Secondary Organic Aerosol Yields from NO ₃ Oxidation of Phenolic, Aromatic, and Heterocyclic VOCs: Implications for Biomass Burning Plumes

Biomass burning secondary organic aerosol (BBSOA) has become an important research area in atmospheric science, particularly due to the ongoing global increase in wildfire activity. BBSOA can form from the reactions of emitted volatile organic compounds (VOCs) and gas-phase evaporated primary organic aerosols (POA) with atmospheric oxidants such as O3, OH, and NO3. While some studies have examined SOA formation from OH during daytime BB events, fewer have considered the potentially significant role of NO3. In this chamber study, vapor wall loss (VWL)-corrected SOA yields from the NO3 oxidation of five known BBVOCs: catechol, phenol, styrene, furfural, and methyl furfural are reported. SOA from NO3 reactions of phenol, furfural, and methyl furfural have not been previously reported, to our knowledge. VWL corrections increased the measured SOA yield by 30–41% across an OA range of ∼5 to ∼500 μg m–3, which represents aerosol concentrations from dilute to concentrated biomass burning plumes. Catechol had the highest yield at OA = 100 μg m–3 (1.5), followed by furfural (0.17) and styrene (0.17), with phenol (0.08) and methyl furfural (0.10) having the lowest yields. A wildfire case study is also presented to illustrate the importance of both evaporation and chemistry in understanding BB aerosol composition, though their relative importance is highly dependent on oxidant concentrations, temperature, and dilution rates. Finally, an extractive electrospray soft ionization mass spectrometer (EESI) was used to obtain data on potential molecular species in each experiment, and the nitrocatechol mass yield for the reaction of catechol with NO3 is determined to be 0.90 ± 0.35.