal transition zone fluoride is also evident.
the samples in the surficial aquifer system ptbewtrsuc
I exceeded the Primary Drinking Water Standard. The data from SJRWMD (Figure 41c) suggest Fluoride concentrations are generally low in
Four tenths of a percent of the samples from the a coastal source of fluoride High fluoride occurs Data from NWFWMD, SRWMD. and SJRWMD the Floridan aquifer system in SJRWMD (Figure
intermediate aquifer system exceeded the in the transition zone in Nassau and Duval (Figure 42a-c) show similar patterns to other 43c) High concentrations exist in Flagler and
standard, and 0.1 percent exceeded it in the Counties, and in St Johns County These highs analytes. The concentrations range from below Volusia Counties. There are minor indications of
Floridan aquifer sample set cnidwthregions of well-field development, detection limits to maximum of 1 75 mg/L The the coastal transition zone Since most of the
Th pglum uof ydissolved phosphate that crosse data do not reveal systematic patterns because of coastal communities in Flagler County utilize the Flager ount ino nrthwsten Vlusi Contythe complex, local nature of production zones, intermediate aquifer system, the transition zone in



35






SPECIAL PUBLICATION NO. 34


the Floridan 's not well represented. nitrate are the compounds considered important in the legumes, directly convert nitrogen into tissues nitrogen compounds is not completed within theI
ground-water systems These compounds are and nitrogenous by-products. Plants require nitrate root zone, if the nitrate is unavailable to plants and
related through a sequence of reduction and as a major nutrient, and they are responsible for denitrifying microbes, or if nitrate is produced in
The Floridan aquifer system in SWFWMD can oxidation reactions as indicated below removal of much of the nitrate that is taken from quantities too great for biological agents to fix,I
be ivdedino dmans asd o fuone Figresoils and ground water. Average nitrogen content nitrate migrates with the ground water. With the
43d). The northern half of the District contains low of living organisms is 16 percent. These living exception of plant and microbial activity, there are
alundte isnclitrtleorno, Hawtorgn to unct as aed rgNi NOge (TKNO) tissues contain amino acids and other nitrogen few mechanisms for nitrate removal in aquifers.
andthee s ltte, r o, awhor t ac a a N4 -N~ compoundss that can be released back into the Once nitrate enters the aquifer and is isolated from
source. The coastal transition zone is well (15) environment upon death or waste elimination, environments where denitrification and plant
developed in this area. The southern half of the - -Oxidation - xainccntrtbevsmr-r-ssomap clearly indicates that fluoride, derived from --- Reduction -- servatively and can move long distances in
waters passing through the Hawthorn, slowly Animal wastes and decaying plant tissues aquifers.I
increases in concentration along the flow paths. release ammonia and ammonium, nitrite, nitrate,
With the exception of the re-entrant along the wdth oxidation being the normal sequence in urea 0, and a number of nitrogenous organic
Hitisborough River, the 0.2 mg/L isoline closely ground-water systems. The reduction/oxidation molecules. Soil and aquifer microbes metabolize Ideal, land-based, waste-disposal practices approximates the northern edge of the Hawthorn transformations between the compounds indicated these according to the reduction-oxidation include sufficient vadose zone and biomass to
Group Fluornde uniformly increases to the south in reaction 15 can be driven by inorganic process- potential (reaction 15) of the soils and aquifers. convert nitrogen compounds to nitrate and then to and west from this isoline. The coastal transition es, but the primary mechanisms for the reactions Under reducing conditions, microbes convert utilize the nitrate. Unfortunately, high water tables, zone is delineated by a steepened gradient near are microbial, these compounds to armmonium, and other plugging of soils by particulate matter, under-I
the coast and by a re-entrant along the Peace reduced nitrogen species Under oxidizing design of treatment facilities, crowding of wasteRiver lineament. The largest reservoir of nitrogen is the atmos- conditions, they are converted to nitrate, often with disposal facilities or animals on too small a tract of
phere, which is 78.93 percent nitrogen, mostly as an intermediate nitnte step. land, and many other factors tend to lead to
N2gs.N, n N3 ccrnaualyintefailures of natural nitrogen-removal mecha-nisms.I Little can be said about fluoride in SFWMD UnderasucNHciandmsOanoccrnnaruralymmnntue
(Figure 43e). There are indications that fluoride atmosphere as a result of releases by terrestrial Therefore, in reducing environments, such as Und er uhnirgcumstances itate ammnirmth content increases to the south, into the non- plants (Stallard and Edmond, 1981). Atmospheric water-saturated, reducing soils and aquifers, am- grand-ther sstrgend ompondisantersth potable portions of the aquifer system where nitrogen is also converted to NO.9 by lightning. monium may persist and become a part of the gon-ae ytmadtae ogdsacs connate water predominates. There is a high in Lee Modern precipitation contains increased nitrogen ground-water system. Under these circumCounty, where pumpage and free-flowing wells oxides as a result of combustion of fossil and stances, ammonium can travel considerable Swamps and organic horizons in soils can
induce upconing of deeper waters along the modern organic fuels. The oxides of nitrogen are distances before sorption, microbe metabolism, contribute natural ammonium and/or nitrates to
transition zone, then converted by oxidation and hydrolysis to nitric dilution, or dispersion reduce concentrations to aquifers. Under most circumstances, however,
acid (HNOJ), which dissociates to H+1 and NO; below detection imits. Ammoniurn tends to sorb decay of the organics is sufficiently slow that the Consequently, precipitation is a source of nitrate onto clays and soil particles, so some soil and nitrogen compounds are utilized within the wetland Nitrate and ammonium derived from both natural and aquifer materials mitigate ammonium migration and adjacent aquifers. High nitrate and ammoanthropogenic causes. Nitrate in precipitation in Septic-tank systems, land-application waste- nium concentrations in aquifers are more likely to IMPORTANCE AND CONTROLS Florida ranges from 0.00 to 10.32 mg/L (Table 3), treatment systems, and feed-lot wastes can, under be caused by inadequate soil and aquifer conand the statewide mean is 0.97 mg/L. Ammonium circumstances of overloading or failure of sorption ditions and contamination by human or animal ion ranges from 0.00 to 17 12 (Table 3) and the systems, cause widespread ammonium con- wastes.I
Nitrate (NO3) is one member of a sequence of mean is 0.17 mg/L. tamination.
related nitrogen compounds that includes nitrogen Frmcoildcmoiino irgnu
gas (N2), nitrogen dioxide gas (NO2) and other Clearly, conversion of nitrogen compounds in Oxidizing conditions are necessary for compounds to occur, there must be a source ofI
oxides, ammonia and ammonium (NH3, NH, ), the atmosphere followed by precipitation intro-mirbstpodcthcmpxreton gnicrbnadotrnunn.Thrlef
nitrite (NO2), a number of other inorganic duces nitrogen to the ground-water system. rmqiroes to rodute nthoen som le rains. oirgnicrbond rother nutrpiens Ths roleo
compounds, and many organics. The gaseous Modern rainfall, however, cannot be used as an Treuied tob m h irogen usneabte formplntsm niroen-aeuatil mcesinaeepI auiers hant
phases exist in the atmosphere and in Soil argument for high nitrogen in most aquifers. This Tea r obic mraiciroes convertues moniumt mibee dalyesalrated.s nappers th ulateI
atmospheres, but are not of importance in the is because of the long time intervals involved in and then nitrate. Ammonium and organic-nitrogen reduction may occur Availability of organic saturated zones of aquifers. Ammonia gas also ground-water flow. Waters in surficial environ- compound concentrations are low in most aquifers carbon and nitrogen compounds is limited in escapes into the atmosphere. Ammonia is present ments, including the surficial aquifer system and because oxidizing conditions are widespread near deeper portions of the Floridan aquifer system, so in ground water as the ammonium ion (NH4 ) shallow, unconfined portions of the Floridan the land surface, where these nitrogen compounds nitrogen-utilizing microbes are probably ineffectiveI
because of prevalent pH and reduction-oxidation aquifer system, may be affected by high-nitrogen are generated. Oxidizing conditions occur in in the same way as are sulfate-reducing microbes. potentials. The complex organic compounds can precipitation. Deeper waters were recharged as oxygenated soils, vadose environments and Our present concepts suggest that the majority of
occur as soluble organic molecules and as par- meteoric waters before the advent of the industrial salw xg ntdprin faufr.nto e iaino c r ns al w xdzn
tculates. Concentrations of dissolved, organic- revolution. These older waters entered the aquifer shlooyentdprinqu qe iroes fain occrnshlosxdzn
nitrogen compounds, including amino acids and system with some natural nitrogen content, but ataqiesndol. proteins, are reported as Total Kjeldahl Nitrogen much lower concentrations than the present If nitrates are available in small amounts near
(TKN) in samples from aqueous systems and soils. the land surface, plants will utilize the nitrates The presence of nitrate, and the other nitro-I
.,There are also microbes that denitrify soils by genous compounds in ground water, is not conOrgncntoeamoim irtadCertain microbes can fix nitrogen gas in soils. conversion of nitrate to nitrogen gas. If nitrate sidered in Florida to be a result of interaction of
rgni itogn amoimnirte adThese microbes, in conjunction with plants such as production from ammonium and more complex aquifer system water with surrounding rock


36







FLORIDA GEOLOGICAL SURVEY


H ~materials. Nitrate in ground water is a result of Floridan aquifer system exceeded it. This does not The distribution of nitrate is summarized in Nitrate Table 24 lustrates the distribution of
specific land uses. If the land use is widespread, a mean that there are no problems, only that the Table 24 Nitrates are characteristically at or below nitrate in the aquifer system With the exception of
Body of nitrate-enrched water that is large enough problems are localized, detection limits statewide. The median nitrate con- NWFWMD, the median nitrate concentrations are
I ~ to be contoured may result. Otherwise, detection centration statewide is below detection limits below detection limits Maximum nitrate
of nitrate is an isolated phenomenon (Table 24), and only the Sand and Gravel Aquifer in concentrations are low compared to the other
DISTRIBUTION IN GROUND WATER the NWFWMD shows significant nitrate con- aquifer systems, and three samples were found to

Nitrate contamination of ground water is of centrate oxs. txcnedfthee10JmWML Nlstdndardt
concern in Florida. Numerous areas of the state Wt h xeto fteSRM l itit
have reported nitrate problems These are asso- analyzed for nitrate. SJRWMD analyzed its The distribution of nitrate in the northern Nitrate concentrations are moderately high
coated with areas of intense agriculture use and samples for nitrate plus nitrite" Unless stated districts (NWFWMD, SRWMD, Figure 44a,b) throughout the NWFWMD (Figure 45a), but
suburban housing Some of the areas where otherwise, all concentrations given below are illustrates the "point-source" nature of nitrate The correlations between the wells are impossible
nitrates are of concern include dairies and cattle reported as nitrogen data are highly variable, and they cannot be cor- Concentrations are variable, indicating local
ranches in the Suwannee and the Kissimmee River related from point to point It is important to note sources. In contrast, nitrate concentrations in the
I valleys, crop lands in the northern Everglades, and Surficial Aquifer System that there are many nitrate "hits", indicating that intermediate aquifer system in the SRWMD,
suburbs served by on-site waste treatment (septic nitrate contamination of the suricial aquifer system SJRWMD, SWFWMD, and SFWMD (Figure 45b-e)
tanks) throughout the state, is widespread are generally low, with a few widely scattered deThe only nitrogen species widely measured in tections
U the surficial aquifer system in the Background
Finally, Barcelona (1984) has pointed out that Network asnmtrate. Other analytes have been There are 64 NO, analyses from the surficial
drilling fluids can serve as sources of organic included in a few samples. In all cases, most aquifer system in the SJRWMD (Table 24). The Floridan Aquifer System
carbon and nitrogen compounds Care should be samples have no detectable nitrogen compounds. maximum concentration found was 7.50 mg/L.
Taken to validate any high nitrate concentrations Detection of nitrate, ammonium, and other The median concentration in the SJRWMD isThditbuonfnir nseesnth
reported below, especially if the data come from compounds is unusual <0 01 mg/t. Given data from other districts and Th itiuino irgnseisi h
newly drilled wells, studies, most of the NO, is nitrate, and nitrite is Floridan aquifer system is related to proximity to
rare as a constituent Therefore, most of the con- the land surface and karst conduits. Lawrence I ~Ammonium SFWMD analyzed 511 samples centrations reflected In the map (Figure 44c) and Upchurch (1982) attributed nitrates in the
STANDARD OR GUIDANCE and found a mean concentration of 0.437 mg/L represent nitrate. Nitrate in the SJRWMD is at or poorly confined Floridan aquifer system near Live
CRITERION (standard deviation = 0.341, range = 0.000 below detection limits throughout much of the Oak (Suwannee County) to local recharge through
1 550). No other surficial aquifer system analyses district Moderate nitrate concentrations occur in drainage wells and sinkholes and transport in karst The nlycomoun fo whch her isa san-are available, Characteristically, if ammonium is agricultural areas along the St. Johns River conduits The waters with nitrates were subject to The ony comound or whch thre isa sta^ preent a allit shuld ocur nar relativelyfae rapdid rintiltyrrtidonn.lErsewnhersewhrntnrrggn
dard or guidance criterion in ground water is prnt wastali soulc cur ea the land srfanc scorriduorb asntorrae
nitrate. Nitrate is subject to the Primary Drinkinganwatsore.Gvnheigogncspissoudbasntrrr.
IWater Standard (Florida Department of Envi_ contents of soils and water in the central portion ofTh W MDndFMDnrtedt
ronmental Regulation, 1989). The limit under the the SFWMD, moderate ammonium concentrations Thgue SWdWM ans SF WMD nrhmntrate dfaa Ammonium There is not enough ammonium
Primary standard is 10 mg/L as N, or 44 mg/L as are not unexpected. aquifer system waters under large agricultural data to draw conclusions
NO3. There is a health advisory for nitrate at 1 mg areas. There is some indication of elevated nitrates
N/ 44m O Las well The major cause of TKN Total Kjeldahl Nitrogen (TKN) represents in the upper Everglades and along portions of the Nitrate The distribution of nitrate reflects
cocr smethemoglobinemia, an excess of the nitrogen included in complex, nitrogen- Kissimmee River valley characteristically low concentrations. With the
mhmglbnwhich causes oxygen deprn- containing organics and some ammonia. The exception of the NWFWMD (Table 24), median
vation. This condition is especially hazardous in SFWMD found an average of 0.775 mg/L (standard nitrate concentrations are at detection limits.
infants and young children, where it produces a deviation = 0 679 mg/L, range = 0 000 2.660, Maximum concentrations are high (>10 mg/L) and
condition known as 'blue baby syndrome" (Hersh, number of samples = 20) in the surficial aquifer reflect near-surface conditions and flow through
1968; Hem, 1985) There are no standards for system. TKN is closely related to ammonium In Intermediate Aquifer System karst conduits.
ammonium or other nitrogenous decay products in the oxidation/reduction sequence (reaction 15) ground water (Florida Department of Environ- Therefore, high TKN should be related to the land
mental Regulation, 1989) surface and proximity to organic nitrogen sources Because of the confining properties of clay- A belt of moderate nitrate concentrations
rich horizons in the intermediate aquifer system, occurs in central Okaloosa and Walton Counties
Table 24 lists the number of samples in which Nitrate Nitrate is relatively widespread in the one would not expect nitrogen species to be a (Figure 46a) This belt is large and includes a the 0 m/L stadar wa excede GienPtepsrfiialequierayste.yTis s a esutdouappi-,robem vrieysoslan ussuuchusrslviuntueaadUaU.S
the 1 mg/LN stadard as exeededGiventhe urfical aqifer ystem Thisisir Forceof base-. rAFsimibla.rAbemlta b ccurscurfrrm
notoriety of nitrate contamination problems in the cation of fertilizers and wastes on the land surface,nrhesrnByhrghLnCutesThsra
I ~ state, the Background Network detected Surpnis- which is the upper boundary of this aquifer system. Ammonium and TKN One hundred and fifty- northeasternarsy trough on Contes. Tsw are
ingly little nitrate contamination above the water- Animal wastes are generated in range lands, feed five samples from the SFWMD have an average Lawrence and Upchurch (1982) to be subject to quality standard Statewide, 0.6 percent of the lots, and dairies Human wastes also contaminate ammonium concentration of 0.32 mg/L (standard recharge of nitrate-rich surface waters. Additional I samples from the surficial aquifer system the surficial aquifer system in some areas as a deviation = 0.11 mg/L, range = 0.00-0.78 mg/L) work is needed to determine the reasons for the
exceeded the standard. No samples from the consequence of septic-tank use in rural areas. No other ammonium or TKN data are available extensive nitrate occurrences in the district.
intermediate aquifer system exceeded the stan* dard, and one percent of the samples from the


37






SPECIAL PUBLICATION NO. 34


The most extensive area of nitrate in waters of OTHER CONSTITUENTS STANDARD OR GUIDANCE zone or the base of the aquifer system. TheseI
the Floridan aquifer sytmin the SRM Fgr RTRO wells yield high total dissolved solids waters and
46b) is centered on Suwannee County This is an The constituents discussed in this section bias the summary statistics.
area known to have contributions of nitrates from include the general descrnptors of water quality The Florida Secondary Drinking WaterI agriclurfae (Upcurchrand Lawrenceu 194)an (Total Dissolved Solids and Specific Conductance) standard for total dissolved solids is 500 mg/L The most significant patterns in total dissolved
fromr surfacnae werls rehulagd though storm- and the organic chemistry of the state's aquifer (F.A.C. CH. 17-550 310-320; Florida Department of solids data (Table 25) reflect equilibration with waterednge we(Hl and Yurrc 192 ewscz,~e 199) systems The discussions of organic compounds Environmental Regulation, 1989). This standard is carbonates and poor flushing of aquifer systems. Lawecand Uprchrch (182 dremriu d nthae in the aquifer systems are divided into three based on a number of concerns. Waters with high In the surficial aquifer system, total dissolvedI mecthe an oufergeo aytmmntium anireatey subjects: Total Organic Carbon, Synthetic tota dissolved solids content have an unpleasant solids tends to increase southward, which reflects
toun the ia hcaquinfer encths: area Thewy Organics, and Pesticides Total Organic Carbon 's taste. The high total dissolved solids may result in the increase in reactive carbonate minerals in the founrd wr threcmial infece: (1) slowly a measure of the natural organic content of the development of scale and precipitates in water, surficial and intermediate aquifer systemsI recharged watersnha ere a2)ffecnrteb contact water, while Pesticides and Synthetic Organics especially In boilers, hot water heaters, and other southward. Total dissolved solids data from the wih we athonu Grop2 igh nitrate wtrsg reflect anthropogenic compounds. heated-water systems Finally, persons who Florndan aquifer system show similar medians for
sinkholes, and (3) amrnoniurm-rich waters that consume high total dissolved solids water are at alt districts except the SFWMD The high total
rapidly infiltrated through drainage wells and Total Dissolved Solids risk of developing kidney and gall stones dissolved solids concentrations in the SFWMD
sinkholes. Other areas of moderate to high nitrate reflect low quality of water in the Florndan, over
concentrains wit silar oigis occu D in IMPORTANCE exTablet25 summarizestthedarples found much of he diustrit Thsti a rsult incomplete

Counties. The Floridan is unconfined to poorly Background Network includes wells that are d.
confined in all of the areas indicated, and surface Total dissolved solids (TDS) is a measure of located in the salt-water transition zone, the runoff drains directly into sinkholes that penetrate the total mass of ions dissolved in water The number of samples found to exceed the standard Surficial Aquifer SystemI
the Floridan aquifer system. procedure for determining total dissolved solids largely reflects deeper wells, that sample the
involves weighing the mass of salts deposited after transition zone near the lower confining beds, and
Similar arguments can be made for the spotty the water is evaporated Volatile materials may be coastal wells. Statewide, 22 percent of samples Figure 47 illustrates the distribution of total
distribution of nitrate in waters of the Floridan lost in this procedure, and there is some difficulty from the surficial aquifer system exceeded the dissolved solids in water of the surficial aquiferI aquifer system in the SJRWMD (Figure 46c) High in obtaining a moisture-free environment for weigh- standard. Most of the samples that exceeded the system. Total dissolved solids concentrations are nitrate concentrations occur under the agricultural ing. Consequently, total dissolved solids is, at standard came from the SFWMD (Table 25), where quite low, indicating minimum weathering of the areas that extend across the center of the district best, a general estimator of the total load of chem- upconing of connate water and coastal intrusion SRlWMD.laTre s a ncraenalse in NWFWMl disovdI
fro StJohs ad Fa er ouniesto arin cals dissolved in the water are widespread. Samples from the intermediate RM.Teei nices oa isle
from S John and lagle Countes toMario aquier sytem inlude 7 perentdtattexceddth solisctowrdsatedcoascand scambayBaywithi
County. The western and central portions of this standard Testem ncedanpce are lrelyctedh the San ad Grae Aifer(iue4a The
belt have high recharge potentials (Scott et al The more reactive arock is, the higher the total nsut hes SWxM ande wrestern SFW D, are a fewacoasta wells that ehirt high total 1991), but the eastern third does not. The sources dissolved solids content of waters within that rock wher the Hawthor Gru setnieaddissolved solids in SJRWMD (Figure 47c), but mostI of nitrates in the high recharge areas are similar to are likely to be. For example, total dissolved solids utliea a wte sorceTh high ttlrissved inland wells have low total dissolved solids waters those of the SRWMD, while the causes of high are likely to be higher in a limestone aquifer than in solids ats ae loucted in cota areas and The high total dissolved solids coastal wells are in nitrates in th eastern part of th district are les a siliciclastic aquifer Total dissolved solids also reo s or p oningThirty-oneptercet ofthe areas of both connate water and heavy pumpage,I
eaiy idniid Iti osbeta ehrei tends to increase with residence time and as water sape fro the Forda aufe syte which may have induced some salt-water
being induced by pumpage in the eastern area, progresses along a flow path. An important exceeded the standard Tlhese sarmples ae uni intrusion. Coastal salt-water intrusion is well
consequence of this is that waters in the Florndan formly distributed through the districts and reflect documented in SWFWMD (Figure 47d), where the Nitrates in the SWFWMD (Figure 46d) also aquifer system that go deep into the aquifer coastal and upconing areas in the aquifer system 250 mg/L total dissolved solids isoline in theI
reflect differences in recharge potential. The system and contact the reactive, gypsum- and Given the purposeful location of wells in transition surficial aquifer system parallels the coast and
northern half of the district, which is characterized anhydrite-bearing lower confining beds may zones, little significance can be attached to the major embayments. The high total dissolved by high recharge potential, has a spotty pattern of contain high total dissolved solids due to dissolved high proportion of samples that exceeded the solids content of waters in the re-entrant along the nitrate concentrations that reflects local land uses, calcium and sulfate (Table 4). Therefore, total standard. Examination of the maps discussed Peace River axis result from calcium-sulfate rich The Floridan is better confined in the southern half dissolved solids can be used to understand the below is a better way of evaluating the total waters that are released to the surficial aquifer of the district, and nitrate concentrations are chemical maturation and flow history of certain dissolved solids content of the potable portions of system by irrigation and natural upwelling. characteristically lower, aquifer systems. the aquifer systems.I

There is little data for the distribution of nitrate Total dissolved solids in the Floridan aquifer DISTRIBUTION IN GROUND WATER (Figure 47e). SFWMD can be divided into three
concentrations in the Floridan aquifer system in the system have been discussed by Shampine (1975), zones (Figure 47e): the Kissimmee and
SFWMD (Figure 46e) Most values are at or below Kaufman and Dion (1967, 1968), Hull and Irwin Caloosahatchee watersheds, the Everglades and
detection limits. (1979), Sprinkle (1989), and others. Sprinkle The distribution of total dissolved solids in Big Cypress Swamp, and the Atlantic Coastal
(1982b) presents a map of the distribution of total Florida ground waters is summarnzed in Table 25 Ridge. In the Kissimmee and Caloosahatchee dissolved solids in the Floridan aquifer system. Note that, while several important trends are watersheds, the total dissolved solids concen-I Sprinkle's map agrees in general with the data pre- apparent, the data reflect all samples from within a trations range from below 250 mg/L to over 500 sented below, although the level of detail of his district. Some districts utilized monitor wells that mg/L Highest total dissolved solids waters seem map is less. are either near the coastal salt-water transition to follow the rivers and most likely represents

38







FLORIDA GEOLOGICAL SURVEY


upwelling and discharge of deeper waters. This encourage upooning, in other areas pumpage is Specific Conductance salt-water intrusion
upwelling has been documented in Lee County by the cause
Wedderburn et al (1982) and Upchurch (1986)IMOTNESADRORGDNC
I ~ While few data are present from the surficial FloridRTANCEerSTANemARITERINC
aquifer system in the Everglades and Big CypressFlnaAufrSytrCRTRN
Swamp, total dissolved solids concentrations are Specific conductance is a measure of the
elevated there as well. This is a result of poor The pattern of total dissolved solids in waters ability of material to conduct electrical currents There are no standards or guidance criterna for I ~ flushing of connate waters and of upconing of the Floridan aquifer system is directly related to The American Society of Testing and Materials specific conductance Specific conductance, per
subsequent to draining wetlands to enhance the salt-water transition zone and regional flow (1980) has defined specific conductance as the se, does not constitute a water-quality hazard to
agriculture. Finally, the Biscayne Aquifer, which systems (Figure 49) High total dissolved solids "reciprocal of the resistance in ohms measured be- water users, It is commonly used as a field analyte
comprises the Atlantic Coastal Ridge, has waters concentrations in the Floridan aquifer system are a tween opposite faces of a centimeter cube of an for evaluation of gross water quality, so it is with total dissolved solids concentrations in the result of long contact times with soluble limestones aqueous solution at a specified temperature". The included in this report Given certain assumptions range of 250 to 500 mg/L This water is locally and dolostones of the Floridan and mixing with inverse of the ohm (the measure of electrical resis- about the composition of the water, specific conrecharged, and it represents the highest quality high total dissolved solids, saline waters at the tance) is the mho. Natural waters are moderately ductance can be correlated with salinity, and many ground water in southeast Florida. base of the aquifer system and at the coast. resistive, so specific conductance is measured in aquifer salinity measurements given in the literature
Lowest totai dissolved solids concentrations are in rmcromhos/cm (pamhos/cm) The micromho is are based on specific conductance uncorrected for
Intermediate Aquifer System the interior, where recharge is prevalent and equivalent to the microSiemnen (p5) in SI notation, water chemical speciation. Consequently, it is not
residence times in the aquifer system are too short safe to assume that high specific conductance
I ~for effective equilibration with the aquifer system. waters are necessarily in violation of standards for
Totl isolvd olds n heintrmditeThe ability of water to conduct electricity is important electrolytes for which standards exist,
aquifer system ranges from 18 mg/L to 6,892 mg/L primarily a function of the concentration of such as sodium and chloride
(Table 25). This wide range is a result of the The potentiomnetric surface of the Floridan electrical charges in the water and of water
N diversity of lithologies represented in the Hawthorn aquifer system controls the position of the temperature (Miller eta., 1988). When an electrical
Group, as well as the influences of the coastal transition zone (see the potentiometric maps in potential is applied to water, cations tend to mi- DISTRIBUTION IN GROUND WATER
transition zone. Where water has been in contact Scott et al., 1991). Where head is high near the grate to the cathode, while anions migrate to the
Only with siliciclastic materials, the total dissolved coast, the salt-water transition zone beneath the anode. It is this potential for ionic migration thatThdsnbtnsfspcf oduaneda
solids content is low Where it has been in contact land surface is narrow, or it may be offshore. The specific conductance measures. Therefore, spe Thelnd distibt ofseiio dac data with carbonates and chemically unstable silicates transition zone also slopes steeply inland where cific conductance is sensitive to the concentrations 2n Floinda grun watersnu ae shared wiTl
(clays, opal; Tables 4,5), total dissolved solids potentials are high Re-entrants occur near river and types of ions in the water. Miller et a/ (1988) 26ta Sic specdi codcacscorltdwt
conentis igh Hihes toal isslve soidsmouths, where the potential is lowered These re- have discussed the effects of mixtures of ions on toa issole solids, the arguments concerning concentrais aregin Hhsth lora, wshere saline entrants can be seen near the Escambia and specific conductance All of the ions previouslythdsnbtnofdslvdslsdaa(eTta
water insrpreset inthe aquifer~lna syseesln Apalachicola Rivers (Figure 49a), and the Hills- discussed contribute to the electrolytic properties Dissolved Solids) hold for specific conductance borough, Manatee, and Peace Rivers (Figure 49d). of water.
I ~Other re-entrants along the coast are related to In Florida's aquifer systems, high chloride
The intermediate aquifer system data cannot intrusion caused by pumpage Where the potential wtr as ihs pcfccnutneao
be contoured in north and central Florida due to is low, such as occurs in the Everglades and Big Specific conductance roughly reflects the wates. caus thigst pecfn, conducted aeno
the heterogeneity of the aquifer system units Cypress Swamp areas of the SFWMD, the total same processes as total dissolved sohids, and malieas Fowrd threasn conducstivitestedo
(Figure 48a,b,c). The data can be contoured in dissolved solids content of the Flondan aquifer there is a good statistical correlation between theinraetwdshecstndsure.
southern SWFWMD and western SFWMD (Figure system is high, and the coastal transition zone is two variables. However, specific conductance is
S48d,e), where the aquifer system is moderately broad, with a shallow slope (Figure 49e). dependent upon the specific combinations and High conductivities inland reflect several
I deep and continuous, Where the intermediate concentrations of the electrolytes in the solution, factors, including upconing of deeper, more saline
aquifer system is near the coast, the salt-water so two water samples with the same total dis- waters into shallow wells; release of deep Florndan
transition zone is characterized by high total The 500 mg/L isoline defines the extent of solved solids contents may not have the same aquifer system water on the land surface as
dissolved solids (Figure 48d,e) potable water in the Floridan aquifer system Note conductivities (Miller et at, 1988). As a rule of irrigation water, which is then recharged to the
that it crosses the state from Sarasota County thurmb, at equal TDS concentrations, the following surficial aquifer system; increases of chlorides due H ~(Figure 49d), north of Lake Okeechobee (Figure anions can be ranked according to ability to to evaporation of meteoric water in unconfined
In areas where the intermediate aquifer system 49e), to southern Brevard County (Figure 49c). conduct electricity portions of aquifer systems, and residual (or concontains abundant carbonate horizons, fracture South of the 500 mg/L 1soline the flow system in nate) waters from earlier high sea-level stands that
I traces appear to affect water quality. For example, the Floridan aquifer system is weak, and high total Cr > 5042 > HCO- have yet to be flushed from the aquifer systems
re-entrants of salty water can be delineated in dissolved solids waters have not been flushed (16)
Sarasota County (Figure 48d). These coincide with from the aquifer system by fresh-water flow <- High Conductivity
major I1neaments that can be identified from Low Conductivity Surficia Aquifer System
satellite imagery (Culbreth, 1988) There is also
local upconing of deeper, high total dissolved Locally, waters high in total dissolved solids
Solids water along a lineament which is occupied content in the interor of the state (Figure 49) re- where chloride-rich waters are more conductive Specific conductance of water from the surI by the Peace River (Figure 48d; G Jones, 1991). present wells that either are deep enough to reach than sulfate-rich waters, and so on Because ficial aquifer system is characteristically low due to
These areas of upconing follow zones of high high-sulfate concentrations near the base of the specific conductance and total dissolved solids are the low concentrations of electrolytes. Median vertical permeability In some areas the relative Flordan aquifer system or are in regions of up- correlated, specific conductance can be utilized to conductivities increase southward (Table 26), head distribution of the aquifer systems will coning as a result of pumpage evaluate chemical maturity along a flow path and indicating an increase in total dissolved solids as

