中國(guó)地質(zhì)大學(xué)(武漢)環(huán)境化學(xué)08 Water Pollution

ChapterEightWaterPollutionOxygenConsumingWastesPlantNutrientsWaterPollutionGeneraltypesofwaterpollutantsTypesofTraceElementsPesticidesGeneraltypesofwaterpollutantsDisease-causingagents(Pathogens，病原體)Oxygen-consumingagentsPlantnutrientsToxicsubstancesHeavymetalsPesticidesDissolvedsolidsAcidsSuspendedsolidsandsedimentsOilRadioactivesubstances(Radionuclides)Heat(thermalpollution)TypesofTraceElementsHeavymetals–transitionmetals(Cr,Cd,Cu,etc.)andafewrepresentativeelements(Sn,Pb).Metalloids–As,Se,B,Sb.Non-metals–S,I,F.HeavyMetalsofParticularConcernCadmium–Usedingalvanization(電鍍)process(likezinc).Replaceszincinkeyenzymes,extremelytoxic.PaldiskiBayinEstoniacontainsupto62.5g/kgCd.LeadUsedastetraethylleadingasolineasanti-knockingagentuntilthe’80s–stillusedindevelopingcountries.U.S.childrenbetween1-5withleadlevelsabove10mg/dLstandard:Whitechildren:85%in1976to6%in1992.Blackchildren:98%in1976to21%in1992.MercuryMetalwithmostconcernduetomobilityofmethylatedforms.AnaerobicbacteriaconvertHgCl2–>CH3HgCland(CH3)2Hg.Bothmethylatedformsarefatsolubleandconcentrate1000xineachtrophiclevel.Hgoisonlyvolatilemetal-->atmospherictransport.TragiceffectsofpointsourceHgMinamataBay,Japan,2,265officialHgpoisoningvictimsfromeatingseafood1953-1960.(水俁,日本)ChissoCorp.usedHgascatalysttomakeacetaldehydeforplastics.Concentrationinfish~5-20ppm,now<0.4ppm.NationalInstituteforMinamataDiseaseManymorepotentialHgvictimsHealthstandardwasoriginally>50ppminhumanhair.Newstudyshowsthat>10ppmcouldcauseneurologicaldamage.Mayincreasenumberofvictimsseekingretributionto>2million.Env.NewsNetwork,APStory,Oct.11,2001Subtle(微妙的)effectsoflong-rangetransportofHgRocktypicallycontains80ppbHg.Becauseofmetal-attractinghumicsubstances,coalcontains~100ppb.VolatileHgcarriedaroundglobe.Arcticspringcausesrapid“rain-out”.Nativedietishigh-fat,marinemammal.HgDepositionNetworkinU.S.andCanadaMetalloids–ArsenicArsenic:naturallypresentinearth’scrust,releasedtoairthroughcoalcombustion.CanbemethylatedlikeHg:CH3AsO(OH)2(methylarsinicacid).NewAsindrinkingwaterstd.10ppb,downfrom50ppb.Watersystemsmustmeetnewstd.by2006.(EPAwebsite)Pressure-treatedwoodcontainscopper-chromium-arsenicbiocide.One12ftboardcontainsenoughAstokill250adults.(VermontPublicInterestGroup).SeleniumKestersonReservoirintheSanLuisDrain.HighlevelsofSeaccumulatedinwetlandsandcausedbirthdeformitiesofbirdsandwildlife.KestersonReservoirTinTBT–tributyltinchloride(C4H9)3SnCl.Usedasabiocideonshiphulls.Actsasanendocrine(內(nèi)分泌)systemdisruptor(混亂劑).ThreespeciesofMurex(骨螺)

shellfishinSicilyfacingextinction(消失)ashormone(激素)-disruptingtributyltininshiphullpaint(船體外殼油漆)

