Atmos. Chem. Phys. Discuss., 8, 20901-20924, 2008
© Author(s) 2008. This work is distributed
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This discussion paper has been under review for the journal Atmospheric Chemistry and Physics (ACP). Please refer to the corresponding final paper in ACP.
Source apportionment of elevated wintertime PAHs by compound-specific radiocarbon analysis
R. J. Sheesley, M. Kruså, P. Krecl, C. Johansson, and Ö. Gustafsson
Department of Applied Environmental Science (ITM), Stockholm University, 10691 Stockholm, Sweden

Abstract. Natural abundance radiocarbon analysis facilitates distinct source apportionment between contemporary biomass/biofuel (14C "alive") versus fossil fuel (14C "dead") combustion. Here, the first compound-specific radiocarbon analysis (CSRA) of atmospheric polycylic aromatic hydrocarbons (PAHs) was demonstrated for a set of samples collected in Lycksele, Sweden a small town with frequent episodes of severe atmospheric pollution in the winter. Renewed interest in residential wood combustion means than this type of seasonal pollution is of increasing concern in many areas. Five individual/paired PAH isolates from three pooled fortnight-long filter collections were analyzed by CSRA: phenanthrene, fluoranthene, pyrene, benzo[b+k]fluoranthene and indeno[cd]pyrene plus benzo[ghi]perylene; phenanthrene was the only compound also analyzed in the gas phase. The measured Δ14C for PAHs spanned from −138.3‰ to 58.0‰. A simple isotopic mass balance model was applied to estimate the fraction biomass (fbiomass) contribution that was constrained to a range of 71% for indeno[cd]pyrene+benzo[ghi]perylene to 87% for the gas phase phenanthrene and particulate fluoranthene, respectively. Indeno[cd]pyrene plus benzo[ghi]perylene, known to be enhanced in gasoline-powered motor vehicle exhaust compared to diesel exhaust, had the lowest contribution of biomass combustion of the measured PAHs by 9%. The total organic carbon (TOC, defined as carbon remaining after removal of inorganic carbon) fbiomass was estimated to be 77%, which falls within the range for PAHs. This CSRA data of atmospheric PAHs demonstrate the non-uniformity of biomass combustion contribution to different PAHs even in a location with limited local emission sources and illustrates that regulatory efforts would not evenly reduce all PAHs.

Citation: Sheesley, R. J., Kruså, M., Krecl, P., Johansson, C., and Gustafsson, Ö.: Source apportionment of elevated wintertime PAHs by compound-specific radiocarbon analysis, Atmos. Chem. Phys. Discuss., 8, 20901-20924, doi:10.5194/acpd-8-20901-2008, 2008.
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