给水排水论文中英对照翻译水污染和社会的关系.docx
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给水排水论文中英对照翻译水污染和社会的关系.docx
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给水排水论文中英对照翻译水污染和社会的关系
英文资料
WATERPOLLUTIONANDSOCIETY
By
DavidKrantzandBradKifferstein
INTRODUCTION
Comprisingover70%oftheEarth’ssurface,waterisundoubtedlythemostpreciousnaturalresourcethatexistsonourplanet. Withouttheseeminglyinvaluablecompoundcomprisedofhydrogenandoxygen,lifeonEarthwouldbenon-existent:
itisessentialforeverythingonourplanettogrowandprosper. Althoughweashumansrecognizethisfact,wedisregarditbypollutingourrivers,lakes,andoceans.Subsequently,weareslowlybutsurelyharmingourplanettothepointwhereorganisms
aredyingataveryalarmingrate. Inadditiontoinnocentorganismsdyingoff,ourdrinkingwaterhasbecomegreatlyaffectedasisourabilitytousewaterforrecreationalpurposes. Inordertocombatwaterpollution,wemustunderstandtheproblemsandbecomepartofthesolution.
POINTANDNONPOINTSOURCES
AccordingtotheAmericanCollegeDictionary,pollutionisdefinedas:
“tomakefoulorunclean;dirty.” Waterpollutionoccurswhenabodyofwaterisadverselyaffectedduetotheadditionoflargeamountsofmaterialstothewater. Whenitisunfitforitsintendeduse,waterisconsideredpolluted. Twotypesofwaterpollutantsexist;pointsourceandnonpointsource. Pointsourcesofpollutionoccurwhenharmfulsubstancesareemitteddirectlyintoabodyofwater. TheExxonValdezoilspillbestillustratesapointsourcewaterpollution. Anonpointsourcedeliverspollutantsindirectlythroughenvironmentalchanges. Anexampleofthistypeofwaterpollutioniswhenfertilizerfromafieldiscarriedintoastreambyrain,intheformofrun-off
whichinturneffectsaquaticlife. Thetechnologyexistsforpointsourcesofpollutiontobemonitoredandregulated,althoughpoliticalfactorsmaycomplicatematters.Nonpointsourcesaremuchmoredifficulttocontrol. Pollutionarisingfromnonpointsourcesaccountsforamajorityofthecontaminantsinstreamsandlakes.
CAUSESOFPOLLUTION
Manycausesofpollutionincludingsewageandfertilizerscontainnutrientssuchasnitratesandphosphates. Inexcesslevels,nutrientsoverstimulatethegrowthofaquaticplantsandalgae. Excessivegrowthofthesetypesoforganismsconsequentlyclogsourwaterways,useupdissolvedoxygenastheydecompose,andblocklighttodeeperwaters.
This,inturn,provesveryharmfultoaquaticorganismsasitaffectstherespirationabilityorfishandotherinvertebratesthatresideinwater.
Pollutionisalsocausedwhensiltandothersuspendedsolids,suchassoil,washoffplowedfields,constructionandloggingsites,urbanareas,anderodedriverbankswhenitrains. Undernaturalconditions,lakes,rivers,andotherwaterbodiesundergoEutrophication,anagingprocessthatslowlyfillsinthewaterbodywithsedimentandorganicmatter. Whenthesesedimentsentervariousbodiesofwater,fishrespirationbecomesimpaired,plantproductivityandwaterdepthbecomereduced,andaquaticorganismsandtheirenvironmentsbecomesuffocated. Pollutionintheformoforganicmaterialenterswaterwaysinmanydifferentformsassewage,asleavesandgrassclippings,orasrunofffromlivestockfeedlotsandpastures. Whennaturalbacteriaandprotozoaninthewaterbreakdownthisorganicmaterial,theybegintouseuptheoxygendissolvedinthewater. Manytypesoffishandbottom-dwellinganimalscannotsurvivewhenlevelsofdissolvedoxygendropbelowtwotofivepartspermillion. Whenthisoccurs,itkillsaquaticorganismsinlargenumberswhichleadstodisruptionsinthefoodchain.
Pathogensareanothertypeofpollutionthatproveveryharmful. Theycancausemanyillnessesthatrangefromtyphoidanddysenterytominorrespiratoryandskindiseases. Pathogensincludesuchorganismsasbacteria,viruses,andprotozoan. Thesepollutantsenterwaterwaysthroughuntreatedsewage,stormdrains,septictanks,runofffromfarms,andparticularlyboatsthatdumpsewage. Thoughmicroscopic,thesepollutantshaveatremendouseffectevidencedbytheirabilitytocausesickness.
