Aerosol

ContentslistsavailableatScienceDirectAtmosphericEnvironmentjournalhomepage:www.elsevier.com/locate/atmosenvComparisonoforganiccompositionsinduststormandnormalaerosolsamplescollectedatGosan,JejuIsland,duringspring2005GehuiWanga,b,KimitakaKawamuraa,*,MeehyeLeecaInstituteofLowTemperatureScience,HokkaidoUniversity,Sapporo060-0819,JapanStateKeyLaboratoryofLoessandQuaternaryGeology,InstituteofEarthEnvironment,ChineseAcademyofSciences,Xi’an710075,ChinacDepartmentofEarthandEnvironmentalSciences,KoreaUniversity,Seoul136-701,SouthKoreabarticleinfoArticlehistory:Received1July2008Receivedinrevisedform22September2008Accepted22September2008Keywords:OrganicaerosolsWater-solubleorganiccompoundsHydrophobicorganiccompoundsMolecularcompositionsAsianduststormLipidsLevoglucosanabstractTobetterunderstandthecurrentphysicalandchemicalpropertiesofEastAsianaerosols,anintensiveobservationofatmosphericparticleswasconductedatGosansite,JejuIsland,SouthKoreaduring2005spring.Totalsuspendedparticle(TSP)sampleswerecollectedusingpre-combustedquartzfiltersandahigh-volumeairsamplerwiththetimeintervalsrangingfrom3hto48h.Thekindsandamountofvariousorganiccompoundsweremeasuredinthesamplesusinggaschromatography–massspec-trometry.Amongthe99targetcompoundsdetected,saccharides(average,130Æ14ngmÀ3),fattyacids(73Æ7ngmÀ3),alcohols(41Æ4ngmÀ3),n-alkanes(32Æ3ngmÀ3),andphthalates(21Æ2ngmÀ3)werefoundtobemajorcompoundclasseswithpolyols/polyacids,ligninandresinproducts,PAHs,sterolsandaromaticacidsbeingminor.Comparedtothepreviousresultsreportedfor2001latespringsamples,nosignificantchangeswerefoundinthelevelsoftheirconcentrationsandcompositionsfor4years,althoughtheeconomyinEastAsia,especiallyinChina,hassharplyexpandedfrom2001to2005.DuringthecampaignatGosansite,weencounteredtwodistinctduststormepisodeswithhighTSPconcen-trations.ThefirstdusteventoccurredonMarch28,whichwascharacterizedbyapredominanceofsecondaryorganicaerosols.Thesecondeventthatoccurredonthenextday(March29)wasfoundtobecharacterizedbyprimaryorganicaerosolsassociatedwithforestfiresinSiberia/northeasternChina.Asignificantvariationinthemolecularcompositions,whichwasfoundwithinaday,suggeststhatthecompositionsofEastAsianaerosolsareheterogeneousduetomulti-contributionsfromdifferentsourceregionstogetherwithdifferentpathwaysoflong-rangeatmospherictransportofparticles.Ó2008ElsevierLtd.Allrightsreserved.1.IntroductionAtmosphericaerosolshaverelevancefortheEarth’sradiativeforcingbalancedirectlybyscattering(Charlsonetal.,1992)orabsorbingsunlight(Ramanathanetal.,2001),andindirectlybyinfluencingthealbedo(Charlsonetal.,1987),lifetime(Albrecht,1989),extentofcloudsandprecipitationofrainviaactingascloudcondensationnuclei(CCN).AtmosphericaerosolsinEastAsia,especiallyinChina,aredifferentfromthoseinEuropeandNorthAmerica,sincecoalandbiofuelcombustionarestilladominantenergysource,andsootandorganicaerosolsaremuchmoreemittedintotheatmosphereinEastAsia(Huebertetal.,2003).AroundonefourthofcarbonaceousaerosolsontheglobearegeneratedfromChina(Cookeetal.,1999),whereasharpincreaseinNOxemissionsfromfossilfuelcombustionhasledtotheexcessof*Correspondingauthor.Tel.:þ81117065457;fax:þ81117067142.E-mailaddress:kawamura@lowtem.hokudai.ac.jp(K.Kawamura).1352-2310/$–seefrontmatterÓ2008ElsevierLtd.Allrightsreserved.doi:10.1016/j.atmosenv.2008.09.046NO2concentrationsintheChineseatmosphereoverthoseinEuropeandNorthAmerica(Richteretal.,2005).ChineseeconomicexpansionmayberesponsibletotheincreasedNO2,organicmatter,andsootinEastAsia.Moreover,thepresenceofChinesedesertdustaddscomplexity,sinceitcanscattersunlightbacktospace,absorbsolarandterrestrialradiation,andprovidesanalkalinesurfacefortheuptakeofacidicgases.Thoseorganicandinorganicpollutantspotentiallyimpacttheclimateandhumanhealthonaregional/globalscalevialong-rangeatmospherictransport(Wilkeningetal.,2000;VanCurenandCahill,2002;Healdetal.,2006).GosansiteislocatedonthewesternedgeofJejuIsland,Korea,andonthepassagewaysofoutflowsofAsiandustsandChinesepollutedairmasses.GosanhasbeenusedasasupersiteduringACE-AsiacampaigntostudytheatmosphericaerosolsinEastAsiaandthewesternNorthPacific(Kimetal.,2005).Numerousaerosolstudieshavebeencarriedout,bothatJejuisland(Arimotoetal.,2004;Hanetal.,2006;Kimetal.,2007),anditssurroundings(Simoneitetal.,2004b).However,theyaremostlyassociatedwithinorganiccomponentssuchasionsandmetals,aswellasblack220G.Wangetal./AtmosphericEnvironment43(2009)219–227

120º125º130º

Japan Sea

Korea

Yellow Sea

35º

35º

China

Japan

EastChinaSea

Jeju island

30º

30º

Pacific Ocean

120º

125º

130º

Fig.1.Locationmapofsamplingsite(Gosan,JejuIsland)intheEastChinaSea.