causesalmostallfemalestochangeintomales.(10/19/2001)ThreepopularspeciesofSicilianshellfisharefacingextinctionbecausepoisonouscompoundsinpaintusedonships‘hullsarecausingtochangesex.AstudybytheWorldwideFundforNature(WWF)foundthatpracticallytheentiresampleoffemalesbelongingtothreeMurexspeciesofmollusks(軟體動(dòng)物)foundnearthebusyportsofPalermoandUsticahadchangedsex.Scientistssaythattributyltin(TBT),anorganotincompoundusedinpainttokeepships'hullsclearofmarinelife,booststheproductionoftestosteroneinfemalemollusks,causingthemtochangefromfemaletomale.Thepoisonous,hormone-disruptingcompoundshavebeenusedinships‘paintsfordecades,leavingatoxicwakearoundtheworld.“Thesesubstanceshavedevastating(破壞性的)

effectsonthehormonesystemsofsomespecies,andhumanscouldalsobeatriskiftheyconsumecontaminatedfish,"theWWFsaid.EarlierthismonththeInternationalMaritimeOrganizationfinallytookstepstoeventuallybanTBTandotherharmfulorganiccompoundsinshiphullpaints.Theywillbephasedoutbeginningin2008,toolateforthePalermomollusks.(FromEarthC)Organo-metalcompoundsummaryComplexationinvolvesligandswhichareboundsomewhatreversibly:ML+2H+

M2++H2L“Organometallic”bondisverystable,organicentitynotstableawayfromcompound.Importantorganos–alkyls(ethyl),carbonyls(CO),p-donors(havingdoublebonds).Toxicityandmobilityoforganometallicsisveryhigh.SummaryofInorganicSpeciesCyanide:CN-,weakbase,strongligand,usedinmetalextractionduringmining.Ammonia:NH4+,weakacid,associatedwithnitrogenouswaste(fecalmatter).Hydrogensulfide:H2S,weakacid,precipitateswithheavymetals,rotten-eggodor.Carbondioxide:CO2,weakacid,associatedwithdecayoforganicmatter,canbecorrosiveathighlevels.Nitrite/Nitrate:NO2-,NO3-,excessesoccurindrinkingwaterduetoover-fertilization,health-hazard.Sulfite:SO32-,scavengesoxygenfromwater,formingSO42-.PesticidesInsecticide(殺蟲(chóng)劑)Herbicide(除草劑)Fungicide(殺真菌劑)Nematocide(殺線蟲(chóng)劑)Allattempttotargetaspecificfunctionofpestandnototherorganism(specificity).EvolutionofPesticidesPreWW-II,AsandHgcompoundswereused.Notveryspecific,persistent,toxictohumans.PostWW-IIproducedinsecticides:organochlorines(DDT)andorganophosphates(usedasnervegases).Developmentofherbicidesin1950s–2,4-D(agentorange),paraquat(百草枯),atrazine(莠去津).Herbicidesallowedno-tillweeding(雜草).“Modern”herbicides:glyphosate(草甘膦)(Roundup)andgeneticallymodifiedcropsthatareresistanttoit.OrganochlorinesPropertiesofOCsLowacutetoxicities.Carcinogens.Highpersistenceinsoilsandtissues.Bioaccumulationinfoodchain.Causesthinningofegg-shellsofraptors.MostallarebannedinU.S.sincetheearly1970s.Continuedwidespreaduseintropicsasweaponagainstmalaria(瘧疾).HighlevelsofpesticideDDTfoundinLakeChelantrout

