大氣化學課件lecture10

Discussionproblem(lastMaximumphotonfluxduringsummerresultsinaseasonalmaximumofozoneinpollutedregionsbutaseasonalminimumofozoneinverycleanregions.Brieflyexplain.ImagineanatmospherewherethedominantHOxradicalsinkistheRO2+NO2reactiontoformstableperoxynitrates.WouldozoneproductioninsuchanatmospherebeNOx-limitedorVOC-limited?DependenceofDependenceofO3productiononNOxandTakehydrocarbonasexampleof

7

=

??????=

“NOx-saturated”or“VOC-limited”regime

“NOx-limited”DependenceDependenceofO3productiononNOxandTakehydrocarbonRHasexampleofVOC

7

ORIGINORIGINOFTHEATMOSPHERICSizerange:0.001m(molecularcluster)to100m(small

(~5 SoildustSeasalt

raindrops(102~103m) “NOx-saturated”or

??????=“NOx-limited”AmbientAmbientPMofteninthreesize

Fromnucleationofprecursorgasmolecules(~10-3μm)formingnew

Frommechanicalforces,e.g.winds,evaporationofseaspray,machinegrinding1nm

10~100 Aitkenrange(<0.1μm)

range(0.1~2.5μm)

Coarserange(>2.5μm)

Pari.lediameter(m)

Fineparticles,Nucleimode核 mode累積

CoarseCoarseORIGINORIGINOFTHEATMOSPHERICSizerange:0.001m(molecularcluster)to100m(small Seasalt

(~5raindrops(102~103m)????(nequivm?3)??????????(nequivm?3)??????Jimenezetal.AmbientAmbientPMofteninthreesize

Fromnucleationof(~10-3μm)formingnew

Frommechanicalforces,e.g.winds,evaporationofseaspray,machinegrinding1nm

(<0.1μm)

range(0.1~2.5μm)

(>2.5μm) Pari.ldiameter(m) Tian,Xu,Chen,Zhang,Fu*,workinFineparticles,Nucleimode核 mode累積

CoarseCoarseTheGlobalSulfurBudget????(nequiv ??????Aerosols????(nequiv ??????GlobalSGlobalGlobalSO2GLOBALGLOBALSULFURBUDGET(2)[Chinetal.,(fluxtermsinTgSyr-

OH

2720

644

Jimenezetal.SulfurSulfurgas-phase??????+????+??????????+????????+??????????+

OH~1-2??????+??????+????????????+ Butthisdoesnotexplainwhyobservedrainwater[SO42-]ishighestandconcentratednearsourceTheremustbeamissingmechanismtransformingSO2toSO42-SulfurSulfuraqueouschemistry

??(??)+?????????????

=[???????[??+][??????

??? ??++??????

??????

[???????

??++????

??????

][??????]

??????? ??????+

]]Tian,Xu,Chen,Zhang,Fu*,workinSulfuraqueouschemistryOxidationbyH2O2 ????????(????) ???????+?? +??+???????+ OxidationbyO3 ????(????) ???????+ OxidationbyO2catalyzedby??(????)+??

TheGlobalSulfurBudgetFORMATIONOFSULFATE-NITRATE-AMMONIUMThermodynamicHSO(g)

2H

Sulfatealwaysformsanaqueous

Ammoniadissolvesinthesulfateaerosoltotallyoruntiltitrationofacidity,whicheverhappensfirst

H

Nitrateistakenupbyaerosolif(andonly excessNH3isavailableafterNH3(g)

NH4

HNO3andexcesscanalsoformasolidaerosolifRHislowaerosolaerosolLowHigh[S(VI)]>2[N(-NH4HSO4,(NH4)2SO4(NH4+,H+,SO42-[S(VI)]≤2[N(-(NH4)2SO4,NH4NO3(NH4+,NO3-CONTRASTCONTRASTTOTHEAEROSOL Parketal.GlobalSDiscussionDiscussionquestions(nextAqueous-phaseoxidationofSO2bySO32-+O3(aq)→SO42-+producesacidityeventhough isnotdirectlyinvolved.ExplainAqueous-phaseoxidationofSO2byH2O2isacid-catalyzedandthisiscriticalfortheimportanceofthisreactionasasourceofsulfate.Explainwhy.Aerosolnitrateconcentrationspeakinwinter.ExplainAerosolnitrateisusuallymoresensitivetoammoniaemissionsthanaerosolammonium.Explainwhy.IthasbeenarguedthatdecreasingSO2emissionstodecreaseaerosolsulfatecouldresultinanincreaseinaerosolnitrate,increasinginfactthetotalPM2.5massconcentration.Explainwhy.GlobalSO2AcidrainAcidrainNATURALNATURALpHOFEquilibriumwithnaturalCO2(280ppmv)resultsinarainpHofCO(g)H