carbonandorganiccarbon.Incontrast,studiesoforganicaerosolsonamolecularlevelarerathersparse(Simoneitetal.,2004b,c).Inspring2005,anintensivecampaignwasconductedatGosansitetobetterunderstandthephysicalandchemicalpropertiesofaerosolsinthecurrentEastAsiantroposphere(Nakajimaetal.,2007).Duringthecampaign,twodusteventswereobservedinwhichuniquemolecularsignaturesforvariouscompoundclassessug-gestedcontributionsfrommarineandterrestrialplantsandmicroorganisms,andanthropogenicactivities.HerewereportabundancesandmoleculardistributionsoforganicaerosolscollectedatGosansiteusingthesameanalyticalprotocols(Simoneitetal.,2004c),andcomparetheresultswithpreviousstudiesconductedatthesamesiteanditssurroundingareas(Simoneitetal.,2004b,c;Wangetal.,2006,2007)todetectanysignificantchangesintheorganicaerosolcompositionsandconcentrationsinEastAsia.Further,wediscussdifferencesintheorganicchemicalcompositionsbetweentheAsiandustandnon-dustaerosolstobetterunderstandtheoriginandsourceregionsoftheAsianaerosolsovertheEastChinaSea.2.Experimentalsection2.1.AerosolsamplingGosansite(33󰀄290N,126󰀄160E,seeFig.1)islocatedonacliffat71mabovesealevel.ThesitefacestheAsiancontinentbutisiso-latedfromresidentialareasontheisland(Kawamuraetal.,2004).Duringspringtime2005(March18–April8),totalsuspendedparticles(TSP)werecollectedonapre-combusted(450󰀄C,over-night)quartzfilterusingahigh-volumeairsamplerinstalledonthetopofatrailerhouse,3mabovetheground.Samplingwasper-formedingeneraldaily,andoccasionallycontinuedfortwodayswhenthelocalairwasquiteclean.However,whenaduststormeventoccurred,thesamplingwasconductedevery3h.Intotal,21aerosolsampleswerecollectedwithdifferentsamplingdurationsinthisstudy,includingsix3-hsamplesthatwereobtainedduringthetwoduststormevents(Table1).Aftersampling,eachfiltersamplewasplacedinacleanglassjarwithaTeflonlinedscrewcap,transportedtothelabinSapporo,andstoredinafreezerroomatÀ20󰀄Cpriortoanalysis.2.2.Sampleextraction,derivatizationandGC/MSanalysisDetailedmethodsforextraction,derivatizationandgaschro-matography/massspectrometer(GC/MS)analysisaredescribedelsewhere(Simoneitetal.,2004c;Wangetal.,2006,2007).Briefly,aliquotsofthesampleandblankfilterswereextractedwithamixtureofdichloromethaneandmethanol(2:1,v/v)underultrasonication.TheextractswerefilteredthroughquartzwoolpackedinaPasteurpipette,concentratedusingarotaryevaporatorundervacuumandthendriedunderapurenitrogenstream.Thecompoundscontaininghydroxy/carboxyfunctionalgroupsintheextractswerereactedwith60mLofBSTFAat70󰀄Cfor3h.Finally,thederivativesweredilutedwith140mLofn-hexanecontainingC13n-alkaneasaninternalstandardpriortoGC/MSdetermination.GC/MSanalysisofthederivatizedfractionwasperformedusingaHewlett–Packard6890GCcoupledtoaHewlett–Packard5973MSD.TheGCseparationwascarriedoutonaDB-5MSfusedsilicacapillarycolumn(30mÂ0.25mmi.d.,0.25mmfilmthickness)withtheGCoventemperatureprogrammedfrom50󰀄C(2min)to120󰀄Cat15󰀄CminÀ1andthento300󰀄Cat5󰀄CminÀ1withfinalisothermalholdat300󰀄Cfor16min.Thesamplewasinjectedonasplitlessmodeataninjectortemperatureof280󰀄C.Themassspectrometerwasoperatedonelectronimpact(EI)modeat70eVandscannedfrom50to650Da.GC/MSfactorsweredeterminedusingauthenticstandards.Averagerecoveriesofthe66compoundsincludingsugars,n-alkanes,fattyacids,fattyalcohols,polyols,polyacids,ligneouscompounds,sterolsandaromaticacidswerebetterthan80%.NoseriouscontaminationwasfoundinthefieldblanksexceptforC16:0andC18:0fattyacids,whoseabundanceswerelessthan2%ofthoseofrealsamples.Thedatareportedherewerecorrectedforthefieldblanksbutnotcorrectedfortherecoveries.Duetothedifferentsamplingdurations,meandatareportedherearetime-weightedasfollows:nXi¼1X¼XitiTwhereXismeanconcentrationofaspecifiedcompound,Xiistheconcentrationofthespecificcompoundinsamplei,tiistheG.Wangetal./AtmosphericEnvironment43(2009)219–227

