贵阳市PM_(2.5)微观特征的季节变化分析

Seasonal variations of microscopic characteristics of PM_(2.5) in Guiyang City

大气颗粒物的污染特性与其理化性质有密切关系.本文利用高分辨率场发射扫描电镜(FESEM)和图像分析技术(IA)对贵阳市PM2.5进行研究,分析其微观形貌、数量贡献、体积贡献和粒度分布特征.结果表明:贵阳市PM2.5中颗粒物类型以烟尘及其集合体为主,其次是不规则矿物颗粒、规则矿物颗粒、燃煤飞灰和未知颗粒;4个季节PM2.5样品中烟尘及其集合体占多数,较多分布在0.1~0.2μm的粒径范围内,冬季数量比达到88.24%,体积比为60.45%;研究区PM2.5样品中含有较多的规则矿物颗粒,春季数量比、体积比分别为13.49%、33.58%,春、夏、秋季数量集中分布在0.5~0.6μm粒径范围,冬季主要分布在1.0~2.5μm粒径范围.

Pollution characteristics and physiochemical properties of atmospheric particulate matter are closely interrelated. Microscopic properties,number fraction,volume fraction and size distribution of different types of individual particles were investigated in Guiyang City by high resolution Field Emission Scanning Electron Microscopy( FESEM) and Image Analysis( IA). The results showed that soot and soot aggregates were the main components in PM2.5samples in different seasons,followed by irregular mineral particles,secondary mineral particles with regular shape,fly ash and unknown particles. The size of soot and soot aggregates were mainly around 0.1 ~ 0.2 μm in PM2.5samples in winter,and its number and volume percentage was88.24% and 60.45%,respectively. Mineral particles with regular shape was the tertiary component in PM2.5samples in different seasons,with the number and volume percentage of 13.49% and 33.58%,respectively in spring. The size of mineral particles with regular shape was around 1.0 ~ 2.5 μm in winter and 0.5 ~ 0.6 μm in other seasons.