39






SPECIAL PUBLICATION NO. 34


aquifer carbonate content and influence of salt Flondan Aquifer System this high anion content is a result of poor flushing acidic, siliciclastic sol zones and contribute to theI
water increase, The median specific conductance of the aquifer system under low hydraulic head formation of organic hard pans. In alkaline,
for the surficial aquifer system, statewide, is 475 .conditions carbonate aquifers humic acids can migrate until
imhos/cm, while the district medians range from Figure 52 illustrates the distribution of specific they flocculate or are decomposed. Pu/v/c acidsI
50phsc nteNFM o69mo/mconductance in the Floridan aquifer system are less complex than humic acids (molecular
In the SFWMD lpowfi odthandcentalFlorida Specific con-t Total Organic Carton weights of 500 to 2,000 daltons [6,000 -24,000
are lwin not n eta lnaSeii o-a rm u ;Thurman, 19851), and they are soluble ductances tend to increase toward the coast IMPORTANCE under both acid and alkaline conditions. TheI
Increases in specific conductance have been (Figure 52a), which reflects maturation along long smaller fulvic acid molecules do not coior water,
documented towards the coast and estuaries in flow paths and mixing with salt water near the wiehmcaismy uesaeislbei
NWFWMD (Figure fi0a) and SWFWMD (Figure transition zone. Total organic carbon (TOC) in aquifers and both acids and bases The particulates and
50d). Specific conductances in the SRWMD monitor wells can have three sources: (1) natural cotloids that constitute the majonty of organics in
(Figure 50b) are relatively uniform, indicating that The Suwannee River divides the SRWMD humic substances, (2) synthetic organic soils, especially organic hard pans, and sediments
aquer tsysmtem hasael atiely hromohenosufc (Figure 52b) into two flow systems, east and west contaminants, and (3) drilling fluids. Data are humins
qufrssmhaaretveyhmgnusfthrvrBthfwsytm lurtetepresented below (see sections on SyntheticU
composition. The surficial aquifer system in the othrie Bthfwsyem iluraeheOrganics and Pesticides) indicate that the
SJRWMD (Figure 50c) has several good examples increase in specific conductance along flow paths. cocnrtoso nhooei raisaeThree processes affect the mobility of organic
of high specific conduc-tance waters inland. Many dranae codivi tigest secific couancear orders of magnitude less than the total organic acids: (1) microbial decay, (2) pH of the host of these are asso-ciated with areas of irrigation, wara e dinvthe coast taspiti zonduotnte carbon concentrations Barcelona (1984) suggests water, and (3) total dissolved solids content of theI where deeper waters or evaporative concentration weter an east flowsse an nerthe that the concentrations to be expected from drilling host water (Thurman, 1985).
elevate specific conductance. Floridan aquifer muaneRvri h atr ytm ihruds are also much less than the TOG
andscrop water ea, weret imtehagstre specific conductances are also found in the concentrations reported herein. Therefore, theMcrbaDey-Mcrbadcyofrgnandcrpsin hearawhee t echrgs heNorthern Highlands physiographic province in the TOG concentration data discussed in this section rich material is associated with many of the
surficial aquifer system (Dalton, 1978) Increased SRWMD. These result from equilibration of the reflect naturally occurring organics, or humic processes previously discussed. Iron, sulfur, and
spe) are canuted by In central SFWMD (Figure water with the host rock under nearly stagnant flowsbtnesntrgnrnsrmtnsressctdwthsi
50)aecue contamination of irrigation conditions. Note that there are several, isolated, microbes, especially bacteria. Reaction 6 is an
morersminer-aized water, and salt-water intrusion. "plume-lke" water masses, such as in Alachua Humic Substances Most of the total organic example of a microbially driven reaction in which
County. These appear to be related to slightly carbon reported in ground water is composed of organic carbon and sulfate are metabolized.
elevated chloride levels near karst recharge areas humic substances (humic and fulvic acids) which Therefore, bacteria require a source of organic
Intermediate Aquifer System along the Cody Escarpment (Lawrence and are derived from microbial decay of leaf lUtter, sot carbon, as well as the other nutrients. The bacteria
Upchurch, 1976, 1982) organics, and soil biota waste products. Humic form mats composed of a number of different
Specific ondctane i theintrmedatesubstances are complex molecules with a wide species, all of which support each other in a
aquifer system is generally higher than in the Specific conductance data from the SJRWMD rhange moeclaroitso prdTthumin,18)Siccmlxomuiy
srialqufrssm(Tbe26). These specific (Figure 52c) indicate relatively low specific te r eopsto rdcs ui
sourcia s aqur syste (nTrspbl e toicesdcnutne nadTeei ag eetasubstances can include a number of different In order for microbial mats to thrive, they
anion concentrations that result from chemical centered on St Johns and Flagler Counties, which Uoeua tutrsadfntoa rus uhrqie()asldsbtaefratcmn n 2
weathering of the host rock. Inland, where can be attributed to connate waters and intrusion as carboxyl, amino, and carbonyl groups. Humic- a constant bath of water rich in organic carbon and
chlorides are of minimal importance, sulfates under pumping stress. There are also several substance molecules have flexible structures, Large other nutrients. In intergranular aquifers, there is
produced by the oxidation of pyrite (Table 4) centers of high specific conductance along the St. sizes, and a diversity of functional groups, so they abundant substrate and particulate organic
contribute most significantly to the specific con- Johns River which appear to reflect upooning epfectia eo meals.Te c pleg gn-s microbes) (artmcanhuic susteed rom theae
ductance. The southward increase in specific along faults and fractures (Leve, 1983). epcal o eas hyaecpbeo o-mcoe)aemcaial itrdfo h ae
conductance as a result of increased total forming to clay surfaces and of flocculation as In karstic flow systems, the caverns and karst
dissolved solids is evident (Table 26). Teifuneocaslsltwerswllparticulates in their own right. conduits provide less substrate per unit volume of3
The nflenceof oasal slt waters ellwater, so microbial activity may be reduced and illustrated by specific conductance of waters of the Tewd ag nmlclrwihdvriyTCmyprit nkrtcaufrteeoe
Figure 51 illustrates the distribution of specific Floridan aquifer system in the SWFWMD (Figure The wde sranges ndleclarweght nuiberst TfdsOv man prit Inkrgtic aifers, tree conductance in the intermediate aquifer system. In 52d) A strong specific conductance gradient is fn clar trcups esk andharen mbnrfofumisoled dsantcuateforganuic crondicans trae south Florida (Figure S1de), where data can be shown at the salt-water transition zone. Re- functonal dgroups make carcerizatio of hmic smeditan before suaiale conppitns fonrb
icnoree twsarden oast anstues. Thi sodcame Withracosoc ur Hlsorogth Maaeeo P ee method of classification is by their response to the realized. While they are produced in most soils,
panternsis pntonrd cothe ndstricts Thwevermi WanMyakka Riversbog, aae, cpH of surrounding water (Thurman, 1985). Hum/c humic substances are best preserved in waterpatenisprsntinte thrditct, oevri ad ykk fier.acids are humic substances that are soluble in saturated, reducing soils and aquifers whereI
is not contourable (Figures S1a,b,c). Upconing basic solutions and insoluble in acidic solutions complete oxidation and aerobic microbial decay
ison evie ie lnaent (FiueGd) si aJone ihspecific)In south Florida (Figure S3e) the Floridan has (pH < 2) or ethanol Humic acids include large, aeihbtd
coneduter wiuates aong the Goahthee i high sulfate, chloride, and bicarbonate contents complex molecules with molecular weights ofU
Rie(iue1)This causes the Florndan water to have 2,000 to >5,000 daltons (24,000 to 60,000 a.m.u.; Transformation Mechanisms and Carbon
River(Figre S e).conductivities in excess of 4,000 gmhos/cm south Thurman, 1985). Because of their low solubility in Fixation Organic carbon can be fixed in a sol or
of the line from Lee to Brevard Counties. Again, acidic solutions, humic acids tend to flocculate in aquifer as a particle or as organic tissue, or it can3


40







FLORIDA GEOLOGICAL SURVEY

be released as a gas. The gas can then be lost to contribute total organic carbon to ground water. metals, which may be hazardous, organic carbon Hem (1985).
the atmosphere, or it can become involved in Thus, in most places total organic carbon may be of secondary concern
Inorganic reactions. Most organic carbon is decreases in concentration with depth (Watrous
consumed by microbial activity with a sequence of and Upchurch, in prep.). This is not to say that Total organic carbon is distributed throughout
degradation steps leading to the ultimate there are not other sources of total organic carbon Considerable attention has been given to aI aquifer systems, but is highest in the surficial
production of carbon dioxide (GO2) or methane Clays in the Hawthorn Group contain organics that organic carbon in public water supplies in aquifer system (Table 27). Given the regional
(CH) an e ecopoed o rodcesolbl toalsoutheast Florida because of the potential for extent and continuity of the total organic carbon
(OH)anbe dcromposedstoe produc oluben ttarlino naoehae(rTM opud.cocnrtos ti larta oto h rai
Avon Park Formation contain widespread organic- When organic-rich water is sterilized by carbon in Florida's aquifer systems 5s a result of
Microbes have the capability of converting rich zones that myalso cnbuetalorganic chontoclnemay substitute for hydrogen local recharge of humic substances
Sorganics into 02 under aerobic conditions", and carbon.my cnrbt oa on methane radicals. An example of this reaction
pass out of the soil and aquifer by degassing. chloroform), which has the structure Surficial Aquifer System
Carbon dioxide gas can enter into inorganic Trace organic contamination of ground water
3 ~ ~~~reactions with carbonates as indicated in reactions by synthetic organics is rarely represented in totalHThsufcaaqiesytmholcnante
1 and 2 Carbon dioxide released by microbes in organic carbon data because the small concen- highe total oranuicrbemon co ntatinsh
the soil contributes to the production of carbonic trations that are usually present are below the because t otai rgnc humusn spczonerand
acid in soil and aquifer waters Partial pressures of detection limits of the total organic carbon bl-e-Cluppe si hoins anditus in shaow oils tad
C0 characteristically rise from 10 to analytical method None of the total organic mostC Cmicprol decyof an t materisaJlo ous Thet
approximately 1 0-"> as a result of CO2 production in carbon data reported herein can be shown to be sficafr syt em mepian coenaios.
soiis. This results in a drop in water pH from primarily a result of anthropogenic, synthetic or- CI 14urmg/ oal organic carbon Tablen),tthe i
Around 5 5 to pH values of 3.5-4.5. In aerobic, ganics S14MD haigg/Lhges eda total organic rbn(bl27,wtth
3curovr sytdstenms, microbial dcasy may The trhalomethanes are known to be carcinogenic, carbon. The highest maximum concentration is
resulting ground water will become relatively free Many muds used in well drilling contain orga- and considerable effort is expended to avoid 380 mng/L, which must include considerable I ~ ~~of total organic carbon In anaerobic systems, nics as emulsifiers, binders, and/or coagulation- formation of THM's in drinking water. clodladpriuaehmcmtnl ie h
microbial activity is somewhat inhibited, and total control additives. These can contaminate poorly wet and highly vegetated nature of many areas of
orgaic arbo ca peristorganic carbon concentrations (Barcelona, 1984). DISTRIBUTION IN GROUND WATER total organic carbon in the surficial aquifer system
IThe latter is a known problem in the Background Temda n aiu ocnrtosices
Soluble organic acids can be removed from Network data set, and isolated reports of high total The total organic carbon data are among the to the south, also indicating the prevalence of
ground water by flocculation (Thurman, 1985). organic carbon must be considered as probable most interesting and important data in this report. organic-rich, wetland environments to the south. SFlocculation of organic acids takes place when contamination4 by drilling fluid until confirmed by No other known study has compiled a data set of
I ~ chemically reactive sites on the organic molecule further sampling For example, in the SRWMD the organic carbon in aquifer systems that is as ex- The pattern of total organic carbon in the
become saturated with cations. If abundant, origina data set of 24 surficial aquifer system wells tensive It is also of interest that the total organic surficial aquifer system is largely controlled by
hydrogen ions are sufficient to cause flocculation contained 11 wells (46%) with over 10 mg/L total carbon levels are so high Hem (1985) noted thatprxmttorgncihsuiiaevrnet,
of humic acids, which results in a loss of solubility organic carbon. When the wells that had known Or all natural waters contain organic carbon because such aswetlands,nrivers, srfpea depoits Total
flocculate if they come in contact with high total particulates are removed from the data set, the matter. His review of total organic carbon data system due to microbial decay and flocculation
dissolved solids waters, such as occurs when number with high total organic carbon drops to 4 from aquifers indicates, however, that total organic
meteoric waters enter a carbonate-rock aquifer or out of 15 (27%). carbon concentrations can be expected to be less
se ae.than 20 mg/L as carbon Thurman (1985) Surficial aquifer system wells that are high in
summarized the distribution of dissolved humic total organic carbon in NWFWMD and SRWMD
Trasprt f rac Mtal -Humc nd ulicsubstances in filtered ground and surface waters. (Figure 53a,b) are closely associated with marshes,
anp ortcuof Tace nMeals s uic (arndlv He reported the concentration range in ground swamps and rnverne drainage. High TOC is also
crbid meuls inclde umro sites (carrbonmy, STANDARD OR GUIDANCE water to be 0.03 to 0 10 mg/L as carbon The associated with swamps and other surficial
caroxlxino-, and simlr seas) wf hee heicas, CRITERION samples described in this section were not filtered, sources of organics in the SJRWMD (Figure 53c)
comphes xings a n c cura B ue of tngets so one would expect higher concentrations. High total organic carbon occurs in some coastal
theseu c ids re cranpable o tbindn etas atnr wells in all three districts in regions where coastal
induin tertasotFothsraowerThere are no standards or criteria for naturally swamps and marshes abound Sediments of the
hgh in total organic carbon is usually high in iron occurring organic carbon Where synthetic Florida total organic carbon data indicate that coastal ridges include peats and disseminated
and trace metals (Young and Comstock, 1986) At organics constitute all or part of the organic organic carbon is very widespread and con- organics which may also contribute to the total
I ~ contaminated sites humic and fulvic acids may carbon, individual cnteria would be in effect. centrations range as high as 380 mg/L (Table 27) organic carbon concentrations in the aquifer
case uneial oeeto ag mutfTe satewide mean concentrations in mg/L as system waters. Total organic carbon in the
metalsga aro i o hrfu carbon are: surficial aquifer system 14.0, surficial aquifer system in SFWMD (Figure 53e) is
ural orgmani ca irbton no haru tnd intermediate aquifer system 4.8, and Floridan generally low in the Atlantic Coastal Ridge, where Ioreso TOC Most organic materialis hmans stay casen iscrtions aer andi aquifer system -. 2.2 mg/L All of the medians highly oxidizing environments have reduced the
Surve of mayan ufaeSwmsan stance an fixtres Bndeaser humc exceed Thurman's (1985) expected concentration organic content. Elsewhere, total organic carbon
drgaive fromne an surfae w apsprad sbtne a oplex adtnsotrcerange, and they are near the upper level cited by is high in waters related to the Everglades and Big


41






SPECIAL PUBLICATION NO. 34


Cypress drainage systems and portions of the In the lower Wacissa and Aucilla drainage basins. carbon water Only those compounds that have beenI
Caloosahatchee and Kissimmee River drainages! These areas are dominated by fresh-water swamp tentatively found in Florida aquifer systems are
which are characterized tby extensive swamps, communists andarx l drie pin awoodsrbauitetenrhe he RT dicsed elow Manys o te toccurrence

concentrations are in areas where the Floridan is 27), with a median of 3.3 mg/L and a maximum of occurrences have not been confirmed by reIntermediate Aquifer Systern well confined by the overlying Hawthorn Group 29 0 mg/L. The majority of the high total organicsmpng
High total organic carbon concentrations also carbon samples came from a large area centeredsapig
occu inthelimstoe oucro bet (uwaneeon Flagler County (Figure 55c). It appears from
Total organic carbon in the intermediate ocu nte1retn uco et(uaneother data that this water has a significant connate Table 29 lists the number of samples in which
aquifer system can result from rapid recharge of Limestone and Ocala Limestone) in Walton, cmoet n h ihttlognccro a n ftecmonsi al 8wr on n
surface and surficial aquifer si stem waters, or it Holmes, Washington, and Jackson Counties. In compet, andci the ightoamogniccrbnma n of the coie ten m pounds inaale 28n woexeeud ande
may be derived from decomposition of organics in this area the Floridan aquifer system is unconfinedsytmstnrd.Tetbencusunnfrd
th atonGroup (Miller, 1 978) Median total ndschrtrzdbykrtrang occurrences Care should be taken in interpreting
organic carbon concentration in the system is 4 8 these data because the data are unconfirmed The
mgL Tale27. hehihstTO cncntatoni Hghtoaloranc abo cncntaton aeTotal organic carbon in the SWFWMD (Figure discussions that follow list the compoundsI
71mg/L h FM (Table 27). h hs TOcncntatoni Hih stotlrgani csabong concentation Cady 55d; Table 27) is high relative to the remainder of tentatively detected and some important concerns
71.0 mg/Lin the SFMD (Table21)pfoun in te wells alongthe karsti Cody the state The median concentration is 16 8 mg/L about each. The proportions of samples that
Esa rnccarpmet n SnRrMD i(Fsgur e bHig and the maximum concentration is 78.8 mg/L. contain each analyte are given in thetext.
The high total organic carbon concentrations total orgnthi carbo cocntLaktins haves be High total organic carbon concentrations are throughout the northern and central portions of the noe nteLv a n aeCt ra consistently high throughout the district, but the
state are generally related to rapid recharge Upchurch and Lawrence (1984) and Brown (1989) highest concentrations occur in regions where No maps are given for this and the following
environments, such as in karst terrains and the Brown found two sources of total organic carbon wetlands and rnverine systems overlie unconfined, Pestioides sections because of the uncertainties vicinity of drainage well systems Total organic nthLkeCity area (Columbia County). She orpol ofndprin fteaufrsse.encountered in confirmation by resampling, anacarbon in intermediate aquifer system waters of cnuddtttta rnicrbnonn-lytical procedures (many of the positive results are
southern Flonda (southern SWFWMD, Figure 54d, rton nheC sa LwndadCdytoo near the practical quantitation limit5), and
western SFWMD, Figure 54e) are probably not Escarpment are a result of direct recharge of the Total organic carbon concentrations are attribution to causes.
related to rapid recharge These high Floridan by organic-rich surface waters, The relatively low In the Floridan aquifer system of the
concentrations, including the highest in the aquifer moderately high total organic carbon SFWMD (Table 27; Figure 55e). Median consystem, may be related to disseminated organics concentrations in the Floridan aquifer system centration is 1.9 mg/L, but the maximum IMPORTANCE AND CONTROLS
in the Hawthorn Group Figure 54e indicates that beneath the Northern Highlands, where the aquifer cnetaini h ihs eoddi h
most of the areas characterized by high total system is confined by the Hawthorn Group, were Floridan at 80.6 mg/L. Subsequent sampling of Tesnhtcognc aeadvriyo
organic carbon concentrations in the intermediate attributed to leaching of organics found in the this wefl yielded total organic carbon concentra- sTuresytheti rgan cs have irsity of aquifer system water are inland from the coastal Hawthorn (Miller, 1918) tions of 1.0 and 3.5 mg/L, indicating that the initial, sourcs.hey raes rome avy ivndstrs loal,
salt-water transition zone, so total organic carbon high concentration may be anomalous. High lbcns oeaeo aua rgn.Tedr
may also be derived from local recharge of An extensive area of hgtta gnicrbnconcentrations are associated with the Kissimmee Luiats.Nar of nh ran ara orignspc The daensurficial, organic-rich waters occurs in the Coastal Rivers Basin (Figure 55b), the Rvrcrdrndwtanre nwtrnLedo the solubilities As a result, they may exist
coastal drainage system west of the Suwannee Conydissolved in water or, locally, as an non-aqueous
Floridan Aquifer System River in Taylor, Lafayette and Dixie Counties, This phase. None of the samples in this study are of
area is characterized by a thin clay (the "San Pedro Synthetic Organics free product; all are dissolved in water. Several
clay") that overlies the Flonidan aquifer system. The factors affect the mobility of synthetic organics.
Total rgn carbon in the Floridan aquifer Floridan is exposed at a number of sites in the ThH nld 1 deto,()dlto n
system (Table 27, Figure 55) ranges from below embayment and the clay is penetrated by many DEFINITION AND ANALYTES dispersion, (3) volatization, (4) density stratification,
detection limits to over 80 mg/L within the state sinkholes. The land surface is characterized by (5) dissolution, (6) sorption, and (7) biological
While the median total organic carbon concentra- extensive woodlands and swamps The large area Synthetic organics include a list of 142 (Table conversion and hydrolysis.
tion is relatively low (2 2 mg/L) compared to other of organic-rich water in the Coastal Rivers Basin is 28) anthropogenic organic compounds This list Florida aquifer systems, it is high compared to remarkable because it so accurately defines the includes most of the compounds on the U.S. Advection -Advection is the term used to
data from aquifer systems outside of Florida (Hem, extent of the basin Total organic carbon in this EvrnetlPoeto gnypinyls eeb rnpr ihtefo fwtri h
195 hra,18bsste appdais mosteliknlroalrdsulttof local carg These compounds range from primary compounds aquifer system. All constituents in ground water
strugm wp and the a reas witha rhgl used in manufacturing and energy industries to are subject to advective transport. The highest total organic carbon concen- ohrgcsurface wateand organicrich soils. Th degradation products produced by microbial
trations inq nothesys Forida aein areas where the large re-entrant of water with less than 3 mg/L total decay and hydroysis. Manyas te st sheti DIuinadDsesin-Dlto n

characterized by poor confinement in a well- sognds torbhn FnhTayRie aon posblyre- inclusion in Synthetic Organics, as opposed to dispersion are caused by individual packets of
developed karst terrain. In NWFWMD (Figure 55a) upconins tof dhee FloidanRwaer nard Prssbnd Pesticides, is based on common uses. For water following flow paths of different lengths
highest total organic carbon concentrations are in Fpo.nisag e of prlondoal oranic ncarbo aern additional information on these and other synthetic Dilution and dispersion are highly effective in areas where the Floridan is unconfined and Foe.Dshreo o oa rai abnwtrorganics, refer to Montgomery and Welkom (1990). reducing the concentration of synthetic organics in
in the Aucilla and Suwannee basins appears to intergranular flow systems, but less effective in
overlain by thin, organic--rich, sandy soils, such as limit the lateral extent of the higher total organic


42







FLORIDA GEOLOGICAL SURVEY

conduit flow. Hero, flow paths are less tortuous = density of the organic (g/mL or g/cm3 ), and p, In a sense, therefore, solubility in water and In all cases, the median and upper quartires of and dispersion is limited Dilution within the con- density of water at 40C (g/mL or g/cm3 ). retardation on humins are related and the synthetic synthetic organic data (Table 29) are detection
howver msaindiaty eueth ocntain opbed lith, hi fcondl s thn greare organics can be classified on the basis of either imits. The proportions of samples with detected
howver sid o e Igh, wil copondswih p, reaersolubility in water or by Ks Table 31 gives the synthetic organics are as follows:
than 1 3 are said to be dense mobility classification of Fetter (1988). In this
Volatzatin any f th synheti orgnicsclassification mobility is classified on the basis ofSuf Fisted herein are volatile. That is, given proper Solubility All of the organics exhibit some prpotonlote, wKhi prxmteyivreycalaufrsse
conditions, the organic may go to a gaseous state solubility in water. This ability to dissolve into
and pass out of the system. This process is water encourages transport. The solubilities of the NWFWMD 2 8%
especially important in unconfined, water-table organtcs are highly variable, and inversely related Biolog oal Transformations and Hydrolysis Many SRWMD 0.0%
aquifers where the gaseous phase can pass to sorption onto sol or aquifer particulate organics of the synthetic organics can serve as sources of SJRWMD 6.9%
directly into the soil or aquifer atmosphere, Table organic carbon for soil and aquifer microbes As aSW MD24
30 gives the classification utilized in discussing result, some of the chemicals listed in Table 28 are SFWMD 8.9%
volatility below This classification (Lyman et al., Sorption One of the governing principles of degradation products, not primary contaminants.
190 sbsdo h Henry's Law constant, or the synthetic organic transport is the octano/-water Microbial degradation behaves chemically much Saeie 66
airwatr arttio ceffciet enr's awcon- partton ooeffhcient (Kow). This coefficient is a ratio like hydrolysis, with cleaving of radicals and Saeie 66 Sstant is defined as the ratio of the partial pressure of the solubility of a synthetic organic in octano, a substitution of water or OH-. The rate of degraof the organic vapor in air to the concentration in representative organic solvent, and water Low Km dation has been likened to radioactive decay as Intermediate aqufer system
water. At 1 atmosphere the Henry's Law constant organics are more soluble in water than in organic biodegradation and hydrolysis in ground-water is calculated by ~~~~~~solvents. High Ko. compounds are more soluble In ssesflo nepnnildcyrt
is calcuated byorganic solvents than in water In aquifer systems, sytm olwa xoeta ea aeNWFWMD 0.0%

P FW one of the possible places where high Ko, organics SRWMD 0.0%
H = (17) can be fixed is particulate organics (humins, see STANDARD OR GUIDANCE SJRWMD 0 0%
7605 Total Organic Carbon). There is some debate as CRITERION SWFWMD 0.0%
to whether the high K simply adsorb onto available surface sites. At any Table 28 gives the standards or guidance partial pressure (mm Hg), S -sluity(g),ndrate, given the presence of humins in the soii or concentrations for the synthetic organics. Only the Saeie 13
FM n gra orulan eight9)f the compound aquifer, high Ko, organics are likely to be fixed on hazards or health consequences of analytes deU (Mntgoery nd elko, 190).the particles and thereby retarded from advective tected In the Background Network are discussed Floridan aoufer system
transport Domenico and Schwartz (1990) present below.
SDensity Stratification Many of the compounds an excellent discussion of the sorption process.
found in Flornda waters are liquids with densities that Us ftetr mi nTbe2 infe htNWFWMD 0.0%
differ significantly from water. If free product is The otanowtr patitio coffien isthe standard for the organic compound is the SJRWMD 143%
present in the aquifer system, it will come to density deteind baoratr erpr imnceents n dat detection or practical quantitation limit. In these SWFWMD 471%
Sequilbrum with the water. If it Is less dense than casesetere iboraspecyfcexpanmadntsutnde daterSFWMD 3.1%
water, the product floats on the water surface and are readily available for many compounds (see isasuec teei o sei tnad u the waretfor"proisinsDf 3oria%
fom ihNnAuosPaeLqi LAL.Montgomery and Welkom, 1990). A more realisticissbettth'refrmpvson fFnds
If ts mor dese, the-A liquisdhsinks aud formaL. coefficient for use in ground-water systems is the water quality statutes (Oh 17-550 FAGC.) Under
De e o qeoth ui ins n frnsaorganic-carbon partition coefficient (Ko0). The this provision, the water must be "free from" Statewide 3 1%
I DeseNon-queus PaseLiqud (NAPL Inorganic-carbon partition coefficient is the ratio of deleterious contaminants, including compounds
either case, sampling may miss the non-aqueous sorbed chemical per unit mass of humin (as C) to that harm biota, use of the water, or humans. Harm
phase and detect only that portion of the organic subly nwe.Mnyqutnshvbento humans includes toxicity, mutagenicity, carcino- As one might expect, the highest proportions of
dissolved In the water Given the design of the deolbidity inewate Many equationr hae eenyoertgniiy samples with detectable synthetic organics are
I ~Background Network sampling plan, it is unlikely denvglopnd tonnglate8K) rtoated For exapletiititertoenciy from the surficial aquifer system and unconfined
that non-aqueous phase liquids are present at most Koffen anbyig(98)rltdte w atto portions of the Floridan aquifer system This mndiof the sample sites,.ofiinsb Given the large number of samples from cates the suscept blity of those aquifer systems to
Florida's aquifer systems and the fact that the contamination from surficial sources. The
Ilsh c m o n th g s uso logKcc 1 138 etections have not been confrmed, t is ntermediae aquifer syterm contanst lttl
clsseified donsthe asi fheir reatvydnit+ 054 logK0w (19) synthetic organics. Many of the analytes that were confined nature of the water-producing zones in
(speifi denity asdefied y .found to be present were from a single sample, so the aquifer system. Areas at greatest risk include
U the areal distribution of "problems" is highly the unconfined Floridan aquifer system in westOther equations are discussed in Freeze and limited. Most of the samples are from wells near central Florida (SRWMD, SWFWMD) and in
S,(18) Cherry (1979) and Domenico and Schwartz (1990). urban, industrial, or heavy agriculture areas, which SJRWMD, and the surficial aquifer system,
I VSP Care should be taken in choosing which of the suggests that it is unlikely that any significant especially the Sand-and-Grave! Aquifer Irn
rw equations (e.g. equation 19) to use because there problem of wide extent exists NWFWMD and the Biscayne Aquifer In SFWMD.
is no general agreement as to which is most
where p,= the specific density (dimensionless), p, appropriate.