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Table1Sampletypeanddatesofatmosphericaerosolsusedinthisstudywithsomemeteorologicaldata.SampletypeSampleSamplingdateTSP,mgmÀ3T,󰀄CRH,b%number3h,Daytime628–29,MarchNda–7488–1051–848h,Daytime2March30,April4136,1356–1048–6012h,Overnight4March28,29,3090–2536–1048–84andApril424h6March18,21,22,141–2366–1953–85andApril2,3,548h3March19–21,23–25,94–1765–1256–69andMarch31–April2aNd:notdetermined.bRH:relativehumidity.samplingdurationofsamplei,Tisthesumofcollectingtimeofallsamples,andnisthenumberofsamples.3.Resultsanddiscussion3.1.Compositions,abundancesandsourcesoforganiccompoundsintheTSPsamples3.1.1.GeneralresultsAsshowninTable2,10classesoforganiccompoundsweredeterminedinthesamples.Amongthem,sugars(average,130Æ14ngmÀ3),fattyacids(73Æ7ngmÀ3),fattyalcohols(41Æ4ngmÀ3),n-alkanes(32Æ3ngmÀ3),andphthalates(21Æ2ngmÀ3)weredetectedasmajorcomponentswhereaspolyols/polyacids,ligninandresinproducts,polycyclicaromatichydrocarbons(PAHs),sterolsandphthalic(aromatic)acidswereasminorclasses.Onaverage,sucrose(51.5Æ9.3ngmÀ3)isthemostabundantsinglecompound,followedbylevoglucosan(36.3Æ5.0ngmÀ3),bis(2-ethylhexyl)phthalate(20.4Æ2.0ngmÀ3),glucose(14.8Æ2.7ngmÀ3),fructose(14.3Æ2.3ngmÀ3),C26andC28fattyalcohols(9.9Æ1.1and10.6Æ1.1ngmÀ3,respectively),andmalicacid(9.5Æ1.7ngmÀ3).Thismoleculardistributionissimilartothoseobtainedatthesamesitein2001springbySimoneitetal.(2004c),butitisdifferentfromthosereportedinthewinteraircraftmeasurementsovercoastalChina,wheremalicacidisthemostabundant,followedbylevo-glucosan,glucose,C19/C20n-alkanes,andcholesterol(Wangetal.,2007).Thisdifferencemaybeduetothedifferencesinthesamplingaltitudes(aircraftvsgroundsite)andthusthedifferenttransportandremovalprocessesinthetroposphere.Averagedconcentrationofthetotalquantifiedcompoundsis343Æ27ngmÀ3,accountingfor0.21Æ0.1%ofaerosolparticlemass.AverageconcentrationofTSPis166Æ17mgmÀ3duringthecampaign,whichissimilartothelevelsreportedpreviously(Simoneitetal.,2004c).However,averyheavyduststormeventwasobservedwithamaximal3-hTSPconcentrationof748mgmÀ3on29March2005,alongwithamoderateduststormeventon28March2005(285mgmÀ3,amaximal3-hTSPconcentration).TheformerepisodeismuchheavierthanthatreportedinApril2001(440mgmÀ3ofTSP)atthesamesite(Simoneitetal.,2004c).Comparedtothosein2001spring(Simoneitetal.,2004c),nosignificantdifferencewasfoundintheabundancesofTSPandorganicsinthe2005springsamplesasdiscussedbelow.The2001samplesweremostlycollectedinApril(Simoneitetal.,2004c),whereasthe2005samplesweremostlycollectedinMarch.Suchadifferenceintheperiodisprobablyoneofthereasonswhywecouldnotfindthesignificantchangesbetweenthetwostudies(2001Apriland2005March).AlthoughitmightbeexpectablethatTSPandorganicaerosolconcentrationswouldincreaseatGosansitefrom2001to2005,transpacifictransportofEastAsiaaerosolsisingeneralmoresignificantinAprilthaninMarch(Healdetal.,2006).3.1.2.Water-solublecompoundsThewater-solublefractionconstitutesasubstantialproportionoforganiccompoundsinatmosphericaerosolsandhasasignificantimpactontheglobalclimatechangebyactingasCCNduetoitshygroscopicproperties(Mochidaetal.,2003).Sugarsinouraerosolsamplesarecharacterizedbyapredominanceofsucrose(51.5Æ9.3ngmÀ3,Table2).However,thisisdifferentfrompreviousstudiesofcontinentalChineseaerosols(WangandKawamura,2005;Wangetal.,2006,2007),inwhichlevoglucosanisthedominantsugar.Anextremelyhighlevel(254ngmÀ3)ofsucrosewasobservedduringthepresentcampaign,whichisaround10timesgreaterthanthelevelsofothersaccharides.Asimilarresultwasobservedinthespring2001aerosolsamples,inwhichsucroseconcentrationswereupto444ngmÀ3(Simoneitetal.,2004c).Primarysaccharidessuchasfructose,glucose,sucrose,andtrehaloseareamajorfractionofsoilorganicmatter,whilesaccharidepolyolssuchasarabitol,mannitolandinositolareproductsoffungalmetabolism(Simoneitetal.,2004a).Gosansiteislocatedfarfromtheresidentialareasandthusthelocalaerosolemissionisinsignificant(Kimetal.,2005).Hencethehighabun-dancesofthesesaccharidesinthesamplessuggestasignificantcontributionofre-suspendedsoilorganicmatterfromagriculturalactivitiesinEastAsiancountriestothetroposphericaerosolsoverGosansite,althoughlocalcontributionofsoilorganicmattercouldnotbeexcluded.Concentrationsoflevoglucosan,akeytracerforbiomassburning(Simoneitetal.,2004c),were2.8–102ngmÀ3(average36.3ngmÀ3,Table2)intheaerosolsamples,beingsimilartothose(8–74ngmÀ3)reportedin2001spring(Simoneitetal.,2004c).Thissimilarityalsosuggeststhatbiomassburningisanimportantsourcethatcontributestotheorganicaerosolcomposi-tionsinEastAsia.Polyolsandpolyacidsaredetectedasarelativelyminorcompoundclassinthesampleswithatotalconcentrationof20Æ3ngmÀ3.Malicacid(9.5Æ1.7ngmÀ3)isthemostabundantinthisgroup,followedbyglycericacid(6.8Æ0.8ngmÀ3)andglycerol(3.8Æ0.6ngmÀ3)(Table2),beingsimilartothelevelsreportedinspring2001atGosan(Simoneitetal.,2004c)butlowerthanthose(47Æ28ngmÀ3formalicacidand7.3Æ4.9ngmÀ3forglycericacid)reportedinwinterChineseaerosolscollectedbyaircraft(Wangetal.,2007).Malicandglycericacidsaresecondarilyproducedbyphotochemicalprocessesintheair(Kawamuraetal.,1996;Simoneitetal.,2004c).TherelativelylowabundancesintheGosansamplescouldbeexplainedbyscavengingand/ordilutionduringlong-rangetransportfrominlandChinatothecoastalocean.Aromaticacids(i.e.,phthalicacid,iso-andtere-phthalicacids),aminorwater-solublecompoundclass,haveatotalconcentrationof11Æ2ngmÀ3withphthalicacidbeingthemostabundantfol-lowedbyterephthalicandisophthalicacids(Table2).Theaverageconcentrationofphthalicacidislowerthanthat(25Æ13ngmÀ3)reportedin2001spring(Simoneitetal.,2004c),butclosetothat(13Æ13ngmÀ3)reportedintheaircraftaerosolsamplesoverEastChina(Wangetal.,2007).3.1.3.LipidclasscompoundsFattyalcohols(C18–C32),fattyacids(C12–C34),n-alkanes(C19–C36)andphthalatesaremajorlipidclasscompoundsdetectedinthesampleswithPAHsandsterolsbeingrelativelyminor.Theconcentrationoftotalfattyalcoholsis41Æ4ngmÀ3(Table2),whichissimilartothose(49Æ26ngmÀ3)reportedinspring2001(Simoneitetal.,2004c).AsshowninFig.2a,C30andC32fattyalcoholsareoneofthedominantspeciesinthecurrentsamplesbutwereundetectableinthe2001springsamples(Simoneitetal.,2004c).Long-chainfattyalcoholsaremainlyderivedfromhigherplantwaxesandloessdeposits,althoughtheymayalsobeemittedtotheairbybiomassburning(Kawamuraetal.,2003).Therefore,222G.Wangetal./AtmosphericEnvironment43(2009)219–227