Matm- COHO

H

K9107 HCO

H

71010[H]

(K

)1/ ThispHcanbemodifiedbynaturalacids(H2SO4,HNO3,RCOOH…)andbases(NH3,CaCO3)enaturalrainhasapHinrange5-7“Acidrain”referstorainwithpH<5whichdamagesGLOBALGLOBALSULFURBUDGET(2)[Chinetal.,(fluxtermsinTgSyr-

8

27dry20

6dry44 PRECIPITATIONPRECIPITATIONPHOVERTHEUNITEDSulfurSulfurgas-phase??????+????+ ????????+????????+ ??????+

OH~1-2??????+??????+ ??????????+ 4Butthisdoesnotexplainwhyobservedrainwater[SO2-]ishighestandconcentratednearsource4TheremustbeamissingmechanismtransformingCHEMICALCHEMICALCOMPOSITIONOF??eq=moleofdissociableion=??M?numofdissociable=????(當量摩爾濃度NeutralizationbyNH3isillusorybecauseNH4+ NH3+H+inSO2toU.S.SOU.S.SO2UNITEDSulfuremissions,Tga-1SulfurSulfuraqueouschemistry

(??)+ ???????

=[???????

[??+][????????????? +?????? ?????? [???????[??+][?????????? ??++???? ??????

[??????? +

?????????????+AMMONIAAMMONIATgNa-Biomass

UNITEDSulfuraqueouschemistryOxidationbyH2O2 ?????????+

+ ???????+????++??OxidationbyO3 ?????????+

???????+OxidationbyO2catalyzedby +??LONG-TERMLONG-TERMTRENDINUSSO2 ??????

AMMONIUMAMMONIUMANDSULFATETRENDS,1985-LehmannFORMATIONOFSULFATE-NITRATE-AMMONIUMThermodynamicHSO(g)2H Sulfatealwaysformsanaqueous NH(g)OH Ammoniadissolvesinthesulfate totallyoruntiltitrationofacidity,whicheverhappensfirstHNO(g)H Nitrateistakenupbyaerosolif(andonly excessNH3isavailableaftersulfateNH3(g)HNO3( HNO3andexcesscanalsoformasolidaerosolifRHislowTRENDTRENDINFREQUENCYOFACIDRAIN(pH<Lehmannetal.aerosolaerosolLowHigh[S(VI)]>2[N(-NH4HSO4,(NH4)2SO4(NH+,H+,SO2- [S(VI)]≤2[N(-(NH4)2SO4,NH4NO3(NH+,NO- BUTECOSYSTEMACIDIFICATIONISPARTLYATITRATIONPROBLEMFROMACIDINPUTOVERMANYYEARSAcidfluxAcid-neutralizingcapacityfromCaCO3andothertHFdtH0

ANC

CONTRASTCONTRASTTOTHEAEROSOL RangeofrainwaterpHinParketal.Acidrainisbecomingincreasinglyseriousin

DiscussionDiscussionquestions(nextAqueous-phaseoxidationofSO2bySO2-+

(aq)→

2-+ producesacidityeventhough isnotdirectlyinvolved.ExplainAqueous-phaseoxidationofSO2byH2O2isacid-catalyzedandthisiscriticalfortheimportanceofthisreactionasasourceofsulfate.Explainwhy.Aerosolnitrateconcentrationspeakinwinter.ExplainAerosolnitrateisusuallymoresensitivetoammoniaemissionsthanaerosolammonium.Explainwhy.ChineseSO2ChineseSO2emissions:20Tgy-1E+SAsiaSO2:34Tgy-1Globalsulfur78TgSy-IthasbeenarguedthatdecreasingSO2emissionstodecreaseaerosolsulfatecouldresultinanincreaseinaerosolnitrate,increasinginfactthetotalPM2.5massconcentration.Explainwhy.ChineseNOxChineseNOxemissions:11Tgy-1E+SAsiaNOx:27Tgy-1GlobalNOxemissions:38TgNy-GlobalNOxemission[vanderAetal.,AcidAcidrainChineseNH3ChineseNH3emissions:14Tgy-1E+SAsiaNH3:28Tgy-1BiomassBiomass55TgNy-ChemicalChemicalcompositionindifferentpartsof[Yangetal., ??eqNATURALNATURALpHOFEquilibriumwithnaturalCO2(280ppmv)resultsinarainpHofCO(g)H 3102Matm-

