Online data acquisitions of 5 representative atmosphere monitoring sites in Guilin were carried out for analyzing chemical composition and its distribution of PM2. 5 by single particle aerosol mass spectrometry. The results showed that more than 80% of the PM2. 5 were in small size range from 0. 2 μm to 1. 0 μm, and less than 20% were in large size range from 1. 0 μm to 2. 5 μm. Chemical ion composition of PM2. 5 contained Na+, K+, NH4+, C2 H3+/Al+, Fe+, HSO4-, NO3-, NO2-, CNO-, CN-, SO3-, O- and carbon ions. PM2. 5 could be clas-sified into 9 sorts: elemental carbon, organic carbon, elemental-organic mixed carbon, manganese-rich, iron-rich, potassium-rich particulates, mineral substance, levoglucosan and other metals, according to ion composi-tion characteristics. Elemental carbon accounted for more than 50% of the total particulates in each monitoring site. Elemental carbon tended to mix with sulfate, ammonium salt and nitrate inside, in which elemental carbon and sulfate mixing were the most, up to 90%.%选取桂林市5个代表性监测点,采用单颗粒气溶胶飞行时间质谱仪在线分析该市夏季大气PM2. 5的化学组成及化学成分分布. 结果表明:5个监测点,>80%的PM2. 5分布在0. 2 μm~1. 0 μm的小粒径范围,<20%的PM2. 5分布在1. 0 μm~2. 5 μm大粒径范围; 大气PM2. 5中离子成分包含Na+、K+、NH4+、C2 H3 + /Al+、Fe+、HSO4-、NO3-、NO2-、CNO-、CN-、SO3-、O-和元素碳离子;PM2. 5中离子按成分特征可分为元素碳、有机碳、元素碳有机碳混合颗粒、富锰颗粒、富铁颗粒、富钾颗粒、矿物质、左旋葡聚糖以及其他金属等9类,各监测点元素碳占比均超过50%; 元素碳与硫酸盐、铵盐、硝酸盐发生内混合的程度极高,其中各监测点元素碳与硫酸盐混合程度最高,均达到90%左右.
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