Abstract View
Secondary Organic Aerosol and Brown Carbon Formation from Furanoid Oxidation via OH Radicals: Important Precursors from Biomass Burning
TAEKYU JOO, Linghan Zeng, Yuchen Wang, Tori Hass-Mitchell, Rodney J. Weber, Drew Gentner, Benjamin Brown-Steiner, Matthew Alvarado, Nga Lee Ng, Georgia Institute of Technology
Abstract Number: 430
Working Group: Aerosols, Clouds and Climate
Abstract
Biomass burning is an important source of both primary and secondary organic aerosol (SOA), and recent studies demonstrate the importance of nontraditional organic vapors, such as furanoids, as precursors of SOA formation. Furfural and 2- and 3-methylfuran are the major furanoid species emitted from biomass burning. Here, we investigate SOA and secondary brown carbon (BrC) formation from photooxidation of these compounds in the Georgia Tech Environmental Chamber. Experiments were performed under dry (RH<5%) and humid (RH 50-60%) conditions with ammonium sulfate seeds in the presence of NOx. Light absorption spectra of soluble SOA extracted from filter samples were measured with a Liquid Waveguide Capillary Cell (LWCC) and higher absorption was observed for furfural SOA compared to 2- and 3-methylfuran SOA. SOA bulk composition and functional group distributions were measured using a high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS) and an offline electrospray ionization and high-resolution quadrupole time-of-flight tandem mass spectrometry (LC-ESI-Q-TOF), respectively. The results showed that the fraction of nitrogen-containing aerosol to total organics was 4 times higher in furfural SOA compared to methylfuran SOA. For furfural oxidation under humid conditions, the time evolution and thermogram of particle-phase nitrogen-containing compounds measured using a Filter Inlet for Gases and AEROsols coupled with time-of-flight chemical ionization mass spectrometer (FIGAERO-HR-ToF-CIMS) confirmed the occurrence of rapid uptake of first-generation products followed by oligomerization in the particle phase. Unlike 2- and 3-methylfuran, furfural contains a carbonyl that leads to the production of multi-functionality compounds. This facilitates hydration and higher yields of carbonyl-containing products via fragmentation during photochemical aging, which can then undergo heterogeneous browning reactions with ammonium salts. Consequently, enhanced brown carbon species formation can be expected. Results from this study contribute to our understanding of SOA and BrC formation of furan-containing compounds in biomass burning plumes as well as its impact on the climate.