Laboratory Constraints on Photochemical Processing of Biomass Burning-Derived Secondary Organic Aerosol
MARIA ZAWADOWICZ, Yuzhi Chen, John Shilling, Gregory W. Vandergrift, Tania Gautam, Swarup China, Arthur J. Sedlacek,
Brookhaven National Laboratory Abstract Number: 385
Working Group: Aerosol Chemistry
AbstractBiomass burning events, such as wildfires, are a substantial, and potentially increasing, source of primary and secondary aerosol and reactive gas emissions into the free troposphere. As the fire plumes age, biomass burning-derived aerosols and gases undergo photochemical processing, which can result in changes to aerosol organic mass and chemical transformations that impact their optical and hygroscopic properties. Capturing those processes in global climate models is important for constraining organic aerosol mass and correctly predicting both direct and indirect effects of aerosols on climate. Recently Sedlacek et al. have described biomass burning aerosol lifecycle using data from multiple field measurements, showing a fast (first few hours) initial organic coating accumulation through secondary organic aerosol (SOA) formation, followed by a slow (1-10 days) loss of 75% of the organic coating. This presentation reports results of laboratory experiments aimed at constraining the efficiency of SOA production from two biomass burning-derived volatile organic compounds, guaiacol and furfural, and its subsequent loss via direct photolysis. Guaiacol and furfural SOA was produced via OH oxidation in a 10.6 m
3 environmental chamber under low- and high- NOx conditions, and subsequently aged with UV exposure for ~12 hours. Additionally, changes to the SOA composition following aging were characterized using high-resolution mass spectrometry. Guaiacol- and furfural-derived SOA was found to be non-photolabile compared to biogenically-derived SOA produced from oxidation of isoprene and ɑ-pinene, suggesting longer atmospheric lifetimes of biomass burning-derived SOA, consistent with field campaign data.