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1、Section5ChemicalreactionintroposphereAssortofatmosphericconstituents(1)Semi-permanencegas,suchasN2,Ar,Ne,Kr,Xe(2)Alterableconstituents,suchasCO2,CH4,H2,N2O,O3,O2(3)Intensivealterableconstituents,suchasH2O,CO,NO,NH3,SO2,HC,H2S.Accordingtolifetime,atmosphericconstituentsaredi
2、videdintothreeassorts.Cleanatmosphericconstituentsintroposphereisshownintalbe1.Carbondioxidehasbeenincreasinginconcentrationduringthiscentury,mostlythroughtheburningoffossilfuelssuchascoalandpetroleumproducts.Traceconstituentsmayvaryinconcentrationindifferentpartsoftheatmos
3、phereandindifferentpartsoftheglobe.2.Gaseousconstituentsoftheatmosphere3.SourceandcollectionofatmosphericconstituentsandgaseouscirculationThesubstanceexchangeortransformofatmosphericconstituents,amongatmosphere,aquaticsphere,soilsphere,andbiologicalsphere,arecarriedoutconti
4、nuously.Thisiscalledgaseouscirculation.Theprocesstoproducegasesiscalledsourceofgases.Itincludeschemicalprocess,biologicalactivity,volcano,andfossilfuelscombustion.Theprocesstoremovegasesiscalledcollectionofgases.Itincludeschemicalprocess,biologicalactivity,andphysicalproces
5、s.4.Importantlightabsorptionsubstances4.1lightabsorptioncharacteristicofNO2NO2+hγ(λ≤420nm)→NO+O(3P)O(3P)+O2+M→O3PhotolysisNO2ofisonlyartificialsourceofO3introposphere.入<380nmφNO≈1入=405nmφNO≈0.36入>420nmφNO≈04.2PhotolyticreactionofO3,HNO2,andH2O2O3+hγ(λ≤320nm)→O(1D)+O2O(1D)+H
6、2O→2OHHONO+hγ(λ<400nm)→OH+NOH2O2+hγ(λ<360nm)→OH+OH4.3PhotolyticreactionofHCHOandCH3CHOHCHO+hγ→H+HCOH+O2+M→HO2HCO+O2→HO2+COCH3CHO+hγ→CH3+HCOCH3+O2+M→CH3O2HCO+O2→HO2+COformaldehydeacetaldehydeO3+hγ(λ≤320nm)→O(1D)+O2O(1D)+H2O→2OHInpollutionatmosphere,thefollowingphotochemicalr
7、eactionismoreimportant.HONO+hγ(λ<400nm)→OH+NOH2O2+hγ(λ<360nm)→OH+OHOnaverage,theconcentrationoffreeradicalOHis7*105/cm3ontheglobe.Seventimestentothepoweroffive5.Freeradicalinatmosphere5.1SourceoffreeradicalOHcubiccentimetre5.2SourceoffreeradicalHO2Photolysisofformaldehydean
8、dacetaldehydeinatmosphere:HCHO+hγ→H+HCOH+O2+M→HO2HCO+O2→HO2+COHCHO+NO3→HNO3+HCOHCO