Secondary organic aerosol formation from straw burning using an oxidation flow reactor

Herein, we use an oxidation flow reactor, Gothenburg: Potential Aerosol Mass (Go: PAM) reactor, to investigate the secondary organic aerosol (SOA) formation from wheat straw burning. Biomass burning emissions are exposed to high concentrations of hydroxyl radicals (OH) to simulate processes equivalent to atmospheric oxidation of 0-2.55 days. Primary volatile organic compounds (VOCs) were investigated, and particles were measured before and after the Go: PAM reactor. The influence of water content (i.e. 5% and 11%) in wheat straw was also explored. Two burning stages, the flaming stage, and non-flaming stages, were identified. Primary particle emission factors (EFs) at a water content of 11% (similar to 3.89 g/kg-fuel) are significantly higher than those at a water content of 5% (similar to 2.26 g/kg-fuel) during the flaming stage. However, the water content showed no significant influence at the non-flaming stage. EFs of aromatics at a non-flaming stage (321.8 +/- 146.2 mg/kg-fuel) are larger than that at a flaming stage (130.9 +/- 137.1 mg/kg-fuel). The OA enhancement ratios increased with the increase in OH exposure at first and decreased with the additional increment of OH exposure. The maximum OA enhancement ratio is similar to 12 during the non-flaming stages, which is much higher than similar to 1.7 during the flaming stages. The mass spectrum of the primary wheat burning organic aerosols closely resembles that of resolved biomass burning organic aerosols (BBOA) based on measurements in ambient air. Our results show that large gap (similar to 60%-90%) still remains to estimate biomass burning SOA if only the oxidation of VOCs were included. (C) 2022 The Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences. Published by Elsevier B.V.

Automated summary

In this study, the formation of secondary organic aerosol (SOA) from wheat straw burning was investigated using a Gothenburg: Potential Aerosol Mass (Go: PAM) reactor. The study found that the water content had significant effects on the flaming stage but not on the non-flaming stage. Furthermore, the enhancement ratio of OA was higher during the non-flaming stages, and the mass spectrum of primary wheat burning organic aerosols resembled that of resolved biomass burning organic aerosols (BBOA).