USE OF GIS TO IDENTIFY AND DELINEATE AREAS OF FLUORIDE, SULFATE, CHLORIDE, AND NITRATE LEVELS IN THE WOODBINE

Transcription

1 E OF GI TO IDENTIFY AND DELINEATE AREA OF FLORIDE, LFATE, CHLORIDE, AND NITRATE LEVEL IN THE WOODBINE AQIFER, NORTH CENTRAL TEXA, IN THE 1950, 1960, 1970, 1980, AND 1990 iichai anmanee, B.. Thesis Pepaed fo the Degee of MATER OF CIENCE NIVERITY OF NORTH TEXA August, 2001 APPROVED: Paul F. Hudak, Majo Pofesso Minhe Ji, Mino Pofesso Donald I. Lyons, Committee Membe Donald I. Lyons, Coodinato of the pogam in Applied Geogaphy C. Reid Feing, Chai of the Depatment of Geogaphy C. Neal Tate, Dean of the Robet B. Toulouse chool of Gaduate tudies

2 anmanee, iichai, se of GI to Identify and Delineate Aeas of Fluoide, ulfate, Chloide, and Nitate Levels in the Woodbine Aquife, Noth Cental Texas, in the 1950s, 1960s, 1970s, 1980s, and 1990s. Maste of cience (Applied Geogaphy), August, 2001, 194 pp., 10 tables, 45 illustations, efeences, 49 titles. AcView and AcInfo wee used to identify and delineate aeas contaminated by fluoide, sulfate, chloide, and nitate in the Woodbine Aquife. Wate analysis data wee obtained fom the TWDB fom the 1950s to 1990s coveing 9 counties. 1990s land use data wee obtained to detemine the elationship with each contaminant. peaman s ank coelation coefficients and Kuskal-Wallis tests wee used to calculate elationships between vaiables. Land uses had little effect on distibutions of contaminants. ulfate and fluoide levels wee most poblematic in the aquife. Depth and lithology contolled the distibutions of each contaminant. Nitate pattens wee contolled mainly by land use athe than geology, but wee below the maximum contaminant level. In geneal, contaminant concentations have deceased since the 1950s.

3 ACKNOWLEDGEMENT I wish to thank my Majo Pofesso, Associate Pofesso D. Paul F. Hudak fo poviding knowledge of goundwate contamination backgound, geology of the aquife, and statistical backgound. I appeciate the committees, Associate Pofesso D. Donald A. Lyons and Assistant Pofesso D. Minhe Ji fo beneficial advising in GI and statistical deteminations, espectively. Also, I would like to thank Buce Hunte fo poviding Texas GAP land use data. Lastly, I would like to thank my wife and my two childen fo suppoting and encouaging me with patience. iii

4 TABLE OF CONTENT Page ACKNOWLEDGMENT.. iii LIT OF TABLE vii LIT OF ILLTRATION viii Chapte 1. INTRODCTION Geneal tatements Objectives Reseach Hypotheses cientific Meits LITERATRE REVIEW Goundwate use in the nited tates and Texas Geneal Geology of Woodbine Aquife Hydogeology of the Woodbine Aquife Dinking Wate tandads ouces of Fluoide, ulfate, Chloide, and Nitate Poblems with Contaminated Wate Fluoide, Nitate, ulfate, and Chloide levels in the 23 Woodbine Aquife Health Effects fom Fluoide, Nitate, ulfate, 23 and Chloide 3. METHODOLOGY RELT AND DICION Well Depth of the collected wate samples Time Plots of the Woodbine Aquife Concentations of each Contaminant by Decade and County Fluoide 44 iv

5 Page Intepolated Concentation Contou. 44 Maps of Fluoide Fluoide Levels in each County and Decade Nitate Intepolated Concentation Contou. 51 Maps of Nitate Nitate Levels in each County and Decade ulfate Intepolated Concentation Contou. 58 Maps of ulfate ulfate Levels in each County and Decade Chloide Intepolated Concentation Contou. 66 Maps of Chloide Chloide Levels in each County and Decade Diffeent Concentations between Consecutive Decades Diffeent Fluoide Concentations between. 78 Consecutive Decades Diffeent Nitate Concentations between. 79 Consecutive Decades Diffeent ulfate Concentations between. 79 Consecutive Decades Diffeent Chloide Concentations between. 80 Consecutive Decades 4.5 tatistics test Kuskal-Wallis Test Kuskal-Wallis Test between. 86 Contaminants and Counties v

6 Page Kuskal-Wallis Test between. 88 Contaminants and Land se Types Kuskal-Wallis Test between. 94 Contaminants and Pimay Well ses peaman s Rank Coelation Coefficient 97 between Well Depth and each Contaminant 5. CONCLION APPENDIX 106 APPENDIX A Plots Though Time. 108 APPENDIX B Wate Quality Data by Decade 127 APPENDIX C Wate Quality Data by County 139 APPENDIX D Kuskal-Wallis Test between Contaminants and 151 County in the Woodbine Aquife by Decade APPENDIX E Kuskal-Wallis Test between Contaminants and 163 Land se Types in the Woodbine Aquife in 1990s APPENDIX F Kuskal-Wallis Test between Contaminants and 167 Pimay Well ses in the Woodbine Aquife by Decade APPENDIX G peaman s Rank Coelation Coefficient between 179 Well Depth and each Contaminant in the Woodbine Aquife APPENDIX H peadsheet of Contaminants and Land se Types 184 in the Woodbine Aquife in 1990s BIBLIOGRAPHY vi

7 LIT OF TABLE Table Page 1. Woodbine Aquife Well Chemisty Database Most Recent Well amples of the Woodbine Aquife in Five Decades Fluoide Levels in each County and Decade Nitate Levels in each County and Decade ulfate Levels in each County and Decade Chloide Levels in each County and Decade Kuskal-Wallis Test between Contaminants and County ove Five. 87 Decades 8. Kuskal-Wallis Test between Contaminants and Land se Types Kuskal-Wallis Test between Contaminants and Pimay Well ses peaman s Rank Coelation Coefficient between Well Depth,. 98 ulfate, Chloide, Fluoide, and Nitate vii

8 LIT OF ILLTRATION Figue Page 1. uface exposue and downdip aea of the Woodbine Aquife 5 2. Most Recent Wate Chemisty amples of the Woodbine Aquife in 1950s Most Recent Wate Chemisty amples of the Woodbine Aquife in 1960s Most Recent Wate Chemisty amples of the Woodbine Aquife in 1970s Most Recent Wate Chemisty amples of the Woodbine Aquife in 1980s Most Recent Wate Chemisty amples of the Woodbine Aquife in 1990s Geological coss-section of the Woodbine Aquife in Collin County Conceptualization fo studying goundwate contamination of the Woodbine Aquife 9. Well Depth of the Woodbine Aquife in 1950s Well Depth of the Woodbine Aquife in 1960s Well Depth of the Woodbine Aquife in 1970s Well Depth of the Woodbine Aquife in 1980s Well Depth of the Woodbine Aquife in 1990s Well Plot-Though-time of the Woodbine Aquife in the study aea Fluoide Concentation of the Woodbine Aquife in 1950s Fluoide Concentation of the Woodbine Aquife in 1960s Fluoide Concentation of the Woodbine Aquife in 1970s Fluoide Concentation of the Woodbine Aquife in 1980s Fluoide Concentation of the Woodbine Aquife in 1990s Nitate Concentation of the Woodbine Aquife in 1950s Nitate Concentation of the Woodbine Aquife in 1960s Nitate Concentation of the Woodbine Aquife in 1970s Nitate Concentation of the Woodbine Aquife in 1980s Nitate Concentation of the Woodbine Aquife in 1990s ulfate Concentation of the Woodbine Aquife in 1950s ulfate Concentation of the Woodbine Aquife in 1960s.. 61 viii

9 Figue Page 27. ulfate Concentation of the Woodbine Aquife in 1970s ulfate Concentation of the Woodbine Aquife in 1980s ulfate Concentation of the Woodbine Aquife in 1990s Chloide Concentation of the Woodbine Aquife in 1950s Chloide Concentation of the Woodbine Aquife in 1960s Chloide Concentation of the Woodbine Aquife in 1970s Chloide Concentation of the Woodbine Aquife in 1980s Chloide Concentation of the Woodbine Aquife in 1990s ban aeas in the study aea Population in the study aea by county Population in the study aea by county Diffeent Fluoide Concentations between Consecutive Decades Diffeent Nitate Concentations between Consecutive Decades Diffeent ulfate Concentations between Consecutive Decades Diffeent Chloide Concentations between Consecutive Decades Fluoide Concentation of land use types in the Woodbine Aquife Nitate Concentation of land use types in the Woodbine Aquife ulfate Concentation of land use types in the Woodbine Aquife Chloide Concentation of land use types in the Woodbine Aquife. 93 ix

10 CHAPTER 1 INTRODCTION 1.1 Geneal tatements Although one-thid of the eath s suface coveed by wate, less than one pecent is fesh wate available fo ou use ( EPA, 1999a). It has been estimated that appoximately 96 pecent of fesh wate is goundwate. As a natual esouce, people utilize goundwate in many ways, such as dinking, bathing, agicultue, and industy. In the last decade, goundwate supplied aound 50 pecent of the dinking wate fo the nited tates of Ameica ( EPA, 1999a). ince people consume lage amounts of goundwate, thee have been many studies about goundwate quality and its effect on human health. Natually, goundwate has moe mineal constituents than has suface wate. Longe esidence times and ockwate inteaction contibute to elevate chemical concentations. Thus, utilizing goundwate without any teatment can cause health poblems in some cases. Fou anions, fluoide, sulfate, nitate, and chloide, wee selected fo this study. These fou elements ae widely found in goundwate and have many effects on human health. Fo example, sulfate can cause diahea ( EPA, 1999b). udden exposue to and intake of nitate causes blue baby syndome among infants (Mitchell et al., 1996). Chloide in dinking wate can cause cosmetic poblems, such as skin o tooth discoloation, and aesthetic effects, such as deteioation of taste, odo, o colo. Lastly, 1