43






SPECIAL PUBLICATION NO. 34


DISTRIBUTION IN GROUND WATER 2.5 pg/L based on cancer r'sks (Florida aquifer system in the SRWMD and one of 100 in Chloroform was widely detected in theI
Department of Environmental Regulation, 1989). the SWFWMD contained possible bromodi- Background Network data set In the surficial
chioromethane. aquifer system, one sample of 98 in the
Rather than divide this discussion into aquifer NWFWMD, one of 57 from SJRWMD, and three of
ssmsand districts, the following discussion One sample out of 29 from the surficial aquifer U3 rmSWDcnandclrfr.Nn
deals with the specific chemicals found or system in the SFWMD contained possible Bromoform was detected in the intermediate aquifer system.
suspected in the aquifer systems. The chemicals acrylonitrile. The chemical was not detected in One sample of 302 from the Floridan aquifer
are in alphabetical order for ease in location, as other districts or aquifer systems.Brmor(C r) sadnelqd.IisysminteRWDndwos pesf16
opposed to being placed in order of origin Or moeaeyvolatile (H = .-.x0 t 3/o) from the SWFWMD contained probable chiorochmclsmlnis nessae tewsteBenzene and is mobile in ground water (Ko = 110 280). It form.
Henry's Law constants! Ko's, and uses of the is used as a solvent for waxes, greases, and oilsI
folwn heiasae rmMngoeyadand as a component of fire-resistant chemicals. Chloromethane
Welkorn (1990). Benzene (C0H6) is widely utilized by the energy Bromoform is a trihalomethane, and the Pnmary
and manufacturing industries. It is an additive in Drinking Water Standard for total concentration of
Care should be taken in placing importance on utmtvfelpnspsisndrss.tistrihalomethanes is 100 g/L Chloromethane or methyl chloride (CH3CI) is a
the occurrences reported below, At this time there one of the most widely used solvents, and is a highly volatile liquid (H = 6.6-8.Sx1 0- atm m3/mol).
isqustonastowhthr hechmialisacualycommon contaminant in ground water. It is a The Kt. value of 25 estimated by Montgomery and
isqesin stowete techmca s cua(common contaminant in plumes from Leaky Bromoform was reported from one sample out Welkom (1990) indicates that chioromethane is
in the water or is spurious The following litunderground gasoline storage tanks. The Henry's of 532 from the surficial aquifer system in the very mobile in ground water. U S. Environmental
shudb tiie ntw as 1)t w *Law constant for benzene is 5.Sx10Q-3 atm mV/mol, SFWMD. It was not reported elsewhere Protection Agency draft preliminary protective
even at the worst case, there is little background which categorizes it as highly volatile. Benzene is concentration lhmit data (Florida Department of
contamination of Florida's aquifer systems and (2) very mobile in ground water (Koc = 49.0 -100). Sol Environmental Regulation, 1989) have resulted in a3
to identify chemicals that may be present and microbes can break down benzene to catechol Chlorobezenegudnecnnrtonf3,0p/L
require further study' and other products. The Primary Drinking Watergudneccntaino3,0M/L
Standard for benzene i 1pg/L. Chlorobenzene (CsH5Cl) is used in the
As this discussion continues, it will be appar- manufacture of a number of organic chemicals It Chhorornethane was not detected in the
Floridats anyuife sytehe bemp nsted inh Benzene was detected, but has not yet been is also utilized as a solvent, insecticide, pesticide, surfica or intermediate aquifer system It wa
Fpand's pestiies. Mystm ae olneiensed fnotr confirmed, in a number of samples around the and heat transfer agent. Chlorobenzene is highly detected itwo of 1J6 W sape from teFoia pus in Floriids an the akgounde Netw ori state. In the surficial aquifer system eight out of 98 volat ile (H = 3 6-3 9x1 0- at m m/m ol) an d aquifer system in th .RM.
useinFiodaan th Bckgoud etwrkisfrom the NWFWMD contained possible benzene. moderately mobile to mobile in ground water (Kot
detecting residual contamination. Also, note that One out of 81 from the SWFWMD and 12 out of 48 330) It can be photodegraded to phenol and Dibromochloromethane
most of the chemicals are only moderately volatile, 575 from the SFWMD also contained possible chlorophenol under certain circumstances. There which is consistent with the residual occurrences. benzene. In the intermediate aquifer system, three is an Environmental Protection Agency HealthI Very highly volatile compounds (H > 102 atm out of 52 samples from SWFWMD and two out of Advisory on chlorobenzene, and it is organoleptic Dibromochloromethane (CHBr2CI) is utilized In
ma/mol) are suspect because the Background 136 from SFWMD contained possible benzene. (it imparts taste or odor problems to water) (Florida the manufacture of fire extinguishing agents and
Network actively avoided sites likely to have active Benzene was detected by most districts in the Department of Environmental Regulation, 1989). propellants. It has been used as a refrigerant and releases and older releases should have previously Floridan aquifer system, as well The occurrences As a result the guidance concentration in Florida is as a pesticide. It is moderate to highly volatile (H = volatized. There is also an absence of highly were: one out of 101 (NWFWMD), one out of 302 10 g/L 9.9x104 to 7.8x10-3 atm m3/mol), and mobile in
mobile or immobile compounds. Immobile comn- (SRWMD), six of 161 (SWFWMD) and three of 153 ground water (Koc = 83). It is a member of the
pounds do not spread widely, which reduces the (SFWMD). hbwsdtce nte dl trihalomethane group, and the Primary DrinkingI
probability of detection. Highly mobile compounds -CorbnnewsdttdintesrialWater Standard for total concentration of
are diluted and dispersed to concentrations below aquifer system in One sample out of 57 from the trihalomethanes is 100 pg/L
detection limits. Bromodichloromethane SJRWMD and in 16 out of 652 in the SFWMD It
was not detected in the intermediate or Floridan3
aquifer systems. Dibromochloromethane was not detected in
Acrylontile Bromodichloromethane (CHBrC2) is a the surficial or intermediate aquifer systems. It
component in fire extinguisher fluids and a solvent was detected in the Floridan aquifer system in one
for fats, waxes, and resins. It is used as a Chloroform sample out of 160 from the SWFWMD.I
Acrylonitrnle (C3H3N) is copolymerized with degreaser and flame retardant. It is dense and
other organic compounds to produce acrylics, moderate to highly volatile (H = 2.1 x1 0- to 2 4x1 0-Clrfr CCji es iui.I shgl irmehn
ABS (acrylonitnle-butadiene-styrene), and other atm mjmrol). It is mobile in ground water (Ko = volatile r (HCHC 9-)4x1s at m3ns fl d. vershihy1,Dbrmthn plastics It is used as a grain fumigant, and in phar- 62). Brormodichloromethane is a trihalomethane, mobaile in grun 2wa-e.4x10 44). mC/lorofo has r maceuticals, antioxidants, dyes, and surfactants. It and the Primar Drinking Water Standard for total mben hond to ecr oba44) Cdegraderm in12Dbooehnasbttrkona
is a x1ightm m/ond Bwstd moderat olatlit (.4H concentration of trihalomethanes is 100 kg/L. anaerobic environments to methyl chloride and ethylene dibromide or EDB It has the composition
compound is very mobile. According to lterature other products. It 5s a member of the C2H4Br,, and has been widely used in the state of
cited in Montgomery and Welkom (1990), No bromodichloromethane was detected in trihalomethane group, and the Primary Drinking Florida as a soil fumigant. It is dense and
acrylonitrile can be photo-oxidized. The practical the surficial or intermediate aquifer system Water Standard for total concentration of essentially insoluble in ground water. EDB had
quantitation limnit, the guidance concentration, is samples One sample in 302 from the Flonidan trihalomethanes is 100 g/L been considered immobile. However, EDB was

44I







FLORIDA GEOLOGICAL SURVEY

H ~detected in a number of wells in Florida in the 1,4 Dichlorobenzene Toxicological Research at Florida State University. 1,2 Dichloropropane
1980's and this apparent rnoblihty made EDB a
I chemical of major concern The Dnking Water
I ~ Standard for EDB sO 02pag/L 1,4 Dichlorobenzene (p-1,4 dichlorobenzene, 1,1 Dichloroethane was detected in the 1,2 Dichloropropane (C3H6C2) is a dense
C6H4C2) is highly volatile (H = 2.7-3.1x1-3 atm surficial aquifer system in the SWFWMD In one compound. It is highly volatile (H = 2 3-2.9x10-3 m3/mol). It can be photodegraded to chiorophenol sample out of 57 Three samples out of 632 In the atm m3/mol), and it is very mobile in ground water No EDB was detected in the surficial or or phenol It is moderately mobile in ground water SFWMD also may contain the compound. None (Koc = 27 S1). It is used as a scavenger in certain
intermediate aquifer systems, statewide. Two out (K0. = 160). 1,4 Dichiorobenzene is utilhzed as a was detected in the intermediate aquifer system or leaded gasolines; metal cleaner and degreaser; sol SWFWMD had possible EDB and germicide, sol fumigant; and disinfectant The fats, waxes, and other organics. The guidance
Primary Drinking Water Standard is 75 tg/L concentration is 1 pig/L, which is the practica
,2Dhlrbnne12Dichioroethane quantitation limit, based on an Environmental
Ten samples out of 572 from the surficial iPr2tDichonroethayeH(etyleneddichryridr, rnskr
aquifer system in the SFWMD contained possible 41,2 ihmoratloatle (tHylen.1- d8x1rd4 rasks 1,2 Dichlorobenzene (o-Dichlorobenzene, 1,4 dichlorobenzene. One sample out of 62 from CHC2 smdrtl oaie( .- x0 t
C6H4CLJ) is moderately dense and highly volatile (H the intermediate aquifer system in the SWFWMD m3/moO. It is very mobile in ground water (Koc =44 Only one sample out of 81 from the surficial
1219x103 atm m3/mnol). It has mobilities that and one out of 138 from the SFWMD also 19) It is used as a vinyl chloride solvent; lead aquifer system in the SWFWMD contained posare moderate to low in ground water (K0c = 180 -contained possible traces of the chemical. One scavenger in certain leaded gasolines; paint and sibie 1,2 dichloropropane. The chemical was not 1,700). The compound has been detected to be sample of 162 from the Floridan aquifer system in varnish remover; degreaser; wetting and detected In samples from any other districts or

transformation products 1,2 Dichlorobenzene is dichlorobenzene. and food fumigant. The Primary Drinking Water
U widely used as a solvent for organic compounds standard for 1,2 dichioroethane is 3 pg/L because
and nonferrous metals, and as a fumigant and of its carcinogenicty. Ethylbenzene
insecticide, degreaser for hides and wools, metal Dichlorodifluoromethane
polish, among others. The compound imparts
I taste and odor to water and there is a U.S. No 1,2 dichloroethane was detected in Ethylbenzene (CQH0) is a highly volatile liquid
Environmental Protection Agency Health Advisory for Dichlorodifluoromethane (Freon-12, CC2F2) is samples from the surficial or intermediate aquifer (H = 6 4-6.Ox1O-3 atm m3/mol) It is mobile to
at (Flonda Department of Environmental Regulation, widely utilized as a refrigerant and aerosol systems. One sample out of 116 from the Floridan moderately mobile in ground-water systems (K0. =
1989) The guidance criterion is 10 pgL propellant. It is also used in plastics and as a low aquifer system in the SJRWMD and one out of 176 95 260). Ethylbenzene is an additive to gasoline
U e temperature solvent. Dichlorodifluoromethane can from the SFWMD may have contained 1,2 products and a widely used solvent. It is utilized in
occur as either a gas or a liquid, and the liquid is dichloroethanethmnuaur fpstsadohrogni.
Three samples out of 632 from the surficial very highly volatile (H = 4.3x1 0- to 3 atm m3/mol). The guidance concentration is 2 g/L (Florida
aquifer system in the SFWMD contained possible The estimated K00 is 360, which makes it Department of Environmental Regulation, 1989),
I ~ 1,2 dichlorobenzene. None of the intermediate moderately mobile in ground water. The guidance trans-i1,2 Dichloroethene which is the practical quantitation limit The
aquifer samples contained 1,2 dichlorobenzene concentration in ground water is 1,400 pag/L, based guidance concentration is based on toxicant
One sample out of 160 from the Floridan aquifer on the Integrated Risk Information System (Florida The primary uses of trans-i1,2dichloroethene profiles from the Center for Biomedical and system in the SWFWMD and one out of 175 from Department of Environmental Regulation, 1989). (trans-i1,2 dichloroethylene, C2H2C2) are as Toxicologica Research at Florida State University.
the SFWMD contained the compound. solvents for fats, phenols, and other compounds. It
One sample out of 116 from the Floridan is an ingredient in perfumes, and is used as a low- Ethylbenzene was detected in one sample out
1,3 Dichlorobenzene aquifer system in the SJRWMD contained possible temperature solvent and refrigerant The of 79 from the surficial aquifer system and two out
dichiorodifluoromethane. Elsewhere, it was not compound is highly volatile (H = 5.Sx1 0- to 0.38 of 48 from the intermediate aquifer system in the detected. atm m3/mol) and mobile in ground water (K<0. = 9) SWFWMD It was also detected in one sample of
S1,3 Dichforobenzene (m-dichlorobenzene, Transformation in methanogenic (anaerobic)15thFordnaufrsteinS WM ad
C6H4Cl2 is highly volatile (H = 2 6-3 6x1 0- atm aquifers is to vinyl chlornde and other compounds. 1i1 one samlof 54 aqine sysWM. WWM n
m3/mol), and has a mobility that is low to 1,1 Dichloroethane The guidance concentration is based on nnsplf14nFWD
moderately low in ground water (Koe = 170 -1,700). organoleptic properties (taste and odor) and
It is used as a soil fumigant and insecticide, as well recommended protective concentrations sug- Hexachlorobenzene
I as In organic synthesis. The guidance .1,1 Dichloroethane has the formula C2H4C2. Ft gested by the Center for Biomedical and
concentration, based on taste and odor problems is highly volatile (H =4.3-5.9xI0a3 atm m3/mol), and Toxicological Research at Flornda State University Hexachlorobenzene (HCB, CeCl6) is used as a and a Health Advisory from the Environmental slightly mobile (K00 = 30). It is used as an The guidance concentration is 4.2 pg/L (Florida seed fungicide and wood preservative. It is highly Protection Agency, is 1 g/L (Florida Department extraction solvent, insecticide and fumigant; Department of Environmental Regulation, 1989). volatile (H = 1.3-1.7x10 3 atm m3/mol), and, even I ~ of Environmental Regulation, 1989). preparation for vinyl chloride; finish remover; though there is a wide range of Kt. values (360
solvent for plastics, oils, and fats, and other 3,0)i h ieaue(otoeyadWlo
applications. Under anaerobic conditions 1,1 Four samples out of 632 from the surficial 1990), apparently relatively immobile The
Two samples out of 570 from the surficial dichloroethane can be microbially converted to aquifer system in the SFWMD contained possible guidance concentration is based on the practical I aquifer system in the SFWMD contained possible vinyl chloride. The guidance concentration is trans-i,2 dichloroethene. One sample of 302 from quantitation limit and Environmental Protection
1,3 dichlorobenzene. No samples from the 2,400 g/L (Florida Department of Environmental the Floridan aquifer system in the SRWMD also Agency cancer risk evaluations (Florida
intermediate or Florndan aquifer systems contained Regulation, 1989), based on toxicant profiles contained the compound It was not detected Department of Environmental Regulation, 1989). It
3 the compound prepared by the Center for Biomedical and elsewhere. is set at 10 pg/L


45






SPECIAL PUBLICATION NO 34


Hexachlorobenzene was possibly detected in 1.1,2,2 Tetrachloroethane roethene isS3 pg/L greaser in septic-tank cleaners, The Primary
the surf icial aquifer system in one sample out of 79 Drinking Water Standard for TOE is 3 pg/L.
Frida aqufWMr syse fninte sWFmpDe lsoh 1,1,2,2 Tetrachloroethane (C2H2C4) is dense Tetrachhoroethene was detected in the surficialU
Floda aqifr sstm n te WFWD lsand moderately volatile (H = 3 8-4 6x10 atm aquifer system in two districts, NWFWMD (five of Tnichloroethene was detected in samples fromconaiedheacloobnznem3/mol) It is very mobile to mobile in ground 98 samples) and the SFWMD (four of 632 the surficial aquifer system in the SJRWMD (one of
water (Koc 46-118). It serves as a solvent for samples). It was not detected in the intermediate 57 samples) and the SFWMD (seven of 632
Methylene chloride chlorinated rubber, and is utilized as a paint, var- aquifer system. Two districts detected samples) It was not detected in the intermediate
and cleaner for metals; denaturant in ethyl alcohol; These were the SJRWMD (one of 110 samples)
Methylene chloride (dichloromethane or Freon insecticide and weed killer, fumigant, and and the SWFWMD (three of 160 samples).
30; CH2CI2) is a highly volatile, dense liquid. The herbicide The guidance concentration is 1 pg/L Tnichlorofluoromethane
Henry's taw constant is 2.0-3.2x103 atm m3/mol It based on the practical quantitation limit and
is very mobile in ground water (K00 = 8 7) recommendations of the Center for Biomedical Toluene Tnichlorofluoromethane (Freon 11; CCIaF) is a
Methylene chloride is a widely used solvent. It is and Toxicological Research at Florida State dense liquid. It is highly volatile (H = 5.8x10-3 to
deesead rin g agnts. rItvis a nsd as a Uirsy-Toluene (C7HD) is a highly volatile liquid (H = 1 1x1O' atm m3/mol) and mobile in ground water
fumgasnr and rerinagent. It s beenshousndtosbe 67x10- atm mi/mol). It is mobile in ground water (K0. = 140 160) The primary uses of trichlgnoad efg ridea ethn ol, foi Twbapeeu f57fo h ufca (Kmo = 115 -151). Toluene is widely used as a sol- chiorofluoromethane are as a propellant and
converted to methyl chdrolysisetand omi- aqufe sstmpis th SJWM c7fontied psribl vent for paints and coatings, gums, resins, rubber, refrigerant It is also used as a solvent and aI
acid, or formaldehyde by oillssadoi qifrsse nteSRMDcnandpsil 1s, and vinyl compounds. It is an adhesive "blowing agent" in polyurethane foams. The
dation/reduction reactions. The guidance 1,1,2,2 tetrachloroethane. It was not detected sleti lsi os iun nsm aqesgiac ocnrto s240p/,bsdo
Protcntion gnc Halthdio The En ianena aqsuwfere ystes riil nemdaeoina and high octane gasolines. It is a common solvent Environmental Protection Agency draft preliminary
ProecionAg ncyHelt Adisry.Th gudaceaqufe syte s.in manufacturing processes. Toluene is common Protective Concentration Limits (Florida
conenraio i 5pgL.in plumes from leaky underground petroleum Department of Environmental Regulation, 1989).
1,1.1 Tnichloroethane tanks The guidance concentration for toluene is
Two surficial aquifer system samples out of 57 24 g/IL, based on taste and odor concerns andI
in the SJPWMD and one of 81 from the SWFWMD toxicant profiles of the Center for Biomedical andTnhrfurmehnwsdtcednth
contained possible methylene chloride No 1,1,1 Tnichloroethane has the formula C2H3C3. Toxicological Research at Florida State University surficial aquifer system in one sample out of 57
samples from the intermediate aquifer system were It is dense, highly volatile (H =1 3-1.8x 0-2 atm (Florida Departrment of Environmental Regulation, from the SJRWMD It was not detected in the detected to contain methylene chloride In the m3/mol), and mobile to moderately mobile (K0. = 1989). intermediate u f 302m fome SaafrWM
Floridan aquifer system, ten of 116 samples from 104-151) in ground water. It is used in organic psbyntied.mw samplesou of 116 fromthSWM
the SJRWMD and one of 160 from the SWFWMD syntheses and as a solvent for metal cleaning It is psil otie t w ape f16fo
contained rmethylene chloride, also used in textile processing, as a pesticide, and Toluene was detected in a small number of the SJRWMD also contained possible
as an aerosol propellant. The maximum con- samples in the Background Network In the tnichlorofluoromethane.
centration standard is 200 pg/L, based on the surficial aquifer system, it was detected in the
PCB-1 016 Primary Drinking Water Standards NWFWMD (one of 97 samples), SRWMD (one of
20 samples) and SFWMD (12 of 558 samples). It Vinyl Chloride
was detected in the intermediate aquifer system in
PCB-1016 (polychlorinated biphenyl-1016, 1,1,1 Tnichloroethane was detected in three the SJRWMD (one of 26 samples) and SWFWMD Vinyl chloride (chioroethylene; C2HaCI) is
Arochlor 1016) is a dense liquid used as an out of 51 surficial aquifer system samples in the (one of 19 samples) In the Floridan aquifer normally a gas at earth surface temperatures and
insulating fluid in electric condensers and as an SJRWMD One out of 632 samples from the system, it was detected in the SRWMD (one of 293 pressures. It is available as a liquified compressedI
additive in high-pressure lubricants. It is volatile (H surficial aquifer system in SFWMD also contained samples), SWFWMD (two of 152 samples), and gas. It is highly volatile (H = 2.2x10-2 to 2.8 atm = 750 atm/mol fraction) and immobile in ground- possible 1,1,1 trichloroethane. None of the SFWMD (one of 150 samples). The m3/mol). Montgomery and Welkom (1990)
water systems (Ko = 50,000). The guidance samples from the intermediate aquifer system preponderance of single detection events in the estimated the K(oe to be 2 5, which indicates that it
concentration is set at the practical quantitation contained 1,1,1 trichloroethane. Three samples out district samples suggests that many of these are is very mobile in ground water Vinyl chloride is aU limit for all polychloninated biphenyl compounds, of 116 from the Floridan aquifer system in questionable degradation product of other chlorinated organics
which is 0.5 pg/L The guidance concentration 5s SJRWMD contained the compound. as well as being an ingredient in the manufacture
based on U.S. Environmental Protection Agency of polyvinyl chloride and other copolymers. It is
Health Advisories TrichloroetheneI
TetrachLoroethene used as an adhesive for plastics, a refrigerant, and
an extraction solvent. The Primary Drinking Water
PCR-1016 was not detected in the surficial or TrichLoroethene (trichloroethylene, TCE, Standard is 1 pg/L
intermediate aquifer systems. One sample of Tetrachloroethene (tetrachioroethylene, PERC; C2HC13) is a dense liquid. It is highly volatile (H =
Foridan aquifer system water of two analyzed by C20C4) is a dense liquid used as a cleaning fluid, 9.1x10 3 to 1.7x10 atm m3/mol). It is mobile in the SJRWMD contained possible PCB-1016. degreaser and drying agent, solvent for waxes, grudwtr(o 5-10 C sue saOne sample out of 57 from the surficial aquifer
Given the low sample size (n = 2) and lack of greases, fats, and oils, and in manufacturing of grouend ater(d, 65grIsin) TOEnd sdryn aset aytmi the SJRWMD contained possible vinyl
cofraio yrsmpig lu h mroaiiyinks, paint removers, and fluorocarbons It is very solvent for fats, oils, and waxes; refrigerant; chloride. It was not detected in the intermediateI of PCB-1016 in the Floridan aquifer system, this highly volatile (H = 1.3-1 5x10-2 atm m3/mol). It is fumigant, diluents in paints and adhesives; and aquifer system Vinyl chloride was detected in detection of PCB-1 016 is considered to be false, also moderately mobile (K00 = 210 360) The many other uses. It was previously used as a de- samples from the Florndan aquifer system in the Primary Drinking Water Standard for tetrachlo- SRWMD (one of 302 samples) and SWFWMD (one

46







FLORIDA GEOLOGICAL SURVEY


of 115 samples) in the state's aquifer systems. The table reflects Recall that arsenic is the only pesticide analyzed in system in the SWFWMD contained possible Aidrin.
the first sampling and detections have not been samples from the NWFWMD, SRWMD, and It was not detected in the Flonidan aquifer system.
Pestiidesconfirmed by resampling The median and upper SJRWMD. Therefore, the low number of
Petcdsquartiles are at or below detection limits, with one detections in these districts probably reflectsArei
exception, for all aquifer systems sampling as much as any other factor In theAsni
IMPORTANCE SFWMD, the proportions of samples mn which
As might be expected, the maximum pesticides were detected and detected to exceed Unlike the other analytes discussed in this
standards are low and consistent with the section, arsenic is not an organic compound,
Pesticides are widely used in Florida by concentrations are highest in the surficial aquifer synthetic organic data. The high proportion in the although it is often formulated into organics Some
agriculture, the government, and individuals to system, where most pesticide application occurs. SWFWMD must be studied further. These characteristic arsenic-bearing compounds used as
control unwanted plants and insects. Their use is Maxima in the intermediate aquifer system are detections have not been confirmed by pesticides are listed in Table 34 Arsenic occurs in
closely regulated by the state. Pesticide use in the lowest of the three aquifer systems, the maxima in resampling. In many cases, these detections two valence states (As5 and Ass), which combine past has not necessarily been well regulated and the Floridan aquifer system are intermediate include several pesticides in one sample, so the with oxygen to form arsenates (AsO ) and
persistent pesticides remain as an environmental between the two. The high concentrations number of wells that are believed to be affected is arsenites(AsO2) According to Hem (1985), the
I concern. ~~~~~~~~~~~~~~~~~~~detected in the Floridan aquifer system reflect ls hntenme fdtcinmnvln reaeain(2s4)peoiae
concern. ~~~~~~~~~~pesticide application w here the Floridan is either ss h nth nu b r f d te t nsm n va nt r en t an n(H A O ) r d m n t s
unconfined or poorly confined The individual at pH values of 3 to land positive Eh's At pH 17 to
Pesticides are subject to the same physical pesticides that are responsible for these maxima DISTRIBUTION IN GROUND WATER 11 HAsO2 predominates. Under mildly reducing
I and chemical factors that control the fixation or are discussed in detaiF below, conditions arsenite ion (HAsOO) forms Arsenates
movement of Synthetic Organics, and in fact sorb or co-precipitate with ferrc hydroxides and
man o th snthti orancs av ben sedasAs Table 33 indicates, the surficial aquifer metal sulfides. Arsenic compounds are involved in

Pesticides Physical factors that affect pesticide The proportions of samples that exceed the system appears to be more highly impacted by biological transformations, including methylation.
U concentrations include advection, dispersion, standards or guidance concentrations are given pesticide application than the other aquifer Dimethyl arsenic and methyl arsonic acids
dilution, and volatization. Chemical controls below- systems. The intermediate aquifer system is least [(CH3)2AsOOH anid CH3AsO(OH)2, respectively]
include sorption, decomposition, and biological affected, largely because it is the most isolated of have been synthesized by microbial methylation.
Transformation. Modern pesticide design and Surficial aouifer system the three aquifer systems. There is no large scale
I ~ application criteria emphasize minimization of pattern in the data, except that the maximum conex sue o heesicde Fr xa l, hecentration was detected in the SFWMD, which is a Given the above data from Hem (1985), it
expoure o th pesicid. Fo exapletheappears that both siliciclastic and carbonate pesticide may be approved if it sorbs onto soil NWFWMD 1 2% major cropan area aquifers may have conditions conducive for
mineral or organic matter, thereby minimizing SRWMD 0 0% aqueous transport of arsenic compounds
mobility. It may also be approved for use in Florida SJRWMD 0 0% The following dscussions include only those Organic-rich waters may be characterized by
if it can be shown to be destroyed by photo- SWFWMD 18.1% pesticides detected or suspected in Florida's methylation and transport as an organic complex
oxidation, biological transformation, or some other SFWMD 0.3% aquifer systems Samples reported to contain
mean ofneuralzaton o haard us ffets.pesticides, but not confirmed by resampling and
Statewide 3 2% analysis are included. This is to indicate the nature In the 1920's there was a statewide infestation

SThe Background Network samples in the of probable pesticide contaminants. Recall that, of the Texas tick. Cattle ranchers were required to
SWFMDan SWM wre cane fr 72with the exception of arsenic, only data from the dip their cattle to control the tick Dipping was
pest ic ides (T able 32) Sam ples from th e Intermediate aouifer system SWFWMD and SFWMD are summarized below done in thousands of unlinept le witwh arsenic
NWFWMD, SRWMD, and SJRWMD were scanned these pits have been lost Today, arsenic remains
for arsenic only, and no organic pesticide analyses NWFWMD 0.0% Aldnin in soils and may contaminate the aquifer systems.
were made in these districts. For details of maySRWMD 0.0% Evrnetladt r unn hs
oth rnipstcdsseMntmryndSJRWMD 0.0% contaminated sites up, and today's land owners
Welkom (1990). SWFWMD 41.2% Aldnin (CIHC0) is a widely used insecticide will have to clear up the sites.
SFWMD 0.0% and fumigant. Pure Aldnin is a solid. It has a low
U STNDAR ORGUIDNCE .7%Henry's Law constant (1.4-5.Ox1l-6 atm m'/mol)
StatewideUIANE nd only slightly volatile. In solution, it is Arsenic is highly toxic, and is regulated under
SCRITERION Sttwd .%moderately mobile, with a K00 of 407. The the Primary Driking Water Standards at a
guidance concentration is set at the practical maximum concentration limit of 50 kg/L As
Standards and guidance criterion of the com- quantitation limit of 0 06 pg/L, based on toxicant indicated by Table 33, arsenic was detected in the
mon pesticides are listed in Florida Department of Flondanghifer sstemn profiles from the Center for Biomedical and surficial aquifer system. One sample out of 84
SEnvironmental Regulation (1989). Others are Toxicological Research at Florida State University from the surficial aquifer system in NWFWMD and
subject to the "free from" criteria NWFWMD 0.0% (Florida Department of Environmental Regulation, one surficial aquifer system sample of 324 in the
SRWMD 0.0% 1989) SFWMD contained possible arsenic The single
sample from the SFWMD containing 1,100 kg/L is
SGiven the heavy use of pesticides in Florida, SJRWMD 3.8% by far the highest concentration detected in the
the number of samples in which standards or SWFWMD 21 0% Aldnin was detected in seven samples out of data set. This sample is from a well installed to
guidance concentrations were exceeded is small. SFWMD 0.0% 30 from the surficial aquifer system in the SFWMD. monitor a closed landfill. Therefore, the sample
Table 33 summarizes the distribution of pesticides Sttwd .%One sample out of 30 from the intermediate aquifer may not represent true background conditions in


47






SPECIAL PUBLICATION NO. 34


the area. Two samples out of 53 from the Floridan 4,4'-DDE Endrin following a different flow path All of these eventsI
aquifer system in the SJRWMD also contained affect the chemistry of the water The result is that
possible arsenic, ,'Dclrehnldn~i(-hoo nrn(nlO sa netcd hti the water can be classified on the basis of its
1.1 Diclorethnylienebis4-cloro Enrin(CIHaCIO) s a inectiidetha chemical compositionI benzene), or 4,4'-DDE (C,4H8C4) is a solid utilized slightly volatile in water (H = 5.Ox10' atm ms/mel) a-BHC as an insecticide It is also a transformation It has low mobility in ground water (K0e =1,900).
product of DDT. In water, 4,4'-DDE is slightly Endrin is microbially degraded. The Primary For the purposes of this report, the water-type
volatile (H =2.3x10-5 atm m3/mol). It is immobile in Drinking Water Standard for Endrin is 0 2 Mg/L classification that is used is modified from Davis
-HC (benzene hexachlornde-a-isomer, a- ground water (K0. = 240,000 -1,000,000) It may (Florida Department of Environmental Regulation, and DeWiest (1966). They utilized two standard Lindane, a-hexachloro-cyclohexane; CCH6Ck) iS degrade in water, and it can be photo-oxidized in 1989) Only one sample out of 29 surficial aquifer tnlinear diagrams one for the dominant cations not produced in the U.S. and its sale is not allowed ultraviolet ight The guidance concentration is the system samples from the SFWMD contained and the other for dominant anions in water. Each (Montgomery and Welkom, 1990). It has was used minimum detection level (0.01 g/L; Florida possible Endrin. diagram was subdivided into fields that representI
as an insecticide in the past, however. a-BHC is aDprmntfEninmnaRguton19).dfrntrprtnsfth nsTsedgrs
solid. It is slightly volatile in water (H = 5.3x104 eateto niometlRglto,18) are represented on the predominant water type
atm m3/mol) and mobile (K0. = 1,900). a-BHC is Methoxychlor maps that follow (Figures 56-58) Table 35
subject to microbial decomposition in aerobic and One out of 29 surficial aquifer system samples exlisthe proportions of constituents in each
1990), although it is slow to react. The guidance Two Floridan aquifer system samples out of 134 ehoycho (C,6HC1302) isue ocnrlfed he rprtosarae on covrino concentration is set at the practical quantitation from the SWFWMD may also have contained the mosquito larvae and house flies. It is utilized as a the concentrations to mlliequivalents per lter limit of 0.05 pg/L due to U.S. Environmental pesticide. stock dip to control ectoparasites. It is immobile in (meq). The cation proportions are based on theI
Protection Agency recommendations to minimize ground water (K0. = 79,000 89,000). Methoxy- floigeuto
cancer risks (Flornda Department of Environmental chlor is rnicrobially transformed in aerobic and
Regulation, 1989). 4,4'-DDT anaerobic environments. It is also subject to _______hydrolysis. The Primary Drinking Water Standard
for methoxychlor is 100 g/L. (Florida Department X 100
af-BHC was only detected in the surficial 1,1'-(2,2,2-Trichloroethylidene)bis{4-chloro- of Environmental Regulation, 1989). Two samples
aquifer system in the SFWMD. There, one sample benzene] or 4,4'-DDT (C4H9CG1) was formerly used out of 29 from the surficial aquifer system were Na, + + Ca. + Mg (0I
out of 29 contained possible traces of the throughout the world as an insecticide Use in the detected to contain methoxychlor in the SFWMD. -(0
insecticide. U.S, is now prohibited. It is moderately volatile in
water (H = 3 8-4.9x1 0- atm mi/mol) It is immobile where Xs. is the equivalent percent of cation X.
in ground water (Koo = 140,000-1,800,000) 4,4'- Mirex Cation X includes the following cations: sodiumI
1-BHC DDT can be transformed aerobically and p/us potassium, calcium, or magnesium. X, is
anaerobically to DDD, DDE and other metabolites. the equivalent concentration of X, and Na, K,
B BC ( Lnane B exahioo ccloexaeThe guidance concentration is 0.1 pg/L, based on Mirex (cyclodiene group) was used for fire ant Cam and Mg, are the equivalent concentrations
-BC(Lndn,-hxcor-ylhxn;the practical quantitation limit and Environmental control It is no longer used since one of its of the major cations. The proportions of anions areI
Cs11sCle) is a solid utilized as an insecticide B-BHC Protection Agency recommendations to minimize breakdown products is dioxin. The guidance calculated in the same fashion. Anion groupings has low voiatility in water (H = 2 3x10 atrm cancer risks (Florida Department of Environmental concentration for Mirex is 3.5 pg/L, based on are- (1) bicarbonatep/us carbonate, (2) sulfate, and m3/mol) The chemical exhibits low mobility in Regulation, 1989). One sample out of 134 from the toxicant profiles from the Center for Biomedical() hrd. aquifers, as well The K0. ranges from 2,100 to Flonidan aquifer system in the SWFWMD contained and Toxicological Research at Florida State()choieI 3,600. The guidance concentration is set at the posible 4,4'-DDT. University (Florida Departrment of Environmental
practical quantitation limit of 0 05 g/L due to U.S. Regulation, 1989). One sample out of 134 from the The arrangement of ions on the trilinear
Environmental Protection Agency recoin- Floridan aquifer system in the SWFWMD con- diagrams is based on logical combinations
m dtontomnmzcncrrks(Florida Dieldrin tamned Mirex. expected in ground-water chemistry. For example,
Department of Environmental Regulation, 1989). sodium and chloride are paired because of their
B-BHC was detected in one of 29 surficial aquifer common association in marine aerosols and sea
system samples In the SFWMD. Dieldrin (C2H3Cl6O) is an insecticide. It has a HYDROCHEMICAL FACIES AND water and calcium and bicarbonate are paired
slight to low volatility in water (H = 3 2x10-5 to 2x10-' PREDOMINANT WATER TYPES because they are common weathering products ofatm m3/mol). It is slightly mobite in ground water limestones and a number of other rock types.
2,4-D (K0. = 12,000 35,000) The guidance concen--nrduto
tration is 0 05 pg/L, based on the practical Inrduto
quantitation limit and Environmental Protection The predominant water type is designated by
2,4-Dichlorophenoxyacetic acid, or 2,4-D, is a Agency Health Advisories (Florida Department of As ground water moves along a flow path, it the dominant Ions present. A water mass that is synthetic auxn tor plant hormone-lke compound, Environmental Regulation, 1989). One surficial encounters different rock types with different predominantly calcium and magnesium (area B on

usgsn tr~v ligh btly moil aquifer system sample out of 29 from the SFWMD, mineral assemblages and porosity/permeability the trilinear cation diagram) and bicarbonate (areaI
inkrond water 24ndars euate 1by the PFria and one out of 134 Floridan aquifer system configurations. The residence time of the water in 1 on the anion trilinear diagram), the water is said Derigtmet nardsena Ruati0p/ orida89 samples from the SWFWMD contained possible contact with the rock vares with the nature of the to be a calcium-magnesium-bicarbonate water
Dep amet ouf Enviroma tRegulation, 1989). dicldnin. rock porosity, flow velocity, tortuosity of the flow mass (or Ca-Mg-HCO3 water type; B1 symbo on
Tsaplesn fout of 138 from the sFicidan aquifer path, and hydraulic gradient. The water may also the maps).U
system andfuof8rm the WF blordantaqnui,4-r come in contact and mix with sea water, connate
systm i th SWFMD ossblycontine 2,-D.water, or water that has a different chemistry from Once the predominant water type is identified


