Chemical composition characteristics and source analysis of PM_2.5 in Jiaxing, China: insights into the effect of COVID-19 outbreak

ABSTRACTJiaxing is a medium-sized city in the Yangtze River Delta (YRD), which showed complex local and surrounding pollution sources. To study the COVID-19 impact on the ambient PM2.5 in Jiaxing, we collected the PM2.5 samples from 2 January to 25 April 2020 and analysed their chemical compositions (including carbon components, water-soluble ions (WSIs), and inorganic elements). The concentration of PM2.5 was 83.13 ± 30.93 μg/m3 before COVID-19 pandemic and then remarkably decreased with COVID-19 outbreak due to the suspension of mobility and industrial activities. Meanwhile, the concentrations of main chemical species (carbon components, water-soluble ions and inorganic elements) of PM2.5 all decreased from period A (2–20 January 2020) to period B (23 January to 10 February 2020). Moreover, Trajectory clustering analysis showed that close-range transport was one of the dominant factors throughout all the periods, except for period D (1–25 April 2020). In addition, the PSCF model indicated that the COVID-19 outbreak resulted in a significant decrease of WPSCF value. This study highlighted the differences in chemical compositions and sources of PM2.5 since COVID-19 pandemic was reported and provided a better understanding of its outbreak on PM2.5.KEYWORDS: PM2.5COVID-19chemical compositionair quality Disclosure statementNo potential conflict of interest was reported by the author(s).Data availability statementAll data used during the study are available from the corresponding author by request.Additional informationFundingThis work is supported by the National Key Research and Development Program of China (grant number 2018YFC0213806).