Changes in PM2.5 concentration and responses to anthropogenic emissions in Nanjing during the COVID-19
In the initial stage of the COVID-19,local governments took unprecedented measures to prevent the spread of the virus,providing a rare opportunity to study how PM2.5 concentrations respond to anthropogenic emissions.This study simulates PM2.5 concentrations in Nanjing at the beginning of the COVID-19 in 2020 and during the same period in 2019 by using the air quality model WRF-Chem and the latest published Tsinghua University MEIC2019 and MEIC2020 emission inventories.By designing emission scenarios,this study explored the impact of emission reductions from four major emission sectors on PM2.5 concentration in the initial stage of the COVID-19 in Nanjing.The results showed that compared with 2019,the PM2.5 concentration decreased by about 30％in the initial stage of the COVID-19 in 2020,and the decline ratio showed a law of decreasing from the main urban area of Nanjing.The COVID-19 control measures had the greatest impact on emissions from industrial emissions and residential emissions,which decreased by 37.4％and 21.6％,respectively,in line with the living characteristics,population distribution characteristics and the actual location of major industrial areas in Nanjing.In conclusion,future emission reduction efforts in Nanjing should prioritize controlling industrial and residential emission sources.This study provides a theoretical basis for the subsequent control of PM2.5 concentrations emitted by different sectors in Nanjing.
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