[Size distribution and shape characteristics of subaerial airborne particles]

This research sampled airborne particles in the typical air polluted city of Shijiazhuang to measure the particle size and shape by the instrument of the CIS-50 and the scan electronic microscope in the non-heating period and heating period. The results show that the subaerial airborne particle size distribution mode is coarse with the size range of 0.8-120 microm, mostly under 10 microm, and the semi-square & square like particle shape is dominant, the sphere like lesser, the acute-angle and lathy like sparse. There exist particle size and shape difference in the non-heating period and heating period influenced greatly by the ground emission. When in the heating period, the particle size average value increases by 53.2% principally in the size range of 5-8 microm, and 10-30 microm secondly. Meanwhile, the number of particles with semi-sphere & sphere like shape increases obviously. These semi-sphere particles are agglomerate of finer spheres derived from combustion in the SEM images. The relationship between particle size and shape is demonstrated by that the percentage of PM5 and the one of the semi-square & square like particles are positively correlative with the r of 0.9458; the one of the semi-sphere & sphere like particles negatively correlative with the r of -0.972 6 respectively.