Chemistry of atmospheric fine particles during the COVID-19 pandemic in a megacity of eastern China

Lei Liu; Jian Zhang; Rongguang Du; Xiaomi Teng; Rui Hu; Qi Yuan; Shanshan Tang; Chuanhua Ren; Xin Huang; Liang Xu; Yinxiao Zhang; Xiaoye Zhang; Congbo Song; Bowen Liu; Gongda Lu; Zongbo Shi; Weijun Li

doi:10.1029/2020GL091611

Chemistry of atmospheric fine particles during the COVID-19 pandemic in a megacity of eastern China

Lei Liu, Jian Zhang, Rongguang Du, Xiaomi Teng, Rui Hu, Qi Yuan, Shanshan Tang, Chuanhua Ren, Xin Huang, Liang Xu, Yinxiao Zhang, Xiaoye Zhang, Congbo Song, Bowen Liu, Gongda Lu, Zongbo Shi, Weijun Li^*

^*Corresponding author for this work

Research output: Contribution to journal › Letter › peer-review

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Abstract

Air pollution in megacities represents one of the greatest environmental challenges. Our observed results show that the dramatic NO_x decrease (77%) led to significant O₃ increases (a factor of 2) during the COVID-19 lockdown in megacity Hangzhou, China. Model simulations further demonstrate large increases of daytime OH and HO₂ radicals and nighttime NO₃ radical, which can promote the gas-phase reaction and nocturnal multiphase chemistry. Therefore, enhanced NO₃⁻ and SO₄²⁻ formation was observed during the COVID-19 lockdown because of the enhanced oxidizing capacity. The PM_2.5 decrease was only partially offset by enhanced aerosol formation with its reduction reaching 50%. In particular, NO₃⁻ decreased largely by 68%. PM_2.5 chemical analysis reveals that vehicular emissions mainly contributed to PM_2.5 under normal conditions in Hangzhou. Whereas, stationary sources dominated the residual PM_2.5 during the COVID-19 lockdown. This study provides evidence that large reductions in vehicular emissions can effectively mitigate air pollution in megacities.

Original language	English
Article number	2020GL091611
Number of pages	10
Journal	Geophysical Research Letters
Volume	48
Issue number	2
Early online date	17 Dec 2020
DOIs	https://doi.org/10.1029/2020GL091611
Publication status	Published - 28 Jan 2021

Bibliographical note

Funding Information:
This work was funded by the National Natural Science Foundation of China (42075096 and 91844301), the National Key R&D Program of China (2017YFC0212700), Zhejiang Provincial Natural Science Foundation of China (LZ19D050001), Zhejiang Meteorological Science and Technology Program (2019YB11), LAC/CMA (2020B02), and China Postdoctoral Science Foundation (2020M681823). Gongda Lu thanks the PhD studentship funded by China Scholarship Council.

Publisher Copyright:
© 2020. The Authors.

Keywords

air pollution
chemical composition
COVID-19
fine particles
megacity

ASJC Scopus subject areas

Geophysics
Earth and Planetary Sciences(all)

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LiuL2020ChemistryFinal published version, 3.48 MBLicence: Creative Commons: Attribution (CC BY)

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Liu, L., Zhang, J., Du, R., Teng, X., Hu, R., Yuan, Q., Tang, S., Ren, C., Huang, X., Xu, L., Zhang, Y., Zhang, X., Song, C., Liu, B., Lu, G., Shi, Z., & Li, W. (2021). Chemistry of atmospheric fine particles during the COVID-19 pandemic in a megacity of eastern China. Geophysical Research Letters, 48(2), Article 2020GL091611. Advance online publication. https://doi.org/10.1029/2020GL091611