48







FLORIDA GEOLOGICAL SURVEY

Sfor an aquifer system, hydrochemical facies can be Calcium-Sulfate (A3), Calcium-Magnesium-Sulfate Water History Since the composition of the water water will dictate treatment alternatives. Calciumattributed to areas within that aquifer system that (B3), and Calcium-Magnesium-Bicarbonate-sulfate reflects the sequence of rocks and sediments and calcium-magnesium-bicarbonate waters are
can be characterized by a single predominant (B2), Calcium-sulfate, calcium-magnesium-sulfate, through which it has passed and any anthro- likely to be hard and require softening to prevent
water type or by a specific mixture of water types. and calcium-magnesium-bicarbonate-sulfate pogenic modifications that have occurred, the boiler scale, taste, and soap effectiveness
Hydrochemical facies are interpretational, and waters are characteristically derived by interactionwtr mpstnreet, nabadaythprbmsLwT ,sdu-hodewesar
result from assigning a common origin, history, or with the gypsum and anhydrite at the base of the history of the water. While this history is largely of likely to be soft and require little treatment other
Composition to a volume of water within an aquifer Flodan aquifer system. The mixed waters result academic interest, it can allow deduction of flow than color removal and disinfection. Sulfate-rch
system For example, if a large volume of water from mixing of calcium or calcium-magnesium- paths, vulnerability of aquifer systems to waters may have odor and taste problems from
within the Floridan aquifer system has a common bicarbonate waters with calcium-sulfate waters contamination, and potentials for degradation by included sulfides
calcium-magnesium-bicarbonate composition, one derived from dissolution of the gypsum. chang in g th e flow pat hs, es pec ially th roug h
Could interpret that water mass to reflect a facies Sdu-hode(5-Sdimclrewarsreupconing.,ialueo negon neto el o
controlled by dissolution of dolomite.Fnayuefudrgud nctnwlsfr
Sodim-Crond (E) -Sodim-clone waersaredisposal of storm runoff and waste water is found in two environments Marine aerosol Buffering Capacity Buffering capacity is the ability widespread in Florida (Hull and Yurewicz, 1979;
In the following discussions, predominant dominated waters in the surficial aquifer system of water to neutralize acids or bases Within the Kimrey and Fayard, 1982; Schiner and German,
water types are attributed to hydrochemical facies may have a sodium-chloride composition if little or aquifer systems, buffering capacity involves 1983; Hickey and Veccioli, 1986; Bradner, 1991).
where possible. The symbol used on the pre- no reaction with calcite or aragonite has occurred interactions with rock as webl as water. The Knowledge of the general water type into which
dominant water type maps is given as well, Also, Na-Cl water masses are common in the salt- buffering reactions have been discussed pre- injection occurs will allow prediction of reactions
3 water transition zone. viously (reactions 1-7). When the water is removed between the host and injection waters Also,
Prdoian Wtr ypsfrom the aquifer system, its buffering capacity treated drinking water is stored for later retrieval
Sodiurm-Bicarbonate (El or E6), Calcium-Chloride depends only on reactions within the water (aquifer storage and recovery or ASR) in several
(A5 r A), nd alcum-MgneiumChinde(B5locations throughout the state (Merrtt et al., 1983). 3 Some water types are highly unikely and are( or A6),We ainecag seteClimClim and alcium-agnesium-bhioribenate The facies maps can be used to identify injection
boicbonae w magesimclode, agndm and Sodium sections) occurs sodium-bicarbonate water masses have relatively high buffering ineon ate rsd. Recoso braktw tes for
magnesium-sulfatewanersA-lsormny samples and calcium-chloride waters may result. Sodium- capacities In other words, application of acids and tr ecto atmesbyreverse osmosi is hbweominr
I ~fro the BackgrudNtokhv ope i-bicarbonate waters are most common in Flrinda. bases will result in some degree of neutralizationcmoinoatlrgnsfthsae.Teap
t r ron etokhvecmle -In areas where Na-HCQ3 waters predominate, Sodium-chloride waters in silbciclastic aquifer camnss in lcatagin oft spytell dthe mp
stores and thoroughly mixed compositions. A calcium has exchanged with sodium on the clays have little buffering capacity and cannot tolerate levlno asitrenlat n oent cessary fowcnesin to
number onsamples, for example,n hae apie This phenomenon develops when sodium- addition of acids or bases Msan example of the potable w ratenncsayfr vrint
I compoinsition(u7) hrer alns major si mpn s aresn saturated marine clays are bathed in calcium- application of the principle, consider the acid rain
characteristically transitional between better bicarbonate waters. Calcium-chloride or calcium- problem. Lakes fed by buffered (calciumSdefined water types, and they are not discussed agnesium-chlorde waters are less common, bicarbonate) ground waters have much higher Ion Exchange Aquifer systems in many areas of
below. They result from salt-water intrusion into aquifer tolerances for acidic precipitation than do lakes fed the state can be shown to have waters that have
systems that contain calcium or magnesium- by sodium-chlornde waters in siliciclastic soils been affected by lon exchange. These areas may
saturated clays. Similar arguments can be made for waste disposa be useful for certain types of waste disposal. For
Calcium-Bicarbonate (A1) Calcium-bicarbonate impacts on aquifer systems example, it is possible that movement of trace

They arte di ve frson m ndissoluton o calci t e ord been found in the surficial aquifer system in centra! W ater Use and Treatment Requirementswaesaea o gte m s iepe di lrd S du uft E) -S du -uft-aes hv m tl a e m r fetvl ead di h s
mragnte inlmsoean hlys~cilsi e Florida (Hutchinson, 1978). These waters are Development of ground-water resources for water necessary, the maps can assist in locating these
3 ments.difficult to explain, but may result from addition of supplies requires considerable sensitivity to the areas.
sulfate through oxidation of organics or pyrite to a constraints placed on that development by water
Calcium-Magnesium-Bicarbonate (B1) -Calcium- sodium-rich water. Upchurch et al. (1991) found quality. The state of Florida has developed a One engineering aspect of lon exchange has
Smagnesium-bcarbonate waters are either delved similar water types near phosphogypsum waste ground-water classification system that reserves been extensively studied elsewhere in the country,
U by dissolution of dolomite in dolomitic limestones disposal areas in Polk County. water utilization to its highest uses. G- and G-ll but has not been widely applied in Florida is the
and dolostones or mixing of magnesium-rich designations are utilized for waters that are potable Sodium Absorption Ratio Smectitic clays, such as
waters derived from clay weathering in the ss frdmnntWerTpanand can be used for water-supply aquifer are common in the surficial and intermediate
Hawthorn Group with calcium-bicarbonate waters UssHydohminant aeryp Mand systems'. The designations 0-Ill and G-V"7 are aquifer systems, have the ability to expand and
I ~ ~Facies attribution is largely based on interpretation IdrheiaFaeMpsreserved for aquifer systems that contain non- contract (swell and shrink) depending on the
of local geology and hydrology. If the water is from potable water that is more compatible with land chemical composition of the surrounding water.
dolomitic aquifer, it is attributed to a facies The maps that follow can be used mn a number uses that may degrade G-I and G-Il waters. While The clays swell in sodium-rich waters and shrink in
characterized by dolomite weathering. If it is near of ways, largely related to predicting the outcomes designation of ground water by this scheme calcium- or magnesium-rich solutions. The ability an area of active weathering of the Hawthorn of water-use options. Grouping the predominant requires knowledge of the TDS concentration, of clays to shrink or swell is predicted by the
Group sediments or if the intermediate confining water type data into areally extensive hydro- number of aquifer systems, and degree of Sodium Absorption Patio (SAR)
Zones are highly leaky, the facies is said to reflect chemical facies allows interpolation between data confinement, knowledge of the hydrochemical
I weathering of the clays. points and prediction of background water quality facies can be of assistance as well.
throughout the state The following are just some
of the benefits from hydrochemical facies analysis. In addition, the chemical composition of the


49






SPECIAL PUBLICATION NO. 34


N sodium-chloride water results from the coastal bicarbonate inland and sodium-chloride near the and utilized in southern SWFWMD (Figure 57d). ItI
transition zone and marine aerosols. There is coast The surficial aquifer system is shelly which is spotty to non-existent in the central third of the SAR=- (21) insufficient data to speculate on predominant results in calcium-bicarbonate waters. Upconing district and absent in the northern portion Waters
water type in central and coastal portions of the and irrigation pumpage in many areas of the are characteristically calcium--magnesiumCa___+__Mg_ district. However, sodium-chlornde and calcium- southern third result in introduction of deeper, bicarbonate due to the dolostone and magnesium2sulfate waters do occur along the coast, There is a sulfate- and chloride-rich water, saturated clays of the Hawthorn Group To the
region centered on Jackson and Gadsden south and west calcium-bicarbonate-sulfate and
Counties where calcium-bicarbonate water calcium-sulfate facies develop as a result ofI
where Nae Cam, and Mgne are the predominates. This region is characterized by Figure 56e reflects the surficial aquifer system addition of sulfate during upward flow on the
concentrations In milliequivalents per liter. If the exposures of limestones of the Floridan aquifer water types and facies in the SFWMD. The coastal transition zone. The outer coastal SAR > 8-10, smectites can be expected to swell system, and surficial aquifer system waters Bicaie adargite The remp sultinfiesmisnanytrstnzn shrtndbysdm-hnd
(Bouwer, 1978) It can be assumed that the clays undoubtedly reflect this influence al ndagn Threutgf efacies derived from sea water.
thenequal witho wther scrrindcegshrinkin intrusion near Miami (northern Dade County) is well
Changing th ult fwtrcnidc hnigThe surficial aquifer system is poorly shown by a re-entrant of sodium-chlonide water The intermediate aquifer system is well
or swelling of the clays. For example, if the clay developed in the SRWMD (Figure 56b). Waters are On the west coast the waters are derived from developed on the west coast of the SFWMDI sodcium watr isinoueswellingur illdoccurg largely calcium-bicarbonate due to influences of shelly sands and limestones and belong to the (Figure 57). Elsewhere there is no information as Tsod occr wshenrde s-akelent, ldillcu Floridan aquifer system water. Magnesium- calcium-bicarbonate facies Local sodium- to facies or water types. The intermediate aquifer
Teahateul ocr otherehg sdiu-mnk erst lande bicarbonate water reflects the magnesium-rich chloride in Collier County may reflect upconing of system in Lee County includes sandstoneI intcaed or there aqifer systems waeSodium clays of the Hawthorn Group, and sodium- connate water. The Kissimmee River corridor is cemented by calcite and limestone and dolostone
saturated clays that aruer bte incalcium or bicarbonate waters reflect ion exchange. In predominantly characterized by calcium- aquifers There is considerable clay in the aquifer
magnsiu-rih wtercan hrik. hiscangeneral, surficial aquifer system waters in the bicarbonate water. The scattered areas of a system. The faces represented show the
happnsumrwhe sodium-atusrted clas ian district are calcium-bicarbonate facies derived sodiumchlornde facies are an artifact of the depth "chromatographic" effect in a different way. There
siaiciclasti soadaifes aurtefloodedyswit from the influences of underlying intermediate and of completion of the surficial aquifer wells. The is less sulfate than in the SWFWMD (Figure 57d, calcium-srich Fsoian aquiersyse atersuhFloridan aquifer systems wells in the Kissimmee corridor that exhibit a 58d), so the sulfate-rich belt is absent. There is,
aligmh oridhn awnfares rrmate ruh sodium-chloride facies contain low ionic strength however, a sodium-bicarbonate belt derived by ionU
asmtewater nlws aple.S rinin orrswelled ofrh ufca waters recharged by precipitation. exchange. The clays of the aquifer system are
clascolthereforepcaud e failurng of wLnd fTurica aquifer system in the SJRWMD sodium-rich and, as calcium-rich water upwells
kners, foundan, nther, tru ctaures, It anfl (Figure 56c) includes some regions of mixed water along the inner transition zone, exchange releases
ales fdra atially cange there permealtus. Ithe type inland. There is a large area characterized by INTERMEDIATE AQUIFER SYSTEM etresdmant ong the oaacee.Riveresarso or amuiersyse handede itsmeeffectyveness calcium-bicarbonate fadies along the St. Johns etataogteCloaace ie
so aerspyoste-nddsposts medfimn. s River. This may reflect the upconing described by Wtr fteitreit qie ytmi
as waersuply r ast-dipoal edim.Leve (1983), or shelly horizons in the aquifer th e s NW FM (Fintured1atae pruerdosminl
system. Elsewhere sodium-chloride facies pre- th WW D(iue5a r rdriatyFLORIDAN AQUIFER SYSTEMU
domiatealon th rivr. hereis coatalcalcium-bicarbonate type. This reflects the
Water Types in Florida Aquifer sdrinm-chlod e ie wthre re-etns tat carbonates in the intermediate aquifer system and
Systems soimclnefcewt ag eetat htthe absence of magnesium suggests that calcite Waters in the Flonidan aquifer system of the
probably reflect connate sea water rather that dissolution controls water quality. Water from the NWFWMD (Figure b8a) can be subdivided into

SURFICIAL AQUIFER SYSTEM atv nrsn.intermediate aquifer system throughout the entire three facies The majority of the district is
eastern half of the district area can be said to characterized by calcium-bicarbonate waters that
The surficial aquifer system is well developed belong to a single calcium-bicarbonate facies that maeslc isuiconat waer ases Sttrec There is a general change in predominant in the southern third of the SWFWMD, and it is originates from limestone dissolution. ansu-iabntewtrmse elc
water type from north to south. In the north, the spotty in the middle third (Figure 56d). It is poorly dissolution of dolomite. Near the coastal transition
surficial aquifer system is largely siliciclastic, and developed to not present in the northern third, In zone the predominant water types are mixed.
shell content is limited to coastal areas. Therefore, the central third of the district, the surficial aquifer The intermediate aquifer system is very limited Sodium-chloride and sodium-bicarbonate waters water types are mixed, with sodium-chloride system is largely quartz sand. The water types in extent in the SRWMD (Figure 57b) Where it is predominate. The sodium-chloride waters result
waters near the coast as a result of the coastal present are mixed, with a slight predominance of present, the predominant water type is calcium- or from sea water on the transition zone. The transition zone and inland as a result of calcium-bicarbonate over calcium-sulfate and calcium-magnesium-bicarbonate, which reflects sodium-bicarbonate waters are a result of ion
precipitation of marine aerosols. To the south, the sodium-chloride. Much of the calcium- the dolostones and limestones of the aquifer exchange. Where the samples are predominantly
carbonate content of the aquifer system increases bicarbonate water is Floridan water introduced by system sodium-chloride type, the resulting facies is a seaand the water types become less variable and irrigation. The sodium-chloride water is a result of water or sodium-chloride facies. Where several
dominated by calciurm-carbonate water types marine aerosols. The calcium-sulfate water is There is not much data on the intermediate water types exist because of iOn exchange and
problematical. Water near agrichemical plants is aquifer system in the SJ RWMD (Figure 57c). local calcium-bicarbonate waters, a mixed facies Wate frm te Snd nd Gave Aqife unlikely to be either sodium-sulfate or calcium-sulfate Where data are present, there is an inland calcium- results. Near Gulf County there is a magnesiumweter NFMD (Figund 5a)nd raedoAm inl in composition. Water some distance from the bicarbonate facies and a coastal sodium-chloride bicarbonate facies, which reflects magnesium
sdu-lri WWde i urmpositi s Thredisalm chemical plants may reflect atmospheric fallout, faces enrichment, probably from magnesium-rich clays.I
boicone n soimpbosronat aer mixedum sulfates from oxidation of peats and pyrite, or other
withitbndatin an omplicarbte hitrdfernwassaters nhesoteredir f teditctTeRWDanbsudvednothe
well dths, a miornplcabonate ssources hen aue predoinate calum -r thrmagnesium- The intermediate aquifer system is extensive faciTe SMost ofthe district (Fgre ntb) isr


50







FLORIDA GEOLOGICAL SURVEY


Dominated by calcium-bicarbonate water Local ENDNOTES
calcium-magnesium-bicarbonate samples reflect dissolution of dolomite or additions of magnesium
from the overlying Hawthorn. Most of the facies is 'In order to maintain electrica neutrality of water, the sum of negative charges on anions must equal the
characterized, however! by limestone dissolution sum of all positive charges on cations. The samples described in this report were not filtered prior to analysis
Near the coast there is a sodium-chlornde facies, for metals. Consequently, some of the analyses had excess cationic constituents because particulates were
which reflects the coastal transition zone. In dissolved during sample preservation In other words, the analyses do not reflect electrical neutrality, and the
I ~ central Taylor County there is a calcium- number of positive charges exceeds negative The ior-balance criterion for validating the analytical results of a
magnesium-bicarbonate facies which reflects sample is based on the requirement of electrical neutrality In order to accept an analysis for this report and the
extensive doloniitization in the Floridan aquifer Background Network database, the charge-balance error cannot be more that 30%
System.
2The nomenclature used in this report follows that of the Southeastern Geological Society's (SEGS) Ad Hoc Figure 58c shows the facies and predominant Committee on Florida Hydrostratigraphic Unit Definition (1986) When a local, named hydrostratigraphic horizon
water types for samples from the Floridan aquifer is discussed, the unit is called an aquifer (e.g., Biscayne Aquifer, Sand and Gravel Aquifer). Major, statewide
I system in the SJRWMD. There are large re- aquifers, especially those which contain several different aquifer horizons, are termed aquifer systems (e.g.,
entrants in the sodium-chloride facies near the surficial aquifer system, intermediate aquifer system)
coast These reflect connate waters and modern
Intrusion Scattered sodium-bicarbonate samples Frcneine h ititn m saeabeitdi alsadtx sflo s otws lrd ae
indicate ion exchange The St Johns River region Maagemoen ectD istrict M),unere RivervWater Mnagesment Dtrct sRMw St Jorhws ivndr Water
includes two areas where the sodium-chloride Management District FloMDSwaneridar Water Management Dsnt(SWWMD),a S uth Fride ae

Sfacies exists. These reflect upconing as descrbed MngmnDstt(JWM)SuhwtFldaWater Management DistrictSFWM),(SFWMD).loid
Uby Leve (1983).WtrMngmntDsnt(FM)

The Florndan aquifer system in the SWFWMD 4 pH is a measure of the degree of acidity of waters. Neutral water has a pH of 7, acid waters have pH
(Frgre 8d)is harcterzedby hre faiesvalues <7, and basics, or alkaline, waters have a pH >7. The pH is defined as pH- = -log,0aH+ where aH+ is the figuredd) is carter izedbythreem a esm activity (thermodynamic concentration) of hydrogen lon. Therefore, a change in concentration of the hydrogen
Inlarbndte water dis alu m-ofdlmageium- inons by a factor of 10 results in a change in pH by a factor of 1.
calcite in the aquifer system and magnesium from
I ~ the Hawthorn Group clays. Along the coast there "The vadose zone is the unsaturated zone above the water table. The capillary zone is the partially wetted
is a sodium-chloride facies that reflects the coasta zone just above the water table that results from the interaction of surface tension of water and soil or rock
transition zone. In between, there is a calcium- materials. The phreatic zone is the water-saturated soi or rock below the water table or the confining beds of a
Sulfate facies that reflects upward flow of sulfate- confined aquifer.
I rich water along the inner transition zone. This is an
excellent example of the "chromatographic" effect
produced by upwelling of deeper waters along the LCations have net positive charges, while anions have negative charges.
I coasts of Florida. The inner margin of the
transition zone is sulfate rich because of The Pious Museum at the University of South Florida, Geology Department, has gypsum (selenite) rosettes
dissolution of gypsum and anhydrite at depth in in its collection from the Hawthorn Group in northern St Petersburg (Pinellas County) and chalcedonic casts of
the aquifer system The outer belt is sodium- selenite rosettes from Tampa (Hillsborough County) and New Port Richey (Pasco County). Single and twinned
chrinde-rich due to mixing with sea water gypsum crystals from near Ocala (Marion County) are also in the collection.

There are no data from the Floridan aquifer Siliciclastic sediments are sediments that consist of quartz, silicate minerals and silicate rock fragments

ISa syse in most he sFWMDs (Figue CS e) that have been mechanically transported Characteristic siliciclastic sediment types include quartz sand and
suggest a sodium-chloride facies as a result of poor
I flushing and/or salt-water intrusion The northern
I and central Kissimmee River corridor is Chemical maturation is a term that reflects the changes in chemical composition along a flow path These
characterized by calcium-bicarbonate waters, while changes typically include increases in total dissolved solids content and changes in specific chemical
the southern portion is characterized by calcium- composition.
sulfate and the sodium-chloride facies. This is the
eion o the chromatorgraphicThe~t iscu-sae 'C The salt-water/fresh-water transition zone is the zone of mixing of discharging fresh water with salty water
I a i the pr e u pa ga ph Theacium-snuwhl athe near the coast or at the base of the aquifer system This broad zone s som etim es called the salt-water
sodiurn-chloride facies is the outer portion. The interface, although it is a diffuse zone, not an interface For simplicity, the sait-water/fresh-water transition zone
sodium-chloride facies persist into the Everglades will henceforth be called the "transition zone",
because of little of no flushing of connate waters


51






SPECIAL PUBLICATION NO. 34I

SIn this context the term facies 's used in the same fashion as in stratigraphy. Facies (from the Latin for 22 When a chemical system is capable of supporting chemical oxidation, it is said to be aerobic and3 face or appearance of a object) refers to entities with similar attributes which can be used to identify and assumed to contain an available source of oxygen. In reality, oxidation is possible at reduction/oxidation (Eh) distinguish them. Thus, hydrochemical facies represent water masses with similar chemical compositions and potentials as low as approximately -200 my. Below -200rmV, chemical reduction occurs, oxygen sources are origins absent, and the system is said to be anaerobic.

"Sand crystal' are crystal of calcite that have grown in the pore space of a sand matrix and include the 2" Chemical complexing includes the binding of dissolved anions or cations into a soluble molecule.
sand grains in their original depositionial fabric within the body of the crystal The crystal lattice is typically Complexing occurs in waters with high total dissolved solids contents or in waters with humic substances. An distorted in sand crystals, and crystal faces are convex. In this report, the term sand crystal is used in a more example of an inorganic complex is CaSO0, which is present in high sulfate and TDS waters. This dissolved loose sense to include calcite crystals that have grown around and included any pre-existing material (quartz compound removes calcium and sulfate from availability to react with rock and other chemicals An example of sand and silt-sized dolomite), an organic complex is the formation of lead-humic acid pairs. In basic solutions, this complex is soluble and
can transport lead rather that allowing it to sorb or precipitate.
SMiliequivalents per liter (meq/L) is a measure of charge concentration in water (Hem! 1985). Milligrams per
liter concentrations are divided by combining the weights of the appropriate ions to obtain milliequrvalents per This is especially true if the sample also has high pH, alkalinity (especially as COj-), or high potassium. liter Conversion tables are provided In Hem (1985). Calcium carbonate alkalinity is the carbonate alkalinityU recalculated as if it were calcium carbonate. To convert mg/L bicarbonate to mg/L calcium carbonate, multiply a The Practical Quantitation Limit (POL) is the minimum limit of detection of a chemical that can be the concentration by 0.8202 One meq/L is equal to 0.02 times mg/L as CaCO3 (Hem, 1985). expected from a laboratory under routine analytical conditions. The U.S. Environmental Protection Agency has

"Strictly speaking, connate water is water of deposition. That is, it is water trapped in sediments at the time tePLt efv ie h iiu eeto ii
they were deposited. Since the Flondan Platform has been repeatedly inundated by marine transgressions Most of the detections of synthetic organics and pesticides discussed herein have not been confirmed by during the late Tertiary and Quaternary, one cannot rule out the possibility of sea water trapped in the aquifer re-sampling. The term "detected" is used to indicate the uncertainty present as to the presence of these system as a result of more recent inundations Therefore, connate water is herein defined as sea water trapped compounds.U in the aquifer system as a result of any prior transgression.

SHydraulic potentials represent the driving forces that cause water to circulate in an aquifer system. Their thn3,0 mG-ILund Piary atndedaryal usrsinkingae Sandrds app ly Zonie)o diarerSles spatial distributions are represented by potentiometric-surface maps. Water tends to flow from areas of high rtricte todmesti wandtPn ar and sormar disages, and are lte tonteess of 100sft.arg he potential (high elevations on the potentiometric surface map) to low. Potentials are low in south Florida, and retlne. odmsi at ae n tr-ae icags n r lie hotels f10f.o h there isn't a nearby high to force circulation and flush the aquifer systems pr-li around water is also reserved for potable uses, but the designation is given to areas where multiple,U
potable water supply aquifers exist. TDS is less than 10,000 mg/L Primary and Secondary Drinking Water SEutrophication is over enrichment of a water body with food. An eutrophic water body is characterized by Standards apply, and zones of discharge are restricted to the lesser of the property line or 100 ff., unless over abundance of autotrophs (green plants, such as algae). Plant and animal diversity are imited due to loss of discharge is beneficial to the aquifer oxygen as the plant material decays and to imbalances in the species and abundances of elements of the food G-Ill a round water is not potable, with TDS concentrations greater than 10,000 mg/L. The designation is chain, given to unconfined aquifers. and the zones of discharge are the same as 0-It
G-IV around water is reserved for confined, non-potable aquifers TOS is greater than 10,000 mg/L, and
"Limiting nutrients are those nutrients that are in shortest supply and, therefore, inhibit primary production zones of discharge are allowed on a case-by-case basis.I


'* Mineral names are those presently accepted by the International Mineralogical Association CommissionI on New Minerals and Mineral Names (Fleischer, 1987). Names in quotes have been discredited, but are widely used within the phosphate industry

19 The combination of NO;- and NO;- is collectively termed NO, in this report.

24 Urea is an excretory product manufactured in the livers of animals It is the primary excretory product ofI terrestrial animals and the excretory product of metabolism of ammoniumn, amino acids, and proteins. The structure of urea is 3



H2N NH,

21 Methemoglobin (ferrihemoglobin) is the equivalent of hemoglobin with the exception that the iron is
oxidized to the ferrc state Methemoglobin is, therefore, incapable of carrying oxygen in the circulatory system.

52







FLORIDA GEOLOGICAL SURVEY


SChapter V regional ground-water quality so that the supply development. Evaluation of Health and Use Risks
user can understand and anticipate
cONLUIOSt se and nurlgun-arqaly nThe trace constituents (to., trace metals, trace Major, minor, and trace constituents were
ADRCOMMENDIN S h saeadnutrients, synthetic organics, and pesticides) are determined according to standard protocols of the
AN RCO MEDAIOStypically regulated analytes Inclusion of these American Public Health Association (1980), U.s.
*Provide information for under- constituents allows direct assessment of statewide Environmental Protection Agency (1982) and
I ~Sam B. Upchurch standing the chemical consequences ground-water quaLity as affected by human Florida Department of Environmental Regulation
of water use. activity By comparing the distribution of these (1981). These protocols include use of unfiltered
and other regulated constituents to the samples for metals Since the samples may
SDepartment of Geology hydrogeochemical framework, we can understand contain particulate as well as dissolved metals,
U ~University of South Florida The primary goal of this report is to present tolerance levels of the aquifer systems to use and factors other than ambient water quality are
Tampa, Florida and evaluate the quality of water in the state's the mechanisms that mitigate introduction of these represented in the chemical analyses
aquifer systems Analytes were selected with two anthropogenic constituents into aquifer system
purposes in mind -identification of regional environments
I INTRODUCTION contamination and establishment of the The consequence of use of unfiltered samples
hydrogeochemical framework of the aquifer for metals analyses is that the sample reflects
systems Many of the analytes described in this The concentrations of trace chemicals are water produced by the well, not necessaiy the SThe Water Quality Assurance Act of 1983 report are not subject to water-quality standards or normally highly discontinuous, so they cannot be chemicals dissolved in aquifer system water
I (Chapter 403.063 Florida Statutes) required the guidance crnteria, but their inclusion is necessary in contoured. As a result, this assessment is best There are two justifications for use of unfiltered
Florida Department of Environmental Regulation to order to understand the geochemical processes used, not to identify specific areas of contain- samples First, there is a growing body of evidence assess the quality of water in the aquifer systems that govern reactions in the aquifer systems Other nation, some of which have been identified but not to indicate that particulates travel in aquifer Sof Florida. This report is the second of a series analytes are subject to regulation and their confirmed, but to develop predictive concepts of systems In transport through i1ntergranular
U ~that will discuss the aquifer systems of Florida inclusion is necessary in order to evaluate health the probability of encountering a trace con- porosity, mechanical filtration reduces the
The first (Scott et a?, 1991) deals with the hydro- risks and restrictions on ground-water use, Major taminant. probability of particulate movement, with colloids
stratigraphic framework of Florida aquifer systems. and minor constituents, temperature and specific being most likely to move. Conduit flow in
U This report is an assessment of the quality of water conductance were selected so that the fractured and karstic aquifer systems is conducive
in Florida's three aquifer systems. Water quality geochemical framework of the state's aquifer The data presented in this report assist greatly to particulate transport Second, users with reports that will follow include (1) a study of the systems can be identified Understanding this in identification of recharge and discharge areas, domestic wells usually do not filter the water
Temporal varability of water quality in the three framework allows us to conceptualize how and of flow systems They provide information that before consumption Therefore, use of unfiltered
U aquifer systems, (2) a comparison of background chemical complexing, sorption reactions, supports vulnerability evaluation, and they allow samples in this report constitutes an evaluation of
water quality to the quality of water underlying reduction-oxidation reactions, and dissolution- delineation of a number of specific problem areas exposure upon consumption of the water rather areas of specific land uses with the goal of devel- precipitation reactions affect gross water chemistry that mernt further investigation that a simple discussion of natural water Hoping models for predicting changes in ground- and microchemical reactions in the aquifer chemistry A comparison of filtered and unfiltered
U water quality, and (3) a second evaluation of systems. It is these reactions that mitigate Finally, information as to how one can predict samples is underway and wil be published as part
statewide water quality that will discuss changes in contamination in the aquifer systems and allow us the prospects and outcomes of water uses is of the evaluation of the second statewide
quality and provide comparisons of concentrations to utilize soils and aquifer systems for both water provided. These predictions range from locating background analysis at a later date.
of metals in filtered and unfiltered samples supply and waste disposal. This report, therefore, brackish waters for reverse-osmosis treatment to
attempts to provide a minimum of information that prediction of the amount of boiler scale that will be In many areas of the state, particularly in the Goals will allow the user to understand the whys and developed by use of hard water to understanding surficial aquifer system, water quality criteria are
hows of water-quality transformations in the the ion exchange and sorption reactions that may exceeded by natural causes. These are preI aquifer systems affect migration of metals and anthropogenic dictable and have been discussed in Chapter IV
This report discusses ambient water quality in chemicals in wsedsoa cnns
Flornda's aquifer systems statewide It was written Teassmn fwtrqaiyicue
to meet four goals: cotour asee aopiate Theset mapuds DATA INTERPRETATION AND USE
allow interpolation of water quality into areas not Wncutio heusedareoti eort thatuthe.
Evaluation of background ground- represented by samples. Care should be taken, conepts preusntedse enera in nate.sii Data have been interpreted in each section as
I wterquait inallof loidas auier oweerinextapoatng eyod te ataUseofcontext should be undertaken only by those who to the causes and controls on the distribution of
systems, hydrochemical facies maps is a better approach thoroughly understand the geochemistry of aquifer each chemical It is possible to use these data in a
for extrapolation because of the more general systems Even though this report summarizes the much larger context, however The data constitute nature of these maps. Whie specific concen~ most comprehensive ground-water quality survey a variety of evidence as to aquifer system flow I *@ Development of ground-water-quality trations cannot be determined from the ever undertaken in Florida, the sample distribution paths, recharge and discharge areas, and land
prodiotion techniques through appli- hydrochemical facies maps, general predictions as is still insufficient for site-specific evaluations, uses Use of the data to assist in identification of
cation of hydrochemical facies maps to the chemical constituency and reactions in an Neither the authors nor the Departments of these features will facilitate development of
~and fundamental hydrogeochemical aquifer system can be made. These maps also Environmental Regulation or Natural Resources knowledgeable growth management, zoning, and
concepts, allow recognition of regions of salt-water intrusion can take responsibility for misuse of the data land-use management decisions. This section
and connate water, and they allow prediction of included in this report or the GWIS database from notes some of the ways that the data can be 0 Discussion of the factors that affect general water-treatment alternatives for water- which the data were drawn, utilized to understand aquifer system behavior and


