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Sci Total Environ

Title:		"Atmospheric oxidation capacity and secondary pollutant formation potentials based on photochemical loss of VOCs in a megacity of the Sichuan Basin, China"
Author(s):		Kong L; Zhou L; Chen D; Luo L; Xiao K; Chen Y; Liu H; Tan Q; Yang F;
Address:		"College of Carbon Neutrality Future Technology, Sichuan University, Chengdu 610065, China; College of Architecture and Environment, Sichuan University, Chengdu 610065, China; Yibin Institute of Industrial Technology, Sichuan University Yibin Park, Yibin 644000, China. College of Carbon Neutrality Future Technology, Sichuan University, Chengdu 610065, China; College of Architecture and Environment, Sichuan University, Chengdu 610065, China; Yibin Institute of Industrial Technology, Sichuan University Yibin Park, Yibin 644000, China. Electronic address: lizhou@scu.edu.cn. Sichuan province Chengdu Ecological Environment Monitoring Center Station, Chengdu 610066, China. Chengdu Academy of Environmental Sciences, Chengdu 610072, China"
Journal Title:		Sci Total Environ
Year:		2023
Volume:		20230817
Issue:
Page Number:		166259 -
DOI:		10.1016/j.scitotenv.2023.166259
ISSN/ISBN:		1879-1026 (Electronic) 0048-9697 (Linking)
Abstract:		"Volatile organic compounds (VOCs) are significant precursors to photochemical pollution. However, reactive VOC species are easily oxidized during transportation, resulting in a systematic underestimate of the measured concentrations. To address this, we applied an improved calculation method to correct the measured VOC concentrations into photochemical initial concentrations (PICs) in Chengdu, a megacity in the Sichuan Basin, China, which is highly vulnerable to complex pollution. In this study, 56 VOC species on the Photochemical Assessment Monitor Station (PAMS) target list were quantitatively monitored throughout all four seasons. Comparing to directly measured values, photochemically initialized total mixing ratios of VOCs increased by 18.6 % in general. The photochemical loss percentages of alkenes and aromatics were prominent in summer (68.6 %, 28.7 %) and spring (65.9 %, 24.7 %), respectively. Furthermore, we examined contributions of VOCs to atmospheric oxidation capacity (AOC) depending on PICs and found that maximum daily total AOC showed a surge in spring and summer. Besides hydroxyl radicals, daytime O(3) in spring and late-afternoon nitrate radicals in summer were essential for AOC with PICs. As expected, alkenes and aromatics dominated PIC-based ozone formation potentials (OFPs). Furthermore, contribution of alkenes to secondary organic aerosol formation potentials reached 15.5 % and 7.6 % in spring and summer, respectively. Using positive matrix factorization model, we identified five VOC sources including vehicular exhaust, industrial emissions, solvent usage, biogenic sources, and liquefied petroleum gas/natural gas use. Based on PICs, biogenic sources were significantly underestimated in spring and summer. Meanwhile, m,p-xylene from solvent usage and isoprene from biogenic sources were the primary contributors to OFPs. Consequently, these results emphasize the significance of photochemically oxidized VOC concentrations, especially for reactive species in typical seasons"
Keywords:		Atmospheric oxidation capacity (AOC) Photochemical initial concentrations Secondary pollution Source apportionment Volatile organic compounds (VOCs);
Notes:		"PublisherKong, Lan Zhou, Li Chen, Dongyang Luo, Lan Xiao, Kuang Chen, Yong Liu, Hefan Tan, Qinwen Yang, Fumo eng Netherlands 2023/08/19 Sci Total Environ. 2023 Aug 17; 901:166259. doi: 10.1016/j.scitotenv.2023.166259"