武汉地区疫情管控期间空气质量变化及改善措施研究

2020年1月23日起，武汉地区施行了严格的交通管控措施，对当地的人为活动产生了重大影响。本文基于地面监测站网和卫星遥感分析了管控期间武汉地区的主要大气成分的变化，并研究了人为排放下降对O₃和细颗粒物（PM2.5）污染的影响。研究发现，由于管控期间施行机动车禁行政策，武汉地区的NO₂浓度与2019年同期相比下降53.2%，挥发性有机物（VOCs）下降了25.1%；与NO₂和VOCs的显著下降不同，O₃日最大8小时滑动平均第90百分位浓度平均值与去年同期相比上升16.5%，尤其是2月温度同比增高超过5°C，紫外辐射增长超过100%，O₃浓度显著高于去年同期，说明应基于O₃前体物NO_x和VOCs 活性种类的非线性定量关系加强协同减排；同时，管控期间PM2.5浓度与去年同期相比下降了35.6%，但是PM2.5浓度低值主要集中在风速较大、扩散较好的2月，其他时段PM2.5浓度下降并不明显；值得注意的是，与2月的显著下降不同，3月硝酸盐的浓度同比变化不大，说明导致NO_x转化为硝酸盐的大气氧化能力并未受到较大削减，武汉地区颗粒物减排应基于颗粒物不同组分的形成机理，加强颗粒物一次排放源和关键前体物控制。

Air Quality Change and Improvement Measures during the COVID-19 Epidemic in Wuhan

From 23 January 2020, strict traffic control measures have been implemented in Wuhan, which has had a significant impact on human activities in Wuhan. This study analyzes the changes of the main atmospheric components in Wuhan during the lockdown based on ground monitoring stations and satellite remote sensing. Moreover, the study shows the effects of anthropogenic emissions on O₃ and PM2.5 pollution. Compared with the observed values in the same period of 2019, the results showed that the banning of motor vehicles reduced NO₂ concentration and VOCs (mainly low-activity alkanes) in Wuhan by 53.2% and 25.1%, respectively. On the other hand, the maximum 8-h moving average 90th percentile of the O₃ concentration increased by 16.5% compared with the same period last year. Particularly in February, when the temperature was comparatively 5 °C higher than usual with an increase in surface UV radiation by 100%, O₃ concentration was much higher. This is suggested that the nonlinear quantitative relationship between the NO₂ and VOC active species in O₃ generation should be used to promote collaborative emission reduction. Meanwhile, PM2.5 reduced by 35.6%, which was mainly concentrated in February under favorable meteorological conditions. The reduction of nitrate in PM2.5 was not as obvious in March compared with that in February, indicating that the main driving effects of the atmospheric oxidation capacity in nitrate formation still exist. Therefore, the control of primary particles and key precursors must be strengthened in the emission reduction of particulate matter in Wuhan.