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1、WaterpollutionItcovers71%oftheearth'ssurfaceandmakesup65%ofourbodies.Withouttheseeminglyinvaluablecompoundcomprisedofhydrogenandoxygen,lifeonEarthwouldbenon-existentWaterisEssentialforLifeThreefourthsofthesurfaceoftheEarthiscoveredwithwater.Nearly98%ofthewateronE
2、arth,though,isseawater‑unfitfordrinkingandnotevensuitableformostindustrialpurposes.Somethinglessthan2%ofthewaterisfrozeninthepolaricecaps,leavinglessthan1%availableasfreshwater.Water:UnusualPropertiesManychemicalsubstancesaresolubleinwater.Thus,theyareeasilydispe
3、rsedandeventuallyarescatteredtonearlyinfinitedilutionintheocean.Thosepropertiesofwaterthatmakeituniquelysuitedforthesupportoflifealsomakeiteasytopollute.NaturalWaterIsn’tAllH2ORainwatercarriesdustparticlesfromtheatmospheretotheground.Rainwateralsodissolvesalittle
4、oxygen,nitrogen,andcarbondioxideasitfallsthroughtheatmosphere.Duringelectricalstorms,lightningcausesnitrogen,oxygen,andwatervaportocombinetoformnitricacid.AswatermovesalongorbeneaththesurfaceoftheEarth,itdissolvesmineralsandmatterfromdecayingplantsandanimals.Thep
5、rincipalpositiveions(cations)innaturalwateraresodium(Na+),potassium(K+),calcium(Ca2+),magnesium(Mg2+),andsometimesiron(Fe2+orFe3+).Thenegativeions(anions)areusuallysulfate(SO42-),bicarbonate(HCO3-),andchloride(Cl-).hardwaterWatercontainingthesecalcium,magnesium,a
6、ndironionsiscalledhardwater.Thepositiveionsreactwiththenegativeionsinsoaptoformascumthatclingstoclothesandleavesthemdingylooking.WaterpollutionWaterpollutionisanychemical,physicalorbiologicalchangeinthequalityofwaterthathasaharmfuleffectonanylivingthingWaterpollu
7、tioncausedbyhumanactivitiesisalargesetofadverseeffectsuponwaterbodiessuchaslakes,rivers,oceans,andgroundwaterPollutantsinwaterincludeawideofchemicals,pathogens病原体,andphysicalchemistryorsensorychanges.WaterpollutionWaterpollutionistheleadingworldwidecauseofdeathsa
8、nddiseases,andthatitaccountsforthedeathsofmorethan14,000peopledaily.Effectsofwaterpollutionincludepoisonousdrinkingwater,poisonousfoodanimals,unbalancedriveran