11 even though fluoide is known as an impotant element in dinking wate fo educing dental caies, it can have advese effects on teeth and bones at high concentations. The selected study aea is the Woodbine Aquife located in noth-cental Texas. Its aea extends fom Gayson, Fannin, Lama, and Red Rive Counties in the noth to McLennan County in the south. Gayson, Cooke, Denton, Collin, Taant, Dallas, Johnson, Ellis, and Hill Counties wee studied (Figue 1). Thee wee some pevious epots about the amount of fluoide, nitate, sulfate, and chloide in the egion, such as Hopkins (1996), and Hudak (1999, 2000). Hopkins studied chloide, sulfate, fluoide, ion, magnesium, and boon levels in the Woodbine Aquife. That study used 78 wells sampled fom 1993 though 1995 by the Texas Wate Development Boad (TWDB). The esulting maps of chloide, sulfate, and fluoide showed that some aeas in the aquife had highe concentations than the dinking wate standads. Hudak (1999, 2000) studied fluoide, sulfate, and chloide levels in Texas goundwate. Wate chemisty data obtained fom TWDB wee collected fom The esults showed that some counties in noth-cental Texas had median fluoide concentations above the seconday dinking wate standad of 2.0 mg/l. Counties in noth-cental Texas had median sulfate and chloide levels anging fom 51 to 250 mg /L, and fom 0 to 250 mg/l, espectively. To bette undestand whethe thee is any elationship between land use and concentations of the fou contaminants in goundwate, land use, well location and contaminant concentations wee investigated ove the last five decades, 1950 to

12 (Figue 2 to Figue 6). The depth of wells was also studied in elation to concentations of the fou solutes. This study will not only identify high-isk aeas, but also elate potential souces of contaminants to land use. The elationship between well depth and solute concentation will also help in detemining potential souces fom both geological fomations in the egion and anthopogenic effects. tatistics will be applied thoughout the eseach, including using peaman s ank coelation coefficient and Kuskal-Wallis tests to detemine associations between land use and the concentation of each contaminant, well depth, and the concentation of each contaminant, and each pai of contaminants. By using a Geogaphic Infomation ystem (GI), the distibution of each solute will be mapped to show the diection and intensity of the contaminants elated to thei potential souces ove the past five decades. 1.2 Objectives To identify aeas with elatively high solute concentations in goundwate. To study elationships between well depth and fou contaminants (chloide, sulfate, fluoide, and nitate). To identify whethe land use affects contaminant levels and to identify potential souces of contaminants. To map the distibution of contaminants in five decades, To identify tempoal tends of contaminants, To identify diffeences of contaminants among diffeent pimay well uses. 3

13 1.3 Reseach Hypotheses Thee ae highe concentations of nitate beneath uban and agicultual land uses than othe land uses. Chloide, sulfate, and fluoide concentations incease downdip in the aquife (with well depth). Concentations of nitate decease with well depth. Concentations of each solute have inceased ove time. Concentations of each solute diffe with well use. 1.4 cientific Meits This study will identify aeas of contaminated goundwate. As a esult, we can contol contaminants souces and limit use. This study can be used by planning depatments and envionmental health agencies of each county in the study aea, and by NCTCOG to educe consumption of the contaminated goundwate in the Woodbine Aquife. 4

14 Figue 1 uface exposue and downdip aea of the Woodbine Aquife (TWDB, 1997) 5

15 Most Recent Wate Chemisty amples of the Woodbine Aquife in 1950s Cooke Denton Gayson Collin Taant Johnson Dallas Ellis W N E Hill Miles Texas Well Wate ample Locations County Boundaies Figue 2. Most Recent Wate Chemisty amples of the Woodbine Aquife in 1950s 6

16 Most Recent Wate Chemisty amples of the Woodbine Aquife in 1960s Cooke Denton Gayson Collin Taant Johnson Dallas Ellis W N E Hill Miles Texas Well Wate ample Locations County Boundaies Figue 3. Most Recent Wate Chemisty amples of the Woodbine Aquife in 1960s 7

17 Most Recent Wate Chemisty amples of the Woodbine Aquife in 1970s Cooke Denton Taant Johnson Dallas Gayson Ellis Collin N W E Hill Miles Texas Well Wate ample Locations County Boundaies Figue 4. Most Recent Wate Chemisty amples of the Woodbine Aquife in 1970s 8

18 Most Recent Wate Chemisty amples of the Woodbine Aquife in 1980s Cooke Denton Taant Johnson Dallas Ellis Gayson Collin W N E Hill Miles Texas Well Wate ample Locations County Boundaies Figue 5. Most Recent Wate Chemisty amples of the Woodbine Aquife in 1980s 9

19 Most Recent Wate Chemisty amples of the Woodbine Aquife in 1990s Cooke Denton Gayson Collin Taant Johnson Dallas Ellis N W E Hill Miles Texas Well Wate ample Locations County Boundaies Figue 6. Most Recent Wate Chemisty amples of the Woodbine Aquife in 1990s 10

20 CHAPTER 2 LITERATRE REVIEW 2.1 Goundwate use in the nited tates and Texas In the nited tates, goundwate is used fo agicultue, domestic, industial, and commecial puposes. In 1990, goundwate supplied 51 pecent of the nation s oveall population with dinking wate (.EPA, 1999b) and supplied 95 pecent of the population with dinking wate in ual aeas (. EPA, 1999b). Theefoe, goundwate is the majo dinking wate supply in the nation. Goundwate constituted appoximately 60 pecent of wate consumed in Texas (Hudak, 1999). The emainde was fom suface-wate esevois. Most of goundwate in Texas is contained in unconsolidated sediment and poous, pemeable ock fomations known as aquifes (wanson, 1995). Appoximately 76 pecent of the goundwate consumed in Texas comes fom nine pimay aquifes, which constitutes nine billion ace-feet of dinking wate capacity (wanson, 1995). The Texas Wate Development Boad estimated that Texans in 1984 consumed 8,854,470 ace-feet of goundwate, appoximately 78 pecent of which was used fo iigation (wanson, 1995). Texas wate laws complicate goundwate depletion poblems in the state. The Texas Wate Code consides suface wate as the popety of the state and equies pemits fo its use, which apply to the Texas Natual Resouce Consevation Commission 11

21 (TNRCC); on the othe hand, goundwate belongs to the owne of the land above it and may be used o sold as pivate popety (TWDB, 1997 and Ruesink, 1982). Texas couts have consistently uled that a landowne has the ight to pump all the wate he o she can fom beneath his o he land egadless of the effects on othe wells. Goundwate pumped fom a enewable aquife should be balanced against the aveage annual echage ates, while quantities pumped fom a nonenewable aquife detemine how long a time the existing goundwate supply will last. Gound-wate consevation disticts on the High Plains contol the distance between wells to educe competition fo wate (TWDB, 1997 and Ruesink, 1982). 2.2 Geneal Geology of the Woodbine Aquife The name of Woodbine stata containing the Woodbine Aquife was fist named and published by B.F chmad in 1863 (ellads et al., 1932). The Woodbine aquife, a mino aquife of Cetaceous age, is located in Noth Cental Texas. It funishes wate fo municipal, industial, and small iigation supplies. The aquife cops out in a naow belt, tending south (Figue 1) fom southeasten Cooke County, and is exposed in patches in a west-east diection paalleling the Red Rive in Gayson, Fannin, Lama, and Red Rive Counties (Mulle et al, 1979). It consists of the Templeton, the Lewisville, the Red Banch, and the Dexte Membes of the ppe Cetaceous Woodbine Fomation (TWC, 1989). The aquife consists of fine to coase feuginous sand and sandstone, clay, shale, sandy shale, some lignite, and some gypsum (TWC, 1989). 12

22 Woodbine sand outcops fom Hill County nothwad to Gayson County ae leaf beaing, and ae not typically maine, o at least no maine invetebates have been ecoded fom them (ellads et al, 1932). Eastwad fom Hyatts Bluff, Fannin County, Woodbine clays contain decomposed volcanic mateial and may epesent outwash on a athe flatly depositional plain, but they may be in pat maine because they wee closely associated with beds containing invetebate fossils (ellads et al, 1932). These beds wee suggested to be of uppe Woodbine age (ellads et al, 1932). The Lewisville beds ae a nea shoe sandy deposit and contain maine fossils. The uppe black, lustous clays contain oystes, and nea shoe, maine, o blackish deposit. The ovelying Eagle Fod is a neitic maine deposit (ellads et al, 1932). Those maine souces may contibute to elevated fluoide, sulfate, and chloide levels in the Woodbine Aquife. 2.3 Hydogeology of the Woodbine Aquife The Woodbine Aquife is inteesting because it undelies both pime agicultual land and apid sububan gowth (T, 2000). The Woodbine aquife extends fom McLennan County, south of Hill County, in Noth Cental Texas nothwad to Cooke County and eastwad to Red Rive County (Figue 1). Wate poduced fom the aquife funishes municipal, industial, domestic, and agicultual supplies thoughout this extensive Noth Texas egion. Total pumpage fo all puposes in 1994 was 15,572 ace-feet. The lagest use of goundwate fo public supply puposes was the city of heman, which pumped 6,604 ac-ft (TWDB, 1997). This 13

