Coarse aerosol particle size and shape characteristics near ground level of Shijiazhuang city, China

摘要

This research sampled subaerial ambient coarse aerosol particles (＞2μm of equivalent area diameter) in the typical air polluted city of Shijiazhuang to measure the particle size distribution and shape characteristics by the analyzer of CIS-50 and the scan electronic microscope of S-570 in the non-heating period and heating period respectively. The results show that the coarse aerosol particle size distribution mode is 2～4μm in the non-heating period and 3-5μm in the heating period, with the size range of 0.8～120μm, mostly under 10μm; and the square or square like particle shape is dominant, the sphere like lesser, the acute-angle and lathy shape sparse. There exist particle size distribution and shape characteristics differences in the non-heating period and heating period influenced greatly by the ground coal combustion emission and windblown dust In the heating period, particle size average increases by 53.2%, principally in the size range of 5～10μm, and 20～50μm secondly. Meanwhile, the particle number of quasi-round & round shape group and those with convex-concave fractal edge increase obviously. These quasi-round particles are agglomerate derived from combustion in the SEM images. The relationship between particle size and shape is demonstrated by that the percentage of PM5 and the particle number of the quasi-square & square shape group are positively correlative with r of 0.9458; quasi-round & round shape group negatively correlative with r of -0.9726 respectively.