53






SPECIAL PUBLICATION NO. 34U


impacts of land use on aquifer system water Floridan aquifer system. designed to do this. By comparison of the data siliciclastic horizons, buffering capacity is low andU
quality, collected in areas specifically selected to represent the aquifers are vulnerable to contamination. Clay
Flow a given land use with the Background Network minerals, iron and aluminum oxyhydroxides, and
RhrgArsFowSystems data, these correlations can be drawn. Results of humins range from non-existent to abundant in
the VISA study will be published in the future. sihiciclastic horizons. These particles give these Flow systems can be recognized within the aquifers a wide range in sorptive capacity and
A number of programs at state and local levels Floridan aquifer system by examining the anatyte The data presented in this report indicate that make it difficult to generalize as to ability of
require identification of aquifer system recharge maps. Analytes that reflect equilibration with there is a high chance of success for the VISA siliciclastic aquifers to tolerate waste loadingU areas. Recharge areas are sensitive to ground- aquifer system rocks (t~e., total dissolved solids, studies A number of regions characterized by ineana mchanicta fltratn ansorptuionrsars water contamination. Maintenance, or enhance- pH, calcium, bicarbonate) typically increase along specific land uses do have anomalous ground- enheaned. ehnia itato n orto r ient, of recharge is necessary to insure the long- a flow path Orthogonals to the concentration water quality. Some agricultural areas have high Inacd term water supply. Recharge areas may also isolines should roughly indicate flow paths. concentrations of nitrate, pesticide, or other
muepreen poentia fo noptirnal developmntho constituents. Synthetic organics were found in Carbonate-Rich Silioiclastic Aquifers
require low total dissolved solids water, such as Some analytes allow identification of specific, industrial and suburban, as well as agricultural, the bottled-water industry conduit-flow systems. For example, phosphate areas. Considerably more study is required beforeI
may form plumes along karst conduits and indicate confidence can be placed on the correlations, buti Carbonate-rich siliciclastic aquifers, such as a rapid recharge and local flow system. Fluoride, it appears that we may be able to anticipate the the shelly portions of the surficial aquifer system The water-quality data presented in this report nitrate, temperature, total organic carbon, and contaminants and a probable level of con- ndttrmedind- aqufed yse espe c iallrzin theU assist in identification of recharge areas in several sulfate may allow recognition of these more local tamination for a given land use. Itreit qie ytm(seilyi h
ways(Tale 3). charge rea ar typical fow sstens.Hawthorn Group) are intermediate between true whaysa leri 36) Rck f hr aeas are typcal floatstms siliciclastic and limestone/ dolostone aquifers. The
cih actere bytm lackoferuilbraindo w tera GENERAL SUMMARV OF presence of carbonate minerals provides buffering
widnh aqufe systemalotials, sund widspads ufc-WtrFau THE QUALiTY OF FLORIDA capacity, while abundant clays and organicsI
pheric temperatures, human activities, and GON AE rvdsrto aaiy
wetlands. While there are many exceptions to the The effects of several interesting surface-waterI criteria listed in Table 36, the data do provide a features appear in the data set. For example, thereGera ulyofFrd'sMhaclflrtonssilimrttbcus
starting point for identification of recharge areas. is evidence in the Floridan aquifer system of Ground Water flow is through intergranular porosity. Siliciclastic
disappearing streams along the Cody Escarpment. horizons in the Hawthorn Group usually occur beIt may also be possible to recognize recharge Several large wetland areas were mirrored by high In general, the quality of ground water in tween clay-rich strata which provide both confine-I areas by vertical contin uity of water chemical total organic carbon, low pH, and other analytes. Flonda is exce/lent and has been little affected by ment and isolation from anthropogenic chemicals quality. If water-quality, for example hydro- humans. However, many local areas of the state's
chemical facies, present in the surf icial aquifer Lakes, streams, and wetlands affect aquifer aquifer systems have been affected by human Limestone and Dolostone Aquifers
system persists downward into the Floridan aquifer systems through introduction of organic carbon activities. Water quality is consistent with the system, there is indication of interconnection. This and nutrients. Several major rivers, notably the lithologies of the aquifer systems. Part of theLietnaddosoeaqfrsreoul interconnection can be the result of downward or Peace and St. Johns Rivers, follow hinear features reason that water quality has not been adverselyLmstnaddlstnaufr redby
upward flow, so other water quality criteria and that appear to be fractured lineaments. Upcoming, affected is the slow rate of recharge and flow in the porous While they exhibit intergranular porosity,U hydraulic head relations (Scott et a/., 1991) must and possibly preferential recharge, along these' aquifer system. Much of the water is simply too which can be locally important, much of the flow is also be considered features provides clear evidence of the inter- old to have been exposed to human impacts at the through fracture and cavernous porosity. Thererelaionhipof srfae faturs ad goundwatr. ime f rchage.fore, carbonate-rock aquifers have lower Trelinhpguaes eatnsurfesa rn atrse frchre mechanical filtration capabilities than siliciclasticI
Discharge Areas Teelnaebewesufc-trfauesaquifers, and wastes and particles are capable of
ssnb rea ground-water quality represent Siliciclastic Aquifers travel through conduit flow for some distance.
The arguments above can be reversed to Intense Study Area (VlSA) projects.I
idetiy om rgina dscare res.Tale36In very general terms, siliciclastic aquifers, Because of the presence of abundant
surmmarizes some of the water quality criteria that such as the Sand and Gravel Aquifer o otws abnt ieas ufrn aaiisaehg
might be useful in identifying discharge areas. Land Uses Florida and the surficial aquifer system In the and the waters of these aquifers are usually
Typically, water-quality data are less variable, interior of north and central peninsular Florida are alkaline and calcium, magnesium, and bicarbonateI
chemicals reflective of surficial conditions more Two of the requirements of the Water Quality characterized by water quality associated with rich Sorption capacities vary. There is little clay masked, and water more highly buffered (high Assurance Act are to detect and predict con- precipitation composition. The water usually has or organic material in the rock, and much of that
bicarbonate and pH) in discharge areas. tamination in Florida's aquifer systems It is not low total dissolved solids content, and is rich in present is isolated from the conduits by lowI
possible to detect a significant number of areas of sodium and chloride as opposed to calcium and permeability rock. Detrital clays and other particles Coastal discharge areas may be represented contamination because of the high costs of an bicarbonate. Water from these aquifers often in the conduits may provide sorption capacity. by a calum- or calcium-magnesium-sulfate exhaustive well network, One can, however, contains high total iron and organic carbon
hydrochermical facies if the water has followed a predict water-quality degradation if one can concentrations FIna qie ytm ae otissr
deep flow path and come in contact with gypsum- establish correlations with specific land uses and prisingly high total organic carbon concentrations.
and anhydrite-bearing strata at the base of the ground-water quality. The VISA program is Due to the lack of carbonate minerals in This high organic carbon may reflect particulate


54







U FLORIDA GEOLOGICAL SURVEY


orancs articularly in the Avon Park Formation, High Salinity Water flow and low hydraulic potential. Regions where ground Network are contained in the OWLS
oansm sptio caait o atrpoe the transition zone is steep are associated with database management system This database can
oranics Tee ist ap ty a nriskpofi more dynamic flow and higher potentials. These be used to assist in predicting depths to lower
Srgns.Tresasoankof development ofThis report delineates a number of regions data can be used to assist in locating well fields, quality waters.
halogenated hydrocarbons! especially trihalo- where water with high total dissolved solids Rgnswhere the transition zone slopes gently
getne, apear hat edition and tdsp ers are content adversely impairs use. By volume, most of are much more susceptible to intrusion that are
mer it antar tha sorption once dwspersienters this water is naturally 'contaminated", and the only regions with steep transition zones. Interaquifer Transfer moreimprtat thn srpton nce ate enershuman impact is causing that water to move into
imestone/dolostone aquifers. potable-water horizons. Suitable uses for this There are many areas of the state where
water include augmentation of potable water Connate Waterupnngndntrufrtrsfrbg wquly
DEFINITION OF BACKGROUND supplies by reverse-osmosis or other treatment, (pcngh and disstedsquifer transer rigtow quality
suchQUL Y as cososl adtertare mnustnb ake nppticto Connate water (salt water) is present in all systems that otherwise would have higher water
inuce ga onof wthis lor uaty ater ntto aquifer systems in regions where hydraulic quality Upconing because of natural, upward flow Pruistgrine f hi lweWatetyraerinopotentials are insufficient to flush the aquifer is common near the coasts and along some
I rsieWtrhigher quality waters, systems with fresh water This is particularly a proposed fracture systems, such as along the St.
problem in the Everglades/Big Cypress Swamp Johns and Peace River axes. Elsewhere, upcOning
Pristine water is water that has not been Not all of the high salinity water In Florida regions of SFWMD and in some portions of the because of pumping stress is a common local
affected by human activity. After several hundred aquifer systems is derived from the modern sea. SJRWMD. Not all of the horizons with connate problem. One of the most dramatic artifacts of years of human activity in Florida, it is difficult to Connate water (sea water residual from previous waters have been identified in this report. Many human activity documented in this study is the assess how much pristine water remains. Surely, marine transgressions) is present in many areas. In have been recognized, and this experience should transfer of calcium-magnesium-bicarbonate water water deep in the Floridan aquifer system and far addition, sulfate-rich water in deep flow systems assist in predicting the locations of others from the Floridan aquifer system to the surficial
Saway from injection and water-producing wells is pose a water-qualt problem. aquifer system through irrgation
pristine, but much of it may not be potable for
natual ause. Sallo waers ay r ma no beDeep-Flow-System Water ptnrle s. Coastwalter mIytrruysntob NATUJRE OF ANTHROPOGENIC

I pstn.CstlnrsinCONTAMINATION
Waters that recharge the Floridan aquifer
Since this is the first ground-water quality All of Florida's aquifer systems contain salt system near the center of the state and that follow
survey of its kind, we have little or no data with water near the coasts Salt-water intrusion along deep flow paths which skim along the top of the There are numerous, minor exceptions to the
Which the Background Network data can be the coasts is an historical problem in Florida. The gypsum-and anhydrite-rich, lower confining units conclusion that human impacts, other tan
compared. The baseline for comparison began sampling plan was not constructed to identify the gain significant sulfate concentrations. As a result, upconing and salt-water intrusion,tare minima
with the development of the Background Net- transition zone and it has not been mapped water deep in the Flordan aquifer system and Scattered occurrences of anthropogenic
work. Therefore, determinations of degradation of everywhere in the state. Likewise, these data do along the inner (landward) margin of the coastal contaminants were detected, but most tare
I ground-water quality begin with this data set and not allow differentiation of natural intrusion and transition zone are often sulfate rich These waters unconfirmed by re-sampling. It is inappropriate at
go forward. In large sense, we are constrained to intrusion caused by human activities. The data may include sulfate in excess of the standards due thi tetimens conrelu de that thesescattere monitoring and enforcing changes from the included in this report do give indication of the to natural causes, detckgron aretrea because of thendirmgn, ofndh
present status of ground-water quality. This data extent of the transition zone, which will help in Bag robubndt Ntwokhako f dtctoniration andu
set constitutes the baseline against which future planning and management of our ground-water Teqatyfgrudwater in the Floridan h ihd pob ablity trobmemdtctosar.rsl
changes will be gauged. Background Network resources. aquifer system generally decreases with depth.
wells were chosen from or drilled in locations be- This drop in water quality results from the
Slieved to be minimally affected by human activities. In the 1990's we are concerned with global cumulative history of chemical reactions along Users of the Generalized Well Information
change, especially global warming. Should global lengthy flow paths (Jones et alI press) and also System (GWLS) are advised that caution must be Background Water warming cause a rise of sea level, baseline data from mixing with sulfate-rich waters at the base of used when interpreting the data contained therein.
are needed to evaluate the resulting loss of potable the aquifer system. A number of regions of sulfate- Until such time as contamination is confirmed, the U ~water and salt-water intrusion, These data are rich water have been attributed in this report to data must be considered to represent a 'worstThe quality of water today reflects back- present in this data set Those data from rural upconing under heavy pumpage stress In most case scenario" for planning and management
ground, not pristine, conditions. For some of the coastal areas where anthropogenic intrusion is cases, the production wells were not completed in purposes
I state, ~we can surmise that background water unlikely will be especially helpful for evaluating the teslaenhwtr.Rdcino yrui
quality is near pristine conditions. However, large effects of sea-level rise. potentials by pumping has, instead, induced flow Teeaeanme feape fpsil
portions of the state's aquifer systems have been upward along fractures and karst conduits. ntmntn.Nrtectmntonswdaffected by human activity Salt-water intrusion, Therefore, it is important to anticipate where the contadmination. Nirasted naain irsr werIupconing of deeper waters, interaquifer transfers, Another important consequence of this study spureydaaddwtrsaereaie ofud in soe sarpes lead and tmercury woe
waste disposal, water withdrawals, land drainage, has been documentation of the slope of the naturally degrade war terndis are fratre tnoniaintatsnhtcognisadpsiie
and other activities have induced change transition zone and its chemical zonation. The proucin tes well coutis and cturs n inarp tin amsyteti ranics and esticde
Background water quality is, therefore, a mixture of chemical data clearly indicate that the slope of the adjusted accordingly. The experiences described aepeeti iie ra ftesae
human and natural conditions. transition zone is directly related to hydraulic head. in this report should assist in identifying conditions
The data indicate that regions where the transition- where upconing of deep water may occur The zone slope is gentle are associated with minimal depths of sampling for each well in the Back55






SPECIAL PUBLICATION NO 34

Point-Source Contamination Drinking Water standard requires the pH of water Mercury regional discharge zones along the coasts, or toI
to falN between 6.5 and 8 5 $ u. Thirty-seven loca upooning.
The Bakgroud Netwrk wa desiged percent of the surficial aquifer system samplesThPrmyDinngWtrSaddfo
avoi kro nd ontore coameignato failed these criteria, largely because of low pH's. TChPlorrrikdgWee Sanad
Based kofwnh paingsofrell c nnotin' These low pH values are generally natural and mercury is 2 pg/L Mercury is of concern in Flornda Clrd
Becus o te sacg f els, t anotberesult of carbonic and organic acid content of the because of recent discoveries of the metal in the
assumed that single wells that detect anomalous water, Intermediate and Floridan aquifer system aquie syste shample anwte percent offca
concentrations of an analyte reflect a point Source, water samples contained 16 and 14 percent, Tqie ytmsmlsadtrepreto h eondar isnkedoin at andar ins 250r
That determination must be made upon further respectively, that failed the criteria. Many of these intermediate aquifer system samples contained TeScnayDikn ae tnadi 5
investigation of activities near the well and of the failures are a result of samples that exceeded the possible mercury in excess of the standard Only mg/L Exceedances are related to the coastal lateraJ extent of the anomaly. upper pH limit of 8.5. Some of these exceedances 0 9 percent of Florndan aquifer system samples transition zone and to upconing in areas of pumpare natural, most appear to reflect high pH values contained possible mercury. Occurrences of ing stress.
Non-Point Source Contamination associated with drilling fluids and cements, thercre n dbisrea tofgcouctentatn.and
especially in the SRWMD.thr sn biuaraf nctrtn.TeFord
surficial and intermediate aquifer systems may be Furd
Non-point source contamination ,s conta- sources of mercury since both aquifer systems
mination caused by a widespread activity. Typical Sodium contain particulate organics The abundance of Exceedances of the 4 mg/L Primary Drinking
non-point sources include application of fertilizers organic carbon in Florida ground water is con- Water Standard are low. Fluoride is derived from
andpesicdesin gnultrewiespeadus ofThePrmar Drnkng ate Sandrd orducive for transport of mercury An exceedance weathering of Hawthorn Group phosphate
an-ste spticsi agrutre,n widespread use of Thdeu Pim1ryDg/LnkingyW4terctndard for level of four to five percent of the samples seems minerals, and is not considered a problem inaont septnic systems, n iepedapi sodim s 160omg/L. Onfl 4qupereto sytem high, given the abundance of sorption sites in FHondaU
saex sfdod the urficid. aquif, 3 ercsystem Flonida aquifer systems. Given that the sample
The Background Network data clearly indicate samples from the intermediate and 17 percent of co nfie yre-samng diton av wo shoul Nitrate
several regions that have been affected by non- sample from the Floridan aquifer system exceeded beconred to co-sfmrm ing, occurrensand dermineu point source contamination. For example, high that standard. The high levels of exceedance in thei dorns. TheoPrirmryhDrinkirreWatsrandaddardmfnr
nitrate concentrations in the Floridan aquifer the intermediate and Floridan aquifer systems ronnsThPrm yDrkngWtrtaddfr
system in Suwannee and Flagler Counties reflect reflects salt water in coastal and deep wells. Mostntrtsntrg, s1m/.Thprprinf widely dispersed agricultural practice. This report of the intermediate aquifer system wells that Lead samples wtth excess nitrate is low. The exceedsuggests the locations of many regions where non- exceeded the standard are located in southwest acsrfetasalpretg fsmls(.
point source contamination has impaired water Florida (Lee, Charlotte, Collier Counties) where the percent surficial aquifer system, zero percent -I
quality. Inemdaeaquifer system is used for public A relatively large number of samples detected intermediate aquifer system, one percent Floridan
intermeupies el nteFoia r eea lead in excess of the 50 pg/L Primary Drinking aquifer system) and does not reflect the findings of
woatedupie el in the Floridantransigennralny Water standard. Lack of sample filtration and this report. While there are few samples that
It must be noted here that, while non-point lctditecosatrntonzeconfirmation by re-sampling clouds interpretation exceed the standard, there is a health advisory for
souce ar sggete ina umbr f auierof the extent of any lead problem. Eight percent of nitrate concentrations of 1 mg/L N. Samples with
systems and locations, the overall water quality of Iron samples from the surficial aquifer system, eight concentrations in the 1 mg/L range are
thestte' auier ysem cano b shwntopercent of intermediate aquifer system samples, widespread. They usually occur in clusters that
hav ben ignfianty ipatedbynonpont he os wiesrea volaionofwatr ualtyand nine percent of Floridan aquifer system reflect local land use, especially agricultural uses.
havre beentasinfnatlyipctdbnnnpin.h mondrs idsreadn olato w of aer quality samples detected excess lead There is a good Nitrates are becoming a subject of concern at the
stnrdos meis rIo.l we ls sed in thsnalss on chhance that some of these detections are a result time of the writing of this report because of the STAEWIE LVELOF apers mrls e russved nd pthiunlyseis, o t of wefl or plumbing materials or of use of lead potential for eutrophication of surface water
S TA IEAEVTSOF saes srflctiolvTed andparytninWatero weights on water-level recorders Lead mobility bodies. Several coastal springs (iLe the Kings Bay
CONTAMINATIONdwe d c onsruion 3 mg/e Senda y -Drinkin aern should be limited through sorption on clays and spring complex in Citrus County and Lithia and
stanard frfirnis 0.3f systLm Speve s-fv recent organics and precipitation of lead carbonates. The Buckhorn Springs, Hilisborough County) have
Tale3 smanosfe rpoaillfte h sutcadaquifertsystem sapesce ededth large proportion of samples with lead suggests a been subjected to significant Increases in nitrates
Ttab amle 7summiz hc pes thexootinofed termtadard quFrytwon4 percent of the possible problem, and additional work is needed to in recent years. A state-funded U.S. Geological
t-alapl stnr. whc saampe weekeded intermidate aquifer system sand4pre ntiofa the determine if the threat is real or an artifact. Survey study in the Suwannee River Basin has
pedngsections and the reader is cautioned to stnsd heeioramptlevolat then shown high nitrate concentrations (up to 140 mg/L)
refer to those sections for a sense of the extent of violations are anthropogenic Iron is a natural con- Sulfate nopeaion Aditols wsorkisateed t o ar
contamination In most cases, the proportions are stituent, and chemical conditions are conducive to determinh Aoiin rk nitrts aneden to
high, not because the problem is widespread, but transport of the iron. Iron sources are widespread SeodrdrnigWaeetnadfrmtigating wtpe args o bhe nat rwn problem.
because an area with a problem has several wells, in aquifer systems. It is present as ferrc iron in The Ieodr nkn ae tnadfrmtgtn htapast eagoigpolm
deeper portions of the aquifer systems and 1s sulfate is 250 mg/L The proportions of samples
pHhighly mobile that exceeded the standard are as follows
pH surficial aquifer system two percent, intermediate aquifer system 13 percent, and Floridan
The ecod mst ideprea vilaton f aaquifer system 13 percent. These exceedances water-quality standard is for pH The Secondary are typically related to high sulfate waters in3


56








FLORIDA GEOLOGICAL SURVEY


Total Dissolved Solids which the standards were exceeded Arsenic is and distribution need to be studied Finally, the On the regional scale, background groundnot a widespread problem, although a few synthetic organics and pesticides found include a water quality takes on another meaning. Water
Toaldisovd oldscntntofgoud atrsamples contained excess arsenic in several number used in the agricultural industry These resources are finite and, in a state with a growing
Tota disoled slid coten of roud wterdistrids. The proportions given in Table 37 largely occurrences need to be confirmed and the origins population, one must anticipate and protect future U reflects the presence of saline waters, such as represent detections in SWFWMD, and to a lesser of the contaminants identified. water supplies. Data from the Background
occur in the coastal transition zone, at depth In the extent in SFWMD Most of these were not verified Network allow delineation of these future
Floridan aquifer system, and in poorly flushed, by confirmation re-sampling If these proportions Th eodrudo akrudNtokresources and monitoring of threats to them.
connate water zones The exceedances reflect are representative of the other districts, then a Th eodrudo akrudNtokConsultants and water-supply authorities can
these naturally "contaminated" regions anid regions p b em m y xst A dt na w rk e pe alysampling, including filtered and unfiltered metalsut ze he d a n w l fed stng nd d s n
ofinucd egaatonthouh upae ndladscreening of the other districts is needed before samples, will assist in answering some of those Managers can evaluate well field sitings in the
drainage The Secondary Drinking Water Standard firm conclusions can be drawn. questions. The VISA and Temporal Variability regional context and evaluate potentials for
is 500 mg/L. studies will address others Specific studies will be ucnn rohravreefcs
warranted in the future as the water-quality ucnn rohravreefcs

Synthetic Organics Total Organic Carbon problems become better defined. Sniiiyt otmnto

There is no standard for total organic carbon, MANAGEMENT IMPLICATIONS
The group of chemicals defined as synthetic and it has not been considered a problem in the Recharge areas, aquifer systems with low
organics in this study includes 142 organic past. Within the last few months the U.S buffering, sorption, or microbial degradation
U chemicals. Some of these chemicals are organic Environmental Protection Agency has indicated It is important that the data reported in this capacities, and aquifer systems with conduit flow
solvents, plastics components, and degradation that it intends to set controls on the use of water publication be utilized in every way possible are sensitive to contamination. The data
products of other chemicals. Many of the high in organic carbon for public water supplies These data are useful for water management, presented herein identify these conditions and
chemicals detected are, or have been, utilized as because of the widespread occurrence, nationally, including monitoring of water-quality change, allow a qualitative judgement of sensitivity to
pesticides, as well. All are either carcinogenic, of trihalomethanes and other halogenated location of water-use facilities, and establishing ntmn1n.Mriprttyhedt
teratogenic, toxic, or mutagenic. Standards vary hydrocarbons in finished drinking water These cause and effect relationships from aquifer system collected include all major and minor constituents
with compound and the reader is referred to Table compounds result from sanitization of water with use We have attempted to provide some basicnessytomdlqulbusrpiad
28 for a list of compound included in this group chloride and other strong oxidants in treatment concepts to a! low the reader to understand how ncessary tysof bmolgqialiriumtos.ptin mandb and the associated standards. It is important to plants. aquifer systems work in a chemical sense and to certaib tperofr, biologcalreactos t ay be
note thttepeec fteeorganics hsntanticipate the consequences of water-man- capacity of the aquifer system In other words,
been confirmed by re-sampling. agement options. The following is a summary of proper use of the data may allow one to quantify
amondaf aquifer systems have an extraordinary some of the ways that the data can be utilized. how much effluent an activity, such as waste Table 37 lists the percentage of samples in tbtoftota orgnic cabon in watenr. The disposal, can release to an aquifer system before
which exceedances for any of the 142 chemicals inTbe2.Comparison to Background water quality adversely changes
were found. Most of these were not confirmed by
re-sampling. Seven percent of the surficial aquifer Tecneto akrudwtrqaiyEfcso osmtv s
~~~system sarnples contained possible synthetic Need for Additional WorkThcnep fbkgudwtrqutyEetsfCnsmivUs
organics in excess of standards, It is not unex- allows wise resource management at two scales,
I pected that a proportion of the surficial aquifer local and regional. At the local scale, all Coastal intrusion, upconing or recharge, and
system samples would contain synthetic organics Additional work needs to be done on several contamination assessments, environmental impact induced lateral flow of contaminants may result
given that the surficial aquifer system supports specific problem areas First of all, it is necessary studies, environmental audits, and many from heavy pumpage of ground water These data
much of the state's agriculture. One and three to re-sample and confirm or reject the detections consumptive-use applications require devel- provide a basis for detecting proximity to low percent of the samples from the intermediate and of contaminants in this first round of sampling opment of an evaluation of background water quality water and, by comparison with regions Floridan aquifer systems, respectively, contain Filtered and unfiltered sarnples need to be quality for comparison to on--site water-quality where adverse movement of water exists today,
excess synthetic organics These proportions of compared so that mobility of these suspected con- impacts The person preparing a local study one may be able to anticipate degradation of local
detections are relatively low and suggest relatively tarminants can be evaluated, should not expect to use the data presented herein or regional water quality by pumpage
U ~little human impact on these aquifer systems to support a site-specific application or evaluation,
Whl helvlfcnamnton tteie s low, Nitrate contamination is much more wide- u hs data can be used to determine what to
suhville tlevlso containation taewiadei s pedta niiatdAsuyo h niso expect when background water quality deter- Long-Term Resource Evaluation
of synthetic organics this nitrate and means of mitigation of the problemmnaisarmd. flalbkgudwtr
shoud b unertaen n a oranizd wy. eadquality differs greatly from that predicted by this
shul b udetaeninanoranze wy.Ledreport, one should not take alarm, but an It is clear that the intent of the Legislature
Pesticides may not be a ground-water quality problem (sensu investigation as to the reason for the difference is when it adopted the Water Quality Assurance Act
stnctt). Lead in the sample set may result from appropriate. The water-resources manager can in 1983 was to begin a program that will allow
choice of wells sampled, not aquifer system con- also utilize the Background Network data In water-resource managers to closely monitor future
~~~~The 172 chemicals included in the Pesticides ditions The widespread occurrence of lead mustevuangprtaplatnsndnvrmnt hngsnwtrqalyadrsutglssfth
grop (abe 3) wreanayze fr i th b futhr ivesigtedanda etemintin mdeassessments These data provide a basis for resource The Background Network provides
SWFWMD and SFWMD. Only arsenic was tested as to the source. Mercury was detected in a cmnsnwith the local background quality in baseline for evaluating the future of our aquifer
for in NWFWMD, SRWMD, and SJRWMD Table number of samples and, given the current the submission and for determination of any do- systems. Ft allows us to identify change, but it
S37 summarizes the percentage of samples in problems with mercury in surface waters, its orngin gradation of water quality does not allow us to predict it with any confidence.


57






SPECIAL PUBLICATION NO. 34

The VISA and Temporal Variability Networks will several large regions where non-point source help with our ability to predict, but only continued nitrate is abundant. While we may understand the monitoring will allow confidence in identification of sources of the nitrate, we must understand how change and successful management and those sources result in nitrate contamination. If theI
enforcement synthetic organic and pesticide problems are
confirmed, then additional study will be required to determine the origins and fates of these cornNeed to Continue the Program and pounds. Fourth, efforts should be made to develop
the Fturedemonstration projects to show how the data can be used to calculate aquifer system carrying The Ground-Water Quality Monitoring Program capacities, identify recharge and discharge areas,I has begun the process of assessing the quality of and predict water-quality degradation as a result of ground water in Florida. This report is the first a variety of land uses. statewide assessment of all aquifer systems, ever. Re-sampling of the Background Network hasI begun, and this time both filtered and unfiltered metals analyses will be included. When this survey is completed, we will be able to compare the data to the data reported in this document to identify any changes in water quality. In addition, we will be able to evaluate the concentrations of dissolved and particulate metals. This re-sampling will assistI
synthetic organics and pesticides. It will also allow confirmation of the lead and mercury problems
mentioned above

Sampling of the VISA Network is nearing
completion, and comparisons will be made withI the Background Network to develop predictive models concerning the impacts of specific land uses. This comparison will comply with the charge of the Water Quality Assurance Act to predictI


Finally, the Temporal Variability Network data is being analyzed as this report is being written. This data base indicates that water quality
changes on short-and long-term time frames doI ocusion Tof dthi repow into prspctie wthe
respect to both spatial and temporal changes. It will also assist managers to evaluate the context ofI reports that include only one sampling event.