1,481partsperbillion—almost50timeshigherthanthefederalhealthcriteriaof32partsperbillion.OrganophosphatesIntenselytoxic.2mgofparathioncankillachild.Biodegradesratherrapidly,althoughdegradationproductsmayalsobeharmful.MalathionReplacingParathionCarbamates(氨基甲酸鹽)MorewatersolublethanOCsorOPs.Acetylcholinesteraseinhibitors.HerbicidesBipyridiliums(paraquat)Triazines(atrazine)Chlorophenoxy’s(2,4-D)Substitutedamides(Alachlor)ParaquatandDiquatWatersolubleBindtosoilparticles,andbiodegrade.UsedasdefoliantinVietnam.Highlytoxic.TriazinesAtrazine,simazine,andcyanozineheavilyusedincorn-belt,“no-till”agriculture.ExceededEPAlevelsin121drinkingwatersuppliesinmidwestin1994.2,4-Dand2,4,5-TAgentOrange,heavilyusedinVietnam.Stilloneofthemainherbicides.Alachlor–“Lasso”Killsgerminatinggrassandbroad-leavedweedseedlings.DioxinsByproductsofpesticidemanufactureandmostprocessesinvolvingchlorine.Oneofthemosttoxicsubstancesevercreated,althoughhumantoxicitynotwellstudied.0.6mg/kgLD50inguineapigs.Stable,easilybioconcentrated.OxygenConsumingWastesGeneraltypesofwaterpollutantsOxygenandaquaticlifeDissolvedoxygenBiologicaloxygendemandOxygen-consumingwastesSourcesfororganicwastesRedoxcouplesinnaturalenvironmentsOxygenandaquaticlifeAnimalsandplantslivinginanaquatichabitatdependonoxygendissolvedinthewaterfortheirsurvival.TheavailabilityofO2inwatersetstheboundarybetweenaerobicandanaerobiclife.Thishasimplicationson:WaterqualityHealthofecosystemOxygeninwatercomesfromdissolutionofatmosphericO2.Oxygen–VitalforHigherLifeFormsProcessesthatconsumeoxygen:Respiration:{CH2O}+O2

CO2+H2ONitrogenouswaste:NH4++2O22H++NO3-+H2OIron:Fe2++O2+10H2O4Fe(OH)3(s)+8H+Sulfite:2SO32-+O22SO42-Warmingwater(presenceofsiltorhumicscanabsorbmorelight).ProcessesthatAddOxygenPhotosynthesis:CO2+H2O{CH2O}+O2Turbulentflow:saturation=~9mg/Lat20oC.DissolvedoxygenTheamountofdissolvedoxygen(DO)dependsonthetemperatureandthealtitudeofthewater.RelatestoatmosphericpressureBiologicaloxygendemandEnergyisacquiredbyoxidationoforganicmaterial.Inthisprocess,oxygenisrequired. CH2O+ O2=CO2+H2O