23 aquife is composed of wate-beaing sand and sandstone beds intebedded with shale and clay. The aquife is hydaulically connected to ovelying alluvium along the Red Rive (TWC, 1989). The Woodbine Goup is divided into thee wate-beaing pats that diffe consideably in poductivity and quality. Geneally, the lowe pat of the aquife has been developed to supply wate fo domestic and municipal wells (TWDB, 1997). ince the aquife dips eastwad into the subsuface whee it eaches a maximum depth of 2500 feet below land suface, and a maximum thickness of appoximately 700 feet, its wate is unde wate-table conditions in the outcop and unde atesian conditions in the subsuface (TWC, 1989 and TWDB, 1997). In downdip aeas, the Woodbine aquife is confined above by shales of the uppe Cetaceous Eagle Fod Goup, and below by the Buda Fomation o the Gayson Mal and the Mainsteet Limestone (Figue 7), all of which ae Cetaceous age (TWC, 1989). Yields of wells dilled in the Woodbine aquife ange fom less than 100 gal/min to about 700 gal/min (TWC, 1989; TWDB, 1997). The aveage annual goundwate availability fo the Woodbine Aquife, equivalent to the tansmission capacity of the aquife, was estimated to be 26,100 ac-ft (TWDB, 1997), less than one inch of the aveage annual pecipitation of 35 inches. o, one inch of annual pecipitation is enough to echage this aquife (TWDB, 1997). Wate to the aquife is echaged by pecipitation on aquife outcop aeas, and by seepage fom lakes and steams whee thee is a downwad gadient to the aquife. Wate moves though the aquife fom the outcop in an east-southeast diection, geneally following the dip of the beds. As a esult, wate fom the aquife in the outcop aea has 14

24 an aveage dissolved-solids of aound 550 mg/l, and the aveage dissolved-solids inceases downdip to geate than 3,000 mg/l. Chemical quality of Woodbine wate deteioates apidly at depths below 1,500 feet (TWDB, 1997). In aeas between the outcop and this depth, wate quality is consideed good oveall as long as goundwate fom the uppe Woodbine is sealed off. Kns - Nacatoch and Kne - Neylandville Mal Kmb - Malbook Mal Kpg - Pecan Gap Chalk Ko - Ozan Fomation (clay) Kau - Austin Chalk Kef - Eagle Fod Fomation (shale) Kwb - Woodbine Fomation Kgm - Gayson Mal Kpd - Pawpaw Fm., Weno Limestone, Denton Clay (undiffeentiated) Kfd - Fot Woth Limestone and Duck Ceek Fm. Kki - Kiamichi Fomation Kgw - Goodland Limestone and Walnut Clay (undivided) Ka - Antles and Figue 7 Geological coss-section of the Woodbine Aquife in Collin County (nivesity of Coloado at Boulde, 2001) 15

25 Geneally, the uppe Woodbine Aquife contains extemely poo wate quality in downdip locales and contains excessive ion concentations along the outcop (TWDB, 1997). Locally, the wate has objectionable concentations of ion, sodium, and chloide (TWC, 1989). Wate fom atesian aeas in Dallas, Ellis, and Navao Counties was chaacteized by high concentations of sulfate. In Johnson and Taant Counties, lots of wate wells contained sulfate concentations in excess of the dinking-wate standad and wee appaently associated with extensive non-commecial lignite beds (TWDB, 1997). 2.4 Dinking Wate tandads National Pimay Dinking Wate Regulations (NPDWRs o pimay standads) ae legally enfoceable standads that apply to public wate systems. Pimay standads potect dinking wate quality by limiting the levels of specific contaminants that can advesely affect public health ( EPA, 2000). They ae sometimes efeed to as maximum contaminant levels (MCL). National econday Dinking Wate Regulations (NDWRs o seconday standads) ae non-enfoceable guidelines egulating contaminants that may cause cosmetic effects (such as skin o tooth discoloation) o aesthetic effects (such as deteioation of taste, odo, o colo) in dinking wate. EPA ecommends seconday standads fo wate supply systems, but cannot enfoce them. Howeve, each state may choose to adopt them as enfoceable standads ( EPA, 2000). 16

26 Fluoide has pimay and seconday standads of 4 mg/l and 2 mg/l, espectively. The maximum contaminant level (MCL) of nitate is 10 mg/l of nitate as nitogen (NO 3 - N) in dinking wate, equivalent to 45 mg/l of nitate (NO 3 ), and 1 mg/l fo nitite. ulfate and chloide have seconday standads of 250 mg/l. The seconday dinking wate standad fo chloide is based on taste athe than toxicity (Gaggiani, 1984). Howeve, a fixed limit fo chloide fo agicultual use has not been set because the hamful concentation level vaies with cop, climate, soil, and management pactices (National Economy of ciences, National Academy of Engineeing, 1974). 2.5 ouces of Fluoide, ulfate, Chloide, and Nitate Fluoide eveal factos contibute to elevated fluoide levels in goundwate, including neaby saline fomations and native mineal constituents of the aquifes (Hudak, 1999). Fluoine is the 13 th most abundant element in the eath s cust, and fluoide develops in seveal geologic envionments, including igneous, sedimentay, and metamophic ocks (Hudak, 1999). Howeve, the majo mineals that incopoate fluoide ae fluoite (CaF 2 ) and fluoapatites [Ca 5 (PO4) 3 F] (Hudak, 1999 and Gosselin, 1999). Both ae pesent in sedimentay and igneous ocks, but they have athe low solubility (. EPA, 1999c). Othe potentially impotant F- beaing mineals, that ae ae, ae cyolite (Na 3 AlF 6 ), alsonite (NaMgAl(F,OH) 6.H 2 O), villiaumite (NaF), topaz (Al 2 (F,OH) 2 io 2 ), and 17

27 phlogopite (F-mica). F substitutes fo hydoxyl ions in the stuctues of many silicate mineals such as toumaline, mica, and amphiboles (Gosselin, 1999). Volcanic ash and gases may also be ich in fluoide, and fluoide is pesent in much lage quantities in maine animals than teestial animals (Hudak, 1999). Fluoide concentations in natual wates depend on factos such as tempeatue, ph, pesence o absence of complex o pecipitating ions and colloids, solubility of fluoine-beaing mineals, anion exchange capacity of aquife mateials (OH - fo F - ), the size and type of geological fomations deliveed by wate, and the amount of time that wate is in contact with a paticula fomation (Apambie et al., 1997). odium may exhibit a positive coelation with fluoide in many types of goundwate, especially those having low calcium contents (wates undegoing base exchange). High sodium concentations will incease the solubility of fluoide in wates. A pocess that can lead to vey high concentations of fluoide in wates (values up to 30 mg/l) is called anion exchange (OH - fo F - ) (Apambie et al., 1997). Nitate Nitogen occus in most natual wates pimaily as nitate. Possible souces of nitate in goundwate include unoff, seepage of excess chemicals, manue, fetilize, pecipitation, biological fixation, geological deposits, waste dumps, animal feedlots, leaking sewe lines, impope waste disposals, and inadequate design and maintenance of septic systems (Doshelme and et al., 1997). 18

28 ometimes nitogen is pesent in othe foms, such as ammonia, nitite, and oganic nitogen. Natually, biologically mediated pocesses can hydolyze oganic nitogen, such as amides, amines, amino acids, poteins, and uea, to ammonium, which is oxidized to nitite and then to nitate by nitification (Thodal, 1996). Goundwate contamination with nitate is a pevasive and seious poblem. It is a health theat because of population expansion into ual aeas, and an inceasing population, which elies heavily on pivate wate systems. The EPA (1999d) estimated that 52 pecent of the community wate wells and 57 pecent of the domestic wate wells in the county contain nitate. A vaiety of chemicals can pass though the wate table along with nitate. In agicultual aeas, goundwate often has a distinct wate-quality signatue composed of nitate, potassium, chloide, calcium, and magnesium (Nolan et al., 1997). The souces of these compounds mostly ae agicultual chemicals such as inoganic fetilizes, and animal manue. Extensive application of nitate in fetilize to esidential lawns and golf couses can cause in widespead degadation of goundwate esouces in uban aeas. Nitogen is pat of all plant and animal poteins. Thus, plant, animal, and human suvival ae dependent on an abundance of nitogen in natue. Nitogen, howeve, not used by plants o etuned to the atmosphee, is conveted to nitate in aeated soil. Nitate is soluble in wate and can easily leach to the wate table. Nolan et al. (1997) also epoted that aibone nitogen compounds ae emitted by point souces such as coal and oil buning, electic utilities, automobiles, and othe foms of tanspotation. 19

29 Aibone nitogen compounds dispesed in the ai ae non-point souces of nitogen. Nitate can pesist in goundwate fo decades and can accumulate to high levels by adding moe nitogen fom the land suface evey yea. Othe non-agicultual souces of nitate, such as septic systems and leaking sewes, geneally ae less significant, but can affect goundwate quality locally. eptic systems ae soil-based wastewate teatment systems. The digested liquids fom septic tanks seep into the suounding soil. Cogge (1988) explained that a conventional septic system consisted of thee pats: the septic tank, the absoption aea, and the suounding soil. Nomally, the septic system tank povides peliminay settling and digestion of the wastewate. eptic systems intoduce pathogenic bacteia, viuses, and nitate into aquifes when the systems ae pooly designed, pooly constucted o sealed, and impopely located. The close a well is to a septic tank, the geate the oppotunity fo contamination. Agicultual injection wells also contibute nitate to goundwate. Injection well technology began in the 1920s. TEC (1999a) documented agicultual injection wells in the Lowe Rio Gande Valley, Texas. The agicultual dainage wells help eliminate excess wate fom agicultual poduction. These wells collect suface wate and dain it into subsuface fomations. As a esult, goundwate can be contaminated with nitate and pesticides, when the well casing is eoded. Othe potential souces of nitate contamination in goundwate come fom natual occuences. Wlotzka (cited by Feth, 1966) studied the ammonia-nitogen concentations in vaious suites of ocks. Concentations of NH 3 -N depend upon the type 20

