水体富营养化英文EutrophicationofwaterDefinitionEutrophicationisoneofthewaterpollution.Itismainlycausedbyhumanactivities.Whenalargeamountofnutrients,suchasnitrogenandphosphorus,aredischargedintolargelakes,estuaries,baysandotherwaterbodieswhichflowslowly,itwillcauseaphenomenont...
EutrophicationofwaterDefinitionEutrophicationisoneofthewaterpollution.Itismainlycausedbyhumanactivities.Whenalargeamountofnutrients,suchasnitrogenandphosphorus,aredischargedintolargelakes,estuaries,baysandotherwaterbodieswhichflowslowly,itwillcauseaphenomenonthatalgaeandotherplanktoninwatermultiplyrapidly,dissolvedoxygendecreases,waterqualitydeterioratesandalargenumberoffishandotherorganismsdie.MechanismExcessnutrients(N、P)Autotrophicorganisms(especiallyblue-greenalgaeandredalgae)growquicklyOtheralgaespeciesgraduallyreducePlanktonandothersmallorganismsdieBedecomposedbyaerobicmicroorganismconsumedissolvedoxygeninwaterFishandotheraquaticlifedieOrbedecomposedbyanaerobicmicroorganismProducehydrogensulfideandothergasesIdentificationindexNitrogencontent≧0.2~0.3ppmBiochemicaloxygendemand(BOD)≧10ppmPhosphoruscontent≧0.01~0.02ppmThenumberofbacteriaismorethan100000inpermlofwater(pH=9~10)Thecontentofchlorophyll–aincharacterizedalgae≧10μmg/LSourceExcessnitrogenandphosphorusinthewaterbodymainlycomefromindustrialwastewateranddomesticsewage,organicwaste,livestockandpoultrymanureandagriculturalchemicalfertilizer.ControlmethodEngineeringmethodsDiggingupthelakesedimentsItisthemainwaysofreducingtheself-concentrationofnitrogenandphosphorusineutrophiclake.DeepaerationTakingartificiallakedeepaerationandsupplementingoxygenfromtimetotimeisconducivetoinhibitthereleaseofphosphorusfromsediment.InjectwaterInjectingwatercontaininglowconcentrationsofnitrogenandphosphorusintolakescandilutenutrientconcentration.ControlmethodChemicalmethodsCoagulationandsedimentationManykindsofcationscancausethephosphorustoprecipitatefromtheaqueoussolutioneffectively,suchasiron,aluminumandcalciumForexample,thelonglakeinwesternWashingtonstateisaeutrophicwaterbody.InOctober1980,peopleaddaluminumsaltintothelaketoprecipitatethelake'sphosphate.Inthesummeroffourthyearsaftertheadditionofaluminumsalt,phosphorusconcentrationinthelakewaterbecamefromtheoriginal65g/Lto30g/L,thewaterqualityofthelakehasbeensignificantlyimproved.ControlmethodInthechemicalmethod,anotherwayistokillalgaewithalgaecide.Thismethodissuitableforthewaterbodyofthelakewaterbloom.Afteralgaecidekillsthealgae,thedecompositionofalgaewillstillreleasephosphorus.Therefore,algaekilledbyalgaecideshouldbepromptlyremoved,orsomeappropriatechemicalsshouldbeaddedintothewaterbodytomakephosphateprecipitate.ControlmethodBiologicalmethodsUseaquaticlifetoabsorbnitrogenandphosphorusinordertoremovenitrogenandphosphorusinwater.Forexample,somecountriestrytopurifytheeutrophicwaterbodywithlargeaquaticplants,suchaswaterhyacinth,reed,typhaangustifoliaandsoon.Thankyou!此课件下载可自行编辑修改，供参考！感谢您的支持，我们努力做得更好！
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