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Environ Sci Technol

Title:		Aerosol Promotes Peroxyacetyl Nitrate Formation During Winter in the North China Plain
Author(s):		Xu W; Zhang G; Wang Y; Tong S; Zhang W; Ma Z; Lin W; Kuang Y; Yin L; Xu X;
Address:		"State Key Laboratory of Severe Weather & Key Laboratory for Atmospheric Chemistry of CMA, Institute of Atmospheric Composition, Chinese Academy of Meteorological Sciences, Beijing 100081, China. Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China. Institute of Urban Meteorology, China Meteorological Administration, Beijing 100089, China. College of Life and Environmental Sciences, Minzu University of China, Beijing 100081, China. Institute for Environmental and Climate Research, Jinan University, Guangzhou 510632, China. Guangdong-Hongkong-Macau Joint Laboratory of Collaborative Innovation for Environmental Quality, Jinan University, Guangzhou 510632, China"
Journal Title:		Environ Sci Technol
Year:		2021
Volume:		20210303
Issue:		6
Page Number:		3568 - 3581
DOI:		10.1021/acs.est.0c08157
ISSN/ISBN:		1520-5851 (Electronic) 0013-936X (Linking)
Abstract:		"Peroxyacetyl nitrate (PAN) is an important indicator for photochemical pollution, formed similar to ozone in the photochemistry of certain volatile organic compounds (VOCs) in the presence of nitrogen oxides, and has displayed surprisingly high concentrations during wintertime that were better correlated to particulate rather than ozone concentrations, for which the reasons remained unknown. In this study, wintertime observations of PAN, VOCs, PM(2.5), HONO, and various trace gases were investigated to find the relationship between aerosols and wintertime PAN formation. Wintertime photochemical pollution was affirmed by the high PAN concentrations (average: 1.2 +/- 1.1 ppb, maximum: 7.1 ppb), despite low ozone concentrations. PAN concentrations were determined by its oxygenated VOC (OVOC) precursor concentrations and the NO/NO(2) ratios and can be well parameterized based on the understanding of their chemical relationship. Data analysis and box modeling results suggest that PAN formation was mostly contributed by VOC aging processes involving OH oxidation or photolysis rather than ozonolysis pathways. Heterogeneous reactions on aerosols have supplied key photochemical oxidants such as HONO, which produced OH radicals upon photolysis, promoting OVOC formation and thereby enhancing PAN production, explaining the observed PM(2.5)-OVOC-PAN intercorrelation. In turn, parts of these OVOCs might participate in the formation of secondary organic aerosol, further aggravating haze pollution as a feedback. Low wintertime temperatures enable the long-range transport of PAN to downwind regions, and how that will impact their oxidation capacity and photochemical pollution requires further assessment in future studies"
Keywords:		Aerosols *Air Pollutants/analysis China Environmental Monitoring *Ozone/analysis Peracetic Acid/analogs & derivatives;
Notes:		"MedlineXu, Wanyun Zhang, Gen Wang, Ying Tong, Shengrui Zhang, Wenqian Ma, Zhiqiang Lin, Weili Kuang, Ye Yin, Liyuan Xu, Xiaobin eng Research Support, Non-U.S. Gov't 2021/03/04 Environ Sci Technol. 2021 Mar 16; 55(6):3568-3581. doi: 10.1021/acs.est.0c08157. Epub 2021 Mar 3"