Chen Weiwei, Duanmu Lingjian, Qin Yang, Yang Hongwu, Fu Jing, Lu Chengwei, Feng Wei, Guo Li
Key Laboratory of Wetland Ecology and Environment, Northeast Institute of Geography and Agroecology, Chinese Academy of Sciences, Changchun, 130102 China.
College of Biological and Agricultural Engineering, Jilin University, Changchun, 130022 China.
Chin Geogr Sci. 2022;32(5):824-833. doi: 10.1007/s11769-022-1303-3. Epub 2022 Sep 6.
Depending on various government policies, COVID-19 (Corona Virus Disease-19) lockdowns have had diverse impacts on global aerosol concentrations. In 2022, Changchun, a provincial capital city in Northeast China, suffered a severe COVID-19 outbreak and implemented a very strict lockdown that lasted for nearly two months. Using ground-based polarization Light Detection and Ranging (LiDAR), we detected real-time aerosol profile parameters (EC, extinction coefficient; DR, depolarization ratio; AOD, aerosol optical depth), as well as air-quality and meteorological indexes from 1 March to 30 April in 2021 and 2022 to quantify the effects of lockdown on aerosol concentrations. The period in 2022 was divided into three stages: pre-lockdown (1-10 March), strict lockdown (11 March to 10 April), and partial lockdown (11-30 April). The results showed that, during the strict lockdown period, compared with the pre-lockdown period, there were substantial reductions in aerosol parameters (EC and AOD), and this was consistent with the concentrations of the atmospheric pollutants PM (particulate matter with an aerodynamic diameter ≤ 2.5 µm) and PM (particulate matter with an aerodynamic diameter ≤ 10 µm), and the O concentration increased by 8.3%. During the strict lockdown, the values of EC within 0-1 km and AOD decreased by 16.0% and 11.2%, respectively, as compared to the corresponding period in 2021. Lockdown reduced the conventional and organized emissions of air pollutants, and it clearly delayed the time of seasonal emissions from agricultural burning; however, it did not decrease the number of farmland fire points. Considering meteorological factors and eliminating the influence of wind-blown dust events, the results showed that reductions from conventional organized emission sources during the strict lockdown contributed to a 30% air-quality improvement and a 22% reduction in near-surface extinction (0-2 km). Aerosols produced by urban epidemic prevention and disinfection can also be identified using the EC. Regarding seasonal sources of agricultural straw burning, the concentrated burning induced by the epidemic led to the occurrence of heavy pollution from increased amounts of atmospheric aerosols, with a contribution rate of 62%. These results indicate that there is great potential to further improve air quality in the local area, and suggest that the comprehensive use of straw accompanied by reasonable planned burning is the best way to achieve this.
根据不同的政府政策，新冠疫情封锁措施对全球气溶胶浓度产生了多样的影响。2022年，中国东北的省会城市长春遭受了严重的新冠疫情爆发，并实施了为期近两个月的非常严格的封锁措施。利用地基偏振光探测与测距（LiDAR）技术，我们检测了2021年和2022年3月1日至4月30日期间的实时气溶胶剖面参数（EC，消光系数；DR，退偏比；AOD，气溶胶光学厚度）以及空气质量和气象指标，以量化封锁对气溶胶浓度的影响。2022年的时期分为三个阶段：封锁前（3月1日至10日）、严格封锁（3月11日至4月10日）和部分封锁（4月11日至30日）。结果表明，在严格封锁期间，与封锁前相比，气溶胶参数（EC和AOD）大幅下降，这与大气污染物PM（空气动力学直径≤2.5μm的颗粒物）和PM（空气动力学直径≤10μm的颗粒物）的浓度一致，并且O浓度增加了8.3%。在严格封锁期间，与2021年同期相比，0-1公里范围内的EC值和AOD分别下降了16.0%和11.2%。封锁减少了空气污染物的常规和有组织排放，并且明显推迟了农业焚烧季节性排放的时间；然而，它并没有减少农田火点的数量。考虑气象因素并消除沙尘事件的影响，结果表明，严格封锁期间常规有组织排放源的减少促成了空气质量改善30%以及近地表消光（0-2公里）降低22%。城市防疫和消毒产生的气溶胶也可以通过EC识别。关于农业秸秆焚烧的季节性来源，疫情引发的集中焚烧导致大气气溶胶数量增加，从而出现重度污染，贡献率为62%。这些结果表明，当地空气质量仍有很大的提升潜力，并表明秸秆综合利用并辅之以合理的计划焚烧是实现这一目标的最佳途径。
