AAAR 32nd Annual Conference
September 30 - October 4, 2013
Oregon Convention Center
Portland, Oregon, USA
Abstract View
Source Apportionment of Carbonaceous Aerosol in Urban Environments through Single Particle Mass Spectrometry
ROBERT HEALY, Jean Sciare, Laurent Poulain, Monica Crippa, Alfred Wiedensohler, Andre Prévôt, Urs Baltensperger, Roland Sarda-Esteve, Maygan McGuire, Cheol-Heon Jeong, Eoin McGillicuddy, Ian O'Connor, John Sodeau, Alex K. Y. Lee, Megan D. Willis, Jonathan Abbatt, Greg J. Evans, John Wenger, SOCAAR, University of Toronto
Abstract Number: 196 Working Group: Urban Aerosols
Abstract Single particle mass spectrometers are well suited to the identification of local and regional sources of organic aerosol (OA) and elemental carbon (EC) in urban environments. However, obtaining quantitative mixing state data at the single particle level remains a challenge. In this study, the quantitative chemical composition of carbonaceous particles has been estimated using an aerosol time-of-flight mass spectrometer (ATOFMS) as part of the MEGAPOLI 2010 winter campaign in Paris, France. ATOFMS-derived mass concentrations for OA and EC agreed well with those measured by co-located high resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS) and thermal/optical measurements (R2 = 0.75 and 0.72, respectively). Ten discrete mixing states were identified and quantified for carbonaceous particles. These were associated with traffic, domestic wood combustion, aged wood combustion and mid-to-long range transport. The ATOFMS OA mass fractions associated with each source agreed well with those obtained from positive matrix factorization of the HR-ToF-AMS dataset (R2 = 0.60-0.81). The results indicate that hydrocarbon-like OA (HOA) detected in Paris is associated with two EC-rich mixing states which differ in their relative sulphate content, while fresh biomass burning OA (BBOA) is associated with two mixing states which differ significantly in their OA/EC ratios. A single nitrate-rich mixing state was observed for aged biomass burning OA (OOA2-BBOA), while oxidized OA (OOA) was associated with five particle mixing states, each exhibiting different relative secondary inorganic ion content. These findings demonstrate the diversity of OA mixing states in Paris, and demonstrate the suitability of single particle mass spectrometry for OA apportionment. Preliminary findings from the co-deployment of an ATOFMS and soot-particle aerosol mass spectrometer at a near-road site in downtown Toronto will also be discussed.