Several additional studies are suggested byI the findings of this report. First, a study of the mechanisms by which fracture systems affect water quality should be undertaken These fractures are widespread, and water-managementI policy should include potential for migration of lowquality water within them. Second, the origin of the lead and mercury reported in Florida's aquifer systems should be identified. Third, the origin,transport, and biochemical transformations of nitrogen species should be undertaken. There are

58







FLORIDA GEOLOGICAL SURVEY


SREFERENCES CITED ____, Cherry, R.N., and Hanshaw, B.B., 1966, Ceryak, R., 1977, Alapaha River Basin White Cuibreth, M A, 1988, Geophysical investigation of
Chemical equilibrium between the water and Springs, FL, Suwannee River Water Man- lineaments in south Frinda- Unpublhshed M.S
Altscbuler, Z.S., Clarke, R.S., and Young, E.J., minerals of a carbonate aquifer. Bulletin agement Distrnct Information Circular 5, 20 p. thesis, University of South Florida, Tampa,
1958, Geochemistry of uranium in apatite and National Speleological Society, v. 28. 97 p.
phosphorite U.S. Geological Survey, Kap -. n unoT 93
Professional Paper 3140, p 4590. BizmnK,17,Te oa oontzto h Kn1pp,,R.eohemdstrynofnhe ,o1tact
Badiooman, K. 197, Th dora dolmitiatio Thegeology and water resources of the upper Dalton, M.G.,17,Gehmstyothcntt I ~model -Application to the Middle Ordovician Suwannee River Basin, Florida: Florida Bureau between bicarbonate and upwelling sulfate
Ahrens, L.H., 1954a, The lognormal distribution of of Wisconsin Journal of Sedimentary of Geology, Report of Investigations No. 87, waters in the Floridan aquifer. Unpublished
the elements (A fundamental law of geo- Petrology, v 43, p 965-968. 165 p. M.S. thesis, University of South Florida,
chemistry and its subsidiary) Geochimica et Tampa, Florida, 101 p.
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Standard methods for the examination of Bradner, L A., 1991, Water quality in the upper year old early man site- Flonida Anthropologist, John Wiley &Sons, 824 p.
water and wastewater, 15th edition: American Florndan aquifer in the vicinity of drainage v. 28, n 3, Part 2, 38 p. SPublic Health Associatior, Washington, D C. wells, Orlando, Florida: U.S. Geological
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No. 90-4175, 57 p. Cline, J.T., and Upchurch, 5.B2, 1913, Mercury Waters: Englewood Cliffs, NJ, Prentice-Hall,
American Society for Testing and Materials, 1980, mobilization as an organic complex. 2nd Ed., 437 p.
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I Water -ASTM D-1129-78a: In Annual Book of Brown, D.E., 1989, The role of natural organics in a Research, Proceedings of the 16th Conference
ASTM Standards, Philadelphia, American groundwater system: Unpublished M S. on Great Lakes Research, p 233-242 Duerr, A.D, and Wolansky, R.W., 1986, HydroSociety for Testing and Materials, p.3-6. thesis, University of South Florida, Tampa, geology of the surficial and Intermediate
Florida, 103 p aquifers of central Sarasota County, Florida
I Connell, W.E., and Patrnck, W.H., Jr., 1968, Sulfate U.S. Geological Survey, Water-Resources
Andrejko, M.J., and Upchurch, S.B., 1978, reduction in soil Effects of redox potential and Investigations Report 86-4068, 48 p
Occurrence of anhydrite in naturally burned Burnett, W C Cowart, J B and Chin, P.A., 1988,pHScnev1,p8-7
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Chelsea, Michigan, Lewis Publishers, p. 251- 1985, Authigenic fluorite in dolomitic rocks of water withdrawals of the aquifer systems in SBack, W 1961, Techniques for mapping of 269. the Floridan aquifer. Geology, v. 13, p. 390- southwest Florida, with emphasis on the
hydrochemical facies: U.S. Geological Survey, 391. intermediate aquifer system- U S Geological
Short Papers in the Geologic and Hydrologic Survey, Water-Resources Investigations
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(ed ), The Encyclopedia of the Chemical Cooper, H.H., Jr., Kohout, F.A., Henry, H.R., and Rpr 745,15p
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water flow patterns in northern part of Atlantic Supply Paper 1613-C, 84 p of the intermediate aquifer system and upper
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Professional Paper 498-A, 42 p Cathcart, J.B., 1956, Distribution and occurrence Florida. U.S. Geological Survey, Water-Reof uranium in the calcium phosphate zone of Cowart, J.B Kaufrman, M I., and Osmond, J K sources Investigations Report 90-4104, 46 p. the landpebble phosphate district of Florida 1978, Uranium-isotope variations in and Hanshaw, B.B., 1970, Comparnson U.S. Geological Survey, Professional Paper groundwaters of the Floridan aquifer and
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59






SPECIAL PUBLICATION NO. 34

Fanning! K.A., Byrne! R.H., Breland, J.A., II, Betzer, Crier, N,. 1968, Mercury, in Hampel, C A, (ed.), Hem, J D., 1976, Geochemical controls on lead Jones, G ,1991, Structural controls on ground-I
P.R., Moore, M.S., Elsinger, R.J, and Pyle, The Encyclopedia of the Chemical Elements, concentrations in stream water and sediments. water quality in southwest Florida and
T.E ,1981, Geothermal springs of the West New York, Reinhold Book Corporation, p. 401- Geochimica et Cosmochimica Acta, v. 40, p. implications for water management (abs )
Florida Continental Shelf. Evidence for dolo- 412. 599-609 Minneapolis, Minnesota, Amerncan Institute ofI
mitization and radionuclide enrichment. Earth Hydrology, Conference Abstracts, 1991 Annual
and Planetary Science Letters, v. 52, p 345- Meeting, Orlando, Florida, p. 33.
354. Hanshaw, B.B., and Back, W 1971a, On the origin ___ 1985, Study and interpretation of the
of dolomites in the Tertiary aquifer of Florida: chemical characteristics of natural water: U.SI Seventh Forum on Geology of Industrial Geological Survey Water-Supply Paper 2254, Jones, I.C., 1991, ion transport within the Floridan
Fetter, C.W., 1988, Applied Hydrogeology: Minerals, p 139-153. 3rd Ed ,253 p aquifer, West-Central Florida Tampa,
Columbus, OH, Merrill Publishing Company, University of South Florida, Unpublished M.S.
2nd ed 592 p. and Back, W., 1971b, A geochem- Hersh, C.K 1968, Nitrogen, in Hampel, C.A., (ed.), thesis, 143 p.
cal hypothesis for dolomitization by ground The Encyclopedia of the Chemical Elements: Fleischer, M., 1987, Glossary of Mineral Species: water- Economic Geology, v. 66, p. 710-724. New York, Reinhold Book Corporation, p. 454- _____, Vacher, H L, and Budd, D.A., 1992,
Tucson, Mineralogical Record, 5th Ed., 234 p. 459 in press. Transport of Ca, Mg and S04 in theI
and ackW., 980,ChemcalFlorndan aquifer, west-central Florida IrnpliFlorida Department ofEvrnetlRgltomass-wasting of the northern Yucatan Hickey, J.J., and Veccioli, J., 1986, Subsurface dro ogymnato.aes oralo y
1981, Supplement "A" to standard operating Peninsula by ground-water dissolution- injection of liquid waste with emphasis onU
procedures and quality assurance manual- Geology, v. 8, p. 222-224. injection practices in Florida. U.S. Geological
Florida Department of Environmental Regu- Survey Water-Supply Paper 2281, 25 p. Jones, J.B., and Segnit, E R., 1971, The nature of
lation, Solid Waste Section, Tallahassee, opal I. Nomenclature and constituent phases:
Fnd,1 pBack, W., and Rubin, M., 1965, Journal Geological Society of Austraia, v. 18,
FlordahopRadiocarbon determinations for estimating Hull, R.W., and Irwin, G A, 1919, Quality of p, 5168
ground-water flow velocities in central Florida. untreated water for public supplies in Florida Florida Department of Environmental Regulation, Science, v 148, p 494-495 with reference to the national primary drinking
1989, Florida Ground Water Guidance Con- water regulations- Florida Bureau of Geology Katz, B.G. and Choquette, A F 1991, AqueousI
centrations. Tallahassee, Flornda Department Map Series No. 91. geochemistry of the sand-and-gravel aquifer,
of Environmental Regulation, 14 p. ,Back, W., and Dieke, R.G., 1971, A northwest Florida. Ground Water, v. 29, p 47geochemical hypothesis for dolomitization by 55
ground water- Economic Geology, v. 66, p. _____, and Yurewicz, WOC, 1979, Quality of Foster, M.D., 1950, The orngm of high sodium 710-723. storm runoff to drainage wells in Live Oak,
bicarbonate waters in the Atlantic and Gulf Flornda, April 4, 1979- U.S. Geological Survey Kaufman, M.l., and Dion, N.P., 1967, Chemical
Coastal Plains. Geochimica et Cosmochimica OpenFile Report 791073, Tallahassee, Florida, character of water in the Florndan aquifer in
Acta, v 1, p. 33-48. Hardie, L.A 1987, Dolomitization: A critical view 5p.southern Peace Rwver Basin, Florida: FloridaI
of some current views Journal of Sedimentary Bupu. GooyMp ee 7
Petrology, v 51, p 166-183
Freeze, R.A., and Cherry, R.A ,1979, Groundwater: Hutchinson, CGB., 1978, Appraisal of shallow
Englewood Cliffs, NJ, Prentice-Hall, Inc., ground-water resources and management ,_____ and Dion, N.P., 1968, Ground-U
604 p. Harrns, L., 1968, Lead, in Hampel, C.A., (ed.), The alternatives in the upper Peace and eastern water resources of Charlotte, De Soto, and
Encyclopedia of the Chemical Elements New Alafia River Basins, Florida U S. Geological Hardee Counties, Florida' Florida Bureau of

Garrels, R.M and Christ, C.L., 1964, Solutions, 12,7York, Reinhold Book Corporation, p 357-367. Survey Water-Resources Investigations 77- Geology Information Circular 53, 22 pI
Mnerals, and. Eqilbia ewYrk are Hayes, E.C 1981, The surficial aquifer in east- Kaufrman, R.F., and Bliss, J.D., 1977, Effects of the
and Rw, Ic., 50 central St. Johns County, Florida: U.S Jenne, E.A., 1970, Atmospheric and fluvial phosphate industry on radium-226 in ground
Geological Survey Water-Resources Inves- transport of mercury, in Mercury in the water of central Florida: U.S Environmental
Goldich, S.S., 1938, A study in rock weathering. tigations Report 81-14, 19 p. Environment. U.S. Geological Survey Protection Agency, Office of Radiation ProJournal of Geology, v 46, p 17-58 Professional Paper 713, p. 40-45 grams, Las Vegas Facility, EPA/52O-6-77-010,

Healy, H.G., 1962, Piezometric surface of the 111 p
Gordon Palm and Associates, 1983, Water data Floridan aquifer in Florida- Florida Bureau of Jonasson, l.R 1970, Mercury in the natural
acquisition Surface and ground water: Geology Map Series No.1 environment: A review of recent work: Kenaga, E.E., and Goring, C.A I 1980, RelaUnplshe reportn submitted to the Florida Ottawa, Geological Survey of Canada, De- tionship between water solubility, sol sorption,
Phosphate Council, LaeadFoia .l 1975, Piezometric surface and areas partment of Energy, Mines and Resources, octanol-water partitioning and concentration of
151 andv. 21 p.of artesian flow of the Floridan aquifer in Paper 70-57, 39 p. chemicals in biota- In J G. Eaton, P R Parrnsh,

Florida, July 6-17, 1961: Florida Bureau of and A.C Hendricks (eds), Aquatic Toxicology
Geology Map Series No. 4, Second Edition. ASTM STP 707, Philadelphia, AmericanI
Society for Testing and Materials, p. 78-115.


60







FLORIDA GEOLOGICAL SURVEY


Kimrey, J O., and Fayard, L.D., 1982, Geo- Merrntt, M.L., Meyer, F.W., Sonntag, W.H., and Parker, G.G., 1951, Geologic and hydrologic ___ Stone, G.0 and Saroop, HGC,
hydrologic reconnaissance of drainage wells in Fitzpatrick, D.J., 1983, Subsurface storage of factors in the perennial yield of the Biscayne 1977, Diagenesis of Middle and Upper Eocene
Florida An interim report. U.S. Geological freshwater in south Flonda: A prospectus U.S. aquifer: Journal American Water Works carbonate shoreline sequences, central
Survey, Open-File Report 82.-860, 59 p. Geological Survey Water-Resources Association, v 43, p 817-835. Florida. Bulletin, American Association of
Investigations Report 83-4214, 69 p. Petroleum Geojogists, v.61, p.492-503.
SKlein, H F., and Hull, J E., 1978, Biscayne Aquifer, __, Ferguson, 5.K., Love, 5.K., and
southeast Florida: U.S Geological Survey Miller, J.A., 1978, Geologic and geophysical data others, 1955, Water resources of southeastern ______, and Hickey, E W., 1918, DoloWater-Resources Investigations 78-107, 52 p. from Osceola National Forest, Florida: U S Florida: U.S Geological Survey Water-Supply mitization in the Florndan aquifer: American Geological Survey Water Resources Inves- Paper 1255, 965 p Journal of Science, v. 278, p. 1177-1184.

Kohout, F A 1960a, Cyclic flow of salt water in the tigations 78-799
Biscayne aquifer of southeastern Florida: Plummer, L N 1915, Mixing of sea water with ______, Sarver, T J., and Metrin, D.B,
Journal of Geophysical Research, v. 65, p. Miller, P L., and Suteliffe, H., Jr 1982, Water- calcium carbonate ground water, in E.H T. 1983, Selected geochemical factors
2133-2141. quality and hydrogeologic data for three Whitten (ed.), Quantitative Studies in the influencing diagenesis of Eocene carbonate
I phosphate industry waste-disposal sites in Geological Sciences- A Memoir to William C. rocks, peninsular Florida, U.S.A.. Sedimen16bFwpttr ffshwtrcentral Florida, 1919 to 1980: U.S. Geological Krumnbein, Boulder, Colorado, Geological tary Geology, v 36, p. 1-14.
and___ salt 0bte Flo pBsayen oqf f wthe Survey Water-Resources Investigations 81-84, Society of America, Memoir 142, p 219-236
I ~Miami area, Florida: International Association and Bloom, J L 1985. Mineraof Scientific Hydrology, Commission on ,1977, Defining reactions and mass logical changes along the freshwater/saltwater
Subterranean Waters, Publication 52, p. 440- _____, and Sutcliffe, H., Jr., 1984, Effects transfer in part of the Floridan aquifer: Water interface of a modern aquifer: Sedimentary
448. of three phosphate industrial sites on ground- Resources Research, v. 13, p. 801-812. Geology, v. 43, p. 219-239.
water quality in central Florida, 1919 to 1980
Lawrnce F.., nd pchuchSB. 196, en-U S. Geological Survey Water-Resources
tair, f, gndechicl pattern 1in groun- Investigations Report 83-4256, 184 p. Prasad, 5 1985, Microsucrosic dolomite from the ,eiato and Cook, D.J., 1987, Charactificatio of geocemical paterns rnground 'Hawthorn Formation (Miocene) of Florida: teztinofdloiicrck ro hecasa
water by numerical analysis, in Zaleem, E.A., Distribution and development. Unpublished mixing zone of the Floridan aquifer, Florida,
(ed.), Advances in Groundwater Hydrology: _____, Bradford, W.L., and Peters, N.E M.S. thesis, University of Miami, Rosensteil U.S.A: Sedimentary Geology, v. 54, p. 169American Water Resources Association, 1988, Specific conductance: Theoretical School of Marine and Atmospheric Science, 192.
I p. 199-214. considerations and application to analytical 124 p.
quality control: U.S. Geological Survey Water-PeA.anUphrSB 10,Ifuceo
_______, and Upchurch, S B., 1982, Spyapr3llpPun, H.S., and Vernon, R.O., 1964, Summary of regolith properties on migration of septic tank
I Identification of recharge areas using geo- the geology of Florida and a guidebook to the effluent: Ground Water, v. 18, p.118-125.
chemical factor analysis: Ground Water, v 20, Montgomery, J.H., and Welkom, L M., 1990, classic exposures. Florida Geological Survey
p680-687. Groundwater Chemicals Desk Reference Special Publication No. 5 (revised), 312 p
Chelsea, Michigan, Lewis Publishers, Inc., Rightmire, C T., Pearson, F.J., Jr., Back, W., Rye,
N Lehman, L.L., 1978, Geochemical identification of and Winston, G O., 1914, Geologic sulfur isotopes of sulfates in groundwaters
an intermediate groundwater flow system in framework of the high transmissivity zones in from the principal artesian aquifer of Florida
tePaeRvrbasin, Florida. Unpublished Moore, J W and Ramamoorthy, 5., 1984, Heavy south Florida: Florida Bureau of Geology and the Edwards aquifer of Texas, U.S.A., in
I M S thesis, University of South Florida, Metals in Natural Waters: Applied Monitoring Special Publication No. 20, 120 p. Isotope Techniques in Groundwater HydroTampa, 74 p and Impact Assessment New York, Sprnnger- logy, Vienna, International Atomic Energy
Verlag, 268 p. ~~~Radell, M.J ,and Katz, B.G., 1991, Major-ion andAgny Vo.Ip 1 -27
Leve, G.W., 1983, Relation of concealed faults to selected trace-metal chemistry of the Biscayne
water quality and the formation of solution Muller, H G., and H-offmeister, J.E., 1968, Subaeial aquifer, southeast Florida: U.S. Geological Reik, B A, 1982, Clay mineralogy of the Hawthorn features in the Floridan aquifer, northeastern laminated crusts of the Florida Keys: Geo- Survey Water-Resources Investigations Report Formation in northern and eastern Florida, in
Flornda, U.S.A: Journal of Hydrology, v 61, p logical Society of America, Bulletin, v. 79, p. 91-4009, 18 p. Scott, T.M., and Upchurch, S.R (eds.),
2I-6.1312 icn fth otesenUie tts
Randazzo, A F and Saroop, H.C., 1976, Sedi- Florida Bureau of Geology Special Publication
Lyman, W.J Reehl, W F and Rosenblatt, D H National Atmospheric Deposition Program (IR- mentology and paleoecology of Middle and26p.4750
U 1990, Handbook of Chemical Property fl/National Trends Network, 1990, NADP/NTN Upper Eocene carbonate shoreline sequences,
Estimation Methods- Environmental Behavior Coordination Office, Natural Resources Eco- Crystal River, Florida, U.S.A. Sedimentary Roaza, H.P., Pratt, T.R Richards, C J., Johnson,
of Organic Compounds. Washington, D.C logy Laboratory, Colorado State University, Geology, v. 15, p. 259-291. J.L and Wagner, J.R 1991. Conceptual
American Chemical Society, 964 p. Fort Collins, CO 80523. model of the sand-and gravel aquifer, Escambia
Florida Water Management District, Water
3 Resources Special Report 91-6, 125 p.


61






SPECIAL PUBLICATION NO. 34


Rosenau, JOC, Faulkner, G.L., Hendry, C.W., Jr., Sprinkle, C.L., 1982a, Dissolved-solids concen- _____, and Upchurch, 5.B 1985, ______, and Littlefield, J.R., Jr., 1988,
and Hull, R.W., 1977. Springs of Florida: tration in water from the upper permeable zone Palygorskite distribution and silhcification in the Evaluation of data for sinkhole development
Florida Bureau of Geology Bulletin 31, revised, of the Tertiary limestone aquifer system, phosphatic sediments of central Florida- in risk models: Environmental Geology and
461 p. Southeastern United States: U.S. Geological Snyder, S., Riggs, S., Partin, B., Mallette, P., Water Science, v 12, p. 135-140.I
Survey Water-Resources Investigations. Open and Walker, R., (eds.), Eighth International
Runel, O.,199 iaeneis cemialsei-File Report 82-94, 1 p Field Workshop and Symposium (South-,OuaC.FosDWan
Runls .D,199Dignei, hmia sd-eastern United States): Guidebook, Inter- Broe, H.R.,99, CR.,dohstr, o.W Uranments, and the mixing of natural waters:naonlGogiaCrrltnPrgmBokH.,19,RdohmsryfUrJournal of Sedimentary Petrology, v. 39, p. ______, 1982b, Total hardness of water Project 156 Phosphorites, p. 118-126. urn-Series Isotopes in Ground Water: Florida
1188-1201. from the upper permeable zone of the Tertiary Institute of Phosphate Research, Publication
limestone aquifer system, Southeastern United No. 05-022-092, 199 p.
States: U.S. Geological Survey Water-Re- Swancar, A., and Hutchinson, C.B 1992,
Rye, R.O., Back, W., Hanshaw, B.B., Rightmire, sources Investigations, Open File Report 81- Chemical and isotopic composition and
C.T., and Pearson, F J, Jr., 1981, The origin 12,1ppotential for contamination of water in the Vernon, R. 0., 1951, Geology of Citrus and Levy
and isotopic composition of dissolved sulfide 1p10F2nnA1ier es-cnrp.FoidCounties, Florida: Florida Geological Survey
mn groundwater from carbonate aquifers in 1986-89: U.S. Geological Survey, Open-File Bulletin 33,256 p
Florida and Texas: Geochimica et ______, 1989, Geochemistry of the Rpr9-74p
Cosmochimica Acta, v 45, p. 1941-1950. Floridan aquifer system in Florida and in parts Reporrt 9F2-4,7.R.,M 47p., JW.
of Georgia, South Carolina, and Alabama. WagnerlJimshr,G. adR.S, rne, ..
Schier,0.8,andGeran, R.,198, Efect ofRegional Aquifer-System Analysis- Floridan Thurman, E.M., 1985, DraganiMilsRA. andmarstry., 984
Scier ,ad emnEB, 93,Efct aquifer: U.S. Geological Survey Professional Natural Waters- Boston, Martinus Nijhoff/Dr. Nrthest MFoMidas Water anagemrr, Disic,14
recharge from drainage wells on quality of Paper 1403-I, 105 p. W. Junk Publishers, 497 p. inoFrnws, EFA, nd Wattor. M(aeds), DWstert
water in the Floridan aquifer in the Orlando i enlEAadPtoDJ,(d) ae
area, central Florida. U.S Geological Survey Resources Atlas of Florida: Chapter 15, p.l198Water Resources Investigations Report 82- Stallard, R.F., and Edmond, J.M., 1981, Geo- Thth, J 1962, A theory of groundwater motion in 217.
4094, 124 p. chemistry of the Amazon: I. Precipitation small drainage basins in central Alberta:
chemistry and the marine contribution to the Journal of Geophysical Research, v. 67, p. Wtos n phrh .. npeaain
Scott, T.M., 1988, The lithostratigraphy of the Journal Geophysical Research, v. 86, p 9844- Distribution of organic carbon in the Floridan
Hawthorn Group (Miocene) of Florida: Florida 9858. aquifer. To be submitted to the Bulletin of the
Geological Survey Bulletin 59,.148 p. 1963, A theoretical analysis of ground- Geological Society of America.
Starks, M.J., 1986, Mixing-zone diagenesis in a Geophysical Research, v. 68, p. 4795-481 2.
_____, Lloyd, J M and Maddox, G., (eds.), carbonate aquifer, west-central Florida: Weaver, C.E., and Beck, K.C., 1977, Miocene of
1991 Flrid's Goun Waer ualiy Upubishd M. thsis Unversty f Suththe S.E. United States: A Model for Chemical Monitoring Program Hydrogeological frame- Florida, Tampa, Florida, 98 p.Uie ttsEvrnetlPoeto gny eietto naPnMneEvrnet
work: Florida Geological Survey Special Pub- 1982, Handbook for sampling and sample Amsterdam, Elsevier Scientific Publishing
lication No. 32, 97 p preservation of water and wastewater. United Company, Developments on Sedimentology,
Stringfield, V T., 1966, Artesian water in Tertiary States Environmental Protection Agency EPA- v. 22, 234 p.
limestone in the southeastern States: U.S. 600/4-82-029, Cincinnati, Ohio, 402 p.
Shampine, W.J., 1965, Hardness of water from the Geological Survey Professional Paper 517, 226 p. WdebrLAKap SWlz .. n
upper part of the Floridan aquifer in Florida:WddbrL.,KnpM.,WtDPad
Florida Bureau of Geology Map Series No IS. Upchurch, 5.8., 1986, Use of water chemistry to Burns, W.S 1982, Hydrogeologic recon, and Leerand, H.E., 1966. Hydro- identify interaquifer mixing -- Lee County, naissance of Lee County, Florida: South
logy of limestone terranes in the Coastal Plain Florida- Unpublished contract report available Florida Water Management District, Technical
_________, 1975, Dissolved solids in water of the southeastern United States: Geological from the South Florida Water Management Publication 82-part 1 -Text, 192 p.
from the upper part of the Floridan aquifer inSoetofA napealPpr9,4p.DtrtWsPamBcFord,6p
Florida: Florida Bureau of Geology Map SeriesSoitofAeiaSpcaPae934p.DsrtWtPamBchFoid,6p
No 14 (Revised) White, W.B., 1988, Geomorphology and Hydrology
Strom, R.N., and Upchurch, S.B., 1983, Rea, R.A., and Stevenson, R.G., of Karst Terrains: New York, Oxford University
Palygorskite (attapulgite) rich sediments in the Jr., 1982, Sedimentary pachnolite and fluorite Press, 464 p. Smith, D.L., and Griffin, G.M., (eds.), 1977, The Hawthorn Formation: A product of alkaline from Tampa Bay, Florida: American
geothermal nature of the Floridan Plateau: lake deposition? in The Central Florida Mineralogist, v. 67, p. 1258-1264. WloW. 97 rudwtrrsucso
Florida Bureau of Geology Special Publication Phosphate District. Geological Society of Wesot and. Harde, Goun-tieFria Flsorida f
21 11p. America, Field Trip Guidebook, Southeastern and Lawrence, F.W 1984, in- Bureau of Geology Report of Investigations

SoutheasterneGtologicalcho1ety1s8Ad Hoc7Coin- pact of ground-water chemistry on sinkhole No. 83, 102 p.
SuhstrGelgalSctysAHoCm-development along a retreating scarp, in Beck,I mittee on Florida Hydrostratigraphic Unit B.F., (ed ), Sinkholes: Their Geology,
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Florida: Florida Geological Survey Special Rotterdam, Balkema, BA, p 189-195 carbonate waters: Geochimica et GosmoPublication 28, 9 p. chimica Acta, v. 42, p. 1117-1139.
62







FLORIDA GEOLOGICAL SURVEY


1 Wood, J M Kennedy, F.S., and Rosen, C G,
1968, Synthesis of methyl-mercury compounds by extracts of a methanogenic bactenum: Nature, v. 220, p. 173-174.

Young, T.C., and Comstock, W.G., 1986, Direct
effects and interactions involving iron and humic acid during formation of colloidal phosphorus, in Sly, P.G., (ed.), Sediments and
~Water Interactions: New York, Springer-Verlag,
p. 461-470.












TABLE 1

GROUND WATER QUALITY NETWORK MONITORING PARAMETERS


PARAMETER GROUP NETWORK STANDARD METHOD 12

Parameter Name Background VISA HRS quarterly Monthly

MAJOR IONS

Bicarbonate B V Q 406
Carbonate B V 406
Chlonde B V H 0 407A,407B~or4070
Cyanide B V 412B, 412C, or 412D
Fluoride B V H 0 413A, 41 3B,413C, or41 3E
Nitrate B V H 0 4180Cor 418F
Phosphate B V H 0 424For424G
Sulfate 0 426A or 426C


METALS

Arsenic B V H 303E
Barium B V H 303C
Cadmium B V H 303A or 3036
Calcium B V H 0 303Aor311C
Chromium B V H 303Aor303B
Copper B V H 303A
Iron B V H 0 303Aor315B
Lead B V H 303Aor303B
Magnesium B V H 0 303Aor319B
Manganese B V H 0 3O3Aor319B
Mercury B V H 303F
Nickel B V 303A or 3228
Potassium B V 0 303A or 3228
Selenium B V H 303E
Silver B V H 303A or 3038
Sodium B V H 0 303Aor3258
StrontiumV
Zinc B V H 0 303Aor3038


FIELD PARAMETERS
C,,
Conductivity B V 0 M 205m
pH B V 0 M 423 C
Eh M
DissoLved Oxygen (DO) M
Temperature B V 0 M 212c
Water levels B V 0 M
Odor H r


MICROBIOLOGICAL

Fetal Colitorm B V 9080 or 9090C
Total Coliform B V 908A or 9O9A2


ORGANICS AND PESTICIDES

Total Organic Carbon Cr00) B V 0 505
Volatile Organic Carbon (VOC) B EPA 601 and 602, or EPA 624
Ahdicarb & related compounds VEPA 531
Purgeable Halocarbons VEPA 601
Purgeable Aromatics V H EPA 602
Pesticides VEPA Ah 614
PCB's, Chlorinated Pesticides V H EPA Alt. 617
Pesticides VEPA Alt. 619
Organophosphate Pesticides H EPA 622
Mixed Purgeables H EPA 624
Base!/Neutral/AMid Extractables V H EPA 625
Carbamate Pesticides V H EPA 632
Pesticides VEPA 644
Herbicides H
Fumigant Pesticides V H


RADIOMETRICS

Gross Alpha B V 703
Gross Beta B V 703
Radon 8
Radium B *


OTHERS

Total Dissolved Solids (TDS) B V 0 209B
AmmoniaV
SilicaV



1 Methods are from the American Public Health Association's Standard Methods for the Fxamination of Water and Wastewater, 15th edition
(1980), or from the Flrinda Department of Environmental Regulation's Supplement "A" to Standard Onoratino Procedlures and Quality
Assurance Manual (1981).

2 Other approved methods with the same or better minimum detection limits, accuracy and precision are also acceptable.

A subset of approximately 100 Background Network wells is being sampled for radon and/or radium.


























TABLE 2

FLORIDA PRIMARY AND SECONDARY DRINKING WATER STANDARDS FOR SELECTED PARAMETERS (FROM F.A.C. 17-22)**


PARAMETER GROUP MAXIMUM CONTAMINANT LEVEL @pg/L, unless otherwise noted)

Parameter Name Primary OWS Secondary DWS

MAJOR IONS

Chloride 250,000
Fluoride 4,000 2,000
Nitrate 1iooo
Sulfate 250,000

METALS

Arsen Ic 50
Barium1,0
Cadmium 10
Chrom Uml 50
Copper 1,000
fron 300
Lead 50
Manganese 50
Mercury 2
Selenium 1
Silver 50
Sodium 16e,00o
Zinc 5,000 -1

FIELD PARAMETERS 0

pH >65, Odor 31T0ON"

MICROBIOLOGICAL

Total Coliforrn 4 colL (see rule)O

ORGANICS

Endnnr 02 1
Lindane 4 (
Meihoxychlor 100 "
Toxaphene 5
2,4-D 10
2,4,5-TP (Sirvex) 10
Tetrac hloroeth yle ne 3
Inc hIoroethiylene 3
Carbon Tetrachloride 3
Vinyl Chloride1
1,1,1-Tnichloroethane 200
1,.2-Diohloroethiane 3
Benzene 1
Ethylene Dibrormide (EDB) 0 02
Trihalomethane 100

RADIOMETRICS

Gross Alpha is pCi/L
Gross Beta 4 mrem/yr
Radium 226, 228 5 pCO/L

OTHERS

Totai Dissolved Solids (TDS) 500,000

S U = Standard Units
"T 0 N = Threshold Odor Number
"*Source Flornda Ground Water Gidance Conentrntions, Florida Department of Environmental Regulation. February, 1989













Table 3. Summary of the chemical composition of precipitation from selected sites in Florida. Based on data from the National Atmospheric Deposition Program (IR-7)/National Trends Network (1990).



Stat Ca Mg K Na NH-4 NO3 CI so4 P04 pH Cond Na/Cl Ratio
(mg/L) (mg/L) (mg/L) (mg/L) (mg/L) (mg/L) (mg/L) (mg/L) (mg/L) (field) (fild) (mole dev,
ratio) from
sea
water


Ouincv. Gadsden county

0.14 0.07 0 06 0.44 0 15 1.05 0.75 1.77 0 02 4.68 17 7 0.90 0.05

S0.17 0.08 018 053 0.24 105 0.89 1.84 009 041 159 0.22 0.22
n 179 179 179 179 179 179 179 179 179 160 162 179 179
Min 0.01 0.01 0.00 0.03 0 00 0.00 0 06 0.10 0.00 3.57 4 0 0 40 -0 45 Max 1.15 0.53 2.12 3.23 1.53 6.19 5 58 12 78 0.78 5.90 132.5 2.90 2.05


Austin-Carv Forest. Alachua county

S0.28 0 09 0.09 0.78 0.15 1.00 0 96 2.03 0.00 4.79 17.87 1 39 0.54

s0.28 0.07 0 16 0.85 0.85 0.88 0.99 1 47 0.00 0.53 12.09 1.01 1 01

n 92 92 92 92 92 92 92 92 92 89 92 92 92
Min 0.02 0.00 0.00 0.02 0.02 0.07 0 10 0.10 0.00 3.49 3.70 0 13 -0 73

Max 1.33 0.39 0.95 4.87 4 87 4.70 8 88 8.88 0.00 6.70 66 70 6.04 5.19


Bradford Forest. Bradford County

S0.26 0 11 0.07 0.80 0.16 1.04 1 19 1.96 0 01 4.70 16.77 1 05 0.20
s0.44 0.26 0 22 2.13 0.24 0.95 3.16 2.13 0 07 0.46 12.82 0.64 0.64
n367 367 367 367 367 367 367 367 367 340 337 366 366 /m
Mmn. 0.01 0.00 0.00 0 04 0.00 0.00 0.00 0.00 0 00 3.22 2.20 0.31 -0.54 o
Max 5.40 4.31 3.81 29.30 1 92 6.60 52.62 22.80 1 19 6 60 99.00 6.17 5.32 r

C
Kennedy Space Center. Brevard couintyw

0 28 0 20 0.09 1 58 0.10 1.05 2.81 1.93 0 02 4.92 23.15 0 87 0 02

s 0.34 0 25 0.10 2.03 0.17 1.13 3.64 1.71 0 07 0 37 14.99 0.14 0.14 Q
7
n 229 229 229 229 229 229 229 229 229 208 201- 229 229 Z
Mm. 0.01 0.00 0.00 0 09 0.00 0.00 0.15 0.20 0 00 3.73 0.80 0.37 -0 48

Max. 3.28 1.70 0.80 13.82 1 18 10.12 12.81 12.81 0.58 5.72 85.80 1.91 1.06


Verna Well Field. Sarasota county

0 31 0 14 0.23 0.81 0.21 1.00 1 39 1.53 0 05 4.85 15.02 0 90 0 05

s0.42 0 25 1.40 1.50 0.63 1.15 2.62 1.47 0 39 0.54 10.70 0.22 0.22

n202 202 202 202 202 202 202 202 202 159 177 202 202

Mmn. 0.02 0.01 000 007 0.00 0.00 0.14 0.15 0.00 339 300 0.51 -034
Max. 349 193 17.40 13.31 7.30 10.32 2453 13.64 4.98 7.30 85.30 2.31 1.46


Everglades National Park. ade County

0 36 0.20 0.20 1 32 0.22 0 73 2.31 1 14 0 07 4.98 15.98 0 88 0 03

s0.73 0.31 1.03 1.89 1 12 0.85 3.21 1.62 0 63 0.57 13.90 0.13 0 13 n304 304 304 304 304 304 304 304 304 261 269 304 304

Min 0.01 0.01 0.00 005 0.00 0.00 0.12 000 0.00 300 3.50 0.56 -0.30
Max. 7 68 2 66 12.60 15.91 17.12 8 37 26 89 15.42 9.98 7.27 141 50 2 22 1.37




S0 28 0.14 0 13 1.00 0.17 0 97 1 66 1.76 0.03 4.77 17.58 0 96 O 11

s 0.48 0 25 0.74 1 80 0.61 1.01 2.98 1.80 0 34 0.50 13.80 0.47 0 47
n 1373 1373 1373 1373 1373 1373 1373 1373 1373 1217 1231 1373 1372

Min. 0 01 0.00 0 00 0.02 0.00 0 00 0.00 0 00 0.00 3.0 0 80 0.13 -0.73 Max. 7.68 4.31 17.4 29.3 17 2 10 32 52.62 22.8 9 98 7 3 141 5 6 17 5.32


S= arithmetic median

s= standard deviation
n = number of samples







H FLORIDA GEOLOGICAL SURVEY


Table 4. Common minerals in Flonda aquifer systems and confining beds and their dissolved weathering Table 5 Common minerals in Florida aquifer systems. See Table 4 for mineral compositions and weathernng
products. Mineral formulae from Fleisoher (1987) products Volumetrically or chemically important minerals indicated in bold.

