Substantial changes in gaseous pollutants and chemical compositions in fine particles in the North China Plain during the COVID-19 lockdown period: anthropogenic vs. meteorological influences
Open Access
- 9 June 2021
- journal article
- research article
- Published by Copernicus GmbH in Atmospheric Chemistry and Physics
- Vol. 21 (11), 8677-8692
- https://doi.org/10.5194/acp-21-8677-2021
Abstract
The rapid response to the COVID-19 pandemic led to unprecedented decreases in 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 in air quality. The result suggested that the strict lockdown measures significantly decreased primary components such as Cr (−67 %) and Fe (−61 %) in PM2.5 (p<0.01), whereas the higher relative humidity (RH) and NH3 level and the lower air temperature (T) remarkably enhanced the production of secondary aerosol, including (29 %), (29 %), and (21 %) (p<0.05). The 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 36 %, 27 %, 21 %, 12 %, and 4 % before the COVID-19 outbreak to 44 %, 20 %, 20 %, 9 %, and 7 %, respectively. The rapid increase in the contribution ratio derived from SF to PM2.5 implied that the intermittent haze events during the COVID-19 period were characterized by secondary aerosol pollution, which was mainly contributed by the unfavorable meteorological conditions and high NH3 level.
Keywords
Funding Information
- 13th Five-Year Weapons Innovation Foundation of China (91744205)
This publication has 67 references indexed in Scilit:
- Source Apportionment of PM2.5 in Delhi, India Using PMF ModelBulletin of Environmental Contamination and Toxicology, 2016
- High-resolution ammonia emissions inventories in China from 1980 to 2012Atmospheric Chemistry and Physics, 2016
- Methods for estimating uncertainty in PMF solutions: Examples with ambient air and water quality data and guidance on reporting PMF resultsScience of The Total Environment, 2015
- Identification of the typical metal particles among haze, fog, and clear episodes in the Beijing atmosphereScience of The Total Environment, 2015
- Atmospheric Emission Characteristics and Control Policies of Five Precedent-Controlled Toxic Heavy Metals from Anthropogenic Sources in ChinaEnvironmental Science & Technology, 2014
- Spatial and temporal variations of six criteria air pollutants in 31 provincial capital cities in China during 2013–2014Environment International, 2014
- Understanding primary and secondary sources of ambient carbonyl compounds in Beijing using the PMF modelAtmospheric Chemistry and Physics, 2014
- Update of mercury emissions from China's primary zinc, lead and copper smelters, 2000–2010Atmospheric Chemistry and Physics, 2012
- Effects of temperature on the heterogeneous oxidation of sulfur dioxide by ozone on calcium carbonateAtmospheric Chemistry and Physics, 2011
- Equilibrium analysis of the affect of temperature, moisture and sodium content on heavy metal emissions from municipal solid waste incineratorsJournal of Hazardous Materials, 1997