The particle phase state during the biomass burning events

The phase state of biomass burning aerosols (BBA) remains largely unclear, impeding our understanding of their effects on air quality, climate and human health, due to its profound roles in mass transfer between gaseous and particulate phase. In this study, the phase state of BBA was investigated by measuring the particle rebound fraction f combining field observations and laboratory experiments. We found that both ambient and laboratory-generated BBA had unexpectedly lower rebound fraction f (<0.6) under the dry conditions (RH = 20-50%), indicating that BBA were in non-solid state at such low RH. This was obviously different from the secondary organic aerosols (SOA) derived from the oxidation of both anthropogenic and biogenic volatile organic compounds, typically with a rebound fraction f larger than 0.8 at RH below 50%. Therefore, we proposed that the diffusion coefficient of gaseous molecular in the bulk of BBA might be much higher than SOA under the dry conditions. (C) 2021 Elsevier B.V. All rights reserved.

Automated summary

Through experiments and observations, it was found that under dry conditions, biomass burning aerosols (BBA) are in a non-solid state, differing from secondary organic aerosols (SOA). This suggests that under dry conditions, the diffusion coefficient of gaseous molecules in BBA may be much higher than in SOA.