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Manahan,StanleyE.ENVIRONMENTALSCIENCE,TECHNOLOGY,ANDCHEMISTRYEnvironmentalChemistryBocaRaton:CRCPressLLC,20001ENVIRONMENTALSCIENCE,TECHNOLOGY,ANDCHEMISTRY____________________________________________________1.1.WHATISENVIRONMENTALSCIENCE?Thisbookisaboutenvironmentalchemistry.Tounderstandthattopic,itisimportanttohavesomeappreciationofenvironmentalscienceasawhole.Environmentalscienceinitsbroadestsenseisthescienceofthecomplexinteractionsthatoccuramongtheterrestrial,atmospheric,aquatic,living,andanthropologicalenvironments.Itincludesallthedisciplines,suchaschemistry,biology,ecology,sociology,andgovernment,thataffectordescribetheseinteractions.Forthepurposesofthisbook,environmentalsciencewillbedefinedasthestudyoftheearth,air,water,andlivingenvironments,andtheeffectsoftechnologythereon.Toasignificantdegree,environmentalsciencehasevolvedfrominvestigationsofthewaysbywhich,andplacesinwhich,livingorganismscarryouttheirlifecycles.Thisisthedisciplineofnaturalhistory,whichinrecenttimeshasevolvedintoecology,thestudyofenvironmentalfactorsthataffectorganismsandhoworganismsinteractwiththesefactorsandwitheachother.1Forbetterorforworse,theenvironmentinwhichallhumansmustlivehasbeenaffectedirrreversiblybytechnology.Therefore,technologyisconsideredstronglyinthisbookintermsofhowitaffectstheenvironmentandinthewaysbywhich,appliedintelligentlybythoseknowledgeableofenvironmentalscience,itcanserve,ratherthandamage,thisEarthuponwhichalllivingbeingsdependfortheirwelfareandexistence.Figure1.1.Therefore,inasensethisfiguresummarizesandoutlinesthethemeofTheEnvironmentAir,water,earth,life,andtechnologyarestronglyinterconnectedasshownintherestofthisbook.©2000CRCPressLLCFigure1.1.Illustrationofthecloserelationshipsamongtheair,water,andearthenvironmentswitheachotherandwithlivingsystems,aswellasthetie-inwithtechnology(theanthrosphere).Traditionally,environmentalsciencehasbeendividedamongthestudyoftheatmosphere,thehydrosphere,thegeosphere,andthebiosphere.TheatmosphereisthethinlayerofgasesthatcoverEarth’ssurface.Inadditiontoitsroleasareservoirofgases,theatmospheremoderatesEarth’stemperature,absorbsenergyanddamag-ingultravioletradiationfromthesun,transportsenergyawayfromequatorialregions,andservesasapathwayforvapor-phasemovementofwaterinthehydro-logiccycle.ThehydrospherecontainsEarth’swater.Over97%ofEarth’swaterisinoceans,andmostoftheremainingfreshwaterisintheformofice.Therefore,onlyarelativelysmallpercentageofthetotalwateronEarthisactuallyinvolvedwithterrestrial,atmospheric,andbiologicalprocesses.Exclusiveofseawater,thewaterthatcirculatesthroughenvironmentalprocessesandcyclesoccursintheatmosphere,undergroundasgroundwater,andassurfacewaterinstreams,rivers,lakes,ponds,andreservoirs.Thegeosphereconsistsofthesolidearth,includingsoil,whichsupportsmostplantlife.Thepartofthegeospherethatisdirectlyinvolvedwithenvironmentalprocessesthroughcontactwiththeatmosphere,the©2000CRCPressLLChydrosphere,andlivingthingsisthesolidlithosphere.Thelithospherevariesfrom50to100kminthickness.Themostimportantpartofitinsofarasinteractionswiththeotherspheresoftheenvironmentareconcernedisitsthinouterskincomposedlargelyoflightersilicate-basedmineralsandcalledthecrust.AlllivingentitiesonEarthcomposethebiosphere.Livingorganismsandtheaspectsoftheenvironmentpertainingdirectlytothemarecalledbiotic,andotherportionsoftheenvironmentareabiotic.Toalargeextent,thestronginteractionsamonglivingorganismsandthevariousspheresoftheabioticenvironmentarebestdescribedbycyclesofmatterthatinvolvebiological,chemical,andgeologicalprocessesandphenomena.Suchcyclesarecalledbiogeochemicalcycles,andarediscussedinmoredetailinSection1.6andelsewhereinthisbook.1.2.ENVIRONMENTALCHEMISTRYANDENVIRONMENTALBIOCHEMISTRYEnvironmentalchemistryencompassesmanydiversetopics.ItmayinvolveastudyofFreonreactionsinthestratosphereorananalysisofPCBdepositsinoceansediments.Italsocoversthechemistryandbiochemistryofvolatileandsolubleorganometalliccompoundsbiosynthesizedbyanaerobicbacteria.Literallythousandsofotherexamplesofenvironmentalchemicalphenomenacouldbegiven.Environmentalchemistrymaybedefinedasthestudyofthesources,reactions,transport,effects,andfatesofchemicalspeciesinwater,soil,air,andlivingenvironments,andtheeffectsoftechnologythereon.Environmentalchemistryisnotanewdiscipline.Excellentworkhasbeendoneinthisfieldforthegreaterpartofacentury.Untilabout1970,mostofthisworkwasdoneinacademicdepartmentsorindustrialgroupsotherthanthoseprimarilyconcernedwithchemistry.Muchofitwasperformedbypeoplewhosebasiceducationwasnotinchemistry.Thus,whenpesticidesweresynthesized,biologistsobservedfirsthandsomeofthelessdesirableconsequencesoftheiruse.Whendetergentswereformulated,sanitaryengineerswerestartledtoseesewagetreatmentplantaerationtanksvanishundermeter-thickblanketsoffoam,whilelimnologistswonderedwhypreviouslynormallakessuddenlybecamechokedwithstinkingcyanobacteria.Despitetheselongstandingenvironmentaleffects,andevenmorerecentandseriousproblems,suchasthosefromhazardouswastes,relativelyfewchemistshavebeenexposedtomaterialdealingwithenvironme