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- Title
Changes in Physicochemical Properties of Organic Aerosol During Photochemical Aging of Cooking and Burning Emissions.
- Authors
Xu, Weiqi; Li, Zhijie; Zhang, Zhiqiang; Li, Jinjian; Karnezi, Eleni; Lambe, Andrew T.; Zhou, Wei; Sun, Jiaxing; Du, Aodong; Li, Ying; Sun, Yele
- Abstract
Photochemical aging is a key atmospheric processing, yet the changes in physicochemical properties of organic aerosol (OA) during photochemical aging of primary emissions from cooking and burning are less understood. Here we conducted 12 burning (straw, wood, and coal) and cooking experiments to characterize the evolution of size distributions, volatility, and glass transition temperature (Tg) from fresh smoke to aged OA with an equivalent photochemical age of ∼1.5 days using an oxidation flow reactor‐thermodenuder‐aerosol mass spectrometer system. The mass spectra of OA showed significant changes during photochemical aging, for example, the rapid degradation of m/z 60 for straw and wood burning OA, and the large increase in f44 (fraction of m/z 44 in OA) for all OA. The contributions of non‐volatile compounds to the total OA in aged burning OA (1.6%–5.3%) decreased considerably compared with those in fresh burning smoke (2.3%–17.1%), suggesting that photochemical aging of primary emissions for ∼1.5 days produced more volatile secondary OA (SOA). Consistently, the pronounced formation of SOA below 150 nm was observed, and it showed more volatile properties than aged large particles. The Tg of OA under dry conditions (Tg,org) was estimated based on volatility distributions, and the results showed increased Tg,org during photochemical aging of biomass burning and coal combustion emissions, while decreased Tg,org for aged cooking OA. Overall, our results illustrate the different changes in size distributions, volatility, and Tg,org through photochemical aging of different primary emissions, which in turn affect their impacts on radiative forcing and human health. Plain Language Summary: The properties of organic aerosol (OA) from primary emissions can have rapid changes during photochemical aging, and hence affect the radiative forcing and health effects of OA. However, changes in physicochemical properties of OA during aging, for example, size distributions, volatility, and glass transition temperature (Tg), are less understood, particularly for the OA from different types of primary emissions. In this work, we characterized such changes in size distributions, volatility, and viscosity of OA from biomass burning, coal combustion, and cooking emissions during photochemical aging. We observed pronounced formation of secondary OA (SOA) below 150 nm after aging, which showed higher volatility than the aged larger OA particles. The aged biomass burning and coal combustion emissions showed lower volatilities and higher viscosities than fresh emissions. Our results demonstrate that the size distributions, volatility, and viscosity of OA in regions with high anthropogenic emissions can have significant changes in days and hence exert different climate and health effects. Key Points: The volatility and glass transition temperature of organic aerosol (OA) from primary emissions changed significantly during photochemical agingSecondary OA formed below 150 nm was more volatile than aged large particlesThe aged biomass burning and coal combustion emissions showed lower volatilities and higher viscosities than fresh emissions
- Subjects
COAL combustion; CARBONACEOUS aerosols; GLASS transition temperature; BIOMASS burning; AEROSOLS; RADIATIVE forcing; MASS spectrometry
- Publication
Journal of Geophysical Research. Atmospheres, 2023, Vol 128, Issue 14, p1
- ISSN
2169-897X
- Publication type
Article
- DOI
10.1029/2022JD037911