关键词: 大气颗粒物, 沙尘暴, 粒度分析, 矿物分析, 上海

Abstract: By using Laser Particle Size Analyzer and XRD systems, this paper discusses the characteristics of particle size distribution and mineral components of three different types of atmospheric particles collected in the spring of Shanghai. They are the rain-born dust (RBD) as the dust-storm happening in northwest China, the total suspended particles (TSP) and the normal air-born dust (ABD). The particle size data show that over 99.45% of RBD is less than 60 μm (13.57 μm in average) and the <30 μm part takes the majority with a bad sorting degree. The content of coarse silt, fine silt and clay are 49.02%, 21.75% and 27.14% respectively. Such a particle size distribution is much similar to that of Malan loess (in North China) and Xiashu loess (in lower Yangtze River) formed in Late Pleistocene, supporting that the Xiashu loess is of eoline origin. The particle size distribution of RBD can also be compared to TSP, but both much finer than ABD. The X-ray diffraction analysis data show that all the samples can be identified as clay minerals, quartz, potash feldspar, plagioclase, calcite, dolomite, gypsum and amphibole etc. But there are still some differences between each other. The RBD contains relatively more mineral materials, indicating that it derived from the northwest arid and semiarid areas in China. The content of gypsum in TSP reaches up to 14.59%, which can be considered as the secondly polluted particulates formed by the SO2gas in the air meeting together with calcite. The gypsum in TSP, therefore, can be used as an indicator of SO2 pollutant in the atmospheric environment of Shanghai.

Key words: atmospheric particles, dust-storm, particle size analysis, mineral analysis, Shanghai