Source apportionment of Swiss carbonaceous aerosols using radiocarbon analyses of different fractions References: S. Szidat et al., 2007: Dominant impact of residential wood burning on particulate matter in Alpine valleys during winter, Geophys. Res. Lett., 34, L05820, doi: /2006GL S. Szidat et al., 2006: Contributions of fossil fuel, biomass burning, and biogenic emissions to carbonaceous aerosols in Zürich as traced by 14C. J. Geophys. Res. 111, D07206, doi: /2005JD Acknowledgements: Cantons of Lucerne, Grisons and Zürich Swiss Federal Office for the Environment (BAFU) N. Perron 1, M. N. Wehrli 2, S. Szidat 1,2, J. Sandradewi 1, A. S. H. Prévôt 1, U. Baltensperger 1 1 Laboratory of Atmospheric Chemistry, Paul Scherrer Institute, Villigen, Switzerland, 2 Dept. of Chemistry and Biochemistry, University of Bern, Bern, Switzerland Aerosols were collected on quartz fiber filters using HiVol samplers, at four different sites in Switzerland. AEROSOL SAMPLING SITES Radiocarbon : a powerful tracer that enables to quantify the fossil and non-fossil contributions to the OC and EC fractions of the carbonaceous aerosol (TC). 14 C SOURCE APPORTIONMENT RESULTS Alpine valley (Roveredo, Dec 2005) OC non fossil is by far the most important fraction. At least two thirds of it can be attributed to biomass burning. High contribution from heating wood stoves, which surpassed by far the traffic-related emissions, even close to the highway. Swiss Plateau (Reiden, Sedel and Zürich, Jan-Feb 2006) Comparable particulate carbon composition, in spite of very different environments. Little influence of local sources: the air composition on the Swiss Plateau was controlled by a several-day accumulation of regional sources, due to persistent strong temperature inversions over a large area. Fig. 2: Sites in Switzerland where winter 2005/2006 campaigns were conducted. Fig. 1: Fossil and non-fossil contributions to the OC and EC fractions. In all cases, EC is dominated by fossil sources. OC is dominated everywhere by non-fossil sources. The contribution of OC biomass burning versus secondary production from biogenic emissions was estimated by the EC/OC wood burning emission ratio of 0.16 ± Biomass burning is always significant. In the case of Roveredo, the contribution of secondary aerosols is as high as the uncertainty of the estimation. TC 14 C- depleted Characterised by contemporary 14 C/ 12 C ratios OC EC Fossil fuel combustion Primary and secondary production Primary emission Biomass burning Secondary biogenic production Primary and secondary production Primary emission Sedel: rural environment Roveredo: Alpine valley village, close to a highway Reiden: motorway site Zürich: urban background Fig. 3: Average percentage contributions of fossil and biomass-burning sources to EC and fossil and non-fossil sources to OC for our four sampling sites in winter 2005/2006. The values in brackets are as high as their corresponding uncertainties. CONCLUSIONS RoveredoSedelReidenZürich EC fossil EC biomass burning OC fossil OC biogenic OC biomass burning