大学化学课件5对流层大气化学反应及光化学烟雾英文精编整理

Section5Chemicalreactionintroposphere Assortofatmosphericconstituents 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 atmosphericconstituentsaredividedintothreeassorts Cleanatmosphericconstituentsintroposphereisshownintalbe1 Carbondioxidehasbeenincreasinginconcentrationduringthiscentury mostlythroughtheburningoffossilfuelssuchascoalandpetroleumproducts Traceconstituentsmayvaryinconcentrationindifferentpartsoftheatmosphereandindifferentpartsoftheglobe 2 Gaseousconstituentsoftheatmosphere 3 Sourceandcollectionofatmosphericconstituentsandgaseouscirculation Thesubstanceexchangeortransformofatmosphericconstituents amongatmosphere aquaticsphere soilsphere andbiologicalsphere arecarriedoutcontinuously Thisiscalledgaseouscirculation Theprocesstoproducegasesiscalledsourceofgases Itincludeschemicalprocess biologicalactivity volcano andfossilfuelscombustion Theprocesstoremovegasesiscalledcollectionofgases Itincludeschemicalprocess biologicalactivity andphysicalprocess 4 Importantlightabsorptionsubstances 4 1lightabsorptioncharacteristicofNO2 NO2 h 420nm NO O 3P O 3P O2 M O3PhotolysisNO2ofisonlyartificialsourceofO3introposphere 入 380nm NO 1入 405nm NO 0 36入 420nm NO 0 4 2PhotolyticreactionofO3 HNO2 andH2O2 O3 h 320nm O 1D O2O 1D H2O 2OHHONO h 400nm OH NOH2O2 h 360nm OH OH 4 3PhotolyticreactionofHCHOandCH3CHO HCHO h H HCOH O2 M HO2HCO O2 HO2 CO CH3CHO h CH3 HCOCH3 O2 M CH3O2HCO O2 HO2 CO formaldehyde acetaldehyde O3 h 320nm O 1D O2O 1D H2O 2OHInpollutionatmosphere thefollowingphotochemicalreactionismoreimportant HONO h 400nm OH NOH2O2 h 360nm OH OHOnaverage theconcentrationoffreeradicalOHis7 105 cm3ontheglobe Seventimestentothepoweroffive 5 Freeradicalinatmosphere 5 1SourceoffreeradicalOH cubiccentimetre 5 2SourceoffreeradicalHO2 Photolysisofformaldehydeandacetaldehydeinatmosphere HCHO h H HCOH O2 M HO2HCO O2 HO2 CO HCHO NO3 HNO3 HCOHCO O2 HO2 CO CH3CHO h CH3 HCOCH3 O2 M CH3O2HCO O2 HO2 CO CH3CHO h CH3 HCOCH3COCH3 h CH3 CH3CORH O R OHRH HO R H2OCH3ONO十h CH3O NOCH3ONO2 h CH3O NO2R O2 RO2 5 3SourceoffreeradicalR RO RO2 acetone acetaldehyde formaldehyde methoxy methylnitrates methyl alkyl methylnitrite alkylperoxyfreeradical methanal 5 4Collectionoffreeradical 1 TransformeachotherbetweenfreeradicalCO OH CO2 HH O2 HO2CH4 OH CH3 H2OCH3 O2 CH3O2HO2 NO NO2 OHHO2 O3 2O2 OH 2 ComplexactionHO2 OH H2O O2OH OH H2O2 Section6Photochemicalsmog 1 Appearanceofphotochemicalsmog IntheatmosphereofNOXandVOCS understrongsolarradiation aseriesofcomplicatedchemicalreactiontakeplaceandalotofoxidativesubstances suchasO3 RCHO PAN HNO3 H2O2wereproduced Thesemixedcompoundsofoxidativesubstanceandreactantsiscalledphotochemicalsmog 2 Dailychangelawofphotochemicalsmog 3 Formationmechanismofphotochemicalsmog 4 Formationsignofphotochemicalsmog 1 ozoneBackgroundconcentrationofozoneisbetween0 02 0 06mg Lintroposphere Onaverage itis0 03mg L Whenthephotochemicalreactionoccur theconcentrationofozonereach0 2 0 5mg L 2 PAN peroxyacetylnitrate RC O O2 NO2RC O O