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abstract = "Air pollution in megacities represents one of the greatest environmental challenges. Our observed results show that the dramatic NOx decrease (77%) led to significant O3 increases (a factor of 2) during the COVID-19 lockdown in megacity Hangzhou, China. Model simulations further demonstrate large increases of daytime OH and HO2 radicals and nighttime NO3 radical, which can promote the gas-phase reaction and nocturnal multiphase chemistry. Therefore, enhanced NO3− and SO42− formation was observed during the COVID-19 lockdown because of the enhanced oxidizing capacity. The PM2.5 decrease was only partially offset by enhanced aerosol formation with its reduction reaching 50%. In particular, NO3− decreased largely by 68%. PM2.5 chemical analysis reveals that vehicular emissions mainly contributed to PM2.5 under normal conditions in Hangzhou. Whereas, stationary sources dominated the residual PM2.5 during the COVID-19 lockdown. This study provides evidence that large reductions in vehicular emissions can effectively mitigate air pollution in megacities.",

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note = "Funding Information: This work was funded by the National Natural Science Foundation of China (42075096 and 91844301), the National Key R&D Program of China (2017YFC0212700), Zhejiang Provincial Natural Science Foundation of China (LZ19D050001), Zhejiang Meteorological Science and Technology Program (2019YB11), LAC/CMA (2020B02), and China Postdoctoral Science Foundation (2020M681823). Gongda Lu thanks the PhD studentship funded by China Scholarship Council. Publisher Copyright: {\textcopyright} 2020. The Authors.",

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AU - Du, Rongguang

AU - Teng, Xiaomi

AU - Hu, Rui

AU - Yuan, Qi

AU - Tang, Shanshan

AU - Ren, Chuanhua

AU - Huang, Xin

AU - Xu, Liang

AU - Zhang, Yinxiao

AU - Zhang, Xiaoye

AU - Song, Congbo

AU - Liu, Bowen

AU - Lu, Gongda

AU - Shi, Zongbo

AU - Li, Weijun

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N2 - Air pollution in megacities represents one of the greatest environmental challenges. Our observed results show that the dramatic NOx decrease (77%) led to significant O3 increases (a factor of 2) during the COVID-19 lockdown in megacity Hangzhou, China. Model simulations further demonstrate large increases of daytime OH and HO2 radicals and nighttime NO3 radical, which can promote the gas-phase reaction and nocturnal multiphase chemistry. Therefore, enhanced NO3− and SO42− formation was observed during the COVID-19 lockdown because of the enhanced oxidizing capacity. The PM2.5 decrease was only partially offset by enhanced aerosol formation with its reduction reaching 50%. In particular, NO3− decreased largely by 68%. PM2.5 chemical analysis reveals that vehicular emissions mainly contributed to PM2.5 under normal conditions in Hangzhou. Whereas, stationary sources dominated the residual PM2.5 during the COVID-19 lockdown. This study provides evidence that large reductions in vehicular emissions can effectively mitigate air pollution in megacities.

AB - Air pollution in megacities represents one of the greatest environmental challenges. Our observed results show that the dramatic NOx decrease (77%) led to significant O3 increases (a factor of 2) during the COVID-19 lockdown in megacity Hangzhou, China. Model simulations further demonstrate large increases of daytime OH and HO2 radicals and nighttime NO3 radical, which can promote the gas-phase reaction and nocturnal multiphase chemistry. Therefore, enhanced NO3− and SO42− formation was observed during the COVID-19 lockdown because of the enhanced oxidizing capacity. The PM2.5 decrease was only partially offset by enhanced aerosol formation with its reduction reaching 50%. In particular, NO3− decreased largely by 68%. PM2.5 chemical analysis reveals that vehicular emissions mainly contributed to PM2.5 under normal conditions in Hangzhou. Whereas, stationary sources dominated the residual PM2.5 during the COVID-19 lockdown. This study provides evidence that large reductions in vehicular emissions can effectively mitigate air pollution in megacities.

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Chemistry of atmospheric fine particles during the COVID-19 pandemic in a megacity of eastern China

Abstract

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Keywords

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