英语演讲稿-水污染_英文PPT.ppt

water,environment,Wateristhesourceofallthings,Itstheonlywater,butitstheliquidwonderthatmakesourworldpossible.Waterisabletodissolvemoresubstancesthananyotherliquid.Itstakesalotofwatertokeeplifegoing.,Somedata,wateruse&pollution,whatcanwedo,71%ofearthssurfaceiscoveredwithwater,Arethewatersourcesabundant?,lessthan3%Oftotalwater,Lowlayer,0.3%offreshwater,Chinawaterresourcerankfourthintheworld.Chinaisntrichinwaterresources.Obviously,theprospectofChinesewaterresourcesisntoptimistic.,WaterIssuesinChina,withwaterresourcespercapitabeing2200m3orso,only1/4ofthatoftheworld.,waterresourcespercapita,South:population53%waterresource:78%,North:population:47%waterresource:22%,Unevendistributionofwaterresources,Waterisconsideredpollutedifasubstanceorconditionispresentthatrendersthewateruselessforaparticularpurpose,ThesourcesofwaterpollutionDirectsourceseffluentoutfallsfromfactories,refineries(精炼厂）,wastetreatmentplants.Indirectsourcescontaminantsthatenterthewatersupplyfromsoils/groundwatersystemsandfromtheatmosphereviarainwater.,AgriculturalWaterUse,Fourcommonirrigationmethods:Surface/FloodRequiresextensivecanalsystemsSprayUsepumpsTrickleStrategicallyplacesopeningsSub-irrigationPipescanbeusedfordrainageaswell,Excessivefertilizerusemayleadtoeutrophication（水体富营养化）inmanyaquatichabitats.Agriculturalrunofffromlarge,openexpansesismajorsourceofwaterpollution.,AgriculturalWaterPollution,IndustrialWaterUse,Accountsfornearly50%ofallwaterwithdrawalinU.S.,and23%worldwide.90%ofwaterusedbyindustryisforcooling,andisreturnedtothesource.Verylittleactuallyconsumed.Mostprocessesinvolveheatexchange.Waterusedtodissipateandtransportwaste.ToxicandoverloadwastesleadStreamandlakedegradation.,IndustrialWaterPollution,Allkindsofindustrygeneratetradewaste(工业废水）IronandsteelindustryFoodindustryComplexorganicchemicalsindustryNuclearindustryPollutants:organics,oil,metal,acidMayrequirespecialwastewatertreatment.,DomesticWaterUse,70%usedassolventtocarrywastes.30%usedforlawnandgarden.Verysmallfractionusedfordrinking.Naturalpurificationprocessescannotcopewithhighlyconcentratedurbanwastes.Mustbetreatedbeforerelease.,Domesticwaterpollution,WastewaterfromBathing,dishes,toiletsNotoxicsubstance,abundantinnutrientswithnitrogen(N，氮）andphosphorus(P，磷）Eutrophication（水体富营养化）Trashorgarbage(e.g.paper,plastic,orfoodwaste)discardedbypeopleontheground,alongwithaccidentalorintentionaldumpingofrubbish,thatarewashedbyrainfallintostormdrainsandeventuallydischargedintosurfacewaters.,Forgovernments,1.Toestablishurbansewagetreatmentsystem(城市污水处理系统)2.TorestructureIndustrial3.Toencouragethedevelopmentofnewwatersources4.Tostrengthenlegislation,severepunishment,Forplants,1.Toreducewaterconsumption2.Tobuyequipmentofsewagetreatment3.Dontdischargesewageintowater4.Tousewaterrecyclingsystem,Forindividuals,1.DontusecleanerconcludeP2.Dontthrowthegarbageintotherivers3.Topromoteawarenessofpreservingwaterresources4.Totellthepersonsaroundyoutoprotectthewaterresources,WorldWaterDay(WorldDayforWater),OnMarch22t