Uncovering the dominant contribution of intermediate volatility compounds in secondary organic aerosol formation from biomass-burning emissions

Abstract

Organic vapors from biomass burning are a large source of secondary organic aerosol (SOA). Previous smog chamber studies found that the SOA contributors in biomass-burning emissions are mainly volatile organic compounds (VOCs). While intermediate volatility organic compounds (IVOCs) are efficient SOA precursors and a considerable fraction of biomass-burning emissions, their contribution to SOA formation has not been directly observed. Here, by deploying a newly-developed oxidation flow reactor to study SOA formation from wood burning, we find that IVOCs can contribute ∼70% of the formed SOA, i.e., >2 times more than VOCs. This previously missing SOA fraction is interpreted to be due to the high wall losses of semi-volatile oxidation products of IVOCs in smog chambers. The finding in this study reveals that SOA production from biomass burning is much higher than previously thought, and highlights the urgent need for more research on the IVOCs from biomass burning and potentially other emission sources.

Large contribution of in-cloud production of secondary organic aerosol from biomass burning emissions

“…Mass spectral signatures of aqSOA from residential wood burning are characterized by an abundance of highly oxygenated and high molecular weight species. Additionally, we used an oxidation flow reactor (OFR) to investigate gasSOA formation from the same BB emissions after a simulation of approximately five days of photochemical aging 50 . In comparison to aqSOA, the dominant signals in gasSOA are attributed to C 6-8 H x O 3-7 compounds, while more highly oxygenated and carbon-containing species are observed in aqSOA (Fig.…”

Secondary Organic Aerosol Formation from Ambient Air in Summer in Urban Beijing: Contribution of S/IVOCs and Impacts of Heat Waves

“…However, when considering the IVOCs in SOA estimation, a ∼ 80% mass closure could be achieved between the predicted and observed SOA from gasoline vehicle emissions . Li et al also found that IVOCs from biomass burning emissions contributed ∼70% of the formed SOA. Despite these advances, our understanding of the contribution of different VOC and S/IVOC species to SOA formation in typical urban atmospheric environments is still limited.…”

“…To investigate the formation mechanisms and aging processes of SOA, the oxidation flow reactor (OFR) has emerged as an effective tool. − Briefly, OFR generates oxidants with the concentrations several orders of magnitude higher than those in the ambient atmosphere, enabling real-time measurements of SOA formation due to their high oxidative ability, small volume, and short residence time . So far, many OFR field studies have been conducted in urban areas, especially in the mega city of Beijing. − For example, Liu et al observed a higher SOA formation potential in spring in Beijing compared to Los Angeles, where the elevated concentrations of VOCs were the driving factor.…”