Long-term chemical analysis and organic aerosol source apportionment at 9 sites in Central Europe: Source identification and uncertainty assessment
Kaspar R. Daellenbach1, Giulia Stefenelli1, Carlo Bozzetti1, Athanasia Vlachou1, Paola Fermo2, Raquel Gonzalez2, Andrea Piazzalunga3,a, Cristina Colombi4, Francesco Canonaco1, Christoph Hueglin5, Anne Kasper-Giebl6, Jean-Luc Jaffrezo7, Federico Bianchi1,b, Jay G. Slowik1, Urs Baltensperger1, Imad El Haddad1, and André S. H. Prévôt11Paul Scherrer Institute (PSI), 5232 Villigen-PSI, Switzerland 2Università degli Studi di Milano, 20133 Milano, Italy 3Università degli Studi di Milano-Bicocca, 20126 Milano, Italy 4ARPA Lombardia, Regional Centre for Air Quality Monitoring, 20122 Milan, Italy 5Swiss Federal Laboratories for Materials Science and Technology, 8600 Dübendorf, Switzerland 6Institute of Chemical Technologies and Analytics, Vienna University of Technology, 1060 Wien, Austria 7Université Grenoble Alpes, CNRS, IGE, 38000 Grenoble, France anow at: Water and Soil Lab, 24060 Entratico, Italy bnow at: Department of Physics, University of Helsinki, 00014 Helsinki, Finland
Received: 08 Feb 2017 – Accepted for review: 24 Feb 2017 – Discussion started: 28 Feb 2017
Abstract. Long-term monitoring of the organic aerosol is important for epidemiological studies, validation of atmospheric models, and air quality management. In this study, we apply a recently developed filter-based offline methodology of the aerosol mass spectrometer to investigate the regional and seasonal differences of contributing organic aerosol sources. We present offline-AMS measurements for particulate matter smaller than 10 μm 9 stations in central Europe with different exposure characteristics for the entire year of 2013 (819 samples). The focus of this study is a detailed source apportionment analysis (using PMF) including in-depth assessment of the related uncertainties. Primary organic aerosol (POA) is separated in three components: hydrocarbon-like OA which is related to traffic emissions (HOA), cooking OA (COA), and biomass-burning OA (BBOA). We observe enhanced production of secondary organic aerosol (SOA) in summer, following the increase in biogenic emissions with temperature (summer oxygenated OA, SOOA). In addition, a SOA component was extracted that correlated with anthropogenic secondary inorganic species which is dominant in winter (winter oxygenated OA, WOOA). A factor (SC-OA) explaining sulfur-containing fragments (CH3SO2+), which has an event-driven temporal behavior, was also identified. The relative yearly average factor contributions range for HOA from 3 to 15 %, for COA from 3 to 31 %, for BBOA from 11 to 61 %, for SC-OA from 5 to 23 %, for WOOA from 14 to 28 %, and for SOOA from 14 to 40 %. The uncertainty of the relative average factor contribution lies between 5 and 9 % of OA. At the sites north of the alpine crest, the sum of HOA, COA, and BBOA (POA) contributes less to OA (POA/OA = 0.3) than at the southern alpine valley sites (0.6). BBOA is the main contributor to POA with 88 % in alpine valleys and 43 % north of the alpine crest. Furthermore, the influence of primary biological particles (PBOA), not resolved by PMF, is estimated and could contribute significantly to OA in PM10.
Daellenbach, K. R., Stefenelli, G., Bozzetti, C., Vlachou, A., Fermo, P., Gonzalez, R., Piazzalunga, A., Colombi, C., Canonaco, F., Hueglin, C., Kasper-Giebl, A., Jaffrezo, J.-L., Bianchi, F., Slowik, J. G., Baltensperger, U., El Haddad, I., and Prévôt, A. S. H.: Long-term chemical analysis and organic aerosol source apportionment at 9 sites in Central Europe: Source identification and uncertainty assessment, Atmos. Chem. Phys. Discuss., doi:10.5194/acp-2017-124, in review, 2017.