疫情防控期间荆门市空气质量与污染排放变化

Changes of Air Quality and Pollution Emission in Jingmen City during the Period of COVID-19 Epidemic Prevention and Control

文章基于气象、大气污染物、污染源排放量等数据研究了2020年荆门市新型冠状病毒肺炎疫情防控期间空气质量及污染源排放变化情况,并通过WRF-Chem模型评估了气象条件变化、减排管控措施及外源传输对空气质量的影响。结果表明,与2020年疫情防控前(1月1日~1月23日)相比,疫情防控期间(1月24日~3月14日)荆门市PM10、PM_(2.5)、NO_(2)和CO浓度均有所下降,其中NO_(2)下降幅度最大。疫情防控期间,道路交通功能区受机动车禁行等交通管制影响,NO2浓度改善最明显;城中村功能区受居家隔离生活源排放强度增加影响,空气质量相对最差;工业园功能区受工业企业大幅减排影响,空气质量改善效果最明显;TVOC整体污染水平降低,但一直呈现“南高北低”的分布特征,南部工业园区TVOC浓度超出其他区域均值5~7倍。2020年疫情防控期间气象条件和减排措施的综合作用使荆门市PM_(2.5)浓度较2019年同期模拟浓度平均下降20.8%,O3浓度上升2.3%;外来源对荆门市PM_(2.5)浓度的平均贡献率为53.2%,日均贡献率最高可达69.0%。

In this study,the changes of air quality and emissions from pollution sources during the period of COVID-19 prevention and control in Jingmen city were studied based on the data on meteorology,air pollutants and emissions from pollution sources;and the WRF-Chem model was used to evaluate the impacts of changes in meteorological conditions,control measures for emission reduction and external transmission on air quality.The results showed that the concentrations of PM_(10),PM_(2.5),NO2 and CO decreased during the period of epidemic prevention and control(January 24-March 14)compared with those before the epidemic(January 1-January 23),and the concentration of NO2 decreased the most.During the period of epidemic prevention and control,NO2 concentration showed the most obvious improvement rate due to the influence of traffic control such as a ban on motor vehicles in the road traffic functional areas;comparatively speaking,the air quality was the worst in the urban village functional areas affected by the increased emission intensity of isolated living sources;and the air quality was improved most obviously in the industrial park functional areas affected by the substantial emission reduction by industrial enterprises;the overall pollution level of TVOC decreased,but the distribution feature was always"high in the south and low in the north",and the TVOC concentration in the southern industrial park was 5-7 times higher than the average of other areas.Due to the combined effects of meteorological conditions and emission reduction measures during the period of epidemic prevention and control,PM_(2.5)concentration in Jingmen City decreased by 20.8%on average compared with the simulated concentration in the same period of 2019,while O3 concentration increased by 2.3%;the average contribution of external sources to PM_(2.5)concentration in Jingmen City was 53.2%,and the average daily contribution was up to 69.0%.