深圳市2022年春季新冠疫情管控期间空气质量分析

短期减排是我国城市应对大气污染事件的重要应急管控手段，但短期减排的效益尚未得到完善分析.2022年3月14～20日，广东省深圳市为抑制新冠疫情传播实施了全市管控，为评估短期减排对华南城市春季空气质量的影响提供独特机会.结合深圳市高精度环境空气质量监测与气象观测等多源数据，分析了深圳市管控期间前后的空气质量变化.此次管控前和管控期中均有部分日期天气形势静稳，局地污染水平主要反映本地排放，有利于分析本地减排的影响.观测与WRF-GC区域化学模拟都表明，与珠三角周边城市相比，深圳市管控期间由于市内交通源排放显著减少，深圳市二氧化氮(NO₂)浓度降低(-26±9.5)%,可吸入颗粒物(PM₁₀)浓度降低(-28±6.4)%,细颗粒物(PM_2.5)浓度降低(-20±8.2)%,但臭氧(O₃)浓度无显著变化(-1.0±6.5)%].TROPOMI卫星观测的甲醛和二氧化氮柱浓度数据对比表明，2022年春季珠三角臭氧光化学主要受挥发性有机物(VOCs)浓度控制，对氮氧化物浓度降低不敏感，反而可能因氮氧化物对臭氧滴...

Impacts of COVID-19 Lockdown on Air Quality in Shenzhen in Spring 2022

The short-term reduction of air pollutant emissions is an important emergency control measure for avoiding air pollution exceedances in Chinese cities. However, the impacts of short-term emission reductions on the air qualities in southern Chinese cities in spring has not been fully explored. We analyzed the changes in air quality in Shenzhen, Guangdong before, during, and after a city-wide lockdown associated with COVID-19 control during March 14 to 20, 2022. Stable weather conditions prevailed before and during the lockdown, such that local air pollution was strongly affected by local emissions. In-situ measurements and WRF-GC simulations over the Pearl River Delta (PRD) both showed that, due to reductions in traffic emissions during the lockdown, the concentrations of nitrogen dioxide (NO₂), respirable particulate matter (PM₁₀), and fine particulate matters (PM_2.5) in Shenzhen decreased by (-26±9.5)%, (-28±6.4)%, and (-20±8.2)%, respectively. However, surface ozone (O₃) concentration did not change significantly(-1.0±6.5)%]. TROPOMI satellite observations of formaldehyde and nitrogen dioxide column concentrations indicated that the ozone photochemistry in the PRD in spring 2022 was mainly controlled by the volatile organic compound (VOCs) concentrations and was not sensitive to the reduction in nitrogen oxide (NO_x) concentrations. Reduction in NO_x may even have increased O_3, because the titration of O₃ by NO_x was weakened. Due to the small spatial-temporal extent of emission reductions, the air quality effects caused by this short-term urban-scale lockdown were weaker than the air quality effects across China during the widespread COVID-19 lockdown in 2020. Future air quality management in South China cities should consider the impacts of NO_x emission reduction on ozone and focus on the co-reduction scenarios of NO_x and VOCs.