12mgC 32mg 1mgC 2.7mgO2At20oC,DO=9mg/l,therefore,only~3.4mgofCH2OcanbeoxidizedbytheO2inaliterofwater.Whentheconcentrationoforganicmaterialishigh,watercanbeeasilydepletedofDO.Biologicaloxygendemand(BOD)istheamountofO2(inmilligram)requiredbymicroorganismstocarryouttheoxidationoforganiccarboninoneliterofwater.BOD5:theoxygenconsumedbymicroorganismsinfivedays.BiochemicalOxygenDemand-BODQuantityofoxygenutilizedbyaquaticorganismsinalabtestduringa5-dayperiod.BODcanbeapproximatedbymeasuringtotalorganiccarbon(TOC)byconvertingtoCO2.Oxygen-consumingwastesOrganicwastematerialsreleasedintothewatercanrapidlydepletedissolvedoxygen.Whenwaterisoverloadedwithorganicmaterials,oxygen-consuming(aerobic)bacteriaproliferate.Asaresult,DOisconsumedmorerapidlythanitcanbereplacedfromtheatmosphere.WhenDO<5ppm,fishstarttodie.IfDOdropsfurther,invertebratesandaerobicbacteriawillbeunabletosurvive.IntheabsenceofDO,anaerobicbacteriatakeovertodecomposeorganicmaterialThewaterbeginstosmellunpleasant.DODOvariationwiththedistancefromorganicwastechargepoint鱸小龍蝦蛤鱔EcologicalResponsetoInputofOxidizablePollutantfromPointSourceWhenPollutantDischargeExceedsFlushingRate…Watercanbecomeanaerobicandnotsupporthigherlifeforms.AlgaegrowthcanbestimulatedbyinputsofPandN.BacterialdegradationofdeadalgaecanconsumeO2.SourcesfororganicwastesHumanandanimalsewageIndustrialwastefrompapermills(造紙廠),tanneries(皮革廠),andfood-processingplants(食品加工廠).TypicalBODsforwastesfromvariousprocessesTypeofdischargeBOD(mgO2/literwastewater)Domesticsewage165Allmanufacturing200Chemicalsandalliedproducts314Paper372Food747Metals13DecompositionproductsoforganiccompoundsEpoundEndproductsofdecompositionAerobicconditionsAnaerobicconditionsCarbonCO2CH4NitrogenNO3-NH3andamines(胺)SulfurSO42-H2SphosphorusPO43-PH3andotherPcmpdsThreedefinitionsofoxidationandreductionoxidationReductionIntermsofoxygenGainofoxygenLossofoxygenIntermsofhydrogenLossofhydrogenGainofhydrogenIntermsofelectronsLossofelectronGainofelectronNaturalsequenceofredoxreactionsinaqueousenvironmentRedoxcouplesinnaturalenvironmentsO2/H2ONO3-/N2MnO2/Mn2+Fe(OH)3/Fe2+SO42-/HS-CO2/CH4DecreasingredoxpotentialStudyquestionsWhatdeterminesthemaximumamountofoxygenthatcanbedissolvedinwater?Whatconsumesoxygeninwater?Whathappensafteroxygenisexhaustedinawaterbody?Listthemajorredoxpairsinthenaturalenvironmentsintheorderofdecreasingredoxpotential.PlantNutrientsPlantnutrientsNaturalnutrientcyclinginaquaticecosystemControlofeutrophicationPlantnutrientsPlantgrowthrequiresvariousnutrients.Majornutrientelements:C,N,P.traceelements:S,Si,Cl,I,andmetallicelements(Fe,Mn,Cu,etc).Theminorelements,becauseofthelowdemand,canusuallybesuppliedatadequateratesinnaturalwaters.TherequiredproportionofthemajornutrientelementsisC:N:P=106:16:1.C,despitethelargestdemand,isplentifullysuppliedtophytoplanktonsfromCO2intheatmosphere.NaturalnutrientcyclinginaquaticecosystemNandPareoftenthelimitingnutrientsThelimitingnutrientistheleastavailableelementinrelationtoitsrequiredabundance.NisabundantintheformofN2,butN2canonlybeutilizedthroughN2-fixingbacteria.InwaterswhereN2-fixingalgalspeciesarecommon,Nisnotusuallylimiting.InregionswhereN2-fixingspeciesarelessabundant,especiallytheoceans,Nmaybethelimitingnutrient.ThisleavesPasthelimitingelementtoplantgrowth.Thisshortagekeepsthespreadofvegetationundercontrol.Phytoplankton(浮游植物)productivityasafunctionofNandPconcentrationsandsunlightInwinter,lowtemperatureandsunlightarethelimitingfactorstophytoplanktonproductivity.Insummer,nutrientsbecomethelimitingfactor.Decayofdeadplantmatterreplenish(補(bǔ)充)nutrients,leadingtoasecondarypeakofphytoplanktonproductivity.ConsequencesofexcessivenutrientloadingIfanewsourceofNorPisintroducedintothewater,excessiveplantgrowthoccurs,andthealgaepopulationexplodes(algaebloom),thisphenomenoniscalledeutrophication.Adverseconsequencesofeutrophication:WaterwaysbecomecloggedAlgaemightreleaseunpleasant-smelling,bad-tastingsubstancesDecayofalgaeinducesdecreaseinDO.Eutrophication

富營(yíng)養(yǎng)化SourceofNAgriculturelandtreatedwithnitratefertilizersSlaughterhouses(屠宰場(chǎng))Stockyards(牲畜場(chǎng))Atmosphericdeposition:NOxfromautomobiles,powerplants,etc.SourceofP:DetergentsThetwomainingredientsinsyntheticdetergents