Han Li-Hui, Zhang Hai-Liang, Xiang Xin, Zhang Peng, Cheng Shui-Yuan, Wei Wei
Key Laboratory of Beijing on Regional Air Pollution Control, College of Environmental and Energy Engineering, Beijing University of Technology, Beijing 100124, China.
Huan Jing Ke Xue. 2017 Jun 8;38(6):2211-2217. doi: 10.13227/j.hjkx.201610133.
Atmospheric precipitation samples were collected in a representative region of Beijing in summer of 2015 to investigate the physical and chemical characteristics of atmospheric precipitation, the changes and causes of major chemical components in rainwater during the course of typical precipitation, and the impacts of typical precipitation processes on atmospheric pollutants. The volume-weighted mean pH value of rainwater in the representative region of Beijing in summer was 6.21 with the range of 5.15-7.34,and acid rain seldom occurred. The pollution elements Cd, Ca and Mn were moderately enriched, and Cu, Zn, Pb and S were seriously enriched in rainwater, of which Ca and S were main pollution elements, which accounted for 45.43% and 43.93% of the total pollution elements respectively, and Zn, Mn, Cu, Pb and Cd were main heavy metal pollution elements, which accounted for 1.32% of the total pollution elements. Different rates of precipitations could have different impacts on atmospheric pollutants. PM could be scavenged by raindrop, and SO, NO and O could be scavenged greatly by raindrop during the precipitation episode at a relatively high rainfall rate, containing four significant stages, such as clear-out of atmospheric pollutants, accumulation, both accumulation and clear-out, and another clear-out of airborne pollutants. Atmospheric pollutants such as PM, SO, NO and O could mainly be scavenged by in-cloud scavenging processes during the precipitation episode at a relatively low rainfall rate, including four important stages, such as clear-out, both clear-out and accumulation, accumulation, and another clear-out of atmospheric pollutants. The effect of rainfall at a relatively high rate on atmospheric pollutants was bigger than that of rainfall at a relatively low rate.
2015年夏季，在北京的一个代表性区域采集了大气降水样本，以调查大气降水的物理和化学特征、典型降水过程中雨水中主要化学成分的变化及原因，以及典型降水过程对大气污染物的影响。北京夏季代表性区域雨水平均体积加权pH值为6.21，范围在5.15 - 7.34之间，酸雨很少发生。雨水中污染元素镉、钙和锰呈中度富集，铜、锌、铅和硫严重富集，其中钙和硫是主要污染元素，分别占总污染元素的45.43%和43.93%，锌、锰、铜、铅和镉是主要重金属污染元素，占总污染元素的1.32%。不同降水速率对大气污染物的影响不同。在降雨速率相对较高的降水过程中，颗粒物可被雨滴清除，二氧化硫、氮氧化物和臭氧可被雨滴大量清除，该过程包含大气污染物清除、积累、积累与清除并存以及再次清除空气中污染物等四个显著阶段。在降雨速率相对较低的降水过程中，颗粒物、二氧化硫、氮氧化物和臭氧等大气污染物主要通过云内清除过程被清除，包括大气污染物清除、清除与积累并存、积累以及再次清除等四个重要阶段。较高降雨速率的降水对大气污染物的影响大于较低降雨速率的降水。
