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Environ Int

Title:		"A comprehensive study on ozone pollution in a megacity in North China Plain during summertime: Observations, source attributions and ozone sensitivity"
Author(s):		Sun J; Shen Z; Wang R; Li G; Zhang Y; Zhang B; He K; Tang Z; Xu H; Qu L; Sai Hang Ho S; Liu S; Cao J;
Address:		"Department of Environmental Science and Engineering, Xi'an Jiaotong University, Xi'an 710049, China; Key Lab of Aerosol Chemistry & Physics, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an 710049, China. Department of Environmental Science and Engineering, Xi'an Jiaotong University, Xi'an 710049, China; Key Lab of Aerosol Chemistry & Physics, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an 710049, China. Electronic address: zxshen@mail.xjtu.edu.cn. Key Lab of Aerosol Chemistry & Physics, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an 710049, China. Department of Environmental Science and Engineering, Xi'an Jiaotong University, Xi'an 710049, China. Hong Kong Premium Services and Research Laboratory, Kowloon, Hong Kong Special Administrative Region. Divison of Atmospheric Sciences, Desert Research Institute, Reno NV89512, United States"
Journal Title:		Environ Int
Year:		2021
Volume:		20201201
Issue:
Page Number:		106279 -
DOI:		10.1016/j.envint.2020.106279
ISSN/ISBN:		1873-6750 (Electronic) 0160-4120 (Linking)
Abstract:		"Tropospheric ozone (O(3)) pollution has been becoming prominent in North China Plain (NCP) in China since last decade. In order to clarify the source contribution and formation mechanism of O(3), the critical precursors of volatile organic compounds (VOCs) were measured with both on-line and off-line methods in Luoyang City in summer of 2019. The concentrations of nitrogen oxides (NO(x), sum of NO and NO(2)) and O(3) were simultaneously monitored. Fifty-seven VOCs measured in U.S. Photochemical Assessment Monitoring Station (PAMS) showed daily concentrations in a range of 14.5 +/- 5.33 to 29.2 +/- 11.2 ppbv in Luoyang, which were comparable with those in other Chinese megacities. The mass compositions of VOCs were determined, with comparatively low proportions of alkanes (<50%) but high fractions of photoreactive alkenes and alkyne. Source apportionment of VOCs was conducted by Hybrid Environmental Receptor Model (HERM). The results indicated that industrial (38.5%) and traffic (32.0%) were the two dominated pollution sources of VOCs in the urban, while the biogenic and residential sources had contributions of 15.8% and 13.8%, respectively. To further measure the O(3) formation sensitivity and its source attribution, the WRF-CHEM model was adopted in this study. The variation of O(3) between the observation and the stimulation using the local emission inventory showed an index of agreement (IOA) of 0.85. The simulation conducted by WRF-CHEM indicated an average of 43.5% of the O(3) was associated with the regional transportation, revealing the importance of inter-regional prevention and control policy. Traffic and biogenic emissions were the two major pollution sources to an O(3) episode occurred from July 21 to July 27, 2019 (when O(3) concentration over 150 mug m(-3)) in Luoyang, with average contributions of 22.9% and 18.3%, respectively. The O(3) isopleths proved that its formation in the atmosphere of Luoyang was in transitional regime and collectively controlled by both VOCs and NO(x). This was different from the observations in main cities of NCP before implantations of strict emission controls. The isopleths additionally designated that the O(3) formation regime would move forward or shift to NO(x) regime after a reduction of over 45% during the episode. Similar patterns were also reported in other Chinese megacities such as Beijing and Shanghai, due to the tightening of the NO(x) control policies. Our results do support that the simultaneous controls of NO(x) and VOCs were effective in reductions of tropospheric O(3) in Luoyang. Meanwhile, joint regional control policies on the emissions of NO(x) and VOCs can potentially overwhelm the current O(3) pollutions in China"
Keywords:		*Air Pollutants/analysis Beijing China Cities Environmental Monitoring *Ozone/analysis *Volatile Organic Compounds/analysis NO(x) Pollution control Tropospheric ozone VOCs Wrf-chem;
Notes:		"MedlineSun, Jian Shen, Zhenxing Wang, Ruonan Li, Guohui Zhang, Yue Zhang, Bin He, Kun Tang, Zhuoyue Xu, Hongmei Qu, Linli Sai Hang Ho, Steven Liu, Suixin Cao, Junji eng Research Support, Non-U.S. Gov't Netherlands 2020/12/05 Environ Int. 2021 Jan; 146:106279. doi: 10.1016/j.envint.2020.106279. Epub 2020 Dec 1"