成都地区近3 a空气污染物变化特征及降水对其影响

Variation characteristics of air pollutant concentration and their effects on precipitation in Chengdu area in the recent three years

利用成都市2014-2016年逐时空气污染物质量浓度资料和同期逐时降水资料,分析了成都市空气污染物质量浓度变化特征及降水对其影响.结果表明,成都地区2014-2016年大气颗粒物(PM10和PM2.5)质量浓度逐年减少,气态污染物(SO2、NO2和CO)质量浓度呈波动式降低;5种污染物质量浓度有明显的年内变化,重污染期均出现在冬季,1月污染物质量浓度最高,PM10变化幅度最大,最高达192.9μg/m^3;5种污染物质量浓度均存在明显日变化特征,最大值出现时段为09:00-11:00,其中PM2.5、PM10、NO2和CO质量浓度日变化为双峰型,SO2为单峰型.降水对污染物的清除效率总体上随降水量的增加而增大:暴雨>中雨>大雨>小雨,对中雨清除率高于大雨清除率的原因进行了初步分析.连续性降水对污染物的清除率极大值出现在第2天,之后清除效率逐渐降低;单位时间降水清除效率中,阵性降水明显大于连续性降水.

Using the hourly air pollutant concentration data on Chengdu city from 2014 to 2016 and the hourly precipitation data of the same period,the variation characteristics of air pollutant mass concentration and their effects on the precipitation in Chengdu were analyzed.The results showed that the mass concentrations of PM10 and PM2.5in Chengdu decreased from 2014 to 2016,and the concentrations of gaseous pollutants(SO2,NO2 and CO)decreased in a fluctuating manner.The quality concentration of five pollutants also changed significantly in the years,with the heavy pollution period appearing in winter,the highest concentration of pollution in January,the maximum change range of PM10 and the highest quality concentration reaching 192.9μg/m^3.There were obvious diurnal variations in the concentrations of five pollutants,with the maximum concentration occurring at 09:00-11:00 am.The diurnal variation of PM2.5,PM10,NO2 and CO concentrations was bimodal,while that of SO2 was unimodal.The total removal efficiency of precipitation was increased with the increase of precipitation,the order being rainstorm>moderate rain>heavy rain>light rain,as the removal rate of moderate rain was higher than that of heavy rain.The study also found that the maximum removal rate of pollutants in continuous precipitation occurred on the 2nd day,and then the removal efficiency decreased gradually.However,in terms of precipitation efficiency per unit time,a spurt of precipitation was obviously greater than the continuous precipitation.