二次雾霾气溶胶颗粒的扫描电子显微学分析

北京地区的雾霾是全国,也是世界都在关注的问题.作者利用高分辨环境扫描电镜结合能谱仪,分析了雾霾气溶胶颗粒中的硫酸盐和硝酸盐等典型二次反应颗粒的形貌特征、化学成分、可能的物相及它们的混合态.结果表明:二次颗粒的尺寸为数纳米至数微米.它们呈多种形态,包括梭形、条状、球形、柱状、针状、片层状等.几种二次颗粒之间,以及二次颗粒与天然矿物尘及其它人为来源的飞灰和金属基颗粒等经常形成颗粒间粘附的混合颗粒团聚体.

Scanning electron microscopy analysis of secondary aerosol particles

The haze pollution of Beijing has attracted urgent domestic and overseas concerns. The morphology and chemical composition of aerosol particles produced by secondary reactions, such as sulfates and nitrates, as well as their possible phases and mixing state have been analyzed by high resolution environmental scanning electron microscopy combined with X-ray energy dispersive spectroscopy. The results show that the size of the typical secondary particles covers the range from tens of nanometers to several microns. They exhibit variations in morphology, including spindle, strip, sphere, column, needle, lamellar, and so on. The secondary particles are often mixed with natural mineral dusts and other anthropogenic particles, like fly ash and metal-based particles, as well as other secondary particles.