Preprints
https://doi.org/10.5194/acp-2020-1199
https://doi.org/10.5194/acp-2020-1199

  04 Jan 2021

04 Jan 2021

Review status: a revised version of this preprint is currently under review for the journal ACP.

Substantial changes of gaseous pollutants and chemical compositions in fine particles in North China Plain during COVID-19 lockdown period: anthropogenic vs meteorological influences

Rui Li1, Yilong Zhao1, and Hongbo Fu1,2 Rui Li et al.
  • 1Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention, Department of Environmental Science & Engineering, Institute of Atmospheric Sciences, Fudan University, Shanghai, 200433, P.R. China
  • 2Collaborative Innovation Center of Atmospheric Environment and Equipment Technology (CICAEET), Nanjing University of Information Science and Technology, Nanjing 210044, P.R. China

Abstract. The rapid response to COVID-19 pandemic led to the unprecedented decreases of economic activities, thereby reducing the pollutant emissions. A random forest (RF) model was applied to determine the respective contributions of meteorology and anthropogenic emissions to the changes of air quality. The result suggested the strict lockdown measures significantly decreased primary components such as Cr (−201 %) and Fe (−154 %) in PM2.5, whereas the higher relative humidity (RH) and NH3 level, and the lower air temperature (T) enhanced the production of secondary aerosol including SO42− (47.2 %), NO3 (38.6 %), and NH4+ (22.7 %). Positive matrix factorization (PMF) result suggested that the contribution ratios of secondary formation (SF), industrial process (IP), biomass burning (BB), coal combustion (CC), and road dust (RD) changed from 35.2 %, 28.9 %, 19.4 %, 11.8 %, and 4.75 % before COVID-19 outbreak to 42.7 %, 20.5 %, 19.45 %, 9.80 %, and 7.56 %, respectively. The rapid increase of the contribution ratio derived from SF to PM2.5 implied the intermittent haze events during COVID-19 period were characterized with secondary aerosol pollution, which was mainly contributed by the unfavorable meteorological conditions and high NH3 level.

Rui Li et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • CC1: 'Comment on acp-2020-1199', Markus Furger, 13 Jan 2021
  • RC1: 'Comment on acp-2020-1199', Anonymous Referee #1, 09 Feb 2021
  • RC2: 'Comment on acp-2020-1199', Anonymous Referee #2, 16 Feb 2021

Rui Li et al.

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Short summary
The rapid response to COVID-19 pandemic led to the unprecedented decreases of economic activities, thereby reducing the pollutant emissions. The strict lockdown measures significantly decreased primary components such as Cr (−201 %) and Fe (−154 %) in PM2.5, whereas the higher relative humidity (RH) and NH3 level, and the lower air temperature (T) enhanced the production of secondary aerosol including SO42− (47.2 %), NO3 (38.6 %), and NH4+ (22.7 %).
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