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Sci Total Environ

Title:		"Elucidating the quantitative characterization of atmospheric oxidation capacity in Beijing, China"
Author(s):		Liu Z; Wang Y; Hu B; Lu K; Tang G; Ji D; Yang X; Gao W; Xie Y; Liu J; Yao D; Yang Y; Zhang Y;
Address:		"State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry (LAPC), Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China. State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry (LAPC), Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China; Center for Excellence in Regional Atmospheric Environment, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen, Fujian 361021, China. Electronic address: wys@mail.iap.ac.cn. State Key Joint Laboratory or Environmental Simulation and Pollution Control, College of Environmental Sciences and Engineering, Peking University, Beijing, China. State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry (LAPC), Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China; Department of Environmental Science and Engineering, Beijing University of Chemical Technology, Beijing 100029, China"
Journal Title:		Sci Total Environ
Year:		2021
Volume:		20210122
Issue:
Page Number:		145306 -
DOI:		10.1016/j.scitotenv.2021.145306
ISSN/ISBN:		1879-1026 (Electronic) 0048-9697 (Linking)
Abstract:		"The atmospheric oxidizing capacity (AOC) is the essential driving force of tropospheric chemistry, but its quantitative representation remains limited. This study presents the detailed evaluation of AOC in the megacity of Beijing based on newly developed indexes that represent the estimated oxidative capacity from the prospective of oxidation products (AOIe) and the potential oxidative capacity considering the oxidation rates of major reactants by oxidants (AOIp). A comprehensive suite of data taken from summer and winter field campaigns were used to create these two indexes and in the calculation of AOC. The AOC showed a clear seasonal pattern, with stronger intensity in summer compared to winter. The gaseous-phase oxidation products (O(3) and NO(2)) dominated AOIe (~80%) during summertime at both sites, while the contribution of particle-phase oxidation products (sulfate, nitrate, and secondary organic aerosol) to AOIe increased in winter (~30%). As for AOIp in summer, the dominant contributor was alkenes (31.0%, urban) and CO (38.5%, suburban), whereas CO and NO(2) dominated AOIp at both urban (68.8%) and suburban (61.0%) sites during wintertime. As expected, the dominant oxidant contributor to AOIp during the daytime was OH, while O(3) was the second most important oxidant at both sites. The diurnal variations of normalized AOIe and AOIp were examined, revealing that they share the same daytime peak but showed significant bias during the nighttime. To explore the possible deviation in sources between AOIe and AOIp, a constrained photochemical box model and a constrained multiphase chemical box model were used to evaluate AOC budgets and their source apportionment. Our results suggest that unmeasured OVOC (oxygenated volatile organic compound) species and missed heterogeneous oxidation processes in the calculation of AOIp contributed substantially to the underestimation of AOC by this index, which should be taken into consideration in future studies of AOC"
Keywords:		Aoc Electron transfer reaction Missing AOC mechanism Oxidation rates;
Notes:		"PubMed-not-MEDLINELiu, Zirui Wang, Yuesi Hu, Bo Lu, Keding Tang, Guiqian Ji, Dongsheng Yang, Xinping Gao, Wenkang Xie, Yuzhu Liu, Jingyun Yao, Dan Yang, Yuan Zhang, Yuanhang eng Netherlands 2021/03/20 Sci Total Environ. 2021 Jun 1; 771:145306. doi: 10.1016/j.scitotenv.2021.145306. Epub 2021 Jan 22"