大气化学课件lecture10

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

7

=

𝑷𝑶𝟑=

“NOx-saturated”or“VOC-limited”regime

“NOx-limited”DependenceDependenceofO3productiononNOxandTakehydrocarbonRHasexampleofVOC

7

ORIGINORIGINOFTHEATMOSPHERICSizerange:0.001m(molecularcluster)to100m(small

(~5 SoildustSeasalt

raindrops(102~103m) “NOx-saturated”or

𝑷𝑶𝟑=“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累积

CoarseCoarseORIGINORIGINOFTHEATMOSPHERICSizerange:0.001m(molecularcluster)to100m(small Seasalt

(~5raindrops(102~103m)𝒅𝑪(nequivm−3)𝒅𝒍𝒏𝒅𝑪(nequivm−3)𝒅𝒍𝒏Jimenezetal.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累积

CoarseCoarseTheGlobalSulfurBudget𝒅𝑪(nequiv 𝒅𝒍𝒏Aerosols𝒅𝑪(nequiv 𝒅𝒍𝒏GlobalSGlobalGlobalSO2GLOBALGLOBALSULFURBUDGET(2)[Chinetal.,(fluxtermsinTgSyr-

OH

2720

644

Jimenezetal.SulfurSulfurgas-phase𝐒𝐎𝟐+𝐎𝐇+𝐌𝐇𝐒𝐎𝟑+𝐇𝐒𝐎𝟑+𝐎𝟐𝐒𝐎𝟑+

OH~1-2𝐒𝐎𝟑+𝐇𝟐𝐎+𝐌𝐇𝟐𝐒𝐎𝟒+ Butthisdoesnotexplainwhyobservedrainwater[SO42-]ishighestandconcentratednearsourceTheremustbeamissingmechanismtransformingSO2toSO42-SulfurSulfuraqueouschemistry

𝟐(𝐠)+𝐇𝟐𝐎𝐒𝐎𝟐∙

=[𝐒𝐎𝟐∙[𝐇+][𝐇𝐒𝐎

𝟐∙ 𝐇++𝐇𝐒𝐎

𝐊𝐒𝟏

[𝐒𝐎𝟐∙

𝐇++𝐒𝐎

𝐊𝐒𝟐

][𝐇𝐒𝐎]

𝐒𝐎𝟐∙ 𝐇𝐒𝐎+

]]Tian,Xu,Chen,Zhang,Fu*,workinSulfuraqueouschemistryOxidationbyH2O2 𝐇𝟐𝐎𝟐(𝐚𝐪) 𝐇𝐒𝐎−+𝐇 +𝐇+𝐒𝐎𝟐−+ OxidationbyO3 𝐎𝟑(𝐚𝐪) 𝐒𝐎𝟐−+ OxidationbyO2catalyzedby𝐒(𝐈𝐕)+𝟐

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-phase𝐒𝐎𝟐+𝐎𝐇+ 𝐇𝐒𝐎𝟑+𝐇𝐒𝐎𝟑+ 𝐒𝐎𝟑+

OH~1-2𝐒𝐎𝟑+𝐇𝟐𝐎+ 𝐇𝟐𝐒𝐎𝟒+ 4Butthisdoesnotexplainwhyobservedrainwater[SO2-]ishighestandconcentratednearsource4TheremustbeamissingmechanismtransformingCHEMICALCHEMICALCOMPOSITIONOF𝟏eq=moleofdissociableion=𝟏M∗numofdissociable=𝟏𝐍(当量摩尔浓度NeutralizationbyNH3isillusorybecauseNH4+ NH3+H+inSO2toU.S.SOU.S.SO2UNITEDSulfuremissions,Tga-1SulfurSulfuraqueouschemistry

(𝐠)+ 𝐒𝐎𝟐∙

=[𝐒𝐎𝟐∙

[𝐇+][𝐇𝐒𝐎𝐒𝐎𝟐∙ +𝐇𝐒𝐎 𝐊𝐒𝟏 [𝐒𝐎𝟐∙[𝐇+][𝐒𝐎𝐇𝐒𝐎 𝐇++𝐒𝐎 𝐊𝐒𝟐

[𝐇𝐒𝐎− +

𝐒𝐎𝟐∙𝐇𝐒𝐎+AMMONIAAMMONIATgNa-Biomass

UNITEDSulfuraqueouschemistryOxidationbyH2O2 𝐇𝐒𝐎𝟑−+

+ 𝐒𝐎𝟐−+𝟐𝐇++𝐇OxidationbyO3 𝐒𝐎𝟑𝟐−+

𝐒𝐎𝟐−+OxidationbyO2catalyzedby +𝟐LONG-TERMLONG-TERMTRENDINUSSO2 𝐌𝐧𝟐

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., 𝟏eqNATURALNATURALpHOFEquilibriumwithnaturalCO2(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.,CHEMICALCHEMICALCOMPOSITIONOF𝟏eq=moleofdissociableion=𝟏M∗numofdissociable𝟏𝐍(当量摩尔浓度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

异戊二烯(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.可模拟、预报城市光化学PM2.5ChineseNH3ChineseNH3emissions:14Tgy-1E+SAsiaNH3:28Tgy-1Globalammonia

AnnualSOAAnnualSOAsource[TgCy-

Glyoxalgyloxal8.0BiofueluseBiomassburning

GlyoxalReversible Irreversibleuptakeby(10%)andcloudsFuetal.SOAproductionviairreversibleuptakeofdicarbonylscomparabletoSOAproductionfromreversiblepartitioning55TgNy-变变ChemicalChemicalcompositionindifferentpartsof[Yangetal., 𝟏eqIII.III.SOAmodelingusingVolatilityBasisSetsOrganiccondensablevapors

iiDonahueetal.MeanMeanwintertimeOCIMPROVEdatashownasPyeandSeinfeldIMPLEMENTINGOCVOLATILITYCLASSESINGEOS-“Primary”OCisactuallysemi-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