30 of ocks. Fo example, the aveage NH 3 -N content was 20, 580, 135, and 70 gam / ton fo magnetic ock, claystone, sandstone, and limestone, espectively. NH 3 -N fom these natual souces, when they ae eoded, gadually accumulated in coveed soil ove many yeas. Weatheing by poducts ae pobably fixed by micooganisms living in oot nodes of leguminous plants and by soil oganisms (both aeobes and anaeobes). Alison (1955; cited by Feth, 1966) epoted that leguminous plants geneally fix 40 to 200 pounds of nitogen/ace/yea, appoximately equivalent to 50 to 250 tons/squaed mile/yea of nitate. Also, the degadation of plant potein can geneate nitate in soil. Fo example, when plants die in the fall, the plant potein may be conveted to nitate. Howeve, if this esidue nitate emains in the oot zone, it may be utilized in the sping by new plants and ecoveed to plant potein. In addition, nitate may be tanspoted below the oot zone by winte and sping ains, ultimately contaminating undelying aquifes ( EPA, 1973). Chloide and ulfate Chloide and sulfate, pimay anionic components of goundwate, ae egulaly pesent at concentations ove 5 mg/l (Feeze and Chey, 1979). Chloide, natually dissolved fom ocks and soils (Hopkins, 1996), can each goundwate fom human activities, as it is pesent in sewage, oil-field bines, industial bines, and seawate at concentations epoted to ange fom 37 to 101 mg/l (Cante and Knox, 1985). ince chloide geneally is not emoved fom wastewate by eithe individual sewage-disposal 21

31 systems o conventional community wastewate-teatment systems, it can be used as an indicato of contamination fom sewage-disposal systems (Cante and Knox, 1985). Futhemoe, it can also be used as an indicato of goundwate contamination fom landfill leachate (Cante and et al., 1987). edimentay ocks, paticulaly evapoites and maine deposits, and pecipitation-bone chloide fom oceans, contibute chloide to goundwate and natual wate (Hem, 1985). Kyoto nivesity, Japan epoted an unusual incease in the dischage ate of goundwate with high levels of sulfate and chloide afte the Kobe eathquake in 1995 (Tsunogal et al., 1995). Evidently, custal movements inceased the amount of chloide and sulfate in goundwate. When sodium is fomed togethe with chloide, it will give a salty taste to dinking wate and can incease the coosiveness of wate (Hopkins, 1996). ulfate comes fom dissolution of sulfu fom ocks and soils containing sulfu compounds such as gypsum, anhydite, and ion sulfide (Hopkins, 1996). Gypsum appaently is deived fom pyite sulfu when pyite is oxidized in the vadose zone (Logan et al., 1999). Most of sulfate in goundwate is deived fom gypsum and anhydite (Hudak, 2000). ulfu is mostly pesent in educed foms as metallic sulfides in igneous, sedimentay and metamophic ocks (Hem 1985; Hudak, 2000). In geneal, goundwate in sedimentay ocks contains above 100 mg/l sulfate; howeve, wate in igneous and metamophic ocks geneally contains less than 100 mg/l sulfate (Discoll 1986). ulfate concentations in excess of the dinking-wate standad found in Johnson and Taant Counties, Texas ae appaently associated with extensive non-commecial lignite beds (TWDB, 1997). 22

32 2.6 Poblems with Contaminated Wate Fluoide, Nitate, ulfate, and Chloide levels in the Woodbine Aquife High levels of fluoide, sulfate, chloide, and nitate have been documented at the Woodbine Aquife. High concentations of sulfate in seveal wells fom this aquife wee found in Dallas, Ellis, Johnson, Taant, and Navao Counties (TWDB, 1997). High chloide concentations, exceeding the standad fo dinking wate, also wee found in Collin, Dallas, Kaufman, Ellis, Hill, and Navao Counties (Hopkins, 1996). Fluoide concentations highe than the seconday standad fo dinking wate (2.0 mg/l) wee found in 13 out of 17 counties above the aquife. Finally, nitate concentations in wate quality samples of the TWDB database, which wee highe than the pimay dinking wate standad (45 mg/l of nitate), wee found in some wells in the aquife (TWDB, 1997) Health Effects fom Fluoide, Nitate, ulfate, and Chloide Fluoide Fluoide helps in the nomal minealization of bones and fomation of dental enamel (Agawal, et al., 1997). Fluoide consumed in inadequate quantities, less than 0.5 mg/l, causes health poblems like dental caies, lack of fomation of dental enamel and deficiency of minealization of bones, especially among childen (Agawal, et al., 1997). On the othe hand, if fluoide is consumed in excess of 1.0 mg/l (Agawal, et al., 1997), 23

33 it may cause dental fluoosis (mottled enamel), bittle teeth, non-skeleton manifestation, o a combination of the above (Hudak, 1999; Gosselin et al, 1999; and Agawal, et al., 1997). The seveity and incidence of fluoosis is elated to the fluoide content in vaious components of the envionment, such as ai, wate, goundwate, and soil. Out of these, goundwate is the majo contibuto to the poblem (Agawal, et al., 1997). Futhemoe, intelligence was measued in 907 childen aged 8-13 yeas living in aeas that diffeed in the amount of fluoide pesent in the envionment. The Intelligence Quotient of childen living in aeas with a medium o sevee pevalence of fluoosis was lowe than that of childen living in aeas with only slight fluoosis o no fluoosis. The development of intelligence appeaed to be advesely affected by fluoide (Li and et al., 1995). Nitate The.EPA estimated that about 4.5 million people wee seved by goundwate containing nitate as nitogen geate than the Maximum Contaminant Level (MCL) of 10 mg/l (Bing-Cana, 1997). 66,000 people fom that numbe ae infants less than one-yea old ( EPA, 1992). D Iti and Wolfson (1987) epoted that nitates have the potential to pose both acute and chonic health theats. Acute toxicity comes about though convesion of nitate to nitite by stomach micooganisms and then binding of nitite to the oxygencaying molecules in the blood cells whee nitite oxidizes the feous ion (Fe ++ ) in 24

34 hemoglobin to feic ion (Fe +++ ) ( EPA, 1973). This pevents tanspotation of oxygen by hemoglobin molecule being bound to nitite ove 10 pecent, so victims of nitate poisoning show a geneal symptom of oxygen deficiency called methemoglobinemia o blue-baby syndome (Mitchell, 1996, Johnson and Koss, 1990, and EPA, 1999d). The acidity of small infants stomachs is consideably less than that of adults (. EPA, 1973), which esults in a moe favoable envionment fo the convesion of nitate to nitite by bacteia (Patick et al, 1987). As a esult, nitate toxicity affects mainly small infants, commonly less than thee months old who have digested high levels of nitate. Hubet and Cante (1980; cited by Patick et al., 1987) epoted that death might occu fom the ingestion of wate containing 50 to 100 mg/l of nitate. Anothe potential health effect of nitate ingestion is gastic cances (Knight et al., 1990, Foman, 1989). Futhemoe, Mitchell (1996) explained that nitate and nitite might cause such conditions as cance, mutagenic and teatogenic effects, bith defects, behavioal and developmental abnomalities, and cadiovascula disease. Nitates educed to nitites could lead to nitosation of amines, amides and poteins to give ise to cacinogenic N-nitoso compounds (Foman, 1989). Howeve, thee is inadequate laboatoy data fo the EPA to detemine whethe nitate could incease the isk of cance in humans ( EPA, 1990). Futhemoe, D Iti et al. (1987) epoted that the possibility of chonic theats fom nitate, such as cance in animals, did not necessity apply to humans. Thee wee no good epidemiological studies elating nitate to cance in humans. As a esult, 25

35 cacinogenicity(cance) was not taken into account in the establishment of the dinking wate standad fo nitate. Ruminants, paticulaly cattle, ae also susceptible to nitate toxicity because of the action of umen micooganisms ( EPA, 2000). Fo example, the lage numbes of cattle in Runnels County, Texas died duing 1968 to 1969 due to nitate poisoning ( EPA, 1973). ulfate and Chloide Health concens egading sulfate and chloide in dinking wate have also been aised. Diahea may be associated with ingestion of wate containing high levels of sulfate ( EPA, 1999a). Goups of people may be at geate isk fom the laxative effects of sulfate when they expeience an abupt change fom dinking wate with low sulfate concentations to dinking wate with high sulfate concentations ( EPA, 1999a). The Dakota Depatment of Health suggested that wate with sulfate levels ove 750 mg/l had a laxative effect and less than 600 mg/l had no laxative effect (Peteson, 1951 & 1972). High sulfate and chloide concentations also affected the taste of wate (Hudak, 2000). Chloide in dinking wate might cause cosmetic effects (such as skin o tooth discoloation) o aesthetic effects (such as taste, odo, o colo). Chloide also enhanced the coosion of pipes (TEC, 1999b) and it might cause heat and kidney diseases (TEC, 26

36 1999b). Chloide concentations ove 150 mg/l wee toxic to cops (Bouwe, 1978), and above 350 mg/l in wate ae not suitable fo most industial uses (Discoll, 1986). 27

37 CHAPTER 3 METHODOLOGY Thee wee 9 steps to this study as listed below: 1) Wate chemisty data wee obtained fom the Goundwate Database of the TWDB (Texas Wate Development Boad). amples wee sampled fom each well. The wells wee pumped until tempeatue, conductivity, and ph stabilized. amples wee filteed, peseved, and deliveed to an analytical laboatoy within pescibed maximum holding time (Hudak, 2000). The total obtained wate samples wee 4,244 samples (Table 1) coveing 1,976 wells in the study aea (nine counties). Thee wee 1,211 wells dilled in the Woodbine aquife, but only 679 wells had available wate quality analysis. The latest analysis date given in a decade was used fo each well. The samples wee divided into 1950s, 1960s, 1970s, 1980s, and 1990s (Table 2). 2) Fluoide, sulfate, chloide, and nitate concentations wee tabulated in an attibute table including well type, well location, and sampling date (pimaily used fo public supply and domestic supply). 3) Latitude and longitude wee conveted to decimal fomat. 4) Fluoide, sulfate, chloide and nitate concentations wee evaluated with statistics, such as Kuskal-Wallis analysis, peaman s ank coelation coeficient, and desciptive statistics. 28

