北京、郑州和深圳三城市空气中气溶胶单颗粒特征的扫描电镜分析

分别采集北京、深圳和郑州3个城市气溶胶样品,使用场发射扫锚电镜-能谱仪观察气溶胶单颗粒的显微形貌和元素组成,并利用图像分析系统对PM2.5的粒径进行了分析。结果表明,城市气溶胶单颗粒类型以矿物颗粒、烟尘和球形颗粒(飞灰和二次粒子)为主。对比3个城市气溶胶中不同颗粒类型数量百分比发现,矿物颗粒数量最多的城市是北京,飞灰和烟尘数量最多的城市是郑州,而规则矿物颗粒数量最多的城市是深圳。3个城市气溶胶单颗粒的数量-粒径分布均呈单峰分布。深圳气溶胶中颗粒物的粒径相对较小,其次为郑州、北京。3个城市气溶胶中颗粒物来源不同程度上都受到交通污染源影响,而燃煤源对北京和郑州气溶胶中颗粒物来源影响仍然不容忽视。

Scanning electron microscopic analysis of individual aerosol particle characteristics in three cities of Beijing, Zhengzhou and Shenzhen

In this study, aerosol samples were collected in different cities, and morphologies and elemental compositions of individual particles were determined by Field Emission Scanning Electron Microscopy coupled with Energy Dispersive X-ray Spectrometer(FESEM-EDX). Size distribution of individual particles in FESEM images were further analyzed by an image analysis system. The result shows that mineral, soot, and spherical particles(fly ash and secondary particles) were dominant particles. The quantity proportionof mineral particles of Beijing aerosol was the highest, the amount of fly ash and soot of Zhengzhou aerosol was the highest, and the quantity proportionof regular mineral particles of Shenzhen aerosol was the highest in three cities. Number-size distribution of individual aerosol particles was unimodal in three cities. Particle size of Shenzhen aerosol was relatively small, followed by Zhengzhou, Beijing. Sources of individual aerosol particles of three cities were partly influenced by traffic pollution source, but the effect of coal burning on Beijing and Zhengzhou could not be ignored.