降水对重庆市大气污染物浓度的影响分析

Influence Analysis of the Precipitation on Atmospheric Pollutant Concentration in Chongqing

利用20132015年逐日沙坪坝气象站气象及临近的环境监测数据,探讨降水对重庆市大气污染物浓度的影响,结果表明:PM2.5、PM10、SO2浓度随降水量增加逐渐降低,降低趋势线较为明显,降低幅度为SO2的>PM10的>PM2.5的;NO2和CO随降水量增加减少趋势不明显;O3浓度随降水量的增加而逐渐增加。各类大气污染物在不同量级降水量时变化特征有所不同。在降水量小于1mm时,弱降水的气象条件更有利于污染物的积累,不利于污染的稀释扩散和沉降,空气质量恶化;大于1mm后,降水对各种大气污染物均有明显的清除作用,清除能力随着降水量级的增加而增大,在降水量大于10mm后湿清除能力明显提升,降水量大于20mm时湿清除能力最强,粗细颗粒与雨滴碰并效应增加,降水对PM10和PM2.5的湿清除率分别达30%和25%。连续降水时,各季节降水对各类大气污染物的湿清除能力不尽相同:冬季降水对PM2.5湿清除作用最为明显,对其余污染物清除作用从大到小依次为PM10、SO2、NO2、CO,而O3在冬季降水使O3浓度增加非常明显,通常冬季臭氧浓度相对较低,降水一定程度上使冬季空气质量变好,太阳辐射增加,二次污染物光合作用增强,臭氧浓度也一定程度上增加。

Based on the meteorological and environmental monitoring data from 2013 to 2015, the influence of precipitation on concentration of air pollutants in Chongqing was investigated. The results showed that the concentration of PM 2.5 , PM 10 and SO2 decreased gradually with the increase of precipitation, and the decreasing trend line was relatively obvious, the decreased magnitude was SO2 >PM10> PM2.5 , while the decreasing trend of NO2 and CO with the increase of precipitation was not obvious. The concentration of O 3 gradually increased with the increase of precipitation. The variation characteristics of all kinds of air pollutants are different in different quantity of precipitation. When the precipitation is less than 1mm, the weather conditions of the weak precipitation are more conducive to the accumulation of pollutants, which is detrimental to the dilution and diffusion and settlement of the pollution,and the air quality gets worse. When the precipitation is more than 1 mm, the precipitation has a clear clearance effect on all kinds of air pollutants, the scavenging ability increases with the increase precipitation quantity. When the precipitation is more than 10 mm, the wet clearance ability is obviously enhanced, which is strongest when the precipitation is greater than 20 mm, the coalescence effect between particles and the raindrops increase, and the wet clearance rate of precipitation to PM 10 and PM 2.5 is 30% and 25% respectively. In the continuous precipitation process, the wet clearance of various kinds of atmospheric pollutants varies in each season. In winter,the wet clearance of precipitation to PM 2.5 is the most obviously, the removal effects sequence to the other pollutants is PM 10 , SO2 , NO2 and CO from strong to weak in turn, while the O3 concentration increases obviously.The concentration of O3 in winter is relative. In a certain degree, the quality of the air in winter is better when precipitation occurring, then the solar radiation increases, the photosynthesis of the secondary pollutants increases, and the O3 concentration also increases to a certain extent.