Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters, Key Laboratory for Aerosol-Cloud-Precipitation of China Meteorological Administration, Nanjing University of Information Science &Technology, Nanjing 210044, China; State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China.
Suzhou Environmental Monitoring Center, Suzhou 215000, China.
J Environ Sci (China). 2021 Apr;102:110-122. doi: 10.1016/j.jes.2020.09.019. Epub 2020 Sep 22.
To control the spread of COVID-19, rigorous restrictions have been implemented in China, resulting in a great reduction in pollutant emissions. In this study, we evaluated the air quality in the Yangtze River Delta during the COVID-19 lockdown period using satellite and ground-based data, including particle matter (PM), trace gases, water-soluble ions (WSIs) and black carbon (BC). We found that the impacts of lockdown policy on air quality cannot be accurately assessed using MODIS aerosol optical depth (AOD) data, whereas the tropospheric nitrogen dioxide (NO) vertical column density can well reflect the influences of these restrictions on human activities. Compared to the pre-COVID period, the PM, PM, NO, carbon monoxide (CO), BC and WSIs during the lockdown in Suzhou were observed to decrease by 37.2%, 38.3%, 64.5%, 26.1%, 53.3% and 58.6%, respectively, while the sulfur dioxide (SO) and ozone (O) increased by 1.5% and 104.7%. The WSIs ranked in the order of NO > NH > SO > Cl > Ca > K > Mg > Na during the lockdown period. By comparisons with the ion concentrations during the pre-COVID period, we found that the ions NO, NH, SO, Cl, Ca, K and Na decreased by 66.3%, 48.8%, 52.9%, 56.9%, 57.9% and 76.3%, respectively, during the lockdown, in contrast to Mg, which increased by 30.2%. The lockdown policy was found to have great impacts on the diurnal variations of Cl, SO, Na and Ca.
为控制 COVID-19 的传播，中国实施了严格的限制措施，导致污染物排放大量减少。本研究利用卫星和地面数据评估了 COVID-19 封锁期间长三角地区的空气质量，包括颗粒物（PM）、痕量气体、水溶性离子（WSI）和黑碳（BC）。我们发现，利用 MODIS 气溶胶光学深度（AOD）数据无法准确评估封锁政策对空气质量的影响，而对流层二氧化氮（NO）垂直柱密度可以很好地反映这些限制对人类活动的影响。与 COVID-19 前相比，苏州封锁期间的 PM、PM、NO、一氧化碳（CO）、BC 和 WSI 分别下降了 37.2%、38.3%、64.5%、26.1%、53.3%和 58.6%，而二氧化硫（SO）和臭氧（O）分别增加了 1.5%和 104.7%。封锁期间，WSI 的顺序为 NO > NH > SO > Cl > Ca > K > Mg > Na。与 COVID-19 前期间的离子浓度相比，我们发现封锁期间 NO、NH、SO、Cl、Ca、K 和 Na 离子分别减少了 66.3%、48.8%、52.9%、56.9%、57.9%和 76.3%，而 Mg 则增加了 30.2%。封锁政策对 Cl、SO、Na 和 Ca 的日变化有很大影响。
