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Environ Sci Technol

Title:		"Enigma of Urban Gaseous Oxygenated Organic Molecules: Precursor Type, Role of NO(x), and Degree of Oxygenation"
Author(s):		Tian L; Huang DD; Li YJ; Yan C; Nie W; Wang Z; Wang Q; Qiao L; Zhou M; Zhu S; Liu Y; Guo Y; Qiao X; Zheng P; Jing S; Lou S; Wang H; Huang C;
Address:		"Department of Civil and Environmental Engineering, and Centre for Regional Oceans, Faculty of Science and Technology, University of Macau, Macau, Taipa 999078, China. State Environmental Protection Key Laboratory of Formation and Prevention of Urban Air Pollution Complex, Shanghai Academy of Environmental Sciences, Shanghai 200233, China. Aerosol and Haze Laboratory, Beijing Advanced Innovation Center for Soft Matter Science and Engineering, Beijing University of Chemical Technology, Beijing 100029, China. Institute for Atmospheric and Earth System Research/Physics, Faculty of Science, University of Helsinki, Helsinki 00014, Finland. Joint International Research Laboratory of Atmospheric and Earth System Research, School of Atmospheric Sciences, Nanjing University, Nanjing 210023, China. Division of Environment and Sustainability, The Hong Kong University of Science and Technology (HKUST), Hong Kong SAR 999077, China. State Key Joint Laboratory of Environment Simulation and Pollution Control, State Environmental Protection Key Laboratory of Sources and Control of Air Pollution Complex, School of Environment, Tsinghua University, Beijing 100084, China"
Journal Title:		Environ Sci Technol
Year:		2023
Volume:		20221214
Issue:		1
Page Number:		64 - 75
DOI:		10.1021/acs.est.2c05047
ISSN/ISBN:		1520-5851 (Electronic) 0013-936X (Linking)
Abstract:		"Oxidation of volatile organic compounds (VOCs) forms oxygenated organic molecules (OOMs), which contribute to secondary pollution. Herein, we present measurement results of OOMs using chemical ionization mass spectrometry with nitrate as the reagent ion in Shanghai. Compared to those in forests and laboratory studies, OOMs detected at this urban site were of relatively lower degree of oxygenation. This was attributed to the high NO(x) concentrations ( approximately 44 ppb), which overall showed a suppression on the propagation reactions. As another result, a large fraction of nitrogenous OOMs (75%) was observed, and this fraction further increased to 84% under a high NO/VOC ratio. By applying a novel framework on OOM categorization and supported by VOC measurements, 50 and 32% OOMs were attributed to aromatic and aliphatic precursors, respectively. Furthermore, aromatic OOMs are more oxygenated (effective oxygen number, nO(eff) = 4-6) than aliphatic ones (nO(eff) = 3-4), which can be partly explained by the difference in initiation mechanisms and points to possible discrimination in termination reactions. This study highlights the roles of NO(x) in OOM formation in urban areas, as well as the formation of nitrogenous products that might show discrimination between aromatic and aliphatic VOCs"
Keywords:		*Air Pollutants/analysis *Volatile Organic Compounds/analysis China *Ozone/analysis Environmental Monitoring Nitrogen/analysis high NOx nitrogenous compounds oxygenated organic molecules (OOMs) polluted urban environment;
Notes:		"MedlineTian, Linhui Huang, Dan Dan Li, Yong Jie Yan, Chao Nie, Wei Wang, Zhe Wang, Qian Qiao, Liping Zhou, Min Zhu, Shuhui Liu, Yuliang Guo, Yishuo Qiao, Xiaohui Zheng, Penggang Jing, Sheng'ao Lou, Shengrong Wang, Hongli Huang, Cheng eng Research Support, Non-U.S. Gov't 2022/12/15 Environ Sci Technol. 2023 Jan 10; 57(1):64-75. doi: 10.1021/acs.est.2c05047. Epub 2022 Dec 14"