Dissolved AQUIFER/MINERAL Surficial aquifer Intermediate aquifer Flonidan aquifer
weathering FRACTION system system system
Mineral Composition products
(exol. H20, Silicate Fraction Quartz Quartz Quartz
plus residual Potassium feldspar Potassium feldspar
solids) Potassium mica Potassium mica
Kaolinite Palygorskite

N Anhydnite CaSO, Ca2, SO,.ClrtSpile

SAragonite CaCO, Ca2n, HC03 Kaolinite
Cact aO a CgCartonate Fraction Calcite Dolomite Calcite

Carbonate-hydroxylapatite Ca5(PO,,CCJ),(CH) Ca>, PC,3, HC1, plus Aragonite Calcite Dolomite
trace U"6 Aragonite (?)
Carbonatefluorapatite CaA(PO,CO,F Ca2 P09, F ,HCO;, pbus OyyoieFri yrxd yiePr
sulfides Goethite Ferrnc hydroxide Ferrnc hydroxide
U ~Dolomite CaMg(CO,), Ca2; Mg2", HCO;~ Gibbsite, boehmite, Goethite Goethite
Femrc hydroxide Fe(OH), Fe> diaspore

Gibbsite (G), G: AI(OH), or Al> _ _ _ _ _ _ _ _ _ _
bobmite and A120, 3H20, Other Humic substances* Carbonate- Gypsum
fluorapatito Anhydrite
diaspore (BD) BD: AJO(OH) CarbonateGoethite FeO(OH) Fe> hydroxylapatite
Gypsum CaSO4.2H20 Ca, O Opal-CT
Hematite Fe2O, Fe2+ _________________________ _________________________ Gypsum
K-feldspar KAISiO, K+, H4SiO4, *Humic substances refer to particulate organics, including organics concentrated in peats and mucks, and
K-mica KAI(Si,AI)O(QH,F), K', F-, HSiO,, disseminated In other sediments.
Kaolinite A12Si2O5(OH), AP+, H4S104, *
Opal (-A, -CT) SiO2.nH2O H4SiO4
Palygorskite (Mg,AI),Si4C0(CH).4HC Mg2, AP', H4SiO,, *
Pyrite FeS2 Fe> >, SO?2
Quartz SiC2 Essentialhy inert
Sepiolite Mg4Si6O5(OH),.6HO Mg2; HSO4, *
I ~Smectite, v. Montmorillonite (Na,Ca)03(AI,Mg)2Si0,(CH), nHC Na;,Gaa, Mg',AP+,
HSiO,, *
3 Smectite, v Nontronite Na03Fe2(Si,AJ)4O0(OH)2.nH,0 Na-, Fe', Alt, H4SiO4, *








67






SPECIAL PUBLICATION NO. 34I


Table 6. Summary of temperature d4strnbution (C), by regon and aquifer system. Tabte 7. Summary of pH dtstribution (s.u.), by region and aquifer system.U

A. Surficial aquifer system A. Surficial aquifer system


District Median I Ortile iOrtile #tSamples Minimum Maximum District Median I 0rtile t 0rtile #tSamps #tExc* Min Max
NWFWMD 22 0 21 0 23 1 84 18.0 25 1 NWFWMD 4.9 3.8 5.6 84 78 3.0 10.23
SRWMD 240 22 0 25 0 23 21.0 27.0 SRWMD 5.6 5.1 6.0 25 22 4.5 9.5
SJRWMD 24.0 22.3 25.0 44 19.0 29.0 SJRWMD 6.6 5.9 7.2 53 24 3.5 9.9
SWFWMD 25.0 24.0 25 5 99 21.0 31 5 SWFWMD 6.5 5.5 7.2 97 52 3.9 8.6
SFWMD 24 8 23 3 26 0 671 18.5 30 0 SFWMD 6.9 6.5 7.2 809 219 3 9 13.2
Statewide 24.4 23.0 25.9 921 18.0 31.5 Statewide 6.8 6.3 7 1 1068 395 3.0 13.2
Sand &Gravel 22.0 21.0 23.1 75 18.0 25.1 Sand & Gravel 4.9 3.8 5 6 75 70 3.0 10.2
Biscayne 25 0 24 0 26 0 313 18.5 30 0 Biscayne 6.9 6.6 7.2 477 103 5.6 10.5
Other 24 2 23.3 25 2 533 19 0 31.5 Other 6.7 6.0 7 1 516 222 3 4 13.2

B. Intermediate aquifer system B. Intermediate aquifer system

District Median I Ortile t Ortile #t Samples Minimum Maximum Distict Median I Ordile I Ortile #t Samps #t Exo Mini Max
NWFWMD 23.2 22.2 24.0 24 21.0 26.0 NWFWMD 7.2 6.7 7 9 24 7 4.3 9 5
SRWMD 22 0 21 0 23 0 27 18 0 24.0 SRWMD 6.5 5.2 6.8 36 21 4.0 9.3
SJRWMD 24 0 22 0 25 0 21 IS 0 25.5 SJRWMD 7.1 7.0 7.5 29 3 5.1 11 3
SWFWMD 25.0 24.0 26.0 60 23.0 30.0 SWFWMD 7.5 7.3 7 7 56 4 6.7 10.5
SFWMD 25.1 24.4 25.6 102 22.3 27.5 SFWMD 7.3 7.0 7.5 94 4 6.1 8.5
Statewide 24 6 23.5 25 4 234 48 0 30.0 Statewide 7.3 6.9 7.6 239 39 4.0 11 3

C. Floridan aquifer system C. Floridan aquifer system

District Median Ortile I Grile #t Samples Minimum Maximum District Median I Qrnile t anile # Samps # Ext Min Max
NWFWMD 23.0 22.0 24.9 101 19.0 28.9 NWFWMD 7.5 7.1 7.8 101 3 6.6 8.8
SRWMD 23 0 21.0 24 0 157 15 O 29.0 SRWMD 7.1 6.6 7.9 220 63 4.9 12 5
SJRWMD 23 0 22.0 24 0 77 18 0 27.0 SJRWMD 7.3 7.0 7.7 100 10 6.2 12 2
SWFWMD 25.0 24.0 26.0 191 21.5 30.5 SWFWMD 7.5 7.3 7 8 172 I6 6.0 10.7
SFWMD 26.3 24.8 27.1 131 22.2 30.5 SFWMD 7.4 7.1 7 6 125 8 5.6 8.9 Statewide 24.0 23.0 25.5 657 15.0 30.5 Statewide 7.4 7.0 7 8 718 100 4.9 12.5
Number of samples which exceeded Florida Secondary Dninking Water
Standards for pH ( <6.5 or > 8.5 s.u.).

68







FLORIDA GEOLOGICAL SURVEY

H Tabie S Concentrations of selected constituents in average sea water, ranked by abundance Data compiled Table 9. Classification of water hardness (from Durfor and Becker, 1964).
from various sources by Drever (1988). The predicted concentration in Flornda precipitation is determined by multiplying the mole ratio in sea water times the state-wide average concentration of chlornde in precipitation
(1 66 mig/L, Table 3).
Constituent Cono. in Mole ratio Predicted Hardness Range Description
I Sea Water to Ci- in Cony. in (mg/L as CaCO )
Sea Water Avg. Florida ___________________(mg/kg) Precipitation0-60Sf

(mg/L) 61 120 Moderately hard

Chloride 19,350 1 000 1.66 11-10Hr
Sodium 10,760 0.857 1.42Mretn18Vryhd

Sulfate 2,710 0 052 0 09
Magnesium 1,290 0 097 0 16
Calcium 411 0.019 0.03

Potassium 399 0.019 0.03
Bicarbonate 142 0.0043 0 0071
I Fluoride 1.3 0 00013 0.00022
Trace Constituents ( g/kg) _______ ( g/L)
Nitrate 5-2,000 1.5x107 0.25-98
5.9x1053
Phosphate 1-50 1 9x108* 0.032 -1 6
_ _ _ _ _ _ _ _ _ _ _ _ _ _- 9.7x10-_ _ _ _
Dissolved organic carbon 300-2,000 NA NA
Iron 2 6.6x1O" 0.11
Mercury 0.03 2.7x1 0-<0 00046
Lead 0 03 2.7x10 '0 0.00044

NOTE 1 The predicted concentration in precipitation assumes that the only sources of chemicals in rainfall are
manne aerosols The predicted concentration is calculated by

I =*" 1.66 = 8.57 x lO5 X.
19,350
Xis the predicted concentration in precipitation, in mg/L. X)Q is the concentration of the chemical in sea I water (mg/kg, Table 8). Chloride concentrations are: 19,350 mg/kg in sea water and 1.66 mg/L in precipitation
(Table 3)










69






SPECIAL PUBLICATION NO. 34


Table 10. Summary of total calcium distribution (Ga> mg/L), by region and aquifer system. Table 11 Summary of total magnesium distribution (Mg2), by region and aquifer system

A. Surficial aquifer system A. Surficial aquifer system


District Median I Ortile anrile #tSamples Minimum Maximum District Median I Ortile I Ortile # Samples Minimum Maximum
NWFWMD 3.7 1.6 8 8 84 < 01 38.0 NWFWMD 0.9 0 6 2.0 84 0.2 20.0I
SRWMD 11 0 5.2 40.0 25 0.4 240.0 SRWMD 1.6 1.2 3 2 25 0 1 44.0
SJRWMD 43.0 12.0 94.0 64 < 1.0 857 0 SJRWMD 3 2 1.7 7.5 64 0 3 13&0I
SWFWMD 22.3 7.5 58.8 84 0.2 763.0 SWFWMD 3.5 1.1 11.5 85 < 0.1 401.0
SFWMD 98.0 73.3 124 0 610 < 1.0 756.0 SFWMD 3.9 2.7 6.5 229 0.1 51.9U
Statewide 85.6 27.7 118 0 867 < 0.1 857.0 Statewide 3.1 1.6 6 4 487 < 0.1 401.0
Sand & Gravel 3.6 1 6 8.9 75 < 0.1 38.0 Sand & Gravel 0.9 0.6 2 0 75 0.2 13.0U
Biscayne 97.4 79.4 125.0 248 1 4 260.0 Biscayfle 3.9 2 7 6.5 229 0.1 51 9

Other 85 6 25.6 119.4 544 0.2 857 0 Other 3.0 1.3 8.8 183 < 0 1 401.0

B. Intermediate aquifer system B. Intermediate aquifer system


DistictMedian I rtile t arnile #t Samples Minimum Maximum District Median I Grile I Odtile # Samples Minimum Maximum
NWFWMD 37.5 19.0 60.0 24 3.7 270.0 NWFWMD 2.5 1.2 5 4 24 0 4 59.0
SRWMD 28 0 9.4 46.0 36 4 5 220.0 SRWMD 8.7 1 0 21.0 37 < 0.1 52.0
SJRWMD 52.0 27.0 133.0 33 1.6 3360 SJRWMD 48 2.6 14.0 33 0.1 255.0I
SWFWMD 61.0 43 6 106.0 52 2.3 397.0 SWFWMD 24.0 13.9 47.2 52 < 0.1 135.0
SFWMD 70.5 43.2 100 0 103 2.5 478.0 SFWMD (f) 26.6 19.4 67.6 103 2.2 465.6I
Statewide 58.0 36 0 100 0 248 1.5 478.0 Statewide 17.7 9.5 40 9 249 < CI1 465.6 C. Floridan aquifer system C. Floridan aquifer system


District Median I Grile I Ontile # Samples Minimum Maximum District Median anQrile I Grile # Samples Minimum MaximumU
NWFWMD 34.0 21.0 46.0 101 2.2 443.0 NWFWMD 6 4 3.0 12.0 101 0.3 60.0
SRWMD 82.0 51 0 150.0 220 0.6 1000.0 SRWMD 6 3 2.6 19.0 220 < 0.1 4300 I
SJRWMD 41.0 240 64.0 125 4.0 546.0 SJRWMD 11.0 50 32.0 125 0.4 5210
SWFWMVD 68.1 41.7 98.0 165 36 639.0 SWFWMD 7.0 22 23.0 166 01 180.0I
SFWMD 67.2 42.1 94.1 138 5.9 227.0 SFWMD (f) 46.4 20 7 84 7 137 < 0 1 264.2
Statewide 51.9 28.5 84.1 749 0.6 1000.0 Statewide 14.6 6 3 33 1 749 < 0 1 521.0I

(- Dissolved (filtered) Magnesium, mg/[L


70







FLORIDA GEOLOGICAL SURVEY

H Table 12. Summary of total sodium distribution (Nat mg/L), by reion and aquifer system. Table 13. Summary of total potassium distribution (K+, mg/L), by region and aquifer system.

A. Surficial aquifer system A. Surficial aquifer system


District Median I arile t Ordile # Samps #t Exe Min Max District Median I Ortile I Ortilo # Samples Minimum Maximum
NWFWMD 5.0 3.2 8 2 84 1 1.2 310.0 NWFWMD 1.2 0 7 2 6 84 0.2 31.0
SRWMD 5.0 2.6 7.0 25 0 0 8 30 0 SRWMD 1 5 0.5 3.4 25 < 041 19.0
S.JRWMD 17.5 8.0 47 0 64 10 2.0 868.0 SJRWMD 2 0 0 9 4 4 64 0.2 601.6
SWFWMD 6 4 3.4 15.5 85 2 017 3730 0 SWFWMD 0.8 0.3 2 3 85 < 0 1 29.7
SFWMD 21 1 11 9 45.2 610 25 1 6 620.0 SFWMD 1 3 0 7 2 8 610 < 0.1 159.2
Statewide 17 0 7.0 39.0 868 38 0 7 3730.0 Statewide 1.2 0.7 2 8 868 < 0 1 601.6
Sand & Gravel 5.0 3 2 8.6 75 0 1 3 160.0 Sand & Gravel 1.4 0.7 2 5 75 0.2 31.0
3Biscayne 18 0 11 1 31.0 248 7 2 1 420.0 Biscayne 1.1 0.7 2 2 248 < 0 1 69.0
Other 19.4 7.3 48.3 545 31 0.7 3730.0 Other 1.3 0.6 3.0 545 < 0.1 601.6

B. Intermediate aquifer system B. Intermediate aquifer system

District Median I Ornile t anile # Samps #t Exc Min Max District Median I anile t Ortile # Samples Minimum Maximum
NWFWMD 4.5 3.3 20.0 24 0 1.0 78 0 NWFWMD 2.2 0.9 4 2 24 0.4 78 0
SRWMD 4.3 3.7 7.4 37 0 2.3 23 0 SRWMD 0.6 0 5 0 8 37 < 0.1 19.0
SJRWMD 14 0 8 7 31.0 33 5 5.8 2585.0 SJRWMD 2 3 1 2 8 4 33 0.2 85 0
SWFWMD 31 7 12 9 73.5 52 6 2.9 357 0 SWFWMD 2.7 1.3 6.2 52 0.3 22.4
SFWMD 108.6 51.8 369.0 103 46 11 4 1264.0 SFWMD 9.6 6.8 49 2 103 0.4 46.9
Statewide 41.0 9.6 136.2 249 57 1.0 2585.0 Statewide 4.4 1.3 11.0 249 < 0 1 85.0

C. Floridan aquifer system C. Floridan aquifer system


District Median I Ortile I Ortile # Samps #t Exc Min Max District Median I arnile t Ortile # Samples Minimum Maximum
NWFWMD 6 0 2 9 27 0 102 1 0.7 350.0 NWFWMD 1 6 0 6 4 7 101 0.2 76 0
SRWMD 6.3 3.7 12.0 220 5 0.2 3200 0 SRWMD 1I1 0.4 4 2 220 0.1 320.0
SJRWMD 20.0 7.9 80.0 125 22 1 0 7043.0 SJRWMD 1.7 0.9 4 2 125 0.2 251 0
SWFWMD 7.4 4.3 28.9 165 18 1.8 1450.0 SWFWMD 1.0 0.4 3.2 166 < 0.1 145.0
SFWMD 220.5 42.1 490.0 138 81 2 7 2500.0 SFWMD 9.5 2.5 20.8 138 0.5 99.0
Statewide 11.0 4.5 84 6 750 127 0 2 7043.0 Statewide 1 8 0 7 6.7 750 < 0 1 320.0

Number of samples which exceeded Florida Primary Drnnking Water Standards for Sodium (> 160 mng/L).


71






SPECIAL PUBLICATION NO 34


Table 14 Summary of total iron distribution (F& +Fe&, mg/L), by region and aquifer system Data from non- Table 15 Summary of total mercury distribution (Hg, pg/L), by region and aquifer system metal cased wells.

A. Surficial aquifer system A. Surficial aquifer system

District Median I Ortile I Ortile # Samps #1 Exc Min Max District Median I Ortile I Ortile # Samps #1 Ext Min Max
NWFWMD 2.05 0.78 6.75 80 72 0.07 95 00 NWFWMD < 0.5 < 0.5 < 0.5 84 8 < 0.5 7 3
SRWMD 1.09 0.32 2.85 23 18 <0.01 18.00 SRWMD <0.2 <0.2 <0.2 23 1 <0.2 303
SJRWMD 4.09 0.61 9.73 51 45 0.09 56.21 SJRWMD < 0 5 < 0.5 < 0 5 58 2 < 0.5 52 0

SWFWMD 2.14 0 32 8.39 39 30 < 0.03 43.90 SWFWMD < 01 < 0.1 < 01 67 3 < 0.1 3.1
SFWMD 0.88 0.20 2.58 376 263 < 0.01 41.50 SFWMD < 0 2 < 0.2 < 0.2 424 0 < 0.1 0.6
Statewide 1.08 0.24 2.94 569 428 < 0.01 95.00 Statewide < 0.2 < 0.2 < 05 656 14 < 01 52.0
Sand & Gravel 2.00 0 79 6 30 73 66 0.07 95.00 Sand &Gravel < 05 < 05 < 05 75 8 < 0.5 7.3
Biscayne 1.19 0 27 2.46 155 120 < 0.01 8.46 Biscayne < 02 < 0.2 < 0.2 333 0 < 0.2 < 1.0
Other 0.89 0.24 4 75 341 242 <0.02 56.21 Other <0.2 <0.1 < 0.5 248 6 <0 1 52.0

B. Intermediate aquifer system B. Intermediate aquifer system


District Median I Ortile I Ortile # Samps # Exo'* Min Max District Median I Ortile I Ortile # Samps # Exct* Min Max
NWFWMD 0 60 0 23 2 40 22 14 0.02 35.00 NWFWMD < 0.5 < 05 < 05 37 1 < 03 2.2
SRWMD 117 <023 3.10 14 12 <0.05 15.00 SRWMD <0.2 <0.2 <0.2 27 0 <02 203
SJRWMD 0.46 033 172 21 16 <0.01 4.61 S.JRWMD <0.5 <05 <05 32 4 <05 80
SWFWMD 013 005 054 19 7 <0.02 12.10 SWFWMD <0.1 <01 <0.1 45 0 <0.1 1.3
SFWMD <0.05 <0.05 0.10 63 9 003 26.60 SFWMD <0.1 <0.1 <0.1 10 0 <01 <03
Statewide 007 <0.05 043 139 58 <001 3500 Statewide <0.5 <01 <05 151 5 <01 80

C. Floridan aquifer system C. Floridan aquifer system


District Median I 0,rtile I Ortile # Samps # Ext Min Max District Median 4 0,rtile I Ortile # Samps #1 Ext Min Max
NWFWMD 0.23 0.05 0.87 34 16 < 001 2 50 NWFWMD < 0.5 < 05 < 05 209 4 <0.3 6 5
SRWMD 0.61 0.17 1 60 135 95 < 001 17 00 SRWMD < 0.2 < 02 < 02 157 0 < 02 2.0
SJRWMD 0 19 0.06 0 89 48 24 < 0.01 24.92 SJRWMD < 0.5 < 05 < 0.5 113 2 < 0.5 4.7
SWFWMD 0 13 0 05 0 35 70 21 < 0.01 55.70 SWFWMD < 01 SFWMD < 005 < 005 < 005 32 0 < 0.02 0 29 SFWMD < 01 Statewide 0 21 < 005 1 00 319 156 <0.01 55 70 Statewide < 05 < 01 < 0.5 651 6 <041 6 5

Number of samples which exceed Florida Secondary Drinking Water Standards for Iron ( >0.30 mg/L). Number of samples which exceeded Flornda Primary Drinking Water Standards for Mercury (> 2.0 pg/L).


72







FLORIDA GEOLOGICAL SURVEY

I ~Table 16. Summary of total load distribution (Pb-, pg/L), by region and aquifer system Data from non-metar Tabpe 17 Summary of total bicarbonate distribution (HO, mg/L), by region and aquifer system. (n.d = not
cased wells determined)

A. Surficial aquifer system
A. Surficial aquifer system
District Median I Ortile I Ortile # Samps # Exc Min Max District Median I arnile t Ortile #t Samples Minimum Maximum
H NWFWMD < 10 7 15 80 10 < 1 10NWFWMD S < 1 16 84 < 1 232
SRWMD < 10 SJRWMD 23 < 10 58 46 18<1 3SJRWMD n d n.d n.d n d n d nid
SWFWMD 36 < 30 < 50 53 11 <2 60SWFWMD 34 < 5 136 84 < 1 322

SFWMD < 2 < 1 3 440 9 <173SFWMD 263 229 314 169 64 637
Statewide 2 < I < 10 642 48 < 1 4300 Statewide 138 10 260 362 < I 637
Sand&Gravel < 10 8 16 13 10 < 1 190 Sand&Gravel S < 1 13 75 < 1 134
Biscayne < 2 < 2 2 218 2 < 1 87 Biscayne 263 229 314 169 64 637

Other 7 1 30 351 36 < 1 4300 Other 27 8 101 118 < 1 322


I ~B. Intermediate aquifer system B. Intermediate aquifer system

District Median I Ortile I arnile # Samps # Exc Min Max Ditict Median Iaienle # Samples Minimum Maximum
I NWFWMD < 10 < IC < 10 22 1 3 63 NWFWMD 137 116 133 24 16 1463
SRWMD < 10 < 10 < 10 14 1 < 10 56 SRWMD 90 24 150 36 < 1 490 .
ISJRWMD < 10 < 10 13 21 2 < 4 192 SJRWMD n d n d n.d n.d n d. n d.
SWFWMD < 43 < 30 < 50 25 6 < 30 530 SWFWMD 173 118 213 53 4 306
ISFWMD 1 < 1 5 59 I < 1 71 SFWMD n d n d nid nid. n d n.
Statewide < 10 < 10 24 141 11 < 1 530 Statewide 143 95 200 113 < I 1463J


C. Forian auifr sytemC. Floridan aquifer system District Median I Ortile I arnile # Samps #t Exe Mm Max DsrcMein I rtl 1 Orile # Sarmples MinimumMamm
NWFWMD < 10 < 10 < 10 35 0 1 50 NWFWMD 158 122 207 101 29 451
I SRWMD < 10 < IC < 10 135 4 < 10 100 SRWMD 150 76 230 220 < 1 170

SSJRWMD < 10 < 10 31 41 9 4 260 SJRWMD n d n d n d n d nd. n d
I SWFWMD < 30 < 30 < 36 69 14 < 20 470 SWFWMD 144 116 181 162 3 646
SFWMD < 1 I ~Statewide < 10 < 10 25 316 27 < 1 470 Statewide 146 110 206 483 <171

Number of samples which exceeded Florida Prnmary Drinking Water Standards for Lead (> 50 LIg/L)


73






SPECIAL PUBLICATION NO. 34I


Table 18 Summary of total carbonate distribution (CO32 mg/L) by region and aquifer system. (nd. = not Table 19. Summary of total bicarbonate alkalinity distribution (mg/L), by region and aquifer system .(nd. = notI determined) determined)

A. Surficial aquifer system A. Surficial aquifer system


Ditit Median I anile t Ortile # Samples Minimum Maximum District Median I Ortile I Ordile #t Samples Minimum Maximum

NWFWMD n.d n.d nd. nd. nd. n. NWFWMD 4 < 1 13 84 < 1 190i
SRWMD < 1 < 1 < 1 23 < 1 70 SPWMD nd. nd. nd. nd. nd. nd.

SJRWMD nd. nd. nd. n d. n.d n d ** SJRWMD 147 70 238 59 1 508

SWFWMD < 1 < 1 < 1 71
SFWMD n.d. nd. nd. nd. nd. nd. **SFWMD 251 202 312 581 3 2260
Statewide < 1 < 1 < 1 94 < 1 70 Statewide 111 72 165 742 < 1 2260

Sand &Gravel n.d. n.d. n d n.d nd. nd. Sand & Gravel 4 < 1 11 75 < 1 1101
Biscayne nd. nd. nd. nd. nd. nd. ** Biscayne 242 212 294 219 64 637

Other < 1 < 1 < 1 94 < 1 70 Other 244 160 315 448 < 1 2260

B. Intermediate aquifer system B. Intenrmediate aquifer system


District Mein arnile anOrile # Samples Minimum Maximum DsrtMein anl anile #t Samples Minimum Maximum

NWFWMD nd. n.d. n.d. n.d. nd. nd. NWFWMD 113 95 150 24 < 1 1200I
SRWMD < 1 < 1 < 1 27 < 1 22 SRWMD nd. n d n.d R~d nd. nd.

SJRWMD nd. nd. nd. nd. nd. nd. ** SJRWMD 238 169 290 30 17 561

SWFWMD
SFWMD n d n d n d nd. nd. nd. **SFWMD 234 171 271 102 111 445I

Statewide < 1 < 1 < I 71 < 1 116 Statewide 205 128 243 163 < 1 1200 C. Floridan aquifer system C. Floridan aquifer system


District Median anl ani le # Samples Minimum Maximum DsrtMeian nieI Ortile #t Samples Minimum MaximumI

NWFWMD nd. nd. nd. n.d. nd. n d NWFWMD 130 100 170 101 24 370

SRWMD < 1 < 1 < 1 157 < 1 650 SRWMD nd. n.d. nd. nd. nd. nd.

SJRWMD n.d. n.d n.d. nd. nd. nd. **SJRWMD 145 99 188 103 11 866

SWFWMD < 1 < 1 < 1 152 < 1 46 SWFWMD 468 114 215 10 106 530I

SFWD ~d n. dn~ n. d.*SFWMD 1305 380287

** -Calcium Carbonate Alkalinity, mg/L.
+- Data reported in meq/L.


74I







FLORIDA GEOLOGICAL SURVEY


I Table 20 Sumrmary of total sulfate distribution (5042, mg/L), by region and aquifer system. Table 21. Summary of total chloride distribution (Cl- mg/L), by region and aquifer system.


I ~A. Surficial aquifer system A. Su~rficial aquifer system

District Median I Ortile I Ortile # Samps # Exo Min Max District Median I Ortile I Ortile # Samps # Exo Min Max
NWFWMD 3.3 1 5 6.0 84 2 < 10 380 0 NWFWMD 7.0 5 0 11 5 84 1 1 8 410.0
SRWMD 4 3 < 10 13 0 23 0 < 0.1 33 0 SRWMD 6 0 3 0 8.2 25 0 1.4 32 0
SJRWMD 12.0 3 0 30.0 61 4 < 1.0 597 0 SJRWMD 28.0 13 0 91 0 62 12 4 0 1190 0
SWFWMD SI1 < 1 0 50.6 85 9 < 0.1 1480 0 SWFWMD 12 9 7 0 37.8 86 3 0.6 8520.0 SFWMD 11.8 < 50 24.0 614 4 < 1.0 431.0 SFWMD 48.3 26 2 83 0 857 48 < 04 1100 0
Statewide 17 0 7.0 39.0 867 15 < 0.1 1480 0 Statewide 40.5 16 0 74.3 1114 64 < 0.4 8520 0

Sand &Gravel 3.6 1 4 5.5 15 2 0.8 380.0 Sand & Gravel 7.1 5 0 11 0 15 0 2 3 220 0
Biscayne 14 0 < 2.0 26.0 257 0 < 1.0 185.0 Bhscayne 58.0 34.0 79.0 493 33 4.8 700 0

Other 10 0 < 50 24.5 535 13 < 0.1 1480.0 Other 30.5 13 0 74 7 546 31 < 04 8520 0

U B. Intermediate aquifer system B. Intermediate aquifer system

District Median I Ortile I Ortile # Samps # Ext Min Max District Median I Ortile I Ortile # Samps # Extt* Min Max
NWFWMD < 10 < 1.0 1.9 38 0 < 10 49.0 NWFWMD 5.3 3.0 8 9 24 0 1.7 58.0
SRWMD < 10 < 10 4 7 27 0 < 1.0 27.0 SRWMD 4.5 3.7 21 0 36 0 3.1 54.0

SJRWMD < 1.0 < 10 4 0 33 1 < 10 408.0 SJRWMD 18.5 12.5 42.5 32 4 7.0 4480 0
SWFWMD 369 <1.5 299.0 56 19 <0.1 1590.0 SWFWMD 50.0 13.2 204.0 56 13 2.7 940.0
SFWMD 52.3 14.4 182 0 91 13 2.0 1754.0 SFWMD 172.0 61.1 580.0 103 42 15.2 2092 5
Statewide 5.4 < 1.0 65.5 251 33 < 01 1154 0 Statewide 61 9 18.0 334.5 251 59 1.7 4480.0


C. Floridan aquifer system C. Floridan aquifer system

District Median I Ortile I Ortile # Samps # Ext Min Max District Median I Ortile t anile # Samps # Exe Min Max
NWFWMD < 1.0 < 1.0 4.4 147 1 < 10 310 0 NWFWMD 6.3 3.8 23.0 101 2 1 7 300.0
ISRWMD 6 7 1.7 16.5 157 2 < 1.0 2200 0 SRWMD 8 9 5 0 19.0 220 4 <1.0 5200 0
SJRWMD 8.5 < 1 0 83.5 122 13 < 1.0 2040.0 SJRWMD 28.0 12 0 203 0 122 27 1 0 16270 0
ISWFWMD 3 0 < 1.0 63.5 169 33 < 0.1 3102.0 SWFWMD 11 3 7 3 35.4 169 24 1.7 20500.0
SFWMD 176 4 49 3 308 4 135 46 3.3 713.1 SFWMD 419.6 58.6 922 5 136 84 3 5 3185 0
IStatewide 5 4 < 1.0 53.0 730 95 < 0.1 3102.0 Statewide 21.0 7 6 276.0 748 141 < 1.0 20500.0

Number of samples which exceeded Florida Secondary Drinking Water Standards for Sulfate (> 250 mg/L) Number of samples which exceeded Florida Secondary Drinking Water Standards for Chloride (> 250 mg/L).

