CONCENTRATION AND SIZE DISTRIBUTION PROPERTIES OF ATMOSPHERIC AEROSOL PARTICLES DURING SUMMER AND AUTUMN IN YINCHUAN, CHINA

Using information acquired by an aerodynamic particle sizer deployed in Yinchuan (China), this study investigated the physical and chemical properties of aerosols and provided basic data for the analysis of their climatic and environmental effects. The evolutions of the concentration and size distribution of atmospheric aerosol particles were measured during summer and early autumn, and the mass concentrations, mass size distributions, and PM2.5 concentrations were studied using cluster analysis. In addition, meteorological data were obtained to determine the relationship between size distribution and weather, The following conclusions were obtained. (1) The size distribution and concentration of aerosols changed considerably and their variations wee related closely to weather conditions. (2) The averaged number size distribution was unimodal with a peak in the accumulation mode. The averaged area size distribution was bimodal with peaks in both the accumulation and the coarse modes. The averaged mass size distribution was trimodal with peaks in the accumulation and coarse modes. The maximum peaks of the three types of size distribution were all located in the accumulation mode. (3) In Yinchuan, the mass size distribution could be divided into six categories during summer and early autumn. Cluster A was found to occur during periods following rain, clusters B and C occurred mainly on continuously sunny days, and clusters D-F appeared on cloudy and windless or continuously overcast days. The research results improve the understanding of the distribution characteristics, evolution, and factors affecting the size distributions of atmospheric aerosol particles in the Yinchuan area.