天津市PM2.5中水溶性无机离子污染特征及来源分析

摘要

PM2.5 samples were collected at the Atmospheric Boundary-layer Observation Station of Tianjin using middle-flow impact samplers.The sampling periods were January,April,July and October of 2008.Eight inorganic components (Na+、NH4+ 、K+ 、Mg2+ 、Ca2+ 、Cl-、NO3-and SO42-) of PM2.5 were determined to study the chemical characters of PM.SO42-,NO3-,NH4+ and Cl-were dominated ionic components in PM2.5 and accounted for 87.3％ of the total mass concentration.Pollution character of major water-soluble inorganic ions was indicated.The average ratio of NH4+/(2 * SO42-) was about 1.0,which indicated that most of SO42-in PM2.5 were likely to exist as (NH4)2S04.The mean mass ratio of NO3-/SO42-was 0.65,which indicated that the complex pollution of coal combustion and vehicle exhaust were existent in Tianjin.Sources of major water-soluble inorganic ions were determined by the method of major component analysis of eight water-soluble inorganic ions in PM2.5.%2008年1、4、7月和10月在天津大气层边界站,利用中流量采样器对大气中的细粒子进行了滤膜样品采集,应用离子色谱检测技术分析了8种水溶性无机离子(Na+、NH4+、K+、Mg2、Ca2+、SO42-、NO3-和Cl-)的含量.结果表明,天津市大气PM2.5中总水溶性无机离子平均浓度为47.3μg/m3,其中,SO42-、NO3-、NH4+和Cl-是最主要的水溶性无机离子,占总离子质量分数共计87.3％,表明了天津市细粒子中的主要水溶性无机离子的特征.[NH4+]/2[SO42-]平均比值接近1.0,显示硫酸氨是细粒子中硫酸盐的主要存在形式.NO3-/SO42-浓度比的平均值为0.65,反映了燃煤污染与机动车尾气污染并存的复合型大气污染特征.并通过对PM2.5中8个水溶性离子成分的主成分分析进一步揭示了其来源.