大气氮沉降及其对环境的影响课件.ppt

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1、AtmosphericNitrogen(N)DepositionandInfluencesofNDepositiononEnvironment1.Nitrogen(N)deposition3.InfluencesofNdepositiononenvironment3.1InfluencesofNdepositiononcarbon(C)andNcycle3.2InfluencesofNdepositiononsoilmicrobe3.3InfluencesofNdepositiononsoilacidification2.Componentsofatmo

2、sphericNdeposition2.1InorganicN2.2OrganicN2.3RatioofinorganicNtoorganicN1.Nitrogen(N)depositionHumanactivitiesmodifyandacceleratetheglobalcycleofN.TherateofatmosphericNdepositionhasbeengreatlyincreasedthroughhumanactivities,suchasburningfossilfuelsandfertilizeruse.burningfossilfuel

3、sfertilizeruseFixationofNbyhumansforenergyproduction,fertilizerproduction,andcropcultivationnowexceedstheamountofbiologicallyfixedNonthecontinents.TheYangtzeRiverDeltaRegionisoneofthemostimportantindustrial-agriculturaleconomicregionsinChina.Theatmosphericnitrogen(N)depositionisane

4、xpandingproblemthataffectseveryaspectofecosystemfunctionandcomposition.2.ComponentsofatmosphericNdeposition2.1InorganicNthereleaseofNOxgasfromfossilfuelcombustionNH3gasfromagriculturalproductionTheymaythenbeconvertedtonitrate(NO3−)andammonium(NH4+)respectively,anddepositedontheland

5、surfaceaswetanddrydeposition.AspectsofhumanalterationoftheNcycle:2.2OrganicNMostNbudgetshavefocusedoninorganicN,theorganicN-containingcompoundspresentinrainwaterhavenotroutinelybeenincludedinbudgetassessments.TheyareimportantcomponentsofatmosphericNdeposition,therelativeimportanceo

6、forganicNspeciesisnowrecognized.Thisistrueinallregionsoftheworldwheretheyhavebeenmeasured(Table1.1).ThegroupsoforganicNcompoundsthathavebeenmeasured(Table1.2).2.3RatioofinorganicNtoorganicNOrganicNisalsoanindispensablecomponentintheatmosphereNdeposition.Thepercentageisvariable(10−6

7、9,36.1%inaverage),rapidturnoverrateandshowsahigheffectonforestecosystembothinplantsandsoil.ThecomponentsoforganicNweremainlyinCO(NH2)2andaminoacid,theywerequickhydrolyzedandammonifiedtoproduceNH4+.3.InfluencesofNdepositiononenvironmentTheenrichmentofthebiospherewithanthropogenicNis

8、anexpandingproblemthataffe