The anthropogenic influence on carbonaceous aerosol in the European background |
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Authors: | By BARBARA MAY DIETMAR WAGENBACH SAMUEL HAMMER PETER STEIER HANS PUXBAUM CASIMIRO PIO |
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Institution: | Institut für Umweltphysik, Universität Heidelberg, Germany;;VERA laboratory, University of Vienna, Austria;;Institute for Chemical Technologies and Analytics, Vienna University of Technology, Austria;;CESAM &Department of Environment, University of Aveiro, Portugal |
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Abstract: | To constrain the relatively uncertain anthropogenic impact on the organic aerosol load, radiocarbon analyses were performed on aerosol samples, collected year-round, at six non-urban sites including a maritime background and three remote mountain stations, lying on a west-east transect over Western Europe. From a crude three component model supported by TOC and levoglucosan filter data, the fossil fuel, biomass burning and biogenic TOC fraction are estimated, showing at all stations year-round, a relatively constant fossil fuel fraction of around (26 ± 6)% , a dominant biogenic contribution of on average (73 ± 7)% in summer and the continental as well as the maritime background TOC to be only about 50% biogenic. Assuming biomass burning as completely anthropogenic, the carbonaceous aerosol concentration at the mountain sites was found to have increased by a factor of up to (1.4 ± 0.2) in summer and up to (2.5 ± 1.0) in winter. This figure is significantly lower, however, than the respective TOC change since pre-industrial times seen in an Alpine ice core. Reconciling both observations would require an increase, since pre-industrial times, of the background biogenic aerosol load, which is estimated at a factor of 1.3–1.7. |
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