10th International Aerosol Conference September 2 - September 7, 2018 America's Center Convention Complex St. Louis, Missouri, USA
Abstract View
Chemical Composition of Biomass Burning Particles Measured with a Soot Particle Aerosol Mass Spectrometer Downwind during the BBOP Study
TIMOTHY ONASCH, Anita Avery, John Shilling, Joda Wormhoudt, Arthur J. Sedlacek, Edward Fortner, Mikhail Pekour, Shan Zhou, Sonya Collier, Qi Zhang, Lawrence Kleinman, Ernie R. Lewis, Andrew Freedman, Leah Williams, Aerodyne Research, Inc.
Abstract Number: 1338 Working Group: Carbonaceous Aerosol
Abstract The Biomass Burning Observation Project (BBOP), a Department of Energy (DOE) sponsored field campaign, measured emissions from wildland fires in the Pacific Northwest and agricultural burns in the Central Southeastern US from the DOE Gulfstream-1 airborne platform over a four month period in 2013. Rapid physical, chemical and optical changes in biomass burning particles were measured downwind (< 3 hours temporally) from wildland fires.
The chemical composition of the particulate emissions was characterized using an Aerodyne Soot Particle Aerosol Mass Spectrometer (SP-AMS) and will be presented in the context of the fire location, combustion conditions, and optical property measurements, including extinction and single scattering albedos. The SP-AMS was operated with both laser and resistively heated tungsten vaporizers, alternating between laser off and on. With the laser vaporizer off, the instrument operated as a standard high resolution AMS. With the laser vaporizer on, the SP-AMS was also sensitive to the refractory black carbon (rBC) content, in addition to the non-refractory components. Results from both vaporizer configurations will be presented and contrasted.
Chemical signatures indicate different combustion conditions within a given fire plume, implying a high diversity within a given burn. The non-refractory chemical composition, including the level of oxidation, i.e., O:C, H:C, and organic mass/organic carbon ratios (OM:OC), changes systematically during the hours of atmospheric transport before measurement. The oxidation of the organic compounds increases with downwind advection, while the primary markers, such as m/z 60, decrease. These chemical changes appear to continue downwind, when compared with additional further downwind measurements, even as the ratio of organic mass to carbon monoxide appears to remain constant. We will also discuss the chemistry in light of observations of tar ball formation and evolution, including results from laboratory studies on tar balls.