38 5) Fluoide, sulfate, chloide and nitate concentations fo each decade wee ovelaid on county boundaies (ERI, 1999). 6) Individual wells epesenting each county wee selected fo time tends. 7) A GI (AcView 3.2 and AcInfo 7.2) wee used to map, quey and analyze the data (Figue 7). 8) Land use at each well location was detemined. Land use files wee obtained fom the Texas Gap vegetation data in CD-ROM, developed by Coopeative Fish and Wildlife Reseach Cente, Texas Tech nivesity, Lubbock, Texas, using 52 Landsat images in 1993, and hypeclusteed data, eceived fom the Eath Resouces Obsevation ystems (ERO) Data Cente. Almost all of the images wee classified in Khoos pectum, with gound-tuth GP points and pesonal knowledge of the aeas, and wee then conveted to gids and classified using adjoining image values. The data set is in intechanged file (*.e00), in nivesal Tansvese Mecato, Zone 14, NAD-83, pheoid GR1980. The data esolution is 90 metes. Details ae pescibed below. 9) peaman Ranking and Kuskal-Wallis statistics wee used to evaluate associations between vaiables and land uses. 29

39 Reclassification Goup Texas GAP Class 1. Wate 1. Wate 2. Foest 2. Tempoaily Flood Cold Decidous Foest, Tempeate Boad Leaved Evegeen Woodland, Leaved Evegeen Woodland, Cold Deciduous Woodland, Tempoily Flooded Cold Deciduous Woodland, Planted/Cultivated Woodland, Mixed Boad Leaved Evegeen Cold Deciduous Woodland, Tempoated Boad Leaved Evegeen hubland 3. ban 3. ban Aea 4. Gassland 4. Medium Tall Bunch Tempeate o ubpola Gassland, hot od Tempeate o ubpola Gassland, emipemanently Flooded Tempeate o ubpola Gassland, Tempeate Flooded Gassland with pase Cold, Tempeate o ubpola Gassland with a pase hub Laye, hot Tempeate o ubpola Gassland with a pase Xeomophic hub Laye 5. Copland 5. Copland (iigated, ow, hebaceous, etc.) 30

40 Reclassification Goup Texas GAP Class 6. Wetland 6. Wetland 7. hubland 7. cleophyllous Tempeate Boad Leaved Evegeen hubland, Micophyllous Evegeen hubland, Tempoaily Flooded Micophyllous hubland, Lowland Mixed Evegeen Dought Deciduous hubland, 8. Bae oil 8. Bae oil 31

41 Gap file, e00.gz files Landuse 9 Counties Well Data Fom TWDB Goundwate Database Impot Command Ftp,gunzip AcInfo Coveage 9 Counties Geocode Excel, dbase,convet to decimal degee AcView, shapefile Mapjoin Command One Coveage AcInfo Ftp to AcInfo, hapeac Command Identity Command Acshape Command Point Coveage with landuse Coss Plots Attibute data Well Depth, Pimay Well se, County boundaies, Fou contaminants Acshape Command Land use Reclass Landuse Reclass Aticle AcView Landuse Ovelay MAP AcView Well Concentations of each contaminant tatistics Kuskal-Wallis peaman Ranking ummay of Relationships and souces Identification of high concentation aeas Figue 8 Conceptualization fo studying goundwate contamination of the Woodbine Aquife 32

42 Table 1. Woodbine Aquife Well Chemisty Database County Name Wate amples No. of analyzed wells No. of analyzed Wells in the Woodbine Collin Cooke Dallas Denton Ellis Gayson Hill Johnson Taant Total

43 Table 2. Most Recent Well amples of the Woodbine Aquife in Five Decades County Name 1950s 1960s 1970s 1980s 1990s Collin Cooke Dallas Denton Ellis Gayson Hill Johnson Taant Total

44 CHAPTER 4 RELT AND DICTION 4.1 Well Depth of the collected wate samples Well Depth of the Woodbine Aquife of the collected wate samples fom 1950s to 1990s ae shown in Figues 9 to13. The well depth contous ae elongated in a nothsouth diection along stike of the Woodbine Fomation. The well depth of the westen counties fom Cooke to Johnson Counties was geneally less than 500 feet. The easten counties fom Gayson to Ellis Counties had well depth vaying fom 500 to ove 2000 feet. The easten pat of the study aea had the highest well depths. This well depth tend follows the Woodbine Fomation beds which dip east. Deepe wells wee found in the easten pat of the study aea. 35

45 Well Depth of the Woodbine Aquife in 1950s Cooke TT T T T V T Gayson T V V V V T V V0 0 Denton T V V 0 Collin T V V Taant T V V V V Dallas T V V T V V T V 0 0 Johnson T V 0 0 Ellis T T N T W E Hill Miles Well Depth (Ft) T V Well Depth (Ft) Texas County Boundaies Figue 9 Well Depth of the Woodbine Aquife in 1950s 36

46 Well Depth of the Woodbine Aquife in 1960s Cooke V T T V T V V T V V T V Gayson T V V TV V 0 Denton T V Collin T V V Taant Johnson V T V T V V T V V V 0 T T T V T V 0 T T T T T V T V T TT T V T T T T V TT V 0 T V V V V 0 0 VV T T V V T V V T 0 0 T T V V T T T 0 T 0 V T T V V T T T T T T T T T T Dallas Ellis W N E Hill Miles Well Depth (Ft) T V Well Depth (Ft) Texas County Boundaies Figue 10 Well Depth of the Woodbine Aquife in 1960s 37

47 Well Depth of the Woodbine Aquife in 1970s Cooke Denton Taant Johnson T T V V T V T V V V T V T V T V T V T T T V T T T 0 T V T V V T T V V V T V 0 T T T V V V T TV V V T T T T T T 0 T V T T V V V V 0 T T T T TTT T T T T V T V T T VV V V V V V V V V 0 0 T N V 0 T 0 0 T T V V VV 0 Dallas Gayson Ellis Collin T T T T T T V N W E Hill Miles Well Depth (Ft) T V Well Depth (Ft) Texas County Boundaies Figue 11 Well Depth of the Woodbine Aquife in 1970s 38

48 Well Depth of the Woodbine Aquife in 1980s Cooke Denton T T T V 0 T T V V T T V V V V 0 V V V V T 0 V0 V 0 0 N 0 T 0 V V V V T V T Gayson Collin V V Taant T T V V Dallas Johnson T T T T V T T V VV T V V V T V0 T V V V T V V V N 0 Ellis T T T T T V N T W E Hill Miles Well Depth (Ft) T V Well Depth (Ft) Texas County Boundaies Figue 12 Well Depth of the Woodbine Aquife in 1980s 39

49 Well Depth of the Woodbine Aquife in 1990s Cooke 0 T V T Gayson T V 0 V 0 Denton T T T T V V 0 V V 0 0 Collin V T Taant V Dallas T V T V V Johnson V V V 0 Ellis TT T T T N T W E Hill Miles Well Depth (Ft) T V Well Depth (Ft) Texas County Boundaies Figue 13 Well Depth of the Woodbine Aquife in 1990s 40

50 4.2 Time Plots of the Woodbine Aquife One to thee wells in each county having the most complete wate analysis fom 1950s to 1990s wee selected to illustate time plots of each contaminant shown in Figue 14. The plots ae attached in Appendix A. Thee wee two types of plots of each well, one plot was both sulfate and chloide plotted vesus well depth, and the othe plot was both fluoide and nitate plotted vesus well depth. The state well ID of these wells epesented by lettes such as A, B, and D in Figue 14 ae listed in Appendix A. Chloide levels ove the seconday dinking wate standad (250 mg/l) wee found in well #, located in Hill County, in which chloide concentations ove 250 mg/l wee found in almost all of the five decades. Theefoe, Hill County might expeience a poblem fom the high chloide levels. Futhemoe, chloide levels ove 250 mg/l in well # Q located in Ellis County wee only found in the 1960s, and then deceased fom the 1970s to 1990s. ulfate levels ove the seconday dinking wate standad (250 mg/l) coveing the five decades wee found in well # I, L, M, N, O, Q, R,, and T. Those wells wee located in Collin, Dallas, Johnson, Ellis, and Hill Counties (Figue 14). Theefoe, the southen pat of the study aea having apid uban gowth contained the sulfate concentations ove the seconday dinking wate standad. Howeve, Taant County having many new wells dilled in 1990s showed high sulfate levels (> 250 mg/l) in 1990s. Finally, high sulfate level aeas in 1990s wee also in Collin, Dallas, Johnson, Ellis, Hill, and Taant Counties. 41

51 Fluoide levels ove the seconday dinking wate standad (2.0 mg/l) wee found in well # D, E, F, G, I, L, N, Q, P,, and T, which wee located in Gayson, Denton, Collin, Dallas, Ellis, and Hill Counties. Its concentations in Denton County, in 2 out of 3 wells, wee deceased in the 1990s. Howeve, fluoide levels ove the pimay dinking wate standad (4 mg/l) wee found only in well # Q and located in Ellis and Hill Counties, espectively, in the southen pat of the study aea Nitate levels did not exceed the dinking wate standad (44.3 mg/ L in tems of nitate concentations); theefoe, nitate levels should not be the poblem fo the dinking wate fom the Woodbine Aquife. Most of the nitate concentations in the plots (Appendix A) wee less than 10 mg/l. Howeve, the intepolation suface maps of nitate concentations in each decade showed some aeas having nitate levels ove the dinking wate standad (44.3 mg/ L). Details ae discussed next. 42