CLASSIFYINGWATERPOLLUTION
Themajorsourcesofwaterpollutioncanbeclassifiedasmunicipal,industrial,andagricultural. Municipalwaterpollutionconsistsofwastewaterfromhomesandcommercialestablishments. Formanyyears,themaingoaloftreatingmunicipalwastewaterwassimplytoreduceitscontentofsuspendedsolids,oxygen-demandingmaterials,dissolvedinorganiccompounds,andharmfulbacteria. Inrecentyears,however,morestresshasbeenplacedonimprovingmeansofdisposalofthesolidresiduesfromthemunicipaltreatmentprocesses. Thebasicmethodsoftreatingmunicipalwastewaterfallintothreestages:
primarytreatment,includinggritremoval,screening,grinding,andsedimentation;secondarytreatment,whichentailsoxidationofdissolvedorganicmatterbymeansofusingbiologicallyactivesludge,whichisthenfilteredoff;andtertiarytreatment,inwhichadvancedbiologicalmethodsofnitrogenremovalandchemicalandphysicalmethodssuchasgranularfiltrationandactivatedcarbonabsorptionareemployed. Thehandlinganddisposalofsolidresiduescanaccountfor25to50percentofthecapitalandoperationalcostsofatreatmentplant. Thecharacteristicsofindustrialwastewaterscandifferconsiderablybothwithinandamongindustries. Theimpactofindustrialdischargesdependsnotonlyontheircollectivecharacteristics,suchasbiochemicaloxygendemandandtheamountofsuspendedsolids,butalsoontheircontentofspecificinorganicandorganicsubstances.Threeoptionsareavailableincontrollingindustrialwastewater. Controlcantakeplaceatthepointofgenerationintheplant;wastewatercanbepretreatedfordischargetomunicipaltreatmentsources;orwastewatercanbetreatedcompletelyattheplantandeitherreusedordischargeddirectlyintoreceivingwaters.
WASTEWATERTREATMENT
Rawsewageincludeswastefromsinks,toilets,andindustrialprocesses.Treatmentofthesewageisrequiredbeforeitcanbesafelyburied,used,orreleasedbackintolocalwatersystems.Inatreatmentplant,thewasteispassedthroughaseriesofscreens,chambers,andchemicalprocessestoreduceitsbulkandtoxicity.Thethreegeneralphasesoftreatmentareprimary,secondary,andtertiary.Duringprimarytreatment,alargepercentageofthesuspendedsolidsandinorganicmaterialisremovedfromthesewage.Thefocusofsecondarytreatmentisreducingorganicmaterialbyacceleratingnaturalbiologicalprocesses.Tertiarytreatmentisnecessarywhenthewaterwillbereused;99percentofsolidsareremovedandvariouschemicalprocessesareusedtoensurethewaterisasfreefromimpurityaspossible.Agriculture,includingcommerciallivestockandpoultryfarming,isthesourceofmanyorganicandinorganicpollutantsinsurfacewatersandgroundwater. Thesecontaminantsincludebothsedimentfromerosioncroplandandcompoundsof
phosphorusandnitrogenthatpartlyoriginateinanimalwastesandcommercialfertilizers. Animalwastesarehighinoxygendemandingmaterial,nitrogenandphosphorus,andtheyoftenharborpathogenicorganisms. Wastesfromcommercialfeedersarecontainedanddisposedofonland;theirmainthreattonaturalwaters,therefore,isfromrunoffandleaching. Controlmayinvolvesettlingbasinsforliquids,limitedbiologicaltreatmentinaerobicoranaerobiclagoons,andavarietyofothermethods.
GLOBALWATERPOLLUTION
Estimatessuggestthatnearly1.5billionpeoplelacksafedrinkingwaterandthatatleast5milliondeathsperyearcanbeattributedtowaterbornediseases.Withover70percentoftheplanetcoveredbyoceans,peoplehavelongactedasiftheseverybodiesofwatercouldserveasalimitlessdumpinggroundforwastes.Rawsewage,garbage,andoilspillshavebeguntooverwhelmthedilutingcapabilitiesoftheoceans,andmostcoastalwatersarenowpolluted.Beachesaroundtheworldareclosedregularly,oftenbecauseofhighamountsofbacteriafromsewagedisposal,andmarinewildlifeisbeginningtosuffer.
Perhapsthebiggestreasonfordevelopingaworldwideefforttomonitorandrestrictglobalpollutionisthefactthatmostformsofpollutiondonotrespectnationalboundaries.ThefirstmajorinternationalconferenceonenvironmentalissueswasheldinStockholm,Sweden,in1972andwassponsoredbytheUnitedNations(UN).Thismeeting,atwhichtheUnitedStatestookaleadingrole,wascontroversialbecausemanydevelopingcountrieswerefearfulthatafocusonenvironmentalprotectionwasameansforthedevelopedworldtokeeptheundevelopedworldinaneconomicallysubservientposition.ThemostimportantoutcomeoftheconferencewasthecreationoftheUnitedNationsEnvironmentalProgram(UNEP).UNEPwasdesignedtobe“theenvironmentalconscienceoftheUnitedNations,”and,inanattempttoallayfearsofthedevelopingworld,itbecamethefirstUNagencytobeheadquarteredinadevelopingcountry,withofficesinNairobi,Kenya.Inadditiontoattemptingtoachievescientificconsensusaboutmajorenvironmentalissues,amajorfocusforUNEPhasbeenthestudyofwaystoencouragesustainabledevelopmentincreasingstandardsoflivingwithoutdestroyingtheenvironment.AtthetimeofUNEP'screationin1972,only11countrieshadenvironmentalagencies.Tenyearslaterthatnumberhadgrownto106,ofwhich70wereindevelopingcountries.
WATERQUALITY
Waterqualityiscloselylinkedtowateruseandtothestateofeconomicdevelopment. Inindustrializedcountries,bacterialcontaminationofsurfacewatercausedserioushealthproblemsinmajorcitiesthroughoutthemid1800’s. Bytheturnofthecentury,citie
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