Table2Concentrations(ngmÀ3)oforganiccompoundsintheTSPsamples(n¼21).CompoundsMinMaxMeanStdI.SugarsLevoglucosan2.810236.35.0Arabitol1.413.53.80.5Fructose1.238.914.32.3Glucose1.581.814.82.7Mannitol1.212.43.20.5Inositol0.13.40.50.1Sucrose4.625451.59.3Trehalose0.848.65.71.4Subtotal2933113014II.FattyalcoholsC180.001.180.400.06C190.000.750.270.06C200.001.280.700.08C210.001.790.860.10C220.004.031.940.20C230.001.280.720.07C240.005.432.500.24C250.001.800.780.07C262.9126.549.911.05C270.001.970.940.08C282.4323.410.61.06C290.002.050.960.14C300.0010.96.050.62C310.002.290.620.15C320.008.923.890.55Subtotal587414III.FattyacidsC12:00.004.290.620.15C14:00.372.320.970.11C15:00.151.050.410.03C16:02.9113.77.220.56C17:00.180.680.360.03C18:02.138.235.130.48C19:00.153.270.440.07C20:00.403.862.170.21C21:00.202.161.190.13C22:02.3910.66.180.59C23:00.745.863.150.35C24:02.0916.48.590.90C25:00.454.242.340.28C26:01.2311.16.380.67C27:00.273.561.920.25C28:01.1413.37.590.87C29:00.003.881.940.29C30:01.0120.79.101.23C31:00.002.391.030.19C32:00.008.153.210.62C34:00.001.860.570.15C16:10.000.500.020.02C18:10.0013.42.730.62C22:10.000.700.070.05Subtotal31125737IV.PolyolsandpolyacidsGlycerol1.4513.63.840.63Glycericacid1.8215.96.810.75Malicacid0.6824.49.451.66Tartaricacid0.003.180.050.07Citricacid0.002.080.020.04Subtotal554203V.n-AlkanesC190.001.490.010.03C200.001.460.380.04C210.002.590.750.11C220.162.501.040.10C230.463.691.860.17C240.414.331.940.20C250.855.403.120.26C260.713.862.050.20C271.468.644.820.38C280.563.131.800.16Table2(continued)CompoundsMinMaxMeanStdC291.4710.15.230.44C300.312.121.070.12C310.926.654.070.34C320.151.390.680.08C330.212.301.520.13C340.000.960.410.06C350.001.160.530.07C360.000.730.260.05Subtotal1051323VI.LigninandresinproductsVanillicacid0.050.780.270.03Syringicacid0.000.290.100.01Dehydroabieticacid0.094.910.790.14Subtotal0.2510.2VII.PAHsPhenanthrene0.001.110.500.06Anthracene0.030.510.220.04Fluoranthene0.041.980.780.10Pyrene0.041.340.500.07Benzo(b)fluorene0.000.130.030.01Benz(a)anthracene0.000.130.050.01Chrysene/triphenylene0.000.940.330.05Benzo(b/k)fluoranthene0.052.540.980.13Benzo(e)pyrene0.010.670.260.03Benzo(a)pyrene0.000.460.170.02Perylene0.000.070.030.00Indeno(123-cd)pyrene0.000.720.270.04Dibenz(a,h)anthracene0.000.090.030.00Benzo(ghi)perylene0.000.610.230.03Anthanthrene0.000.030.010.00Coronene0.000.340.140.02Dibenzo(a,e)pyrene0.000.180.060.01Subtotal0.31251VIII.PhthalatesDibutyl0.0411.60.910.30Bis(2-ethylhexyl)8.1537.220.41.96Subtotal847212IX.SterolsCholesterol0.002.190.380.09Ergosterol0.0015.45.181.08Stigmasterol0.000.980.200.07b-Sitosterol0.0011.42.280.62Subtotal0.51981X.Phthalicacidsph0.7218.06.001.00isoph0.112.770.960.16tereph0.539.864.300.72Subtotal1.531112Total11557534327highabundancesofC30andC32fattyalcoholssuggestthatlipidsintheGosanaerosolsinspring2005aremoreattributabletohigherplantemissionsand/orforestfiresthanthosereportedinspring2001.Indeed,the10-daysofbackwardtrajectoryanalysisshowedthattheairmassesarrivingatGosanduringthecampaignmostlyoriginatedfromtheforestregionsinSiberia/northeastChina,wheretheprimaryemissionsofwaxcomponentsfromhigherplantseitherbywindablationorthermalevaporationviaforestfiresaresignificantintheseason.Fattyacids(73Æ7ngmÀ3,Table2)weredetectedinarangeofC12–C34withapeakatC24orC30(Fig.2b),ofwhichcarbonpref-erenceindex(CPI,eventoodd)was8.4Æ3.8forlowermolecularweight(LMW)fattyacids(C12–C19)and4.9Æ2.2forhighmolecularweight(HMW)fattyacids(C20–C34).FattyacidsthatarederivedG.Wangetal./AtmosphericEnvironment43(2009)219–227223

14121086420

Fatty AlcoholsaAverage Concentrations, ng m-318121086420

1920212223242526272829303132Fatty Acidsb121314151617181920212223242526272829303132346543210

192021222324252627282930313233343536

cn-AlkanesCarbon number

Fig.2.Chain-lengthdistributionsof(a)fattyalcohols,(b)fattyacidsand(c)n-alkanesintheaerosol(TSP)samplesfromGosansite,JejuIsland.