75





SPECIAL PUBLICATION NO. 34


Table 22 Summary of total ortho-phosphate distribution (P043 as P, mg/L), by region and aquifer system. Table 23. Summary of total fluornde distribution (F- mng/L), by region and aquifer system.I A. Surficial aquifer system A. Surficial aquifer system

District Median I Ornile I Grile # Samples Minimum Maximum District Median I Ortile I Ortile #t Samps # Exct* Min Max

NWFWMD (P) 0.09 0.05 0.23 84 < 005 1.20 NWFWMD 0 04 0 03 0.07 84 1 < 002 5.90
SRWMD <0.10 < 010 < 010 25 < 001 0.20 SRWMD < 020 < 020 < 0.20 25 0 < 002 0 79
SJRWMD (P) 0.11 0.05 0.32 64 < 0.01 1.82 SJRWMD < 010 < 010 0.14 63 0 < 0.01 1 75
SWFWMD (t) 0.07 0.02 0.27 82 < 0 01 1.84 SWFWMD 0.10 0.04 0.25 84 0 < 0.01 1.95
SFWMD (f) 0.01 < 0.01 0.02 357 < 001 4.00 SFWMD 0 20 < 010 0.30 608 0 0.02 3.733

Statewide 0.06 0.02 0.17 612 <0.01 4.00 Statewide 0 17 <0 10 0.28 864 1 <0.01 590
Sand & Gravel 0.09 0.05 0.22 75 0.01 1.20 Sand & Gravel 0.04 0 03 0.07 75 1 <0 02 5.90I
Biscayne (f) < 001 < 0.01 < 0.01 19 < 001 0.06 Biscayne 0 20 0.15 0.25 279 0 0.06 0.93

Other 0.07 < 0.05 0.06 518 < 001 4.00 Other < 020 < 010 0.31 510 0 < 001 3 733

B. Intermediate aquifer system B. Intermediate aquifer system

District Median I Ortile I Ordile # Samples Minimum Maximum District Median I Ordile I Ortile #t Samps # Exct* Min Max
NWFWMD (P) < 0.05 < 0.01 0.11 29 < 0.01 1.20 NWFWMD 0 19 0 13 0.23 25 0 < 0.05 0.53
SRWMD < 010 < 0.01 < 0.10 36 < 001 2.00 SRWMD < 0.20 0.20 0.30 36 0 < 001 1 00
SJRWMD(P) 0.11 0.03 0.21 33 <0.01 0.43 SJRWMD 012 <010 0.30 33 0 <0.10 175
SWFWMD (t) 0.11 0.04 0.16 52 < 001 1.20 SWFWMD 0.89 0 30 1.15 53 0 0.07 4.00
SFWMD (f) < 001 < 0.01 < 0.01 103 < 001 2.28 SFWMD 0 82 0.43 1.30 103 1 < 010 4.78
Statewide 0.04 0.01 0.10 253 < 0.01 2.28 Statewide 0 39 < 020 __0.97 250 1 < 001 4.78

CFloridan aquifer system C. Floridan aquifer system


District Median I Ortile I Ortile #t Samples Minimum Maximum District Median I Oflile t Ortile #t Samps # Exo Min Max3
NWFWMD (P) 0.04 0.02 0.06 116 < 0.01 1.60 NWFWMD 0.13 < 005 0.37 122 1 < 0.10 6.90

SRWMD < 0.10 < 0.10 <0410 220 < 0.01 21.00 SRWMD < 0.20 < 0.20 < 0.20 220 0 < 002 2.50
SJRWMD (P) 0 04 0.01 0.41 122 < 0.01 0.75 SJRWMD 0.16 < 0.10 0.26 124 0 < 010 1.28
SWFWMD (t) 0 10 0 05 0.17 152 < 0.01 0.80 SWFWMD 0.16 0 10 0.36 162 0 0.01 2.32
SFWMD (f < 001 < 001 < 0.01 115 < 0.01 0415 SFWMD 0.81 0 40 1.26 131 0 < 0.10 3.70
Statewide 0.04 0 02 0 07 725 < 0.01 21 00 Statewide 0.20 0 12 0 41 759 1 < 0.02 6.903

(P) Total Phosphorus (P), mg/L. Number of samples which exceeded Florida Primary Drinking Water Standards for Fluoride ( >4.00 mg/L).
(t) Total Phosphate as P04, mg/L.I
(f) Dissolved (filtered) ortho-phosphate, mg/L.
76







FLORIDA GEOLOGICAL SURVEY


U Table 24. Summary of total nitrate distribution (NO> mg/L as N), by region and aquifer system Table 25 -Summary of total dissolved solids concentrations (TDS,mg/L), by region and aquifer system.

I A. Surficial aquifer system A. Surficial aquifer system

D itdt Median rile Gflrile # Samps # Exe Min Max Distrit Median I arnile t rtile # Samps # Exn Min Max
NWFWMD 0 81 0.29 2 00 84 3 0 07 28 00 NWFWMD 74 46 125 84 3 16 1000
SRWMD <005 <005 <0 05 25 0 <0.05 1.10 SRWMD 70 45 110 23 0 27 320

** SJRWMD <0.01 <0.01 003 64 0 <001 750 SJRWMD 300 151 472 63 14 63 3821
+e+ SWFWMD < 0.01 < 001 0 18 84 1 <0.01 52.52 SWFWMD 187 80 336 83 11 1 17700
SFWMD <0.01 <0.01 <0.01 571 1 <0 01 44.80 SFWMD 388 296 513 656 170 26 2537
Statewide < 0.01 < 001 0.01 828 5 < 001 52.62 Statewide 346 181 474 909 198 1 17700
Sand & Gravel 0.95 0.37 2.30 75 3 0 07 28.00 Sand & Gravel 74 45 110 75 2 15 1000
Biscayne < 0.01 <0 04 < 0.01 239 1 < 001 44.80 Biscayne 392 316 468 288 55 108 1712

Other <0.05 <0.01 0.03 514 1 <0.01 52.52 Other 339 160 612 546 141 1 17700

I B. Intermediate aquifer system B. Intermediate aquifer system

District Median I Oflile t anile #t Samps #t Exe Min Max District Median I Grnie t arnile # Samps # Ext Min Max
NWFWMD O11 <0.01 1.20 35 0 <0.01 6.70 NWFWMD 165 130 260 24 0 36 390
SRWMD <005 <0.05 <005 36 0 <0.01 7.10 SRWMD 100 57 190 27 0 18 350
I** SJRWMD < 0.01 < 0.01 < 0 01 33 0 < 0.01 0 03 SJRWMD 355 241 397 33 6 38 6892
++ SWFWMD 0 01 < 0.01 0 02 52 0 < 0.01 3.50 SWFWMD 525 286 943 54 28 40 2340
USFWMD < 0.01 < 0.01 < 001 100 0 < 0.01 0.19 SFWMD 508 417 1427 103 55 47 4188
Statewide <0.01 <0.01 <0.05 256 0 <0.01 7.10 Statewide 390 219 871 241 89 I8 6892


C. Floridan aquifer system C. Floridan aquifer system

IDistrict Median I Grnile t antile # Sam~ps # Ext Min Max Distriot Median I Grile I anile #t Samps # Exo Min Max
NWFWMD 0.90 < 001 1I5O 123 7 < 0.01 74.00 NWFWMD 200 160 310 101 10 42 810
I SRWMD <0.05 <0.05 <0.05 220 0 <0.01 840 SRWMD 220 160 300 157 21 40 10200
** SJRWMD <0.01 <001 0.03 123 1 <0.01 1840 S.JRWMD 342 183 598 123 37 47 24092

++ SWFWMD 0.01 <0.01 0.05 153 0 <001 4.64 SWFWMD 257 176 656 161 47 55 5990
SFWMD < 0.01 < 001 < 0.01 120 0 < 0.01 1 97 SFWMD 1138 414 2045 138 97 58 7425 '
I Statewide <0.01 <0.01 0.05 739 8 <001 74.00 Statewide 277 176 715 680 212 40 24092

umbr o saple whch eceeed lona Pmar DnningWatr Sandrdsfor* Number of samples which exceeded Florida Secondary Drinking Water Standards for Total Dissolved Solids Nitrate as N (> 10.00 mg/L) or Nitrate as NO, (> 43.00 mg/L). (TDS) (>6500 mg/L)
** -Reported as Nitrate + Nitrite (NO,), mg/L. 77
++. Reported as Nitrate as NO3, mg/L.






SPECIAL PUBLICATION NO. 34


Table 26. Summary of specific conductance distribution (ptmhos/cml), by region and aqurfer system. Table 27 Summary of total organic carbon distribution (TOC,mg/L), by region and aquifer system.

A. Surticial aquifer system A. Surficial aquifer system

District Median i Ortile I Qrnile # Samples Minimum Maximum District Median j arile t Ortile #t Samples Minimum Maximum
NWFWMD 50 35 88 84 15 1522 NWFWMD 6.8 4.2 9 7 84 1 9 42.4
SRWMD 90 60 160 25 20 500 SRWMD 5 9 < 1 0 17 5 23 < 1.0 50.0
SJRWMD 335 140 625 49 40 3900 SJRWMD 90 4 3 16.9 58 < 0.1 257.3U
SWFWMD 255 1OS 450 100 30 24000 SWFWMD 11 4 3.4 22.1 82 < 0.1 122.0
SFWMD 619 450 894 318 41 8281 SFWMD 17.0 9 5 31.1 548 < 0.1 380.0I
Statewide 475 138 743 636 15 240CO0 Statewide 14.0 1.0 27.0 795 < 0.1 380.0
Sand & Gravel 50 34 85 75 15 747 Sand & Gravel 6.6 4.1 8.4 75 1.9 25.2I
Biscayne 517 415 587 19 383 687 Biscayne 14.3 8.4 227 258 1 0 73.0
Other 540 220 805 542 15 24000 Other 16.9 7.8 36 0 462 < 0.1 380.0U

B. Intermediate aquifer system B. Intermediate aquifer system

District Median I Ortile I Ortile #t Samples Minimum Maximum District Median I Ortile t Oflile # Samples Minimum Maximum
NWFWMD 229 193 348 24 41 593 NWFWMD 6 1 2 1 8.9 26 < 1.0 31.0
SRWMD 160 80 270 36 25 500 SRWMD < 1.0 < 1.0 2.8 27 < 1.0 12.0
SJRWMD 575 390 660 22 15O 8000 SJRWMD 5.5 3.9 7.7 32 1.4 26.4I
SWFWMD 600 410 1200 61 50 3325 SWFWMD 9.8 < 1.0 21.6 52 < 0 1 52.3
SFWMD 947 703 2324 100 245 6920 SFWMD 6.3 2.0 19 0 91 < 0 1 71 0I
Statewide 650 319 1500 243 25 8000 Statewide 4.8 < 1.0 13 1 228 < 0.1 71.0

C. Floridan aquifer system C. Flodidan aquifer system

District Median O drile t arnile # Samples Minimum Maximum District Median I Ortile t anile # Samples Minimum MaximumI
NWFWMD 274 216 470 101 81 1542 NWFWMD < 1.0 < 1 0 3.2 178 < 0.1 39.0
SRWMD 310 240 450 220 50 15000 SRWMD 2.0 < 1 0 6.2 157 < 1.0 34.0I
SJRWMD 500 282 899 96 70 14500 SJRWMD 3.3 1.5 5.4 111 < 0.5 29.0
SWWD378 255 800 194 100 46000 SWPWMD 16.8 10.4 27.1 150 < 0.1 78.8I
SFWMD 1787 624 3305 131 120 12204 SFWMD 1.9 0.5 3 5 114 < 0.1 80.6
Statewide 385 251 1000 742 50 46000 Statewide 2.2 < 1.0 7 9 710 < 0.1 80.6I




78







FLORIDA GEOLOGICAL SURVEY


Table 28. List of synthetic organics analyzed in the Background Network, with guidance concentrations or
standards (Florida Department of Environmental Regulation, 1989).

Parameter Parameter Name Units Guidance Parameter Parameter Name Units Guidance
Number Concentration* Number Concentration*



S11 METHYL BLUE ACTIVE SUBSTANCES mg/I 500 121 TRICHLOROETHENE pg/I 3
I ~86 CIS/TRANS-12-DICHLOROETHYLENE jg/I mdl 122 PHENANTHRENE jg/I mdl
87 METHYL ISOTHIOCYANATE pig/I mdl 123 BENZIDINE pig/I md
S88 CIS/TRANS-12-DICHLOROETHYLENE pig/I mdl 124 DI-N-BUTYL PHTHALATE pig/I mdl
89 1 ,2-BENZISOTHIAZOLE pgImdl 125 VINYLGCHLORIDE ag/ 1
90 PETROLEUM HYDROCARBONS vg/ mdl 126 TRIMETHYLBENZENE [g/l 10
91 METHYL-TERT-BUTYL-ETHER ig/ mdi 127 BIS(2-ETHYLHEXYL)PHTHALATE kg/ mdl
92 METHYL N-BUTYL KETONE g/A mdl 128 PYRENE k9/1 mdl
93 TOTAL TRIHALOMETHANE mg/I 100 129 ETHYL BENZENE kg/ 2
3 ~94 METHYL ISO-BUTYL KETONE igI 350 I3O TETRACHLOROETHENE kg/I 3
95 4,6 DINITRO 0-CRESOL tg/l 50 131 CHLOROTOLUENE pg/I rmdl
96 1 ,3-DIBROMO-2-CHLOROPROPANE g/Il mdl 132 VINYL ACETATE ptg/ rmdl
97 P-CHLORO M-GRESOL g/ 3,000 133 BIS(2-CHLORO-1 -METHYL) ETHER pig/I mdl
98 HEXACHLOROBUTADIENE ~g/ 10 134 CAS 1,3 DICHLOROPROPENE pg/I 1
99 2-METHYL-4,6-DINITROTOLUENE pig/I mdl 135 HEXACHLOROETHANE pig/I 10
I ~100 DICHLORODIFLUOROMETHANE pig/I mdl 136 NAPHTHALENE pg/I md
101 DIBENZO(A,H)ANTHRACENE pig/I mdl 137 PHENOL pg/I md
102 1 ,3-DIHLOROPROPENE jg/I mdl 138 TRANS 1,3 DICHLOROPROPENE pig/I 1
I l1O3 TRICHLOROFLUOROMETHANE jg/I mdl 139 1,2-DIBROMOETHANE (EDB) pig/I 0.2
104 1,1 DICHLOROETHANE jg/I 2,400 140 INDENO(1 ,2,3-CD)PYRENE pig/I 10

S105 1,1 DICHLOROPROPANE pg/I mdl 141 1,2,4 TRIETHYL BENZENE g/l mdl
I ~106 1,1 DICHLOROETHENE jg/I 7 142 BENZO(B)THIOPHENE pig/ mdl
107 HEXACHLOROBENZENE pig/I mdl 143 N-BUTYLBENZENE [g/ mdl
S108 PCB-1254 pg/i 0.5 144 N-PROPYLBENZENE g/ mdl
I ~109 TRICHLOROPHENOL ISOMERS vg/ mdl 145 BROMOMETHANE vg/ 20
110 PCB-1 242 vg/1 0.5 146 M XYLENE tg/I 50
li11 1,1,1 TRICHLOROETHANE pg/A 200 147 CHLOROMETHANE g/l 3,800
I 112 CIS-1 ,2-DICHLOROETHENE tg/A mdl 148 STYRENE pig/I 1
113 1,1,2 TRICHLOROETHANE pg/ 1 149 PCB-1016 pig/I 0.6
S114 METHYL ETHYL KETONE pg/I 170 150 BROMODIGHLOROMETHANE pg/I 100
115 1,1,2,2 TETRACHLOROETHANE jig/I 1 151 TOTAL PCB'S jig/I 0.5
116 XYLENE pig/I 50 152 METHYLENE CHLORIDE pig/I 100
117 BENZO(G,H,I)PERYLENE jg/I mdl 153 BROMOFORM jig/I 100
118 DICHLOROBENZENE jig/I 75 154 N-NITROSODI-N-PROPYL AMINE pig/ 10
119 PCB-1232 jig/I 0.5 155 CHLOROFORM ag/i 100
3 120 4-CHLORO-3-METHYL PHENOL jig/I mdi 156 N-NITROSODIPHENYLAMINE g/] 10





I 79






SPECIAL PUBLICATION NO. 34


Table 28. (cont.) List of synthetic organics analyzed in the Background Network, with guidance concentrationsI or standards (Florida Department of Environmental Regulation, 1989)

Parameter Parameter Name Units Guidance Parameter Parameter Name Units Guidance
Number Concentration* Number Concentration*



157 TOTAL PHENOLS jg/I mdl 192 CARBON TETRACHLORIDE pg/I 33
158 N-NITROSODIMETHYLAMINE pg/i 20 193 DIBROMOCHLOROMETHANE ig/ 100
159 BENZENE pg/I 1 194 BENZOFURAN pg/I mdl
160 NITROBENZENE kg/I mdl 195 BENZO(A)ANTHRACENE pg/I mdl
16 CNPTEEpg/I 20 196 ACENAPHTHYLENE pg/I 10
162 ACROLEIN pg/1 110 197 1,2 DICHLOROETHANE pg/I 3
163 ACRYLONITRILE pg/i 2.5 198 BENZO(B)FLUORANTHENE pg/i 10
164 ANTHRACENE pg/A 10 199 1 ,2-DICHLOROBENZENE pg/1 mdl
165 P XYLENE pg/I 50 200 4-BROMOPHENYL PHENYL pg/I mdl
166 BENZO(K)FLUORANTHENE pg/I 10 201 1,2 DICHLOROPROPANE pg/I 13
167 BENZO(A)PYRENE pg/I 10 202 DIMETHYLPHTHALATE pg/I mdl
168 D-BHC pg/I 0.05 203 TRANS 1,2 DIGHLOROETHENE pg/I 4.2
169 BIS(2-CHLOROETHYL)ETHER pg/I 10 204 HEXACHLOROCYCLYPENTANE pg/I 103
170 BIS(2-CHLOROETHOXY)ME. ETHER pg/I 10 205 1 ,2,4-TRICHLOROBENZE pg/I mdl
171 BIS(2-CHLOROISOPROPYL) ETHER pg/I 10 206 O-XYLENE pg/I 50
172 BENZYL BUTYL PHTHALATE pg/I 1,400 207 CARBON DISULFIDE pg/I mdlU
173 CHLOROBENZENE pg/I 10 208 TOLUENE pg/I 24
174 CHLOROETHANE pg/I 6,300 209 4-NITROPHENOL pg/I mdl
175 DIETHYLPHTHALATE pg/I 5,600 210 4-CHLOROPHENYL PHENYL ETHER pg/I mdlI
176 2,6-DINITROTOLUENE pg/I mdl 211 3,3'-DICHLOROBENZIDINE pg/I mdl
177 PCB-1248 pg/i 0.5 212 DI-N-OCTYL PHTHALATE pg/i mdl
178 1,2 DIPHENYLHYDRAZINE pg/I 10 213 2-NITROPHENOL pg/ mdl
179 2,4,6-TRICHLOROPHENOL pg/I mdl 214 2,4-DICHLOROPHENOL pg/ mdl
180 2,4-DINITROPHENOL pg/I mdl 215 1 ,3-DICHLOROBENZENE pg/I mdl
181 2,4-DINITROTOLUENE pg/I mdl 216 1 ,4-DICHLOROBENZENE pg/I mdlI
182 2,4-DIMETHYLPHENOL pg/I mdl 217 2 CHLOROETHYL VINYL ETHER pg/I 1
183 ETHYLBENZENE pg/i 2 218 2-CHLORONAPHTHALENE pg/I mdl
184 FLUORANTHENE pg/I 42 219 2-CHLOROPHENOL pg/I mdl
185 FLUORENE pg/I 10 228 CHRYSENE pg/I 10
186 PCB-1262 pg/I 0.5 281 CHLOROFORM pg/I 100
187 112TRICLA22TRIF ETHANE pg/I mdl 282 TRICHLOROETHYLENE,DISSOLVED pg/I 3
188 ACETONE pg/I 700 283 VINYL CHLORIDE pg/I mdl
189 2378TETRACHLORODIBENZOPDIOXIN pg/I 200 284 M-XYLENE pg/I 50
190 PCB-1221 pg/I 0.5 289 PHENANTHRENEDISSOLVED pg/I mdl
191 PCB-1260 pg/I 0 5 297 PCNB pg/I mdl


mdl = Method Detection Limitu


80I







FLORIDA GEOLOGICAL SURVEY

I Table 29. Surmmary of total synthetic organics concentrations (pg/L), by region and aquifer system. Most Table 30. Classification of anthropogenic organics according to volatility in water. Modified from
detections were not confirmed by resampling. Lyman et al. (1982).

3 A. Surfioial aquifer system

District Median I Ortile I Ortile # Samps # Exo Min Max Horny's Law Constant Volatility
I NWFWMD 0.00 0.00 < 0.00 109 3 0 00 190.00 (atm ma/mol)

SRWMD 0 00 0.00 0 00 22 0 0.00 1 00 <1- o
SJRWMD < 0.50 < 050 < 0.50 58 4 < 050 128 00 10-' 1io5 Slight
SWFWMD < 1.00 < 1.00 < 1 00 83 2 < 1.00 6.70 10< 10 3 Moderate
SFWMD 0 00 0.00 < 1 .00 392 35 0 00 995.00>10 Hg

Statewide 0 00 0.00 < 1 00 664 44 0.00 995 00
Sand & Gravel 0.00 0 00 < 1.00 93 3 0.00 190 00
Biscayne < 10.00 < 1.00 < 10 00 21 2 < 100 12 00

Other 0.00 0.00 < 1.00 550 39 0 00 995.00

B. Intermediate aquifer system

District Median I arnile t Ortile # Samps # Exo Min Max
NWFWMD 0.00 0.00 <1.00 26 0 0 00 3.50

SSRWMD 0 00 0.00 0 00 24 0 0.00 0.00
SJRMD0._ __270 .0 0 2Table 31 Classification of synthetic organic mobility in water. Modified from Fetter (1988).

SWFWMD <1.00 <1.00 <1.00 52 0 <1.00 1.60
ISFWMD < 100 0.00 < 1.00 107 3 0 00 2.10 Mobility SolubilityKo
Statewide 0 00 0.00 -Very mobile miscible=1
C. Floridan aquifer system Very mobile > 4,000 1 50

District Median I anile t Oflile # Samps # Exo Min Max Moie400-__005-5
-Moderately mobile = 1,000 -- 100 150 500
NWFWMD 0 00 0.00 0 00 118 0 0.00 2.70
SRWMD 0.00 0 00 0.00 301 4 0.00 14.00 Low moblity =100 =10 500 -2,000

SSJRWMD < 050 < 0.50 < 0.50 110 5 0.00 20 20Sigtmbly=10- .520 -2.0
SWFWMD <1.00 <1.00 <1 00 168 12 000 70.01 m ble< .2>2,0
SFWMD 0 00 0.00 0 00 133 5 0 00 3.90
IStatewide 0 00 0 00 0 00 830 26 0.00 70.01




81






SPECIAL PUBLICATION NO. 34


Table 32. -- List of pesticides analyzed ,n the Background Network, as of 1989, with guidanceI concentrations or standards

Parameter Parameter Name Units Guidance Parameter Parameter Name Units GuidanceI
Number Concentration* Number Concentrationt


220 CHLOPOPICRIN jag/I 7.3 258 ATRAZINE pg/I mdl
221 PROPAZINE jpg/ mdl 259 PCNB pg/ mdl
222 AZINPH-OS METHYL pg/A mdl 260 PERTHANE pg/I mdl
223 ENDRIN-ALDEHYDE pg/i 0.1 261 2,4-DB jig/i mdl
224 ENDOSULFANI pg/l 0.4 262 METALAXYL pg/I mdl
225 ENDOSULFAN II jg/I 0.4 263 LINURON pg/I 22
226 ENDOSULFAN-SULFATE jig/I 0.3 264 TERBUTHYLAZINE pg/I mdl
227 ETHOPROP pg/A mdl 265 DINOSEB pg/i mdl
229 ALACHLOR pg/I 1I5 266 METHOMYL jig/I mdl
230 CHLORPYRIFOS pg/I mdl 267 ALDICARB pg/I mdl
231 NORFLURAZON pg/I mdl 268 SIMAZINE pg/I mdl
232 ISOFENPHOS pig/i mdl 269 PROMETON pg/I mdl
233 DICAMBA pg/I mdl 270 PROMETRYN jig/I mdl
234 CHLOROTHALONIL pg/i mdl 271 DIQUAT DIBROMIDE (REGLONE) jig/I mdl
235 METHYL PARATHION pg/I mdl 272 TRIFLURALIN pg/I mdl
236 ISOPHORONE pg/I 1050 273 PENDIMETHALIN pg/i mdlI
237 CARBARYL pg/I mdl 274 PERMETHRIN pg/i mdl
238 METAM-SODIUM pgA mdl 275 DIBENZOFURAN jig/I mdl
239 ETHYL PARATHION pg/I mdl 276 OPDDE pg/I mdl
240 KELTHANE pg/I mdl 277 OPDDT pg/I 0.1
241 NALED jig/I mdl 278 4,4'-DDD pg/i mdl
242 OXAMYL pg/i mdl 279 DIELDRIN pg/I mdl
243 DALAPON pg/I mdl 280 ALDRIN jig/I mdl
244 TERBUTRYN pg/I mdl 281 ENDRIN pg/I mdl
245 DICHLORAN pg/I mdl 282 B3-BHC pg/I mdl
246 TRIADEMEFON pig/I mdl 283 ETHION pg/I 14
247 METHIOCARB pg/I mdl 284 CHLORDANE jig/I mdl
248 METHAMIDOPHOS pg/I mdl 285 TOXAPHENE pg/I mdl1
249 PROPOXUR pg/I mdl 286 4,4'-DDT pg/I mdl
250 FENAMIPHOS pg/I mdl 287 ax-BHC pg/i mdl
251 CHLORPYRIFOS pg/i mdl 288 (-BHC pgA mdl
252 BENFLURALIN pg/i mdl 289 OPDDD jig/I mdl
253 1 ,2-DIBROMO-3-CHLOROPROPANE pg/I mdl 290 4,4'-DDE pg/I mdl
254 STROBANE pg/I mdl 291 HEPTACH-LOR pg/I mdl
255 HIEXAZINONE pg/I mdl 292 HEPTACHLOR-EPOXIDE pg/I mdl
256 PENTACHLOROPHENOL pg/i mdl 293 ISODRIN pg/i mdl
257 DALAPON pag/I mdl 294 CHLOROBENZILATE pg/ mdl


82







FLORIDA GEOLOGICAL SURVEY

STable 32 (oont.) List of pesticides analyzed in the Background Network, as of 1989, with guidance Table 33. Sunmmary of total pesticide concentrations (p~g/L), by region and aquifer system. Most detections
concentrations or standards. were not confirmed by resarnpling.

A. Surticial aquifer system

SParameter Parameter Name Units Guidance ,District Median I rtile anQrile # Samps # Ex Min Max
Number Concentrationt___________ __________________________ ____ ___* NWFWMD <2.00 <200 <2.20 84 1 <1.00 100.00
SRWMD <10 00 <10.00 <10 00 22 0 <10 00 50 00
295 METHOXYCHLOR pg/I 100 __29 ABFRNp/ 6* SJRWMD < 1.00 1.00 4.00 22 0 <1.00 27.00
297 METRIBUZIN pig/I 200 SWFWMD < 100 <1.00 <1.00 83 15 < 100 32.40
298 ALDICARB SULFOXIDE jg/I 10 SFWMD 0.00 0 00 < 1.60 321 1 0.00 1100.00
299 ALDICARB SULFONE ptgI 40
300 3-HYDROXYCARBOFURAN gt/ mdl Statewide < 0.01 0.00 < 050 538 17 0 00 1100 00
3301 DISULFOTON pg/ mdl Sand & Grave <2.00 < 2.00 < 2.40 71 1 < 2.00 100 00
302 MIREX pig/I 3.5 _____30 ,- gI10Biscayne < 003 < 0.03 < 003 13 0 0 00 1.40
304 MALATHION pig/I mdl Other <1 50 <050 <2.00 454 16 0.00 1100.00
305 PARATHION ETHYL jig/I mdl
306 2,4,5-TP (SILVE) jg/I 10
307 DIAZINON g/ 0B. Intermediate aquifer system

S308 DCPA g/I 4000 District Median I arile t rtile # Samps # Ex Min Max
309 ATRAZINE pg/I mdl310 DICOFOL pgI d NWFWMD < 200 < 200 < 2.00 31 0 < 100 9.20
311 DIURON pg/I 10 SRWMD 0 00 0.00 0.00 24 0 0.00 0.00

312 LICLDAM jg/I rnd SJRWMD 0.00 0 00 1.00 27 0 < 1.00 5 00
314 TRITHION g9/ 12 SWFWMD < 0.01 < 0.01 < 001 34 14 0 00 1.80
3 315 CAPTN pg/I mdj SFWMD <1.20 <0.90 <1.50 92 0 <0.01 <30.00

317 CARROPHENOTHION jig/I mdl Statewide <050 0.00 <0.50 208 14 0.00 9.20
318 GUTHION jg/I mdlI 319 TEDION pig/I mdl C lrdnaufrsse
320 MEVINPHOS g9/I mdl C.____________ Floridan_ aquifer system321 DIQUAT pg/ mdi ititMda nl die I ap tEc* M a
322 TERBUFOS kg/I mdlDsritMdn rie ril #Sms #Ex* Mn Mx
323 AMETRYN pg/I mdi NWFWMD <2.00 <2.00 <2.00 171 0 <1.00 14.00
324 BROMACIL jig/I 90 *SRWMD <10 00 <10.00 <10.00 299 0 < 1.00 30 00
325 PARAQUAT pg/I 30
373 TOTAL ARSENIC pig/I so SJRWMD < 1.00 < 100 < 1.00 53 2 < 1.00 66.00
3 ~374 ARSENIC,DISSO[VED pig/I 50 SWFWMD <0.01 <0.01 <001 167 35 0.00 1001
391 BENTAZON, TOTAL pig/ rndlSWM<1.0090160l 001042
392 SEVINTOTAL pg/ mdl FM 13 09 16 0 0042
Statewide < 0 01 < 0.01 < 0 50 798 37 0.00 70.01
md! Method Detection Limit
Total Arsenic values only (no organic pesticides sampled)


83






SPECIAL PUBLICATION NO. 34


Table 34. Some arsenic-based pesticides and their uses (from data in Carapella, 1968). Table 35. Proportions of major ions within the trilinear-diagram fields on the Predominant Water TypeI
Maps. Based on the classification of Davis and DeWiest (1966) Percentages are based on total major ion content, in milliequivalents per liter
Pesticide Use _____________________________Calciurm arsenate Insecticide, herbicide Cadion Trilinear Diagram

Lead arsenate insecticide C3inPretg

Sodium arsenite Herbicide, fungicide, Water Type Calcium Magnesium Sodium Dominant
aquatic weed control, 1Wn
animal dips for tick control
A 60-100 0-40 0-40 Ca
Sodium arsenate Wood preservative
B 40 -60 40 -60 0 -20 Mixed
Disodium methylarsonate HerbicideC-M
Ammonium methane arsonate Herbicide C0 -40 60 -100 0 -40 Mg

D 0 -20 20 -60 20 -60 Mixed
Mg-Na3

E 0-40 0-40 60-100 Na

F 40 -60 0 -20 20 -60 Mixed
Ca-Na

G 20 -60 20 -60 20 -60 Mixed
_ _ _ _ _ _ _ __ _Ca-Mg-Na__


Anion Trilinear Diagram3

_______ ______ Anion Percentage _ _ _ _
Water Type Bicarbonate Sulfate Chloride Dominant
_ _ _ _ _ _ _ _ _ _ onI

1 60 -100 0 -40 0 -40 HCO3

2 40 -60 40 -60 0 -20 Mixed
HCO3-SO,3

3 0-40 60-100 0-40 SC,

4 0 -20 20 -60 20 -60 Mixed
SO4-C

5 0-40 0-40 60-100 Cl

640 -60 0 -20 20 -60 Mixed


7 20 -60 20 -60 20 -60 Mixed
HCO3-SO4
__ _ _ _-Cl

84