Jin Qian, Luo Yina, Meng Xiangrui, Feng Miao, Huang Chengmin
Department of Environmental Science and Engineering, Sichuan University, No.24 South Section 1, Yihuan Road, Chengdu, 610065, China.
Chengdu Academy of Environmental Sciences, Chengdu, 610072, China.
Atmos Environ (1994). 2023 Feb 1;294:119479. doi: 10.1016/j.atmosenv.2022.119479. Epub 2022 Nov 15.
As the new coronavirus pandemic enters its third year, its long-term impact on the urban environment cannot be ignored, especially in megacities with more than millions of people. Here, we analyzed the changes in the concentration levels, emission sources, temporal variations and holiday effects of ambient fine particulate matter (PM) and its chemical components in the pre- and post-epidemic eras based on high-resolution, long time-series datasets of PM and its chemical components in Chengdu. In the post-epidemic era, the PM concentration in Chengdu decreased by 7.4%, with the components of PM decreasing to varying degrees. The positive matrix factorization (PMF) results indicated that the emissions from soil dust and industrial production were significantly lower during the COVID-19 lockdown period and post-epidemic era than those in the pre-epidemic era. In contrast, the contribution of secondary aerosols to PM during these two periods increased by 2.7% and 6.6%, respectively. Notably, we found that PM and its components substantially decreased on workdays and holidays in the post-epidemic era due to the reduced traffic volume and outdoor activities. This provides direct evidence that changes in the habitual behavior patterns of urban residents in the post-epidemic era could exert an evident positive impact on the urban environment. However, the higher PM concentration was observed due to the increased consumption of regular (AsS, Xionghuang in Chinese) and "sulfur incense" during the Dragon Boat Festival holiday in the post-epidemic era. Finally, we examined the potential effects of sporadic COVID-19 outbreaks on the PM concentration in Chengdu, and there was no decrease in PM during two local COVID-19 outbreak events due to the strong influence of secondary pollution processes.
随着新冠疫情进入第三年，其对城市环境的长期影响不容忽视，尤其是在人口超过百万的特大城市。在此，我们基于成都高分辨率、长时间序列的细颗粒物（PM）及其化学成分数据集，分析了疫情前后环境细颗粒物及其化学成分的浓度水平、排放源、时间变化和节假日效应。在疫情后时代，成都的PM浓度下降了7.4%，其各成分也有不同程度下降。正矩阵因子分解（PMF）结果表明，在新冠疫情封锁期和疫情后时代，土壤扬尘和工业生产的排放量显著低于疫情前时代。相比之下，这两个时期二次气溶胶对PM的贡献分别增加了2.7%和6.6%。值得注意的是，我们发现疫情后时代工作日和节假日的PM及其成分大幅下降，原因是交通流量和户外活动减少。这提供了直接证据，表明疫情后时代城市居民习惯行为模式的变化可能对城市环境产生明显的积极影响。然而，在疫情后时代的端午节假期，由于常规（中文称雄黄、雄磺）和“硫磺香”消费增加，观测到PM浓度较高。最后，我们研究了新冠疫情零星爆发对成都PM浓度的潜在影响，在两次本地新冠疫情爆发事件期间，由于二次污染过程的强烈影响，PM浓度并未下降。