fromterrestrialhigherplantwaxesarecharacterizedbyastrongeven/oddcarbonnumberpredominancefrequentlywithamaximuminC20–C34range(Simoneit,1984).Thus,fattyacidsinthe2005springaerosolsalsosuggestasignificantcontributionofhigherplantemissionsfromSiberia/northeasternChinaoverGosansite.Aseriesofn-alkanes(C19–C36)wereabundantlydetectedinthesampleswithapredominanceofC27,C29andC31species(Table2andFig.2c).Totalconcentrationsofn-alkanesare10–51ngmÀ3(average,32ngmÀ3)withCPI(oddtoeven)valuesof2.6Æ0.6.Concentrationsandmoleculardistributionsofn-alkanesinourspringaerosolsaresimilartothosereportedfor2001springsamples(Simoneitetal.,2004c).Generally,LMWn-alkanes(C19–C24)withnoodd/evencarbonnumberpreferencearemoreattributabletofossilfuelcombustion,whereasHMWn-alkanes(C25–C36)fromhigherplantemissionshaveasignificantodd/evencarbonnumberpredominance(Wangetal.,2007).CPIvalueswere0.9Æ0.4fortheLMWn-alkanesand3.8Æ1.3fortheHMWn-alkanes,indicatingthattheformeraremainlyderivedfromfossilfuelcombustionsandthelattermainlyfromterrestrialhigherplants(Gagosianetal.,1981).SeventeenPAHsweredeterminedinthesampleswithtotalconcentrationsof5Æ1ngmÀ3(Table2),beingclosetothose(4Æ4ngmÀ3)reportedinspring2001(Simoneitetal.,2004c).Benzo(b/k)fluorantheneisthemostabundantinthisgroup,whichisconsistentwiththeaerosolsfrom14Chinesemega-cities(Wangetal.,2006)andtheaerosolscollectedbyaircraftoverChina(Wangetal.,2007),againconfirmingthatPAHsoverGosansitearemainlylong-rangetransportedfromcoalcombustionsourcesinChinabecausebenzo(b/k)fluoranthenehasbeencharacterizedasamajorPAHincoalburningsmokewithahighestemissionfactorinthecountry(Wangetal.,2006).3.2.Organiccompoundsintheduststormsamplesincomparisontonon-dust-stormsamplesDuringthecampaigntwoduststormeventswereobservedonMarch28and29withmaximumTSPconcentrationsof285and748mgmÀ3in3-hsamples,respectively.Thesevaluesareabout2–5timeshigherthanothersamples(157Æ15mgmÀ3)collectedinthenon-dust-stormperiods.Tendaysofbackwardairmasstrajectoryanalysesdemonstratedthatthesourceregionsandtransportpathwaysforthetwoeventsamplesaretotallydifferent(Fig.3).Thedusteventthatoccurredon28March2005(hereinafternamedasDustStormI)wasmoderate,andtheairmassesoriginatedfromthedesertareasintheeasternboundarybetweenMongoliaandChinaatanelevationofaround4000m.TheymovedtothesouthalongtheeastcoastofChinaandstayedovertheEastChinaSeaforafewdaysbeforearrivingatJejuIsland(Fig.3a).TheairmassesassociatedwiththisdusteventpassedovertheeconomicallydevelopedregionsalongcoastalChina.ThustheaerosolscollectedduringDustStormIshouldbeinfluencedbyairpollutionfromtheseregions.Anotherdusteventoccurredon29March(herein-afternamedDustStormII),whosesourceregionisSiberiaatelevationofmorethan2000mduetotheairmasstrajectoryanalysis.Theairmassestraveledacrossthemajorborealforest224G.Wangetal./AtmosphericEnvironment43(2009)219–227

Fig.3.Backwardairmasstrajectoryanalysesforthetwoduststormevents:(a)DustStormI,and(b)DustStormII.ThetrajectoryplotswereproducedwithHYSPLIT4modelfromNOAAARLWebsite;duration:240h;meteorologicaldata:GDAS1;verticalmotioncalculationmethod:modelverticalvelocity;startpointat100mabovesealevel.

areasinSiberiaandtheeconomicallydevelopingregionsinnortheastChinapriortoreachingJejuIsland(Fig.3b).Thus,parti-clescollectedduringthiseventmaybeinfluencedbybothbiogenicemissionfromtheforestsandairpollutionfromtheeconomicallydevelopingregion,thelatterbeingcharacterizedbycoalandwoodburning.Herewefocusontwo3-hsamplesK352(DustStormI)andK355(DustStormII),whichwerecollectedatpeakofeachdustepisode,K352

sucrose2500000

malic acidα−glucoseβ−glucoseaFatty acidn-AlkaneFatty alcohollevoglucosan1500000

mannitol2000000

1000000

C16:0bis-(2-ethylhexyl)phthalateC18:0500000

Abundance10.0015.0020.0025.0030.0035.00C22:0trehalose40.0045.0050.0055.00K355btrehalose200000016000001200000

malic acidlevoglucosanα−glucosemannitolβ−glucoseC16:0bis-(2-ethylhexyl)phthalatearabitolsucrose2400000

Fatty acidn-AlkaneFatty alcohol400000

10.0015.0020.0025.0030.00C20:0C22:0C27C24:0C29C18:0800000

35.0040.00C26:0C31C28C28:0C2645.0050.0055.00TimeFig.4.Totalionchromatographyoforganictracersinsamplescollectedduringthetwodustevents:(a)K352(March28,2005)and(b)K355(March29,2005).

