离子色谱法同时测定福州大气PM_(2.5)中无机阴离子和有机酸的研究

Simultaneous Determination of Inorganic Anions and Organic Acids in Atmospheric PM_(2.5) in Fuzhou by Ion Chromatography

本文利用离子色谱法对福州市2015-2016年大气PM_(2.5)样品中4种无机阴离子(F^(-)、Cl^(-)、NO_(3)^(-)、SO_(4)^(2-))和5种水溶性有机物(WSOC)(甲酸、乙酸、乙二酸、丁二酸、戊二酸)进行同步测定,结果表明,无机阴离子曲线相关系数大于0.999,有机酸相关系数大于0.994,检出限范围(0.7-25.7)ng/m^(3),精密度范围(0.3-7.9)%,回收率范围(84.0-116)%,方法性能满足测试要求。SO_(4)^(2-)、NO_(3)^(-)、Cl^(-)为主要的水溶性无机阴离子,3种离子浓度之和占PM2.5质量浓度的32.6%。5种水溶性有机酸WSOC的浓度均值范围为(0.031-0.308)μg/m^(3),总和占PM2.5质量浓度的1.6%,其中乙二酸的含量相对最高。总体而言,PM2.5中水溶性无机离子和有机酸浓度的季节变化表现为春、冬季高,夏、秋季低的特点。NO_(3)^(-)、乙二酸在夏季表现出不同的浓度特征可能与物质的性质和夏季高温强辐射天气有关。乙二酸与SO42-、NH4+、NO3-有较强的线性相关性,初步推断其主要来源为光化学反应而形成的二次污染物。

The pollution levels of 4 kinds of inorganic ions(F^(-),Cl^(-),NO_(3)^(-),SO_(4)^(2-))and 5 kinds of water-soluble organic com⁃pounds(WSOC)(formate,acetate,oxalate,succinate,glutarate)in PM2.5 of FuZhou City in the year 2015-2016 were deter⁃mined synchronously with ion chromatography technique.The correlation coefficient of inorganic anion curve was larger than 0.999,while the organic acid was 0.994,the detection limit was(0.7-25.7)ng/m^(3),the precision range was(0.3-7.9)%,and the recovery range was(84.0-116)%,which indicated that the method meet the test requirements.SO42-,NO3-and Clwere the dominant water-soluble species and the sum of the three ions accounted for 32.6%of the PM2.5 quality.The con⁃centrations of 5 kinds of WSOC were(0.031-0.308)ng/m^(3) occupyed 1.6%of PM_(2.5),among which the content of oxalic acid was the highest.Analysis of seasonal change character of the concentration of each chemical component of PM2.5 indicated that higher concentrations pollution appeared in spring and winter while the lower concentrations pollution in summer and autumn.The different concentration characteristics of NO_(3)^(-)and oxalic acid in summer might be related to the chemical prop⁃erty and high temperature and strong radiation.Analysis of interrelativity of oxalate with other component showed that oxa⁃late had relatively high linear interrelativity with SO_(4)^(2-),NH_(4)^(+)and NO_(3)^(-).It was preliminarily concluded that the main source of dicarboxylic acid in PM2.5 in Fuzhou City was the secondary pollutant formed by photochemical reaction.