10th International Aerosol Conference September 2 - September 7, 2018 America's Center Convention Complex St. Louis, Missouri, USA
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Carbonaceous Organic Aerosol Composition and Sources in the Baltic
ATHANASIA VLACHOU, A. Tobler, Houssni Lamkaddam, Carlo Bozzetti, Kaspar Rudolf Dällenbach, Gary Salazar, Soenke Szidat, Urs Baltensperger, Imad El Haddad, Andre S.H. Prévôt, Paul Scherrer Institute
Abstract Number: 677 Working Group: Source Apportionment
Abstract Organic aerosol (OA) is linked to adverse climate and health effects. It is often separated in primary OA (POA) which is directly emitted as particles and in secondary OA (SOA) which is formed in the atmosphere via oxidation of volatile organic compounds. A robust method to study the composition and identify the sources of both POA and SOA is the “offline AMS” technique, which combines aqueous filter extracts measurements with the Aerodyne aerosol mass spectrometer (AMS) and statistical analysis of the resulting organic spectra with positive matrix factorisation. The use of filter samples allows for fast analysis of long term measurements, spatial broadening of the OA monitoring, as well as independence in aerosol size cut-off. In parallel, the radiocarbon analysis of ambient filter samples provides an unequivocal separation between fossil and non-fossil sources, by determining the 14C content of the total carbon. The combination of these two techniques significantly boosts our understanding of the POA and SOA sources.
Despite the few reports on source apportionment and chemical composition of OA in the Baltic region, the coupling of the two techniques has never been applied on filters from this region before. Therefore, the fossil and non-fossil sources of POA and SOA and their seasonal variation still remain unknown. Here we show the combined offline AMS and radiocarbon analysis of OA (particulate matter <10μm), for one year (2013-2014), at three sites in Estonia and three in Lithuania that represent both rural and urban environments. Biomass burning during winter and primary biological OA during late spring and summer are the two most important primary organic aerosols. However, the SOA plays a more crucial role during these two periods with connections to anthropogenic, non-fossil, emissions in winter and biogenic in summer. This is also in agreement with other studies of OA in several European sites where the non-fossil SOA is the main driver in mass.