52 Locations of Plot-Though-Time Wells of the Woodbine Aquife Cooke A D C B Gayson Taant Johnson Denton E G F J K M N P O R T I H Collin Dallas L Q Ellis W N E Hill Miles Texas A,B Locations of Plot Though Time Well Refeence Well numbes County Boundaies Figue 14 Well Plot-Though-time of the Woodbine Aquife in the study aea 43

53 4.3 Concentations of each Contaminant by Decade and County Fluoide Intepolated Concentation Contou Maps of Fluoide Intepolated concentation contou maps (Figues 15 to 19) showed that fluoide concentations ove the pimay dinking wate standad (4 mg/l) wee located in Ellis County fo evey decade, and in Dallas County in the1960s. High concentations wee most common fom the 1960s to 1980s, but fo only two wells in the 1950s (located in Hill and Ellis Counties). In the 1990s, high fluoide concentations wee found in Taant and Ellis Counties, which had fluoide levels ove the pimay dinking wate standad. Aeas having fluoide concentation levels ove the seconday dinking wate standad (2 mg/l) coveed Dallas, Denton, Collin, and Hill Counties. Geneally, fluoide levels have deceased fom the 1960s to 1990s. Coss-plots of fluoide concentations vesus well depth, by decade and by county, wee studied. peadsheets showing fluoide concentations by decade and county ae illustated in Appendices B and C, espectively. Table 3 illustates the fluoide levels ove the five decades and nine counties summaized fom the fluoide concentations attached in Appendices B and C. Oveall, median fluoide concentations have deceased since the 1950s (Table 3). Ellis County had the highest median fluoide concentation, 1.94 mg/l, close to the seconday dinking wate standad (2.0 mg/l); theefoe, esidents of this county may have a elatively high health isk fom dinking wate with high fluoide. 44

54 Fluoide Concentation of Woodbine Aquife in 1950s Cooke Gayson Denton Collin Taant Johnson Dallas Ellis N Hill W E Miles Fluoide (mg/l) Texas County Boundaies Figue 15 Fluoide Concentation of the Woodbine Aquife in 1950s 45

55 Fluoide Concentation of Woodbine Aquife in 1960s Cooke Denton Gayson Collin Taant Johnson Dallas Ellis N Hill W E Miles Fluoide (mg/l) Texas County Boundaies Figue 16 Fluoide Concentation of the Woodbine Aquife in 1960s 46

56 Fluoide Concentation of Woodbine Aquife in 1970s Cooke Denton Taant Johnson Gayson Dallas Ellis Collin N Hill W E Miles Fluoide (mg/l) Texas County Boundaies Figue 17 Fluoide Concentation of the Woodbine Aquife in 1970s 47

57 Fluoide Concentation of Woodbine Aquife in 1980s Cooke Denton Taant Johnson Gayson Dallas Ellis Collin N Hill W E Miles Fluoide (mg/l) Texas County Boundaies Figue 18 Fluoide Concentation of the Woodbine Aquife in 1980s 48

58 Fluoide Concentation of Woodbine Aquife in 1990s Cooke Denton Taant Johnson Gayson Dallas Ellis Collin N Hill W E Miles Fluoide (mg/l) Texas County Boundaies Figue 19 Fluoide Concentation of the Woodbine Aquife in 1990s 49

59 Fluoide Levels in each County and Decade Well depth and fluoide concentations in Appendixes B and C, and Table 3, show that most of the counties had highe fluoide concentation at deepe depths. Fluoide concentations incease in the downdip diection, suggesting a geologic oigin -- goundwate that has taveled futhe in the aquife has dissolved moe fluoide fom ocks. Howeve, fluoide concentations in Collin County, Appendices B and C, and Table 3, had an invese elationship with well depth. The highest fluoide levels between 1000 and 1500 feet possibly wee deived fom neaby geological fomations such as the Gayson Mal and Eagle Fod Fomations (Figue 7), which lie beneath and above the Woodbine Fomation, espectively. Also, highe concentations in shallow wells possibly deived fom locally fluoide-eniched pats of the Woodbine Aquife. Table 3 Fluoide Levels in each County and Decade County The median fluoide concentation (mg/l) 1950s 1960s 1970s 1980s 1990s Relationship fom Coss- Plots Oveall Median Fluoide (5 decades) Collin Cooke N/A N/A No change Dallas Denton N/A Ellis Gayson Hill Johnson Taant No change 50

60 Remak: Relationship: + = deepe depth, highe concentation - = deepe depth, lowe concentation Oveall Tend: = the contaminant levels inceased fom 1950s to 1990s = the contaminant levels deceased fom 1950s to 1990s Nitate Intepolated Concentation Contou Maps of Nitate Nitate levels in the study aea (Figues 20 to 24) wee not excessive the dinking wate standad (44.3 mg/l as nitate). Thee wee only a few wells in the 1970s, which wee ove the dinking wate standad, located in Denton and Johnson Counties. Howeve, Taant County in the 1990s showed nitate levels above 44.3 mg/l; the wells wee dilled to shallow depths making them vulneable to contamination. Low nitate levels in the study aea elate to only small patches of agicultual land and fetilized usage. Nitate concentations and well depths ae in Appendices B and C. In the 1970s and 1990s (Figues 22 and 24), high nitate concentations (> 44.3 mg/l) wee found at shallow depth, Denton, Taant, and Johnson Counties, wheeas nitate levels in the easten pat of the study aea wee less than 44.3 mg/l. Howeve, intepolated contou maps of nitate (Figues 20-24) showed that most of the nitate concentations wee lowe than 10 mg/l fo evey decade. 51

61 Figue 20 Nitate Concentation of the Woodbine Aquife in 1950s 52

62 Figue 21 Nitate Concentation of the Woodbine Aquife in 1960s 53

63 Figue 22 Nitate Concentation of the Woodbine Aquife in 1970s 54

64 Figue 23 Nitate Concentation of the Woodbine Aquife in 1980s 55

65 Figue 24 Nitate Concentation of the Woodbine Aquife in 1990s 56

66 Nitate Levels in each County and Decade Well depth and nitate concentations listed in Appendices B and C, and Table 4, showed that most of counties had highe nitate concentations at shallow depths, which suggests that nitate concentations wee elated to human activities. ouces of nitate in ual aeas include agicultual unoff, seepage of excess chemicals, fetilize, pecipitation, biological fixation, and animal feedlots (Doshelme and et al., 1997). Nitate levels in uban aeas might come fom waste dumps, leaking sewe lines, impope waste disposal, and inadequate design and maintenance of septic systems (Doshelme et al., 1997). Nitate concentations wee contolled pimaily by land use pactice athe than geologic souces. Howeve, the nitate concentations in Dallas and Ellis Counties, Appendices B and C, and Table 4, had both diect and invese elationships with well depth, the highest nitate levels between 500 and 1000 feet. High nitate concentations at deepe levels could esult fom long tem use of fetilize o movement along well annuli. Oveall, fom the 1950s to 1990s (Appendices B and C, and Figues 20-24, and Table 4), nitate levels deceased. The median concentations of nitate wee mainly zeo ove the five decades. 57

67 Table 4 Nitate Levels in each County and Decade County The median concentation ove time (mg/l) 1950s 1960s 1970s 1980s 1990s Relationship fom Cossplots Oveall Median Nitate (5 decades) Collin No tend Cooke N/A N/A Dallas Denton N/A No change Ellis Gayson Hill catteing Johnson Taant Remak: Relationship: + = deepe depth, highe concentation - = deepe depth, lowe concentation Ove all Tend: = the contaminant levels inceased fom 1950s to 1990s = the contaminant levels deceased fom 1950s to 1990s ulfate Intepolated Concentation Contou Maps of ulfate ulfate levels ove the dinking wate standad (250 mg/l of sulfate) wee mainly found in the southen pat of the study aea. Details of the sulfate levels in each well ae posted in Appendixes B and C. In the 1950s (Figue 25), Collin, Dallas, Taant, Johnson, Ellis, and Hill Counties pincipally had high levels. Highe sulfate levels wee obseved fo the 1960s (Figue 26). ulfate levels ove 250 mg/l wee found in Collin, Dallas, Taant, Ellis, and Hill Counties, and also one well in Denton County. 58

68 Howeve, thee wee high sulfate levels locally in nothen counties such as Cooke, Gayson, and Denton Counties in the 1970s (Figue 26). In the 1980s (Figue 27), potentially high sulfate aeas in Cooke and Gayson Counties lacked sample data. The southen pat of the study aea still had elatively high sulfate levels in the 1980s. High sulfate concentations wee found mainly in Taant, Dallas, and Ellis Counties, and locally in Gayson, Johnson, and Hill Counties. High sulfate concentation tends pojected, obseved fom the 1950s to the 1990s (Figues 25 to 29), ae still a poblem in the study aea. Geologic souces such as gypsum deposits and lignite beds likely account fo high sulfate concentations in the southeast pat of the study aea. 59

69 ulfate Concentation of Woodbine Aquife in 1950s Cooke Gayson Denton Collin Taant Johnson Dallas Ellis N Hill W E ulfate (mg/l) Miles Texas County Boundaies Figue 25 ulfate Concentation of the Woodbine Aquife in 1950s 60

70 ulfate Concentation of Woodbine Aquife in 1960s Cooke Denton Gayson Collin Taant Johnson Dallas Ellis N Hill W E ulfate (mg/l) Miles Texas County Boundaies Figue 26 ulfate Concentation of the Woodbine Aquife in 1960s 61

71 ulfate Concentation of Woodbine Aquife in 1970s Cooke Denton Taant Johnson Gayson Dallas Ellis Collin N Hill W E ulfate (mg/l) Miles Texas County Boundaies Figue 27 ulfate Concentation of the Woodbine Aquife in 1970s 62

