| Title: | A retrospect of ozone formation mechanisms during the COVID-19 lockdown: The potential role of isoprene |
| Author(s): | Xu K; Liu Y; Li F; Li C; Zhang C; Zhang H; Liu X; Li Q; Xiong M; |
| Address: | "State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, Beijing, 100875, China. Jining Ecological Environment Monitoring Center, Jining, 272000, China. State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, Beijing, 100875, China. Electronic address: liuxingang@bnu.edu.cn. Wuhan Municipality Environmental Monitoring Center, Wuhan, 430015, China. Chongqing University, College of Environment and Ecology, Chongqing, 400030, China" |
| DOI: | 10.1016/j.envpol.2022.120728 |
| ISSN/ISBN: | 1873-6424 (Electronic) 0269-7491 (Print) 0269-7491 (Linking) |
| Abstract: | "Wuhan took strict measures to prevent the spread of COVID-19 from January 26 to April 7 in 2020. The lockdown reduced the concentrations of atmospheric pollutants, except ozone (O(3)). To investigate the increase in O(3) during the lockdown, trace gas pollutants were collected. The initial concentrations of volatile organic compounds (VOCs) were calculated based on a photochemical ratio method, and the ozone formation potential (OFP) was obtained using the initial and measured VOC concentrations. The O(3) formation regime was NO(X)-limited based on the VOCs/NO(X) diurnal ratios during the lockdown period. The reduced nitric oxide (NO) concentrations and lower wind speed (WS) could explain the night-time O(3) accumulation. The initial total VOCs (TVOCs) during the lockdown were 47.6 +/- 2.9 ppbv, and alkenes contributed 48.1%. The photochemical loss amounts of alkenes were an order of magnitude higher than those of alkenes in the same period in 2019 and increased from 16.6 to 28.0 ppbv in the daytime. The higher initial alkene concentrations sustained higher OFP during the lockdown, reaching between 252.4 and 504.4 ppbv. The initial isoprene contributed approximately 35.0-55.0% to the total OFP and had a positive correlation with the increasing O(3) concentrations. Approximately 75.5% of the temperatures were concentrated in the range of 5 and 20 degrees C, which were higher than those in 2019. In addition to stronger solar radiation, the higher temperatures induced higher isoprene emission rates, partially accounting for the higher isoprene concentrations. Lower isoprene-emitting trees should be considered for future urban vegetation to control O(3) episodes" |
| Keywords: | Humans *Ozone/analysis *Air Pollutants/analysis Environmental Monitoring/methods *covid-19 Communicable Disease Control Alkenes *Environmental Pollutants *Volatile Organic Compounds/analysis China Isoprene Ozone (O(3)) Ozone formation potential (OFP) Phot; |
| Notes: | "MedlineXu, Kai Liu, Yafei Li, Feng Li, Chenlu Zhang, Chen Zhang, Huan Liu, Xingang Li, Qijie Xiong, Min eng England 2022/11/26 Environ Pollut. 2023 Jan 15; 317:120728. doi: 10.1016/j.envpol.2022.120728. Epub 2022 Nov 22" |
