珠江三角洲夜间降雨对大气颗粒物清除作用的研究

The study on the scavenging effect of nighttime rainfall on atmospheric particulate matter in the Pearl River Delta

因独特的发生时段与气象边界条件,夜间降雨(以下简称夜雨)对大气污染物的迁移转化过程影响较大。利用珠江三角洲56个环境监测站于2014年5月至2019年3月记录的逐时大气颗粒物(PM 2.5、PM 10)浓度数据及同期18个气象监测站记录的逐时降雨观测资料,统计分析夜雨和日间降雨(以下简称日雨)影响下的大气颗粒物浓度变化特征,比较了不同降雨强度、降雨持续时间的夜雨和日雨对大气颗粒物的清除作用,并通过相关分析证明了降雨清除作用的滞后效应。结果表明:降雨通过湿沉降作用可以有效清除大气颗粒物,对PM 10的清除效率高于PM 2.5,其中夜雨对大气颗粒物的清除效率相对日雨更高;降雨强度越大,降雨持续时间越长,夜雨清除效果的优越性越明显;在降雨后6 d内,夜雨和日雨对大气颗粒物仍存在清除作用。

Due to the unique occurrence period and climatic boundary conditions,the nighttime rainfall is different from daytime rainfall,which has a great influence on the migration and transformation process of atmospheric pollutants.This paper used the hourly atmospheric particulate matter(PM 2.5,PM 10)concentration data recorded by the 56 environmental monitoring stations from May 2014 to March 2019 in the Pearl River Delta and the hourly rainfall observation data recorded by 18 meteorological monitoring stations in the same period.The characteristics of atmospheric particulate matter concentration under the influence of nighttime rainfall and daytime rainfall were analyzed.The effects of intensity,duration of nighttime and daytime rainfall on atmospheric particulate matter were compared,and the lag effects of rainfall scavenging were proved by correlation analysis.The results showed that the rainfall could effectively remove atmospheric particulate pollutants through wet deposition,the removal efficiency of PM 10 was higher than that of PM 2.5,and the nighttime rainfall had relatively higher removal efficiency of atmospheric particulate matter.The greater the rainfall intensity,the longer the rainfall duration,the more effective the nighttime rain scavenging ability was.In the range of 6 days after rainfall,nighttime rain and daytime rain still kept the scavenging ability to atmospheric particulate matter.