Abstract
Abstract. A one-year study was performed at the Vavihill background station in southern Sweden to estimate the anthropogenic contribution to the carbonaceous aerosol. Weekly samples of the particulate matter PM10 were collected on quartz filters, and the amounts of organic carbon, elemental carbon, radiocarbon (14C) and levoglucosan were measured. This approach enabled source apportionment of the total carbon in the PM10 fraction using the concentration ratios of the sources. The sources considered in this study were emissions from the combustion of fossil fuels and biomass, as well as biogenic sources. During the summer, the carbonaceous aerosol mass was dominated by compounds of biogenic origin (80%), which are associated with biogenic primary and secondary organic aerosols. During the winter months, biomass combustion (32%) and fossil fuel combustion (28%) were the main contributors to the carbonaceous aerosol. Elemental carbon concentrations in winter were about twice as large as during summer, and can be attributed to biomass combustion, probably from domestic wood burning. The contribution of fossil fuels to elemental carbon was stable throughout the year, although the fossil contribution to organic carbon increased during the winter. Thus, the organic aerosol originated mainly from natural sources during the summer and from anthropogenic sources during the winter. The result of this source apportionment was compared with results from the EMEP MSC-W chemical transport model. The model and measurements were generally consistent for total atmospheric organic carbon, however, the contribution of the sources varied substantially. E.g. the biomass burning contributions of OC were underestimated by the model by a factor of 2.2 compared to the measurements.
Highlights
Aerosol particles are known to have adverse effects on human health (Dockery et al, 1993) by affecting the respiratory tract, and the cardiovascular organs (Pope III et al, 2002)
The modelled chemical half-life for levoglucosan was found to be between 72 and 84 h in winter conditions (Hoffmann et al, 2010). This estimate is lower than values reported earlier (Locker, 1988; Fraser and Lakshmanan, 2000), which indicates a further uncertainty in source apportionment based on levoglucosan
Separating organic carbon (OC) and elemental carbon (EC) has the advantage that the EC resulting from biomass burning is not dependent on the levoglucosan values
Summary
Aerosol particles are known to have adverse effects on human health (Dockery et al, 1993) by affecting the respiratory tract, and the cardiovascular organs (Pope III et al, 2002). Be taken into consideration when modelling changes in the Earth’s climate. It is not known in detail how human activities affect aerosol composition, or the degree to which they can alter the climate. Organic aerosols originate mainly from three sources: combustion of fossil fuels, biomass burning and biogenic sources. All these sources can contribute to both primary and secondary organic aerosols (POAs and SOAs).
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