天津2009年3月气溶胶化学组成及其消光特性研究

2009年3月,采集天津城区PM10和PM2.5样品,分析其中的水溶性无机离子、有机碳(OC)和元素碳(EC),并估算其二次有机碳(SOC)浓度及消光系数.结果表明,天津城区PM10和PM2.5污染严重,水溶性无机离子和含碳物质在PM10中的比例为24.8%和10.0%,在PM2.5中的比例为26.6%和13.9%;SO42-、NO3-和Ca2+是主要的无机离子,霾日天气有利于SO2和NO2向硫酸盐和硝酸盐的二次转化;通过OC/EC最小比值法估算SOC的浓度,表明SOC与OC的比值分别为38%(PM10)和24%(PM2.5),霾日天气有利于SOC生成;二次离子(SO42-,NO3-和NH4+)、粗粒子、OC和EC是大气消光的主要贡献者,其消光贡献比例分别为33.1%, 22.6%,22.0%和15.6% 采用化学组分和相对湿度可以较好的拟合大气消光系数及大气能见度.

Main components and extinction characteristic of aerosol during March 2009 at Tianjin

Main components and contribution to atmospheric extinction coefficient were studied using particulate sample data in spring at Tianjin.The pollution of aerosol was heavy,the water-soluble inorganic ion and carbonaceous were main components,accounted for about 24.8% and 10.0% of the total PM10,26.6% and 13.9% of the total PM2.5,respectively.SO42-,NO3-and Ca2+ were main inorganic ions.The meteorological conditions were good for the transformation of sulfate and nitrate during haze days.The SOC mass concentration were estimated with the Minimum ratio method of OC/EC,the ratio of SOC and OC in PM10 and PM2.5 was 38% and 24%.The second icons(SO42-,NO3-and NH4+),coarse mass,OC and EC were main factors influencing the atmospheric extinction coefficient.The average contributions were 33.1%,22.6%,22.0% and 15.6%.The atmospheric extinction and visibility could be fitted well with components and relative humidity.