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Table3Comparisonoftheconcentrations(ngmÀ3)oforganiccompoundsinthetwoduststorm(K352,K355)andnon-dust(normalsamples)samples.CompoundsDustStormIDustStormNon-dustsamples(K352)II(K355)(n¼15)I.FattyacidsC12–C30408367Æ7.1CPI1a(C12–C20)185.87.0Æ1.0CPI2a(C21–C30)8.55.43.8Æ1.1Majorcomponents16,2216,2430,24II.n-AlkanesbC19–C34145131Æ2.4CPI1a(C19–C11.10.9Æ0.4a24)CPI2(C25–C34)3.75.23.3Æ1.0Majorcomponents27,2929,2729,27III.FattyalcoholsC18–C3277541Æ3.4CPI1a(C18–C21)–7.81.5Æ0.9CPI2a(C21–C32)168.98.0Æ1.9Majorcomponents26,2826,2826,28IV.Fossilfuelemissionsn-Alkanesc82818Æ8.1PAHs0.35.64.7Æ0.6CompoundsDustStormIDustStormRegularsamples(K352)II(K355)(n¼15)V.Biomass-burningtracersLevoglucosan3.710236Æ4.8b-Sitosterol5.67.12.1Æ0.6Dehydroabieticacid0.81.30.7Æ0.1Vanillicacid0.050.80.3Æ0.03SyringicacidNda0.30.1Æ0.01VI.SurfacesoildustGlucose401314Æ2.5Sucrose2544248Æ7.8Trehalose2.7495.0Æ1.1VII.SecondaryorganicaerosolsMalicacid200.89.4Æ1.6Glycericacid5.92.26.9Æ0.7Tartaricacid1.3NddNddCitricacid2.1NddNddPhthalicacid4.31.96.0Æ1.0Totale482502340Æ26TSP,mgmÀ3285748157Æ15Total/TSP,%0.170.070.23Æ0.02aCPI:carbonpreferenceindex(even/oddforfattyacidsandalcohols,odd–evenforn-alkanes).bn-Alkanesincludingbiogenicandanthropogenic.cn-Alkanesderivedfromfossilfuelemissionsarecalculatedastheaverageofoddhomologues–adjacentevenhomologues.dNd:notdetected.eTotal:allquantifiedcompoundsasshowninTable2.tobetterunderstandhowabundancesandcompositionsoforganiccompoundsaredifferentwhenaerosolsaresampledduringthedustepisodesofdifferenttypes.Totalionchromatographs,concentrations,andmoleculardistributionsoforganiccompoundsinthetwosamplesareshowninFig.4,Table3,andFig.5,respectively.FattyacidsarelessabundantinK352thaninK355withastrongereven/oddcarbonpreference(Table3).However,higherrelativeabundancesofC12andC14fattyacidsinK352indicatemorecontributionsfrommarinesourcesinDustStormI(Fig.5aandb)becauseC12andC14fattyacidsareenrichedinmarinephytoplanktonandseasurfacewaters(PeltzerandGago-sian,1989).Theconcentrationofn-alkanes(51ngmÀ3)inK355ismuchhigherthanthat(14ngmÀ3)inK352(Table3).HigherabundancesofC27–C33(Fig.5candd)andhigherCPIof5.2(Table3)intherangeofC25–C34n-alkanesinK355thaninK352areindic-ativeofmoreemissionsofhigherplantwaxes.FattyalcoholhomologuesinK352arealmostundetectableexceptforC26,C28andC21,whereasthehomologueswereabundantlydetectedinK355(Fig.4andTable3).HighlevelsofC26,C28,andC30fattyalcoholswithastrongeven/oddpreferenceinK355furthersupporttheenhancedhigherplantcontributions(PeltzerandGagosian,1989).BackwardairmasstrajectoryanalysisshowedthattheairmasscorrespondingtoDustStormIIcameacrosstheareasofSiberia/northeasternChinaatelevationsoflessthan2500m(Fig.3b),wherehotspotsofforestfireshavebeenobservedfromspace(Fig.6).Thissuggeststhatbiomass-burningproductsaresignifi-cantlyemittedtotheairandlong-rangetransportedtoGosansite.Thisexplanationisconsistentwiththeveryhighconcentrationsoflevoglucosan(biomass-burningtracer)andhigherplantwaxes(n-alkanes,fattyacidsandfattyalcohols)inDustStormIIsample(Table3).Thelattercomponentsareofterrestrialplantwaxoriginandcanbeemittedtotheairbyevaporationofplantleafwaxesunderthehightemperaturesthatoccurduringforestburning(Kawamuraetal.,2003).n-Alkanes(C19–C24)andPAHs,whicharebothoffossilfuelcombustionorigin,showedhigherconcentrationsinK355thaninK352.ConcentrationratiosofspecificPAHscanbeusedtorecog-nizetheirsources.Forexample,indeno(1,2,3-cd)pyrene/benzo-(ghi)perylene(IP/BghiP)is0.22,0.50and1.3inthesmokesfromgasoline,dieselandcoalburnings(Grimmeretal.,1983),andbenzo(ghi)perylene/benzo(e)pyrene(BghiP/BeP)is0.8intheemissionsfromcoalcombustion(Nielsen,1996).Inthisstudy,DustStormIsamplegave0.64forIP/BghiPand0.85forBghiP/BeP,whereasDustStormIIsamplegave1.13forIP/BghiPand0.90forBghiP/BeP(Table4).ThehigherratiosofthesesourcefingerprintsfurtherdemonstratethesignificantemissionsduetocoalburninginnortheastChina.WoodburningforhouseheatingandcookingiscommoninnortheastChina.Thisprocesscancausehigherlevelsofbiomass-burningproductssuchaslevoglucosananddehydroabieticacidasdetectedintheK355(Table3).Moreover,theveryhighcon-centrationoflevoglucosanfoundinK355(102ngmÀ3,Table3)suggestsasignificantcontributionfromforestfires,probablyinSiberia.EnhancedconcentrationofdehydroabieticacidintheK355sampleindicatesthatburningofconiferresinisassociatedwithDustStormII(Simoneitetal.,2004c).ThisfindingisconsistentwiththesatelliteimageofhotspotsinSiberia(Fig.6).GlucoseandsucroseweremuchmoreabundantinK352thaninK355,implyingmorecontributionfromsoilorganicmatterbecausebothsugarsareconsideredastracersofsurfacesoilemissionsassociatedwithagriculturalactivity(Simoneitetal.,2004a).TheairparcelrepresentedbyK352hadbeenhoveringovertheEastChinaSeapriortoreachingGosan,whereitexpe-riencedhigherambienttemperaturesandalongertraveltime(Fig.3a).Thus,anenhancedphotochemicaloxidationmayhaveoccurred,leadingtomoreproductionofmalicandphthalicacidsinK352thaninK355(Table3),whicharetypicalsecondaryorganicaerosol(SOA)components.Benzo(a)pyrene(BaP)islabiletophotochemicaloxidation,whereasbenzo(e)pyrene(BeP)ismuchmorestable.Therefore,theBeP/(BaPþBeP)ratiocanbeusedtoevaluatetheextentofphotochemicalagingofatmo-sphericaerosols(Okudaetal.,2002;Tangetal.,2006).InthisstudyBeP/(BaPþBeP)was1.0inK352and0.56inK355,furtherdemonstratinganenhancedphotochemicalalterationinK352aerosols.Dataonorganiccomponentsinallthenon-dust-stormaero-sols(regularsamples,n¼15),excludingthesix3-hduststormsamples,arecomparedwiththetwoduststormsamplesdis-cussedabove(Table3).Generally,moleculardistributionsofprimaryorganicaerosolsincludingnaturalandanthropogenicspeciesinthenon-dustsamplesaresimilartothoseinK355.In226G.Wangetal./AtmosphericEnvironment43(2009)219–227

100a

K352 Fatty acids

Dust Storm I100c

K352 n-Alkanes

Percent relative abundance, %Percent relative abundance, %806040200121416182022242628308060402001719212325272931333510080604020017192123252729313335Dust Storm IIDust Storm I100806040200bK355 Fatty acidsDust Storm IIdK355 n-Alkanes12141618202224262830

Carbon numberCarbon number

Fig.5.Differencesinthemoleculardistributionsoffattyacidsandn-alkanesintheparticlesfromtwoduststormevents:(a)C16¼8.5ngmÀ3,(b)C16¼13.7ngmÀ3,(c)C27¼3.7ngmÀ3and(d)C29¼10.1ngmÀ3.

