Characterization and sources of volatile organic compounds (VOCs) during ozone pollution events in Chengdu plain, Southwest China
- 1State Key Joint Laboratory of Environmental Simulation and Pollution Control, College of Environmental Sciences and Engineering, Peking University, Beijing, China
- 2State Environmental Protection Key Laboratory of Formation and Prevention of Urban Air Pollution Complex, Shanghai Academy of Environmental Sciences, Shanghai 200233, China
Since 2015, the annual average ozone (O3) concentration in Chengdu has shown significant positive trends and reached a maximum of 55.2 ppb in 2018. By 2019, the annual average O3 value has slightly decreased to 52.9 ppb, but it is still at the highest level in the Sichuan Basin. In order to illuminate VOCs characteristics, identify critical ozone precursors and explore potential sources during ozone pollution events in Chengdu plain, we performed a comprehensive field observation campaign from 9 August to 14 September 2019. During the campaign, the averaged O3 concentration was 29.1 ppb, and mean values of ozone precursors NOx and TVOC were 14.9 ppb and 31.3 ppb, respectively. Two severe ozone pollution events occurred in Chengdu during the observation period. In ozone pollution event 1, the ratios of the average O3, NOx, NMHCs, and OVOCs concentration on the polluted days relative to the clean days were 4.1, 0.3, 0.6, and 1.4, respectively. In ozone pollution event 2, the ratios of the average O3, NOx, NMHCs, and OVOCs concentration on the polluted days relative to the clean days were 3.4, 0.4, 0.6 and 2.1, respectively. The difference of the ratios indicates that there are secondary conversions of NMHCs and NOx and secondary formation of O3 and OVOCs during the pollution period. Isoprene, Acetaldehyde, Methyl Vinyl Ketone, m/p-Xylene and 1-Butene constitute a large fraction of the LOH during polluted days. In this study, air mass cluster analysis, the potential source contribution function (PSCF), and positive matrix factorization (PMF) receptor models were used in combination to analyze the sources and potential source areas of VOCs during O3 pollution events.
How to cite: Song, M., Li, X., Yang, S., Yu, X., Chen, S., Dong, H., Lou, S., Lu, S., Zeng, L., Lu, K., and Zhang, Y.: Characterization and sources of volatile organic compounds (VOCs) during ozone pollution events in Chengdu plain, Southwest China, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-18314, https://doi.org/10.5194/egusphere-egu2020-18314, 2020