| 排放和气象对疫情前后武汉不同类型点位大气污染物的影响 |
| 摘要点击 2884 全文点击 1624 投稿时间：2022-03-29 修订日期：2022-05-27 |
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| 中文关键词 新冠疫情 随机森林(RF) 大气污染物 时空变化 功能区 |
| 英文关键词 COVID-19 random forest(RF) air pollutant spatial-temporal variation functional region |
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| 中文摘要 |
| 采用随机森林算法剥离了排放和气象对6种大气污染物（SO2、NO2、CO、PM10、PM2.5和O3）浓度的贡献，识别了疫情前后武汉市中心城区、郊区、工业区、三环线交通点和城市背景点这5种类型点位的大气污染物浓度变化.结果表明，与管控前相比，管控期间PM2.5/CO、PM10/CO和NO2/CO分别减小了10.8~21.7、9.34~24.7和14.4~22.1倍，表明排放对PM2.5、PM10和NO2贡献减小；O3/CO增加了50.1~61.5倍，表明二次生成增加明显.解除管控后排放对各类污染物的贡献均增加.管控期间，受一些不可间断工序的运行影响，工业区PM2.5降幅最小（20.5%）.与管控期间相比，解除管控后居民生活、交通出行和工业生产等基本恢复，使5种类型站点PM2.5排放贡献量的降低值减小.管控期间O3排放贡献量的升高与NO和颗粒物浓度降低有关，O3升高部分抵消了NO2和PM2.5浓度降低带来的空气质量改善效果.解除管控后郊区和城市背景点气象贡献的ρ（O3）分别升高了16.2 μg ·m-3和16.1 μg ·m-3，与气温升高和相对湿度降低有关.三环线交通点和中心城区交通、工业减排导致的PM2.5浓度降低及O3浓度增加，可为当前开展分区域PM2.5和O3协同精准管控提供参考. |
| 英文摘要 |
| The random forest algorithm was used to separate the mass concentrations of six air pollutants (SO2, NO2, CO, PM10, PM2.5, and O3) contributed by emissions and meteorological conditions. Their variations for five types of sites including Wuhan's central urban, suburb, industrial, the third ring road traffic, and urban background sites were investigated. The results showed that the values of PM2.5/CO, PM10/CO, and NO2/CO during the lockdown period decreased by 10.8-21.7, 9.34-24.7, and 14.4-22.1 times compared with the period before the lockdown, indicating that the contributions of emissions to PM2.5, PM10, and NO2 were reduced. O3/CO increased by 50.1-61.5 times, implying that the secondary formation increased obviously. The contributions of emissions to various types of pollutants all increased after the lockdown. During the lockdown period, affected by the operation of some uninterrupted industrial processes, PM2.5 concentrations in industrial areas dropped the least (20.5%). Compared with the lockdown period, residential activities, transportation, and industrial production were basically restored after the lockdown, resulting in the alleviation of the reduction in PM2.5 emission-related concentrations. The increase in emission-related O3 concentrations could be associated with the decreased NO and PM2.5 concentrations during the lockdown period. The elevated O3 partially offset the improved air quality brought by the reduced NO2and PM2.5 concentrations. After the lockdown, ρ(O3) related with meteorology at the suburban and urban background sites increased by 16.2 μg·m-3 and 16.1 μg·m-3, respectively, which could be attributed to the increased ambient temperature and decreased relative humidity. The decrease in PM2.5 and increase in O3 concentrations caused by reduced traffic and industrial emissions at the third ring road traffic and central urban regions can provide reference for the current coordinated and precise control of PM2.5 and O3 in subregions. |
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