水污染-英文版

WaterpollutionItcovers71%oftheearth'ssurfaceandmakesup65%ofourbodies.Withouttheseeminglyinvaluablecompoundcomprisedofhydrogenandoxygen,lifeonEarthwouldbenon-existentWaterisEssentialforLifeThreefourthsofthesurfaceoftheEarthiscoveredwithwater.Nearly98%ofthewateronEarth,though,isseawater-unfitfordrinkingandnotevensuitableformostindustrialpurposes.Somethinglessthan2%ofthewaterisfrozeninthepolaricecaps,leavinglessthan1%availableasfreshwater.Water:UnusualPropertiesManychemicalsubstancesaresolubleinwater.Thus,theyareeasilydispersedandeventuallyarescatteredtonearlyinfinitedilutionintheocean.Thosepropertiesofwaterthatmakeituniquelysuitedforthesupportoflifealsomakeiteasytopollute.NaturalWaterIsn’tAllH2ORainwatercarriesdustparticlesfromtheatmospheretotheground.Rainwateralsodissolvesalittleoxygen,nitrogen,andcarbondioxideasitfallsthroughtheatmosphere.Duringelectricalstorms,lightningcausesnitrogen,oxygen,andwatervaportocombinetoformnitricacid.AswatermovesalongorbeneaththesurfaceoftheEarth,itdissolvesmineralsandmatterfromdecayingplantsandanimals.Theprincipalpositiveions(cations)innaturalwateraresodium(Na+),potassium(K+),calcium(Ca2+),magnesium(Mg2+),andsometimesiron(Fe2+orFe3+).Thenegativeions(anions)areusuallysulfate(SO42-),bicarbonate(HCO3-),andchloride(Cl-).hardwaterWatercontainingthesecalcium,magnesium,andironionsiscalledhardwater.Thepositiveionsreactwiththenegativeionsinsoaptoformascumthatclingstoclothesandleavesthemdingylooking.WaterpollutionWaterpollutionisanychemical,physicalorbiologicalchangeinthequalityofwaterthathasaharmfuleffectonanylivingthingWaterpollutioncausedbyhumanactivitiesisalargesetofadverseeffectsuponwaterbodiessuchaslakes,rivers,oceans,andgroundwaterPollutantsinwaterincludeawideofchemicals,pathogens病原体,andphysicalchemistryorsensorychanges.WaterpollutionWaterpollutionistheleadingworldwidecauseofdeathsanddiseases,andthatitaccountsforthedeathsofmorethan14,000peopledaily.Effectsofwaterpollutionincludepoisonousdrinkingwater,poisonousfoodanimals,unbalancedriverandlakeecosystems,deforestationandmanyothereffectsSourcesofwaterpollutionTheusedwaterofacommunityiscalledwastewater,orsewage.Ifitisnottreatedbeforebeingdischargedintowaterways,seriouspollutionistheresult.Therearetwosortsofsources,pointandnonpointsources.Pointsourcesdischargepollutantsatspecificlocationsthroughpipelinesorsewers下水道intothesurfacewater.Nonpointsources非点(污染)源aresourcesthatcannotbetracedtoasinglesiteofdischarge.FactoriesAgricultureTransportationHouseholdSourcesofwaterpollutionDomesticsewageDomesticsewagereferstowastewaterthatisdiscardedfromhouseholds.Alsoreferredtoassanitarysewage.Domesticsewagecontainsawidevarietyofdissolvedandsuspendedimpurities:a.organicmaterials-foodandvegetablewasteb.plantnutrients-chemicalsoaps,washingpowdersc.disease-causingmicrobes微生物HouseholdChemicalsExample:substancesusedforhousesclean:SoapandsyntheticdetergentsWaxPaintsandpaintremoversBleachesDisinfectants消毒剂PolishesAgriculturalRunoffFertilizers:nitrate,phosphatesPesticides:phenol,chlorinediphenylEutrophication富营养作用:nutrientsartificiallysupplementedresultsinanabnormalincreaseinthegrowthofwaterplantsIndustrialPollutionIndustrialeffluentofmanykindsofwaste,isdischargedintostreams,lakes,oroceans,whichinturndispersethepollutingsubstances.Thepollutantsincludegrit,asbestos石棉,phosphatesandnitrates,mercury,lead,causticsodaandothersodiumcompounds,sulfurandsulfuricacid,oils,andpetrochemicals.Example:Chromeplatingonbumpers,grills,andornamentsisasourceofpollutionPollutantsfromvariousindustriesThetextileindustrydumpsconditioners,dyes,bleaches,andwatereffluentscontainingoils,dirt,andotherorganicdebris.Meat-packingplantsdumpblood,thecontentsofentrails内脏,andotheranimalwastes.Otherfood-processingplantsdischargefruitandvegetableskins,seeds,leaves,stems,andothervegetablewastes.Refineries精炼厂releasedyes,oils,acids盐水,sulfurcompounds,andotherwastes.Chemicalsplantsproduceavarietyofwastematerials.OilspillsOilspillsfromtankersatseaorleaksfromundergroundstoragetanksonlandareverydifficulttocontrolOilspillsatseadecreasetheoxygenlevelinthewaterandcausegraveharmtothecreatureslivinginthesea.OnlandcrudeistransportedthroughpipelinesortankerswhichcangetdamagedandspewoutcrudeoiloverthelandOilspillsareverydifficulttocontrolasoiltendstospreadveryfast,affectingalargeareainaveryshorttime.GroundwateranditscontaminationGroundwaterarecontaminatedwithheavymetals,persistentorganicpollutants,andnutrientsa.Pesticides:Run-offfromfarms,backyards,andgolfcoursesb.Leachate沥出液fromlandfillsitesc.Untreatedorinadequatelytreatedmunicipalsewage:organicmaterial,microbialpathogend.Nutrients:phosphorusandnitrogene.Syntheticorganics:industrialchemicalsandpesticidesChemicalsindrinkingwaterChemicalsindrinkingwatercanbebothnaturallyoccurringorintroducedbyhumaninterferencea.Fluorideb.Arsenicc.Petrochemicalsd.Chlorinatedsolventse.SaltsDifferenttypesofwaterpollutionMicrobiological:Disease-causing(pathogenic)microorganisms,likebacteria,virusesandprotozoa原生动物.Chemicals:Awholevarietyo