AAAR 34th Annual Conference
October 12 - October 16, 2015
Hyatt Regency
Minneapolis, Minnesota, USA
Abstract View
Single Particle Characterization of Biomass Burning Organic Aerosol: Evidence of High Molecular Weight Organics with Low Potassium Content
ALEX K. Y. LEE, Megan D. Willis, Robert Healy, Jon M Wang, Cheol-Heon Jeong, Greg J. Evans, Jonathan Abbatt, University of Toronto
Abstract Number: 20 Working Group: Carbonaceous Aerosols in the Atmosphere
Abstract Biomass burning is one of the major global sources of black carbon and organic aerosol. There is increasing evidence that atmospheric brown carbon is strongly associated with biomass burning organic aerosol (BBOA), introducing significant impacts to regional visibility degradation and climate. The mixing state of BBOA can play a critical role in the prediction of aerosol optical properties and warrants further investigation. In this work, single particle measurements from an Aerodyne soot-particle aerosol mass spectrometer coupled with a light scattering module were used to examine the mixing state of BBOA, potassium and refractory black carbon in a biomass burning influenced air mass. Cluster analysis of the single particle measurement dataset identified five BBOA-related particle types. Only one particle type, associated with small diameters, exhibited a strong signal for potassium, with mass spectra also characterized by low molecular weight organics. The remaining four particle types were classified based on the apparent molecular weight of the BBOA constituents. In particular, there are two particle types with significant amounts of high molecular weight organic fragments in their mass spectra (i.e. > 50% of total ion signal contributed by fragments > m/z 100), which may be the key contributor of low volatility brown carbon in BBOA. These observations provide insights into the sources and chemical properties of atmospheric brown carbon and the input parameters for the current atmospheric models. Relationships between the optical properties and the chemical composition of the aerosol associated with this air mass will also be assessed.