AAAR 36th Annual Conference October 16 - October 20, 2017 Raleigh Convention Center Raleigh, North Carolina, USA
Abstract View
Molecular Composition and Long-term Source Contributions to Organic Aerosol in Central Europe
KASPAR RUDOLF DAELLENBACH, Imad El Haddad, Ivan Kourtchev, Alexander Lucas Vogel, Gaëlle Uzu, Giulia Stefenelli, Carlo Bozzetti, Athanasia Vlachou, Paula Fermo, Andrea Piazzalunga, Jay G. Slowik, Samuel M. Luedin, Valentin Pflueger, Guido Vogel, Jean-Luc Jaffrezo, Markus Kalberer, Urs Baltensperger, Andre S.H. Prévôt, Paul Scherrer Institute
Abstract Number: 270 Working Group: Source Apportionment
Abstract Field deployments of the aerosol mass spectrometer (AMS) combined with the application of positive matrix factorization have advanced the measurement of organic aerosol (OA) and the quantification of its most important sources. However, the investigation of regional and seasonal differences by long-term deployments of the AMS is impractical because of instrument cost and maintenance. To overcome these limitations and in order to assess the detailed chemical composition of OA, we have adapted the AMS for the measurement of offline filter samples (oAMS), in combination with a unique suite of analytical techniques, including laser-desorption/ionization-ToF MS (LDI), and ultrahigh-resolution mass spectrometer (Orbitrap).
We present oAMS source apportionment results of OA (smaller than 10 μm) at 9 stations in central Europe for the entire year of 2013 (819 samples). We demonstrate that the factors governing air quality are region-specific, e.g. biomass burning organic aerosol (BBOA) is strongly enhanced in alpine valleys relative to urban centers. LDI results suggest that the elevated BBOA concentrations in alpine valleys are mainly caused by less efficient burning conditions. In winter, a secondary organic aerosol (SOA) factor correlating with anthropogenic secondary inorganic species is dominant. While samples collected during winter in alpine valleys are similar to fresh wood burning emission from laboratory experiments, in Zurich the wood burning emissions are more aged and also other SOA precursors/formation pathways are important in winter (Orbitrap). We observe the production of SOA in summer, following the increase in biogenic emissions with temperature. The predominance of compounds with an H/C of 1.5 observed in summer is consistent with biogenic SOA (Orbitrap). Using LDI, the influence of aged/secondary traffic emissions with higher summer concentrations is separated from fresh emissions. This thorough assessment of local and regional sources affecting air quality will also be compared to health relevant compounds.