H2OH

91073 HCOH 7103 )[H](K ) ThispHcanbemodifiedbynaturalacids(H2SO4,HNO3,RCOOH…)andbases(NH3,CaCO3)enaturalrainhasapHinrange5-72001~20052001~2005measurementin[Yangetal.,“Acidrain”referstorainwithpH<5whichdamages

potentialofsubstanceis2001–[Yangetal.,SO2SO2emissionsfrompowerplantsaredecreasing,SO2emissionsfromothersectorsareZhangetal.PRECIPITATIONPRECIPITATIONPHOVERTHEUNITEDCarbonaceousaerosolsareimportantcomponentsofPM2.5inChina[Fuetal.,CHEMICALCHEMICALCOMPOSITIONOF??eq=moleofdissociableion=??M?numofdissociable????(當量摩爾濃度Chinesecarbonaceousaerosolemissionsisnot[Fuetal.,NeutralizationbyNH3isillusorybecauseNH4+ NH3+H+inCARBONACEOUSCARBONACEOUSAEROSOLSOURCESINTHEFossilfuelBiomassFossilfuelBiomass0.66Tgyr-

ORGANICCARBON2.7Tgyr-Annualmeanconcentrations U.S.U.S.SO2

UNITEDJimenezetal.Tga-1 RADIATIVERADIATIVEFROMBLACKCARBONIPCCAMMONIAAMMONIA TgNa-AgingAgingofBCaerosolmakesit“BC”or“soot”isopticallydefinedandincludesbothgraphiticelementalcarbon(EC)andlight-absorbingheavyorganicmatterFreshlyemittedBC“Aged”BCbecomes“internally-withotherhygroscopic Biomass

UNITEDAtmosphericAtmosphericagingandscavengingofHydrophobic

gas Hydrophilicresistantto

Agingtimeτ~1

coatedwithsulfate,ImplicationsforBCexportfromsource long-

FREEArcticArcticverticalBC,ngm-3Altitude,LONG-RANGELONG-RANGETRANSPORTOFBCTOTHE(ARCTASaircraftcampaign,AprilBCmgm-2month-QiaoqiaoWang,LONG-TERMLONG-TERMTRENDINUSSO2FRONTALFRONTALLIFTINGINWARMCONVEYORBoundarypost-frontalMarch2010MODIShot MISRinstrumentJianandFu* AMMONIUMAMMONIUMANDSULFATETRENDS,1985-ImpactofdirectinjectionofpollutantsintoFTonFeb-Apr2001-607fire>22000smokeJianandFu Lehmannetal.StandardmodelingoforganicOH,

partitioningof

open

openVOC PRIMARYGlobalsourcesinTgCy- (standardversionofGEOS-ChemTRENDTRENDINFREQUENCYOFACIDRAIN(pH<Terpenesarebiogenichydrocarbonsproducedinplantsbycombinationofisopreneunits(C5H8)Monoterpenes:β-Sesquiterpenes:C15Lehmannetal.SOASOAMODELINGASGAS-AEROSOLVOCoxidationgeneratessemi-volatile…whichthenpartitionbetweenthegasandaerosolwherethepartitioningcoefficientisgiven

Moisthemassofpre-existingorganic…andisastrongfunctionoftemperature.Valuesofand aretosmogchamberChungandSeinfeld,BUTECOSYSTEMACIDIFICATIONISPARTLYATITRATIONPROBLEMFROMACIDINPUTOVERMANYYEARSAcid-neutralizingcapacity(ANC)fromCaCO3andotherbasestFHdt0

ANCOBSERVEDOBSERVEDSOAFORMATIONINMEXICO…cannotbeexplainedbystandardgas-aerosolequilibriumVolkameretal.,Observed/ModelHealdObserved/ModelLab/fieldmeasurementsuggestindicatealargemissingSOAsource,possiblyintheaqueousphase!RangeofrainwaterpHinOrganicOrganicaerosolspresentinawidesize[Jimenezetal.Acidrainisbecomingincreasinglyseriousin IRREVERSIBLEIRREVERSIBLEDICARBONYLUPTAKEBYAQUEOUS ChamberexperimentsofglyoxaluptakebyLiggioetal.[JGR2005]Organicaerosolmassgrowthwithtime Inferredreactiveuptakecoefficientmedian=2.9x10-3observedforaqueoussurfaces;evidenceforsimilarobservedformethylglyoxalonacidicsurfaces[Zhaoetal.ES&TStandardmodelingoforganicOH,

partitioningof

open

openVOC PRIMARYGlobalsourcesinTgCy- (standardversionofGEOS-ChemChineseSO2ChineseSO2emissions:20Tgy-1E+SAsiaSO2:34Tgy-1Globalsulfur

