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Manahan,StanleyE.WATERPOLLUTIONEnvironmentalChemistryBocaRaton:CRCPressLLC,20007WATERPOLLUTION____________________________________________________7.1.NATUREANDTYPESOFWATERPOLLUTANTSThroughouthistory,thequalityofdrinkingwaterhasbeenafactorindetermininghumanwelfare.Fecalpollutionofdrinkingwaterhasfrequentlycausedwaterbornediseasesthathavedecimatedthepopulationsofwholecities.Unwholesomewaterpollutedbynaturalsourceshascausedgreathardshipforpeopleforcedtodrinkitoruseitforirrigation.Althoughtherearestilloccasionalepidemicsofbacterialandviraldiseasescausedbyinfectiousagentscarriedindrinkingwater,waterbornediseaseshaveingeneralbeenwellcontrolled,anddrinkingwaterintechnologicallyadvancedcountriesisnowremarkablyfreeofthedisease-causingagentsthatwereverycommonwatercontaminantsonlyafewdecadesearlier.Currently,waterbornetoxicchemicalsposethegreatestthreattothesafetyofwatersuppliesinindustrializednations.ThisisparticularlytrueofgroundwaterintheU.S.,whichexceedsinvolumetheflowofallU.S.rivers,lakes,andstreams.Insomeareas,thequalityofgroundwaterissubjecttoanumberofchemicalthreats.Therearemanypossiblesourcesofchemicalcontamination.Theseincludewastesfromindustrialchemicalproduction,metalplatingoperations,andpesticiderunofffromagriculturallands.Somespecificpollutantsincludeindustrialchemicalssuchaschlorinatedhydrocarbons;heavymetals,includingcadmium,lead,andmercury;salinewater;bacteria,particularlycoliforms;andgeneralmunicipalandindustrialwastes.SinceWorldWarIItherehasbeenatremendousgrowthinthemanufactureanduseofsyntheticchemicals.Manyofthechemicalshavecontaminatedwatersupplies.Twoexamplesareinsecticideandherbiciderunofffromagriculturalland,andindustrialdischargeintosurfacewaters.Also,thereisathreattogroundwaterfromwastechemicaldumpsandlandfills,storagelagoons,treatingponds,andotherfacilities.ThesethreatsarediscussedinmoredetailinChapter19.Itisclearthatwaterpollutionshouldbeaconcernofeverycitizen.Under-standingthesources,interactions,andeffectsofwaterpollutantsisessentialfor©2000CRCPressLLCcontrollingpollutantsinanenvironmentallysafeandeconomicallyacceptablemanner.Aboveall,anunderstandingofwaterpollutionanditscontroldependsuponabasicknowledgeofaquaticenvironmentalchemistry.Thatiswhythistextcoverstheprinciplesofaquaticchemistrypriortodiscussingpollution.Waterpollutionmaybestudiedmuchmoreeffectivelywithasoundbackgroundinthefundamentalpropertiesofwater,aquaticmicrobialreactions,sediment-waterinteractions,andotherfactorsinvolvedwiththereactions,transport,andeffectsofthesepollutants.Waterpollutantscanbedividedamongsomegeneralcategories,assummarizedinTable7.1.Mostofthesecategoriesofpollutants,andseveralsubcategories,arediscussedinthischapter.Anenormousamountofmaterialispublishedonthissub-jecteachyear,anditisimpossibletocoveritallinonechapter.Inordertobeuptodateonthissubjectthereadermaywanttosurveyjournalsandbooksdealingwithwaterpollution,suchasthoselistedintheSupplementaryReferencessectionattheendofthischapter.Table7.1.GeneralTypesofWaterPollutantsClassofpollutantSignificanceTraceElementsHealth,aquaticbiota,toxicityHeavymetalsHealth,aquaticbiota,toxicityOrganically-boundmetalsMetaltransportRadionuclidesToxicityInorganicpollutantsToxicity,aquaticbiotaAsbestosHumanhealthAlgalnutrientsEutrophicationAcidity,alkalinity,salinity(inexcess)Waterquality,aquaticlifeTraceorganicpollutantsToxicityPolychlorinatedbiphenylsPossiblebiologicaleffectsPesticidesToxicity,aquaticbiota,wildlifePetroleumwastesEffectonwildlife,estheticsSewage,humanandanimalwastesWaterquality,oxygenlevelsBiochemicaloxygendemandWaterquality,oxygenlevelsPathogensHealtheffectsDetergentsEutrophication,wildlife,estheticsChemicalcarcinogensIncidenceofcancerSedimentsWaterquality,aquaticbiota,wildlifeTaste,odor,andcolorEsthetics©2000CRCPressLLC7.2.ELEMENTALPOLLUTANTSTraceelementisatermthatreferstothoseelementsthatoccuratverylowlevelsofafewpartspermillionorlessinagivensystem.Thetermtracesubstanceisamoregeneraloneappliedtobothelementsandchemicalcompounds.Table7.2summarizesthemoreimportanttraceelementsencounteredinnaturalwaters.Someofthesearerecognizedasnutrientsrequiredforanimalandplantlife,includingsomethatareessentialatlowlevelsbuttoxicathigherlevels.Thisistypicalbehaviorformanysubstancesintheaquaticenvironment,apointthatmustbeTable7.2.ImportantTraceElementsinNaturalWatersElementSourcesEffectsandSignificanceArsenicMiningbyproduct,chemicalToxic1,possiblycarcinogenicwasteBerylliumCoal,industrialwastesToxicBoronCoal,detergents,wastesToxicChromiumMetalplatingEssentialasCr(III),toxicasCr(VI)CopperMetalplating,mining,indus-Essentialtraceelement,toxictoplantstrialwasteandalgaeathigherlevelsFluorine(F-)Naturalgeologicalsources,Preventstoothdecayataround1wastes,wateradditivemg/L,toxicathigherlevelsIodine(I-)Industrialwastes,naturalPreventsgoiterbrines,seawaterintrusionIronIndustrialwastes,corrosion,Essentialnutrient,damagesfixturesacidminewater,microbialbystainingactionLeadIndustrialwaste,mining,Toxic,harmfultowildlifefuelsManganeseIndustrialwastes,acidmineToxictoplants,damagesfixtureswater