AAAR 32nd Annual Conference
September 30 - October 4, 2013
Oregon Convention Center
Portland, Oregon, USA
Abstract View
14C-based Source Apportionment of Carbonaceous Aerosols in Switzerland for 2008 – 2012
PETER ZOTTER, Gabriela Ciobanu, Yanlin Zhang, Imad El Haddad, Soenke Szidat, Lukas Wacker, Urs Baltensperger, Andre Prévôt, Paul Scherrer Institute
Abstract Number: 307 Working Group: Source Apportionment
Abstract Radiocarbon (14C) analysis is a direct and quantitative tool for distinguishing fossil and non-fossil sources of carbonaceous aerosols (total carbon, TC), since 14C is completely depleted in fossil fuels whereas other sources have a contemporary 14C-level. This study presents source apportionment results using measurements of 14C in organic and elemental carbon (OC and EC) collected simultaneously at 16 air quality monitoring stations (11 north and 5 south of the Alps) across Switzerland, during 5 consecutive winters (2007/2008–2011/2012). The filter samples are also analysed for EC/OC, major ions and levoglucosan content. A newly developed approach enabling the analysis of filter samples by the aerosol mass spectrometer was also applied. Black carbon (BC) was measured at 4 stations by aethalometers and apportioned into a traffic and wood-burning fraction. This is an unprecedented dataset in terms of number of samples analysed and methodologies applied, providing unique insights into wintertime carbonaceous aerosol sources.
OC and EC account respectively for ~80% and ~20% of TC, the second largest component of PM during the measurement period after Nitrate (25%) contributing 23% of total PM. 14C-results indicate that carbonaceous aerosol is overwhelmingly non-fossil (83% of OC and 46% of EC), suggesting that wood burning is the major source of TC in Switzerland during winter smog episodes. The highest non-fossil values (100% and 87% for OC and EC, respectively) were registered for alpine valley sites and the lowest at highly traffic influenced sites (47% for OCNF and 15% for ECNF). The spatial and temporal trends of biomass burning contribution observed during 5 winters and at the different sites will be further discussed and related to the prevailing meteorological and wood combustion conditions.
This work was funded by the Swiss Federal Office for Environment, inNet Monitoring AG, Liechtenstein and the Swiss cantons Basel-Stadt, Basel-Landschaft, Graubünden, Solothurn, Valais and Ticino.