異戊二烯(400Tgy-1),monoterpenes,acetone,MBO,C2H4,C3H6

Fuetal.OH,O3,

~2.9Acetone,C2H2,isoalkanes,alkenes,primaryemissions

~1.6

~2.9x10-

78TgSy-WhataretheirreversibleprocessesintheAQH*~

1++3+2+2OrganicH*~ChineseNOxChineseNOxemissions:11Tgy-1E+SAsiaNOx:27Tgy-1GlobalNOxemissions:38TgNy-GlobalNOxemissiontrend[vanderAetal.,2006]SOA[gm-Li,Fu*etal.可模擬、預報城市光化學PM2.5ChineseNH3ChineseNH3emissions:14Tgy-1E+SAsiaNH3:28Tgy-1Globalammonia

AnnualSOAAnnualSOAsource[TgCy-

Glyoxalgyloxal8.0BiofueluseBiomassburning

GlyoxalReversible Irreversibleuptakeby(10%)andcloudsFuetal.SOAproductionviairreversibleuptakeofdicarbonylscomparabletoSOAproductionfromreversiblepartitioning55TgNy-變變ChemicalChemicalcompositionindifferentpartsof[Yangetal., ??eqIII.III.SOAmodelingusingVolatilityBasisSetsOrganiccondensablevapors

iiDonahueetal.MeanMeanwintertimeOCIMPROVEdatashownasPyeandSeinfeldIMPLEMENTINGOCVOLATILITYCLASSESINGEOS-“Primary”O(jiān)Cisactuallysemi-2001~20052001~2005measurementinDiscussionDiscussion(nextFormationof“biogenicSOA”fromisopreneandterpenesisthoughttoincreaseinthepresenceofanthropogenicaerosol.Explainwhy.ObservationsshowburstsofSOAformationfollowingcloudprocessingofanairparcel.Explainhowthismighttakeplace.[Yangetal.,HomeworkHomework3(dueMayJacobbookCh11,questionJacobbookCh11,questions11.7,JacobbookCh12,questions12.1,JacobbookCh13,questionstoeis

2001–[Yangetal.,SO2SO2emissionsfrompowerplantsaredecreasing,SO2emissionsfromothersectorsareZhangetal.CarbonaceousaerosolsareimportantcomponentsofPM2.5inChina[Fuetal.,Chinesecarbonaceousaerosolemissionsisnot[Fuetal.,CARBONACEOUSCARBONACEOUSAEROSOLSOURCESINTHEBLACKCARBON0.66Tgyr-

ORGANICCARBON2.7Tgyr-Annualmeanconcentrations Jimenezetal. RADIATIVERADIATIVEFROMBLACKCARBONIPCCAgingAgingofBCaerosolmakesit“BC”or“soot”isopticallydefinedandincludesbothgraphiticelementalcarbon(EC)andlight-absorbingheavyorganicmatterFreshlyemittedBC“Aged”BCbecomes“internally-mixed”withotherhygroscopicaerosolsAtmosphericAtmosphericagingandscavengingofHydrophobic

gas HydrophilicresistanttoAgingtimeτ~1

coatedwithsulfate,ImplicationsforBCexportfromsource

FREELONG-RANGELONG-RANGETRANSPORTOFBCTOTHE(ARCTASaircraftcampaign,AprilAltitude,BCAltitude,mgm-2month-QiaoqiaoWang,FRONTALFRONTALLIFTINGINWARMCONVEYORBoundarypost-frontalMarch2010MODIShot MISRinstrumentJianandFu* ImpactofdirectinjectionofpollutantsintoFTonFeb-Apr2001-607fire>22000smokeJianandFu Standardmodelingoforganic

OH,O

open openVOC GlobalsourcesinTgCy- (standardversionofGEOS-ChemTerpenesarebiogenichydrocarbonsproducedinplantsbycombinationofisopreneunits(C5H8)Monoterpenes:Sesquiterpenes:C15SOASOAMODELINGASGAS-AEROSOLVOCoxidationgeneratessemi-volatile…whichthenpartitionbetweenthegasandaerosolwherethepartitioningcoefficientisgiven

Moisthemassconcentrationofpre-existingorganicaerosol…andisastrongfunctionoftemperature.Valuesofand aretosmogchamberChungandSeinfeld,OBSERVEDOBSERVEDSOAFORMATIONINMEXICO…cannotbeexplainedbystandardgas-aerosolequilibriumVolkameretal.,ObservedObserved/ModelH