(Table4).ThepresentmolecularapproachtotheGosanaerosolsamplesdemonstratesthatmoleculardistributionsandconcen-trationsoforganictracersaresignificantlydifferentbetweennon-dustandduststormsamples.ComparisonsofdetailedmolecularcompositionsofaerosolsamplesfurtherdemonstratethatthetwoduststormsthatoccurredatGosansitewithintwodaysinMarch2005areassociatedwiththelong-rangeatmo-spherictransportofdustparticlesfromdifferentsourceregions(northChinaandSiberia)andthushavedifferentoriginsandchemicalcompositions.4.SummaryandconclusionsTenclassesoforganicspecieshavebeendeterminedinTSPsamplescollectedatJejuIsland,Koreaduringspring2005onamolecularlevelbyusingtheTMSderivatizationandGC/MSquantificationtechnique.Amongthequantifiedcompounds,sugars(average,130Æ14ngmÀ3),fattyacids(73Æ7ngmÀ3),alcohols(41Æ4ngmÀ3),n-alkanes(32Æ3ngmÀ3),andphthalates(21Æ2ngmÀ3)werefoundasmajorclasseswithpolyols/ployacids,ligninandresinproducts,PAHs,sterolsandaromaticacidsbeingminor.TwotypesofduststormswereobservedonMarch28and29withTSPconcentrationspeakingat285and748mgmÀ3,respectively.Theformereventwascharacteristicofsecondaryorganicaerosols,whereasthelatterwascharacteristicofprimaryorganicaerosols,whichismainlyduetothedifferentsourceregionsandpathwaysduringthelong-rangetransportofatmo-sphericaerosols.SuchasignificantdifferenceinthechemicalcompositionsfoundwithinadayindicatesheterogeneityofparticlecompositionsinEastAsia.Fig.6.Averagenumberofforestfirespots(reddots)inMarch2005inSiberia/northeasternChina(datacitedfromhttp://dup.esrin.esa.int/ionia/wfa).(Forinterpre-tationofthereferencestocolorinthisfigurelegend,thereaderisreferredtothewebversionofthisarticle.)

contrast,moleculardistributionsofSOAcomponents(especiallymalicacid,glycericacid)inthenon-dust-stormsamplesaresimilartothoseinK352.SuchmolecularcharacteristicscanfurtherbeconfirmedbytheratiosofPAHsandphthalicacidsTable4RatiosofPAHsandphthalicacidsinthetwodustandnon-dustsamples.DustStormI(K352)IP/BghiPBghiP/BePisoPh/PhaisoPh/terePhaWSOC/WIOCbabDustStormII(K355)1.130.90.090.151Non-dustsamples1.16Æ0.10.91Æ0.010.17Æ0.010.23Æ0.010.87Æ0.05SourcesignatureGasoline0.22Diesel0.51.15Coal1.30.8Reference(Grimmeretal.,1983)(Nielsen,1996)(KawamuraandKaplan,1987)0.640.850.110.273.4Ph,iso-,andterePhmeanphthalicacid,iso-andterephthalicacids,respectively.WSOCandWIOCmeanwater-solubleandwater-insolubleorganiccompounds,respectively.G.Wangetal./AtmosphericEnvironment43(2009)219–227227

