Substantial changes of chemical composition and sources of fine particles during the period of COVID-19 pandemic in Taiyuan, Northern China

Yang Wang; Yanping Wen; Yang Cui; Lili Guo; Qiusheng He; Hongyan Li; Xinming Wang

doi:10.1007/s11869-021-01082-y

Substantial changes of chemical composition and sources of fine particles during the period of COVID-19 pandemic in Taiyuan, Northern China

Air Qual Atmos Health. 2022;15(1):47-58. doi: 10.1007/s11869-021-01082-y. Epub 2021 Aug 21.

Authors

Yang Wang¹, Yanping Wen², Yang Cui¹, Lili Guo¹, Qiusheng He¹, Hongyan Li¹, Xinming Wang³

Affiliations

¹ School of Environmental Science and Engineering, Taiyuan University of Science and Technology, Taiyuan, 030024 China.
² Taiyuan Center of Ecological and Environmental Monitor, Shanxi province, Taiyuan, China.
³ State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, China.

Abstract

To better understand the effects of COVID-19 on air quality in Taiyuan, hourly in situ measurements of PM_2.5(particulate matter with an aerodynamic diameter less than 2.5 mm) and chemical components (water-soluble ions, organic carbon (OC), elemental carbon (EC), and trace elements) were conducted before (P1: 1 January-23 January 2020) and during (P2: 24 January-15 February 2020) the coronavirus disease 2019 (COVID-19) outbreak. The average concentrations of PM_2.5 dropped from 122.0 μg/m³ during P1 to 83.3 μg/m³ during P2. Compared with P1, except for fireworks burning-related chemical components (K⁺, Mg²⁺, K, Cu, Ba), the concentrations of other chemical components of PM_2.5 decreased by14.9-69.8%. Although the large decrease of some emission sources, fireworks burning still resulted in the occurrence of pollution events during P2. The analysis results of positive matrix factorization model suggested that six PM_2.5 sources changed significantly before and during the outbreak of the epidemic. The contributions of vehicle emission, industrial process, and dust to PM_2.5 decreased from 23.1%, 3.5%, and 4.0% during P1 to 7.7%, 3.4%, and 2.3% during P2, respectively, whereas the contributions of secondary inorganic aerosol, fireworks burning, and coal combustion to PM_2.5 increased from 62.0%, 1.8%, and 5.5% to 71.5%, 9.0%, and 6.2%, respectively. The source apportionment results were also affected by air mass transport. The largest reductions of vehicle emission, industrial process, and dust source were distinctly seen for the air masses from northwest.

Supplementary information: The online version contains supplementary material available at 10.1007/s11869-021-01082-y.

Keywords: COVID-19; Chemical composition; PM2.5; Regional transportation; Source apportionment.