AAAR 37th Annual Conference October 14 - October 18, 2019 Oregon Convention Center Portland, Oregon, USA
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Measured and Modeled SOA Formation from Biomass-Burning-Derived Precursors
KELLEY BARSANTI, Isaac Afreh, Jia Jiang, Lindsay Hatch, William P. L. Carter, Weihan Peng, David R. Cocker III, University of California, Riverside
Abstract Number: 763 Working Group: Biomass Combustion: Emissions, Chemistry, Air Quality, Climate, and Human Health
Abstract Fires can emit high levels of trace gases, including nitrogen oxides (NOx); semi-volatile/intermediate-volatility/volatile organic compounds (S/I/VOCs); and primary particulate matter (PM). Quantities and properties of emitted gaseous and particulate compounds are highly variable and largely dependent on burn conditions, as well as fuel type (composition and structure). During plume dilution, primary PM can evaporate, decreasing the amount of primary organic aerosol (POA) but adding reactive gases (e.g., S/IVOCs). During plume evolution, S/I/VOCs react to form secondary organic aerosol (SOA). Thus, predictions of the net amount of OA in evolving fire plumes depend on both the chemistry and dynamics of the partitioning species and their precursors. In this work, we analyzed gaseous organic compounds emitted from laboratory fires during the 2016 FIREX campaign at the Missoula Fire Lab, in which diverse fuel types were burned. We modeled gas-phase chemistry of a subset of the measured compounds using the SAPRC gas-phase chemical mechanism and GECKO-A (Generator of Explicit Chemistry and Kinetics in the Atmosphere); we also performed box-model simulations of SOA formation based on both SAPRC and GECKO-A mechanisms. We used the SOA model predictions and published chamber data to identify a list of likely important but understudied compounds for SOA formation. Based on that list, we then selected a series of compounds for which we ran smog chamber experiments. We will present the modeling study results on SOA formation from substituted furans and fuel-dependent monoterpenes as a function of fuel type, as well as under different dilution conditions. We will also present measurement-model comparisons using the newly acquired chamber data.