AcknowledgementsWethanktheJapanSocietyforthePromotionofScience(JSPS)forafellowshiptoG.W.andfinancialsupportfromChinaMinistryofEducation(No.NCET-07-0424)andNationalNaturalScienceFoundation(Nos.40873083and40475050).ThisstudywasinpartsupportedbytheJapaneseMinistryofEducation,Culture,Sports,ScienceandTechnologythroughGrant-in-AidNo.17340166.WeacknowledgeNOAAUSAforfreeaccesstotheHYSPLIT4modelviatheInternetandProf.TijianWangattheDepartmentofAtmo-sphericScience,NanjingUniversityforthehelpinpreparingtheimageoffirespots.WealsothankProf.PhilMeyersofTheUniversityofMichiganforhiscriticalreadingandcomments.ReferencesAlbrecht,B.A.,1989.Aerosols,cloudmicrophysics,andfractionalcloudiness.Science245,1227–1230.Arimoto,R.,Zhang,X.Y.,Huebert,B.J.,Kang,C.H.,Savoie,D.L.,Prospero,J.M.,Sage,S.K.,Schloesslin,C.A.,Khaing,H.M.,Oh,S.N.,2004.ChemicalcompositionofatmosphericaerosolsfromZhenbeitai,China,andGosan,SouthKorea,duringACE-Asia.JournalofGeophysicalResearch-Atmospheres109,D19S04.doi:10.1029/2003JD004323.Charlson,R.J.,Lovelock,J.E.,Andreae,M.O.,Warren,S.G.,1987.Oceanicphyto-plankton,atmospheresulfur,cloudalbedoandclimate.Nature326,655–661.Charlson,R.J.,Scharwtz,S.E.,Hales,J.M.,Cess,R.D.,CoakleyJr.,J.A.,Hansen,J.E.,Hofman,D.J.,1992.Climateforcingbyanthropogenicaerosols.Science255,423–430.Cooke,W.F.,Liousse,C.,Cachier,H.,Feichter,J.,1999.Constructionofa1󰀄Â1󰀄fossilfuelemissiondatasetforcarbonaceousaerosolandimplementationandradiativeimpactintheECHAM4model.JournalofGeophysicalResearch104,22137–22162.Gagosian,R.B.,Peltzer,E.T.,Zafiriou,O.C.,1981.Atmospherictransportofconti-nentallyderivedlipidstothetropicalNorthPacific.Nature291,312–314.Grimmer,G.,Jacob,J.,Noujack,K.W.,1983.Profileofthepolycyclicaromatichydrocarbonsfromlubricatingoils.InventorybyGC/MS-PAHinenvironmentalmaterials,Part1.FreseniusZeitschriftfurAnalytisheChemie314,13–19.Han,J.S.,Moon,K.J.,Kim,Y.J.,2006.IdentificationofpotentialsourcesandsourceregionsoffineambientparticlesmeasuredatGosanbackgroundsiteinKoreausingadvancedhybridreceptormodelcombinedwithpositivematrixfactor-ization.JournalofGeophysicalResearch11,D22217.doi:10.1029/2005JD006577.Heald,C.L.,Jacob,D.J.,Park,R.J.,Alexander,B.,Fairlie,T.D.,Yantosca,R.M.,Chu,D.A.,2006.TranspacifictransportofAsiananthropogenicaerosolsanditsimpactonsurfaceairqualityintheUnitedStates.JournalofGeophysicalResearch111,D14310.doi:10.1029/2005JD006847.Huebert,B.J.,Bates,T.,Russell,P.B.,Shi,G.Y.,Kim,Y.J.,Kawamura,K.,Carmichael,G.,Nakajima,T.,2003.AnoverviewofACE-Asia:strategiesforquantifyingtherelationshipsbetweenAsianaerosolsandtheirclimaticimpacts.JournalofGeophysicalResearch-Atmospheres108,8663.doi:10.1029/2003JD003550.Kawamura,K.,Kaplan,I.R.,1987.MotorexhaustemissionsasaprimarysourcefordicarboxylicacidsinLosAngelesambientair.EnvironmentalScience&Tech-nology21,105–110.Kawamura,K.,Kasukabe,H.,Barrie,L.A.,1996.Sourceandreactionpathwaysofdicarboxylicacids,ketoacidsanddicarbonylsinArcticaerosols:oneyearofobservations.AtmosphericEnvironment30,1709–1722.Kawamura,K.,Ishimura,Y.,Yamazaki,K.,2003.Fouryears’observationofterrestriallipidclasscompoundsinmarineaerosolsfromthewesternNorthPacific.GlobalBiogeochemicalCycles17,1003.doi:10.1029/2001GB001810.Kawamura,K.,Kobayashi,M.,Tsubonuma,N.,Mochida,M.,Watanabe,T.,Lee,M.,2004.In:Hill,R.J.,Aizenshtat,Z.,Baedecker,M.J.,Claypool,G.,Eganhouse,R.,Goldhaber,M.,Peters,K.(Eds.),GeochemicalInvestigationinEarthandSpaceScience:aTributetoIssacR.Kaplan,vol.9.Elsevier,TheGeochemicalSociety,pp.243–265.Kim,J.,Yoon,S.-C.,Jefferson,A.,Zahorowski,W.,Kang,C.-H.,2005.AirmasscharacterizationandsourceregionanalysisfortheGosansuper-site,Korea,duringtheACE-Asia2001fieldcampaign.AtmosphericEnvironment39,6513–6523.Kim,J.Y.,Ghim,Y.S.,Song,C.H.,Yoon,S.-C.,Han,J.S.,2007.SeasonalcharacteristicsofairmassesarrivingatGosan,Korea,usingfineparticlemeasurementsbetweenNovember2001andAugust2003.JournalofGeophysicalResearch112,D07202.doi:10.1029/2005JD006946.Mochida,M.,Kawamura,K.,Umemoto,N.,Kobayashi,M.,Matsunaga,S.,Lim,H.J.,Turpin,B.J.,Bates,T.S.,Simoneit,B.R.T.,2003.Spatialdistributionsofoxygenatedorganiccompounds(dicarboxylicacids,fattyacids,andlevoglucosan)inmarineaerosolsoverthewesternPacificandoffthecoastofEastAsia:continentaloutflowoforganicaerosolsduringtheACE-Asiacampaign.JournalofGeophysicalResearch-Atmospheres108.Nakajima,T.,Yoon,S.,Ramanathan,V.,Shi,G.,Takemura,T.,Higurashi,A.,Takamura,T.,Aoki,K.,Sohn,B.,Kim,S.,Tsuruta,H.,Sugimoto,N.,Shimizu,A.,Tanimoto,H.,Sawa,Y.,Lin,N.,Lee,C.,Goto,D.,Schutgens,N.,2007.OverviewoftheAtmosphericBrownCloudEastAsianRegionalExperiment2005andastudyoftheaerosoldirectradiativeforcinginEastAsia.JournalofGeophysicalResearch112,D24S91.doi:10.1029/2007JD009009.Nielsen,T.,1996.Trafficcontributionofpolycyclicaromatichydrocarbonsinthecenterofalargecity.AtmosphericEnvironment30,3481–3490.Okuda,T.,Kumata,H.,Naraoka,H.,Takada,H.,2002.Originofatmosphericpolycyclicaromatichydrocarbons(PAHs)inChinesecitiessolvedbycompound-specificstablecarbonisotopicanalyses.OrganicGeochemistry33,1737–1745.Peltzer,E.T.,Gagosian,R.B.,1989.In:Duce,R.A.(Ed.),ChemicalOceanographySEAREX:theSea/AirExhangeProgram,vol.10.AcademicPress,London,pp.281–338.Ramanathan,V.,Crutzen,J.T.,Kiehl,J.T.,Rosenfeld,D.,2001.Aerosols,climate,andthehydrologicalcycle.Science294,2119–2124.Richter,A.,Burrows,J.,Nub,H.,Granier,C.,Niemeier,U.,2005.Increaseintropo-sphericnitrogendioxideoverChinaobservedfromspace.Nature437,129–132.Simoneit,B.R.T.,1984.Applicationofmolecularmarkeranalysistoreconcilesourcesofcarbonaceousparticulatesintroposphericaerosols.ScienceoftheTotalEnvironment36,61–72.Simoneit,B.R.T.,Elias,V.O.,Kobayashi,M.,Kawamura,K.,Rushdi,A.I.,Medeiros,P.M.,Rogge,W.F.,Didyk,B.M.,2004a.Sugars–dominantwater-solubleorganiccompoundsinsoilsandcharacterizationastracersinatmosphericparticulatematter.EnvironmentalScience&Technology38,5939–5949.Simoneit,B.R.T.,Kobayashi,M.,Mochida,M.,Kawamura,K.,Huebert,B.J.,2004b.AerosolparticlescollectedonaircraftflightsoverthenorthwesternPacificregionduringtheACE-Asiacampaign:compositionandmajorsourcesoftheorganiccompounds.JournalofGeophysicalResearch-Atmospheres109,D19S10.doi:10.1029/2004JD004565.Simoneit,B.R.T.,Kobayashi,M.,Mochida,M.,Kawamura,K.,Lee,M.,Lim,H.J.,Turpin,B.J.,Komazaki,Y.,2004c.CompositionandmajorsourcesoforganiccompoundsofaerosolparticulatemattersampledduringtheACE-Asiacampaign.JournalofGeophysicalResearch-Atmospheres109.doi:10.1029/2004JD004598.Tang,X.L.,Bi,X.H.,Sheng,G.Y.,Tan,J.H.,Fu,J.M.,2006.Seasonalvariationoftheparticlesizedistributionofn-alkanesandpolycyclicaromatichydrocarbons(PAHs)inurbanaerosolofGuangzhou,China.EnvironmentalMonitoringandAssessment117,193–213.VanCuren,R.A.,Cahill,T.A.,2002.AsianaerosolsinNorthAmerica:frequencyandconcentrationoffinedust.JournalofGeophysicalResearch107,484.doi:10.1029/2002JD002204.Wang,G.H.,Kawamura,K.,2005.Molecularcharacteristicsofurbanorganicaero-solsfromNanjing:acasestudyofamega-cityinChina.EnvironmentalScience&Technology39,7430–7438.Wang,G.H.,Kawamura,K.,Lee,S.C.,Ho,K.F.,Cao,J.J.,2006.Molecular,seasonalandspatialdistributionsoforganicaerosolsfromfourteenChinesecities.Environ-mentalScience&Technology40,4619–4625.Wang,G.H.,Kawamura,K.,Hatakeyama,S.,Takami,A.,Li,H.,Wang,W.,2007.AircraftmeasurementoforganicaerosolsoverChina.EnvironmentalScience&Technology41,3115–3120.Wilkening,K.E.,Barrie,L.A.,Engle,M.,2000.Trans-Pacificairpollution.Science290,65–67.