资源描述：
《水污染 英文版.ppt》由会员上传分享，免费在线阅读，更多相关内容在应用文档-天天文库。
1、WaterpollutionItcovers71%oftheearth'ssurfaceandmakesup65%ofourbodies.Withouttheseeminglyinvaluablecompoundcomprisedofhydrogenandoxygen,lifeonEarthwouldbenon-existentWaterisEssentialforLifeThreefourthsofthesurfaceoftheEarthiscoveredwithwater.Nearly98%ofthewateronEa
2、rth,though,isseawater‑unfitfordrinkingandnotevensuitableformostindustrialpurposes.Somethinglessthan2%ofthewaterisfrozeninthepolaricecaps,leavinglessthan1%availableasfreshwater.Water:UnusualPropertiesManychemicalsubstancesaresolubleinwater.Thus,theyareeasilydispers
3、edandeventuallyarescatteredtonearlyinfinitedilutionintheocean.Thosepropertiesofwaterthatmakeituniquelysuitedforthesupportoflifealsomakeiteasytopollute.NaturalWaterIsn’tAllH2ORainwatercarriesdustparticlesfromtheatmospheretotheground.Rainwateralsodissolvesalittleoxy
4、gen,nitrogen,andcarbondioxideasitfallsthroughtheatmosphere.Duringelectricalstorms,lightningcausesnitrogen,oxygen,andwatervaportocombinetoformnitricacid.AswatermovesalongorbeneaththesurfaceoftheEarth,itdissolvesmineralsandmatterfromdecayingplantsandanimals.Theprinc
5、ipalpositiveions(cations)innaturalwateraresodium(Na+),potassium(K+),calcium(Ca2+),magnesium(Mg2+),andsometimesiron(Fe2+orFe3+).Thenegativeions(anions)areusuallysulfate(SO42-),bicarbonate(HCO3-),andchloride(Cl-).hardwaterWatercontainingthesecalcium,magnesium,andiro
6、nionsiscalledhardwater.Thepositiveionsreactwiththenegativeionsinsoaptoformascumthatclingstoclothesandleavesthemdingylooking.WaterpollutionWaterpollutionisanychemical,physicalorbiologicalchangeinthequalityofwaterthathasaharmfuleffectonanylivingthingWaterpollutionca
7、usedbyhumanactivitiesisalargesetofadverseeffectsuponwaterbodiessuchaslakes,rivers,oceans,andgroundwaterPollutantsinwaterincludeawideofchemicals,pathogens病原体,andphysicalchemistryorsensorychanges.WaterpollutionWaterpollutionistheleadingworldwidecauseofdeathsanddisea
8、ses,andthatitaccountsforthedeathsofmorethan14,000peopledaily.Effectsofwaterpollutionincludepoisonousdrinkingwater,poisonousfoodanimals,unbalancedriveran
