Water-soluble organic compounds (WSOC)in size-segregated aerosol samples,cloud water and wet depositions collected at Jeju Island during the ACE-Asia experiment were characterized in terms ofmain functional groups and chemical classes by means ofliquid chromatography coupled with total organic carbon (TOC)analysis,and by nuclear magnetic resonance (NMR)spectroscopy.The surface-active character of the WSOC was also deduced by measuring the surface tension (ST)of cloud water,wet depositions and aerosol water-extracts as a function of WSOC concentration.WSOC in the size-segregated aerosol samples at the Kosan coastal site show the occurrence ofoxidized species,enriched in the accumulation mode,and a functional group composition characteristic of continental industrialized areas,with a small impact from biomass burning sources.The chemical classes identi fied and quanti fied by liquid chromatography accounted for 88%of the water-soluble organic carbon on average.The relatively high proportion ofpolycarboxylic acids (PA,33 40%oftotal characterized WSOC)observed throughout the campaign indicates the persistence ofWSOC from continental pollution sources in air masses which spent up to 5 days in the marine boundary layer (MBL)ofthe Yellow Sea.The analysis ofcloud water and wet depositions collected at a mountain site in Jeju shows substantial differences in the organic composition between the cloud/rainwater solutes and the water-soluble fraction of the aerosol at the coastal site,with PA acids contributing to cloud water WSOC in far smaller proportions (6 11%)than in the fine MBL aerosols.It was proposed that such differences resulted from the entrainment of aerosol particles from the lifted layers into the stratiform clouds.Following this hypothesis,the saturated aliphatic compounds determined by NMR analysis in the rainwater samples,which are also responsible for the observed signi ficant ST lowering,were scavenged above the boundary layer and had possibly been transported from the continent in the lifted layers.The hypothesized features of the vertical pro files in the inorganic and organic aerosol chemical composition are in agreement with the results of aircraft-based measurements performed during the same experiment.
The water-soluble organic component of size-segregated aerosol,cloud water and wet depositions from Jeju Island during ACE-Asia.
2005
Abstract
Water-soluble organic compounds (WSOC)in size-segregated aerosol samples,cloud water and wet depositions collected at Jeju Island during the ACE-Asia experiment were characterized in terms ofmain functional groups and chemical classes by means ofliquid chromatography coupled with total organic carbon (TOC)analysis,and by nuclear magnetic resonance (NMR)spectroscopy.The surface-active character of the WSOC was also deduced by measuring the surface tension (ST)of cloud water,wet depositions and aerosol water-extracts as a function of WSOC concentration.WSOC in the size-segregated aerosol samples at the Kosan coastal site show the occurrence ofoxidized species,enriched in the accumulation mode,and a functional group composition characteristic of continental industrialized areas,with a small impact from biomass burning sources.The chemical classes identi fied and quanti fied by liquid chromatography accounted for 88%of the water-soluble organic carbon on average.The relatively high proportion ofpolycarboxylic acids (PA,33 40%oftotal characterized WSOC)observed throughout the campaign indicates the persistence ofWSOC from continental pollution sources in air masses which spent up to 5 days in the marine boundary layer (MBL)ofthe Yellow Sea.The analysis ofcloud water and wet depositions collected at a mountain site in Jeju shows substantial differences in the organic composition between the cloud/rainwater solutes and the water-soluble fraction of the aerosol at the coastal site,with PA acids contributing to cloud water WSOC in far smaller proportions (6 11%)than in the fine MBL aerosols.It was proposed that such differences resulted from the entrainment of aerosol particles from the lifted layers into the stratiform clouds.Following this hypothesis,the saturated aliphatic compounds determined by NMR analysis in the rainwater samples,which are also responsible for the observed signi ficant ST lowering,were scavenged above the boundary layer and had possibly been transported from the continent in the lifted layers.The hypothesized features of the vertical pro files in the inorganic and organic aerosol chemical composition are in agreement with the results of aircraft-based measurements performed during the same experiment.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