72 ulfate Concentation of Woodbine Aquife in 1980s Cooke Denton Taant Johnson Gayson Dallas Ellis Collin N Hill W E ulfate (mg/l) Miles Texas County Boundaies Figue 28 ulfate Concentation of the Woodbine Aquife in 1980s 63

73 ulfate Concentation of Woodbine Aquife in 1990s Cooke Denton Taant Johnson Gayson Dallas Ellis Collin N Hill W E ulfate (mg/l) Miles Texas County Boundaies Figue 29 ulfate Concentation of the Woodbine Aquife in 1990s 64

74 ulfate Levels in each County and Decade Well depth and sulfate concentations ae listed in Appendices B, C and Table 5. Results showed that Dallas, Ellis, Hill, and Taant Counties had median sulfate concentations ove the seconday dinking wate standad (250 mg/l); howeve, only Dallas, Ellis, and Taant Counties had such high sulfate levels in the 1990s. Thee wee both positive and negative associations between sulfate and well depth (Appendices B and C, summaized in Table 5). Negative elationships wee found in Collin, Johnson, and Taant Counties, with depths of the highest sulfate levels at appoximately feet, feet, and feet, espectively. Positive tends of well depth and sulfate concentation wee found in Dallas, Denton, Ellis, Gayson, and Hill Counties, with depths of the highest sulfate levels at appoximately feet, feet, feet, feet, and feet, espectively. The above listed anges of depths might imply that the souces of sulfate wee located nea those aquife depth anges. The souces of sulfate concentations might be mineal deposits such as gypsum, anhydite, and ion sulfide deposited in those depths that high sulfate wee found. Howeve, Taant County having sulfate levels ove 3000 mg/l at depths less than 100 feet, might have sulfate souces in non-commecial lignite beds (TWDB, 1997). Oveall, sulfate levels deceased, except fo Taant County fom the 1950s to 1990s (Appendices B and C, Figues 25-29, and Table 5). 65

75 Table 5 ulfate Levels in each County and Decade County The median concentation ove time (mg/l) 1950s 1960s 1970s 1980s 1990s Relationship fom Coss- Plots Oveall Median ulfate (5 decades) Collin Cooke N/A N/A No No tend Dallas Denton N/A Ellis Gayson Hill Johnson Taant Remak: Relationship: + = deepe depth, highe concentation - = deepe depth, lowe concentation Ove all Tend: = the contaminant levels inceased fom 1950s to 1990s = the contaminant levels deceased fom 1950s to 1990s Chloide Intepolated Concentation Contou Maps of Chloide Fom the 1950s to 1960s (Figues 30-31), chloide concentations in the Woodbine Aquife above the dinking wate standad (250 mg/l) wee found in the easten pat of Dallas and Ellis Counties, southen pat of Collin County, and southeasten pat of Hill County. Howeve, in the 1970s (Figue 32), aeas ove 250 mg/l of chloide deceased, with high clustes in small aeas of Cooke, Gayson, Denton, 66

76 Collin, Dallas, and Ellis Counties. ome of these clustes coincide with aeas of heavy pumpage. Goundwate tends to deteioate as wate levels decline. In the 1980s (Figue 33), high concentation aeas wee found in Collin, Ellis, and Hill Counties, and in the 1990s, mainly found only in Taant County (Figue 34). High chloide levels in Taant County wee obseved at shallow depths suggesting a possible human oigin (Figues 35-37). Howeve, the 1990s data set includes seveal shallow monitoing wells in the uppe Woodbine, which wee not pesent in othe decades. These wells evidently poduce wate fom the poo quality uppe inteval of the aquife. Inceases in chloide with downdip flow though ock deposits, as well as heavy pumpage in cetain aeas, explain most of the chloide tends. 67

77 Chloide Concentation of Woodbine Aquife in 1950s Cooke Gayson Denton Collin Taant Johnson Dallas Ellis N Hill W E Miles Chloide (mg/l) Texas County Boundaies Figue 30 Chloide Concentation of the Woodbine Aquife in 1950s 68

78 Chloide Concentation of Woodbine Aquife in 1960s Cooke Denton Gayson Collin Taant Johnson Dallas Ellis N Hill W E Miles Chloide (mg/l) Texas County Boundaies Figue 31 Chloide Concentation of the Woodbine Aquife in 1960s 69

79 Chloide Concentation of Woodbine Aquife in 1970s Cooke Denton Taant Johnson Gayson Dallas Ellis Collin N Hill W E Miles Chloide (mg/l) Texas County Boundaies Figue 32 Chloide Concentation of the Woodbine Aquife in 1970s 70

80 Chloide Concentation of Woodbine Aquife in 1980s Cooke Denton Taant Johnson Gayson Dallas Ellis Collin N Hill W E Miles Chloide (mg/l) Texas County Boundaies Figue 33 Chloide Concentation of the Woodbine Aquife in 1980s 71

81 Chloide Concentation of Woodbine Aquife in 1990s Cooke Denton Taant Johnson Gayson Dallas Ellis Collin N Hill W E Miles Chloide (mg/l) Texas County Boundaies Figue 34 Chloide Concentation of the Woodbine Aquife in 1990s 72

82 Cities and ban Aeas in the tudy Aea Cooke # Gainesville Denison # # heman Gayson Taant Johnson Denton # McKinney # The Colony Allen # # # # # Plano # Kelle # # # # # # # # # # # # # # # # Iving # Dallas # # Hust # # # # # # # Deoto # # # # Buleson # Lancaste Mansfield Denton # Clebune # Ennis # Dallas Ellis Collin N Hill W E Miles Legend # Cities ban Aeas County Boundaies Texas Figue 35 ban aeas in the study aea 73

83 Population of each county in 1990 Cooke Gayson Denton Collin Taant Dallas Johnson Ellis N Hill W E Miles Population in Texas County Boundaies Figue Population in the study aea by county 74

84 Population of each county in 1997 Cooke Gayson Denton Collin Taant Dallas Johnson Ellis N Hill W E Population in County Boundaies Miles Texas Figue Population in the study aea by county 75

85 Chloide Levels in each County and Decade Well depth and chloide concentation data ae listed in Appendices B and C, and Table 6. Results showed that evey county had median chloide concentations lowe than the seconday dinking wate standad (250 mg/l); howeve, Ellis County had the highest median chloide levels in the 1990s ( mg/l). Thee wee both positive and negative elationships between well depth and chloide concentations (Appendices B and C, summaized in Table 6). Negative elationships wee found in Collin, Johnson, and Taant Counties, with tends simila to sulfate levels illustated in Table 5. Depths of the highest chloide levels wee appoximately feet, feet, and feet, espectively. Taant County had ove 3000 mg/l of chloide at depths less than 100 feet in the1990s, suggesting human athe than geologic souces. A positive association between well depth and chloide concentations was found in Dallas, Denton, Ellis, Gayson, and Hill Counties, simila to sulfate levels in Table 5. Depths of the highest chloide levels in the 1990s wee appoximately feet, feet, feet, feet, and feet, espectively. 76

86 Table 6 Chloide Levels in each County and Decade County The median concentation ove time (mg/l) 1950s 1960s 1970s 1980s 1990s Relationship fom Coss- Plots Oveall Median Chloide (5 decades) Collin Cooke N/A N/A Insufficient No change data Dallas Denton N/A Ellis Gayson Hill Johnson Taant Remak: Relationship: + = deepe depth, highe concentation - = deepe depth, lowe concentation Ove all Tend: = the contaminant levels inceased fom 1950s to 1990s = the contaminant levels deceased fom 1950s to 1990s When both sulfate and chloide concentations ae plotted as coss-plots by county ove the five decades (speadsheets in Appendices B and C). tongly positive elationships wee noticed. The atio of thei concentations in each county and decade vaied, which may eflect vaying contibutions fom geological and human souces in each county and decade. Although concentations vaied ove time in each county, the positive elationship was still ecognized in coss-plots. Both sulfate and chloide incease in the downdip diection as goundwate dissolves mineal deposits. 77

87 4.4 Diffeent Concentations between Consecutive Decades Diffeent Fluoide Concentations between Consecutive Decades Most of the fluoide concentations inceased fom the 1950s to 1960s in the study aea (Laye 2 in Figue 38). Fluoide levels inceased fom 0.1 to 3.0 mg/l in Denton, Collin, Dallas, Ellis, and Hill Counties. Fom the 1960s to 1970s (Laye 3 in Figue 38), almost half of the fluoide levels inceased, anging fom 0.1 to 3.0 mg/l. Fom the 1970s to 1980s (Laye 4 in Figue 38), fluoide concentations in Denton County located in shallow depth had highe concentations in the 1980s than 1970s, anging fom appoximately 2 to 3 mg/l. Highe fluoide levels in shallow wells possibly deive fom fluoide-eniched pats of the aquife. Thee wee some small aeas having inceasing fluoide concentations, appoximately 1.1 to 2 mg/l, located in Dallas, Ellis, and Hill Counties. Counties inceasing fom 0-1 mg/l wee Cooke, Gayson, Dallas, Taant, Johnson, and Hill Counties. Howeve, in the 1990s compaed to 1980s (Laye 5 in Figue 38), highe fluoide concentations, mg/l, wee found in the nothen counties, such as Cooke and Collin Counties. Deceasing fluoide concentations in the othe counties wee appoximately 0.1 to 3.0 mg/l. 78

