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The formation and evolution of secondary organic aerosol during summer in Xi'an: Aqueous phase processing in fog-rain days
Duan, Jing1; Huang, Ru-Jin1,2; Gu, Yifang1,3; Lin, Chunshui1; Zhong, Haobin1,3; Wang, Ying1; Yuan, Wei1,3; Ni, Haiyan1; Yang, Lu1; Chen, Yang4
2021-02-20
摘要Secondary organic aerosol (SOA) is an important contributor to organic aerosol (OA), however, the model simulations of SOA concentrations and oxidation states remain significant uncertainties because of inadequate cognition of its formation and aging chemistry. In this study, SOA formation and evolution processes during summer in XIan were investigated, based on high-resolution online measurements of non-refractory PM2.5 (NR-PM2.5) species and OA source apportionment using positive matrix factorization. The results showed that the total SOA, including less oxidized-oxygenated OA (LO-OOA), more oxidized-oxygenated OA (MO-OOA), and aqueous-phase-processed oxygenated OA (aq-OOA), on average constituted 69% of OA, and 43% of NR-PM2.5, suggesting the high atmospheric oxidation capacity and the dominance of SOA during summer in Xi'an. Photochemical oxidation processes dominated the summertime SOA formation both during non-fog-rain days and fog-rain days, which were responsible for the formation of both LO-OOA and MO-OOA. Consistently, LO-OOA and MO-OOA in total contributed 59% to OA during non-fog-rain days and 56% to OA during fog-rain days, respectively. On the contrary, aq-OOA was mainly observed during fog-rain days, which increased dramatically from 2% of OA during non-fog-rain days to 19% of OA during fog-rain days with the mass concentration increasing accordingly from 0.3 mu g m(-3) to 2.5 mu g m(-3). Episodic analyses further highlighted the persistently high RH high aerosol liquid water content (ALWC) was the driving factor of aq-OOA formation, and high O-x condition could further enhance its formation. Meanwhile, air masses from east and southeast were much favorable for the formation of long-time fog-rain days, which facilitated aq-OOA production during summer in Xi'an. (C) 2020 Elsevier B.V. All rights reserved.
关键词Secondary organic aerosol Aqueous-phase oxidized organic aerosol Fog-rain days Photochemical oxidation
DOI10.1016/j.scitotenv.2020.144077
发表期刊SCIENCE OF THE TOTAL ENVIRONMENT
ISSN0048-9697
卷号756页码:10
通讯作者Huang, Ru-Jin(rujin.huang@ieecas.cn)
收录类别SCI
WOS记录号WOS:000603487500123
语种英语