北京市春夏季大气气溶胶的单颗粒分析表征

Analytical Characterization of Single Particle of Atmospheric Aerosols in Spring and Summer Seasons in Beijing

采集了北京市2000年春夏季大气气溶胶样品5个,采用扫描电镜X射线能谱技术分析大气气溶胶单颗粒约2500个。研究结果表明,沙尘期间,矿物尘是最主要的颗粒物种类,非沙尘期间,北京市大气气溶胶中主要检出矿物尘和含硫颗粒物。夏季随着颗粒物污染的加重,含硫颗粒物的数目百分数增加,是北京市大气颗粒物污染的重要特征。重点讨论了Ca-S颗粒、K-S颗粒和Ca-K-S颗粒三类典型含硫颗粒物的化学组成和粒径分布特征。数目可观的Ca-K-S颗粒以及其他硫酸盐颗粒的生成与相对湿度和云量等气象条件相关,这些颗粒物可能是云中过程的产物。减少SO2排放,减少含硫颗粒物,对于控制北京市的大气颗粒物浓度水平具有重要意义。

Using Scanning Electron Microscopy-Energy Dispersive X-ray analytical methods, single particle (analysis) were performed for 2 500 particles from 5 atmospheric aerosol samples collected in spring and summer seasons in 2000 from Beijing, China. It was revealed that mineral dust is the dominant particle class during Asian Dust episode. While in normal days, mineral dust and S-containing particles are the major particle classes. When aerosol pollution was getting worse in summer in Beijing, increasing number percentage of S-containing particles featured the atmospheric aerosol. Chemical composition and size distribution characteristics were described and discussed for Ca-S, K-S, and Ca-K-S particle classes. Formation of Ca-K-S and other S-containing particle classes with high number percentage was closely related to meteorological conditions such as relative humidity and cloud coverage. Those particles are probably products of cloud processing. It is important for aerosol pollution control in Beijing to reduce the SO_(2) emission, therefore, less S-containing particles.