88 4.4.2 Diffeent Nitate Concentations between Consecutive Decades Nitate concentations between the 1950s and 1960s (Laye 2 in Figue 39) both inceased and deceased anging fom 50 to 25 mg/l. Most of the inceasing nitate concentations wee located in the easten pat of the study aea. Fom the 1960s to 1970s (Laye 3 in Figue 39), most of the inceasing nitate levels wee located in the westen pat of the study aea, whee the aquife is shallow. Howeve, the concentations deceased fom 0.1 to 50 mg/l in laye 4 of Figue 39, except fo Cooke and noth of Denton Counties, located in a shallow pat of the aquife, whee the inceases anged fom 0 to 25 mg/l. High inceases wee ecognized in Taant County, whee thee wee shallow G monitoing wells dilled to obseve high nitate levels in an uban aea. Howeve, ove most of the study aea, nitate levels deceased fom 0.1 to 50 mg/l (Laye 5 in Figue 39) Diffeent ulfate Concentations between Consecutive Decades ulfate concentation diffeences in Figue 40 ae iegula, which is simila to fluoide diffeences in Figue 38. Fom 1950s to 1960s (Laye 2 in Figue 40), inceasing sulfate concentations anged fom 0.1 to 300 mg/l, which the highe sulfate concentation diffeence located in the southwesten pat of the study aea, whee thee to fou spikes wee obseved. Deceasing aeas had sulfate concentation diffeences anging fom 0.1 to 250 mg/l. Howeve, those aeas having high sulfate concentation diffeences fom the 1950s to 1960s deceased in the 1970s (Laye 3 in Figue 40), which 79

89 the deceasing concentations anging fom 0.1 to 250 mg/l. On the contay, those aeas having low sulfate concentation diffeences fom the 1950s to 1960s inceased in the1970s, which inceases anging fom 0.1 to 300 mg/l. ulfate concentation diffeences fom the 1970s to 1980s (Laye 4 in Figue 40) had the same patten as the 1960s to 1970s -- but aeas with inceasing diffeences deceased and aeas with deceasing diffeences inceased. The easons of these pattens might be come fom highe pumping ate causing highe sulfate levels in wate wells. Howeve, fom the 1980s to 1990s (Laye 5 in Figue 40), the highe sulfate concentation diffeences found in Taant County, whee the G s shallow monitoing wells wee dilled in the 1990s, anged fom 0.1 to 1800 mg/l. The souce of those high sulfate levels might be non-commecial lignite beds (TWDB, 1997). Futhemoe, inceasing sulfate diffeences found in the westen pat of the study aea, whee the aquife is shallow, anged fom 0.1 to 900 mg/l. Theefoe, the souce of the high sulfate concentation might be shallow souces, such as non-commecial lignite beds (TWDB, 1997) and shallow gypsum and anhydite deposits (Hudak, 2000) Diffeent Chloide Concentations between Consecutive Decades Fom the 1950s to 1960s (Laye 2 in Figue 41), chloide concentation diffeences ove 500 mg/l wee located in Dallas County, and concentations fom mg/l located in Collin, Denton, Taant, Ellis, Johnson, and Hill Counties. Deceasing chloide concentation diffeences anging fom 0.1 to 1000 mg/l wee found 80

90 in some pats of evey county. Fom the 1960s to 1970s (Laye 3 in Figue 41), chloide concentation diffeences ove 500 mg/l wee found in Gayson County, in the nothen pat of the study aea. The chloide concentation diffeences in most of the othe aeas in the 1970s deceased, anging fom 0.1 to 1000 mg/l. Othe local inceasing diffeences wee found, anging fom 0 to 1000 mg/l. Fom the 1980s to 1990s (Laye 4 in Figue 41), concentation diffeences ove 500 mg/l wee found in Collin and Dallas Counties. In this laye, chloide level diffeences fom 0.1 mg/l to 500 mg/l, wee mainly found in the easten pat of the study aea. The souce of those high sulfate concentations might come fom geology because of deepe aquife intevals. Fom the 1980s to 1990s (Laye 5 in Figue 41), inceasing chloide concentation diffeences wee found in the westen pat of the study aea, whee the aquife is shallow. The possible souce of high chloide in the 1990s was human activities. Futhemoe, Taant County, whee the G s shallow monitoing wells wee dilled in the 1990s, had inceasing chloide concentation diffeences ove 2700 mg/l. These high chloide concentations wee poduced fom the poo quality, uppe inteval of the aquife. 81

91 3-D Map of Fluoide Concentation Diffeence between Decades N Fluoide Diffeence (Mg/L) No Data Laye 1 = Nine Counties Laye 2 = 1960s s Laye 3 = 1970s s Laye 4 = 1980s s Laye 5 = 1990s s Z- Facto = 0.05 Figue 38 Diffeent Fluoide Concentations between Consecutive Decades 82

92 3-D Map of Nitate Concentation Diffeence between Decades N Nitate Diffeence (Mg/L) No Data Laye 1 = Nine Counties Laye 2 = 1960s s Laye 3 = 1970s s Laye 4 = 1980s s Laye 5 = 1990s s Z- Facto = Figue 39 Diffeent Nitate Concentations between Consecutive Decades 83

93 3-D Map of ulfate Concentation Diffeence between Decades N 5 ulfate Diffeence (Mg/L) No Data Laye 1 = Nine Counties Laye 2 = 1960s s Laye 3 = 1970s s Laye 4 = 1980s s Laye 5 = 1990s s Z- Facto = 0.05 Figue 40 Diffeent ulfate Concentations between Consecutive Decades 84

94 3-D Map of Chloide Concentation Diffeence between Decades N Chloide Diffeence (Mg/L) No Data Laye 1 = Nine Counties Laye 2 = 1960s s Laye 3 = 1970s s Laye 4 = 1980s s Laye 5 = 1990s s Z- Facto = 5 Figue 41 Diffeent Chloide Concentations between Consecutive Decades 85

95 4.5 tatistics test Kuskal-Wallis Test Kuskal-Wallis Test between Contaminants and Counties The Kuskal-Wallis test was applied to find elationships between contaminants and counties ove the five decades. The statistical details ae shown in Appendix D. The null hypothesis (Ho) is no diffeence between sulfate, chloide, fluoide, o nitate concentations among diffeent counties, and the altenative hypothesis (Ha) is that sulfate, chloide, fluoide, o nitate diffes among diffeent counties. The significance level ( ) is ummaized statistics listed in Table 7 showed that nitate in the 1950s, 1960s, and 1990s suppoted the null hypothesis (accept Ho), which means no diffeence between nitate concentations among counties. The est of the tests ejected the null hypothesis, which means that sulfate, chloide, fluoide, o nitate diffeed among diffeent counties in each decade. Futhemoe, Table 7 showed the highest median of each contaminant ove five decades. Only five counties, Dallas, Johnson, Ellis, Hill, and Taant Counties, located in the southen pat of the study aea, had the highest median values. Taant and Johnson Counties, located in the shallow pat of the aquife, had the highest median nitate levels. In contast, the highest median values of sulfate, chloide, and fluoide ove the five decades wee found in the easten counties (Dallas, Ellis, and Hill Counties). These esults point stongly to pincipally human souces fo nitate and geologic souces fo the othe thee solutes. 86

96 Table 7 Kuskal-Wallis Test between Contaminants and County ove Five Decades Ho = no diffeence between sulfate, chloide, fluoide, o nitate concentations among diffeent counties Ha = sulfate, chloide, fluoide, o nitate diffes among diffeent counties = 0.05 Contaminants Yeas Accept Ho Reject The highest median Ho Mg/L In county Name ulfate 1950s Ellis 1960s 471 Hill 1970s 405 Dallas 1980s Dallas 1990s 357 Ellis Chloide 1950s Ellis 1960s 132 Dallas 1970s 92 Dallas 1980s Dallas 1990s Ellis Fluoide 1950s 2.4 Dallas, Ellis 1960s 3.2 Ellis 1970s 2.6 Hill 1980s 2.3 Ellis 1990s 1.94 Ellis Nitate 1950s 2.5 Taant 1960s s 3.6 Johnson 1980s 0.68 Taant 1990s 0 - Note: ee statistics calculation in Appendix D 87

97 Kuskal-Wallis Test between Contaminants and Land se Types As detailed land use data was obtained in 1993, the study between land use and contaminants focused on the 1990s. Othe land use data obtained fom 1970 to 1985 fom G with 1-kilomete esolution could not be used because of coase spatial and tempoal esolution. Land use classes wee eclassified into 8 classes, such as wate, foest, uban, gassland, copland, wetland, shub land, and bae soil, as explained in Chapte 3. Fom Figues 42 to 45, the nothwest and southwest pats of the study aea wee pedominantly foest land cove (Cooke, Denton, Johnson, and Hill Counties). Copland aeas wee located mainly in the easten pat of Gayson and Collin Counties. ban aeas wee mainly located in Taant and Dallas Counties. Wetland aeas wee found nea the majo lakes such as Lewisville Lake and Lake Ray Robets. Gassland, and shubland aeas wee located in evey county. Finally, bae soil was found mainly in Dallas County. As the study aea coves nine counties, the land cove types in Figues can not easily be diffeentiated among well locations. Howeve, a speadsheet having contaminants, land use types, and county names of each well is attached in Appendix H. tatistics in Table 8 summaize the Kuskal-Wallis tests with details in Appendix E. Evey test suppoted the null hypothesis, which means no diffeence between each contaminant among diffeent land uses. Theefoe, land use was not an impotant facto contolling the distibution of contaminants in the aquife. 88

98 Table 8 Kuskal-Wallis Test between Contaminants and Land se Types Ho = no diffeence between sulfate, chloide, fluoide, o nitate concentations among diffeent land uses Ha = sulfate, chloide, fluoide, o nitate diffes among diffeent land uses = 0.05 Contaminants Yeas Accept Ho Reject Ho The highest median mg/l In land use type ulfate 1990s 290 copland Chloide 1990s 76 uban Fluoide 1990s 0.7 uban Nitate 1990s 0 - Note: ee statistics calculation in Appendix E 89

99 Figue 42 Fluoide Concentation of land use types in the Woodbine Aquife 90