Characteristics of Air Pollution during 2017-2021 in Quanzhou City and Impacts of COVID-19

MENG Deyou; CAI Hezhang; WANG Hong

doi:10.19672/j.cnki.1003-6504.0620.23.338

Abstract：On the basis of the monitoring data of six major pollutants(PM10,PM2.5,NO2,SO2,CO and O3)and air quality in-dex(AQI)data in the period between 2017 and 2021 in Quanzhou City,the interannual and seasonal variation characteristics of air pollution and the impacts of COVID-19 lockdown period on ambient air quality in the City were analyzed and discussed with a view to providing scientific references for further management of air pollution.The results of the analysis showed that the annual average concentrations of PM10,PM2.5,NO2,SO2 and CO in Quanzhou during the period presented an overall down-ward trend;the maximal annual average SO2 concentration decreaseing rate was 15.8％,followed by NO2 and CO(9.3％and 8.1％,respectively);and O3 pollution was relatively prominent but its fluctuation range of concentration was notably reduced.On the whole,the conditions of the City's atmospheric environmental pollution tended smooth and steady,and as to the seasonal pollution,spring was of particular:all the pollutants of PM10,NO2,SO2,CO and O3 went up to the highest concentra-tions.As for the net environmental benefits,during the COVID-19 lockdown of Quanzhou City,compared with the pre-blockade times,suspended production resulted in 38.5％,36.2％,58.2％,9.2％and 27.7％decreases in terms of PM10,PM2.5,NO2,SO2 and CO concentrations,respectively,concentration of each pollutant being at the lowest level in the five-year period;however,on the contrary,O3 concentration increased,it was speculated that the disproportionate emission reduction of NOx and VOCs,the diminished titration action of NO,to O3 and additionally,unfavorable meteorological condition were the main reasons.The City's efforts for pollution abatement and the outburst of COVID-19 brought about the significant reductions in PM10,PM2.5,SO2,NO2 and CO.But the AQI index did not change much,being not notably responding to COVID-19,which maybe resulted from the relatively high O3 pollution and secondary pollutants transformed from gaseous pollutants.The correlation analysis of various pollutants and AQI in Quanzhou before and after COVID-19 suggested that the air environment of Quanzhou City was significantly affected by secondary pollutants and their precursors,thus strengthening the research on secondary pollutant precursors and their generation mechanism could push forward further improvement of the City's air quality.