Contributions of fossil fuel, biomass-burning, and biogenic emissions to carbonaceous aerosols in Zurich as traced by 14C

Many open questions exist about the importance of different sources of carbonaceous aerosol, which is a substantial contributor to the global aerosol budget and, therefore, to climate change and human mortality. In this work, C-14 was determined in elemental carbon (EC) and different organic carbon (OC) fractions from ambient urban aerosols with aerodynamic diameter <10 mum collected in Zurich (Switzerland). This enabled a more detailed source attribution of the carbonaceous aerosol mass than is possible with other currently available methods. The three major sources, fossil fuel, wood combustion (both anthropogenic emissions), and biogenic emissions, were quantified, making specific regulatory air quality management measures possible. EC originates nearly exclusively from fossil fuel usage during summer, whereas biomass-burning emissions become substantial during winter with approximate to 25%, even though this source contributes only marginally to the local energy consumption. For OC, biogenic sources are dominant in summer with approximate to 60%, where secondary organic aerosol prevails. Wood combustion accounts for up to approximate to 41% of OC in winter. Fossil fuels represent approximate to 30% of OC throughout the year.