| Based on observing data of atmospheric aerosol from July 2006 to November 2007 at the north suburban area of Nanjing, the observing data of PM2.5 and gaseous pollutants SO2,NOx,CO,O3 in Nanjing, the pollution characteristics and influencing factors of aerosol in Nanjing were analyzed. The major contents and conclusions are presented as follows:(1) Characteristics of size distributions of atmospheric fine particles in the north suburban area in Nanjing. The concentrations and size distributions of aerosol particles with sizes ranging from 0.01 to 2.5μm were studied. The results show that the particle number concentration increase evidently in recent years, with ultra fine particles (0.01～0.1μm) contribute the most to the total number concentration. The particle number size spectrum all concentrates in 0.02～0.05μm in spring, summer, autumn and winter. The particle concentration has an obviously diurnal variation: it comes the peak value at morning and evening, and the number concentration reach the peak value at noon when the solar radiation is most intense. The precipitation process has a great effect on scavenging fine particles.(2) Observational studies on aerosol physical and optical properties during autumn in the north suburban area of Nanjing. The particle concentration, size distribution, optical properties and the relation to meteorological factors were analyzed. The results show that aerosol pollution is serious in this region; the deterioration of visibility has close correlation to the fine particles, fine particles increased during hazy periods as compared with non-hazy periods; the scatter coefficient closely correlates to the particle size, concentration and atmospheric humidity. The meteorological conditions play a critical role in formation of hazy weather, that is, weak large-scale weather systems, low wind speed, high humidity and strong inversion are favorable conditions for hazy weather.(3) Study on the aerosol characteristic and analysis of influence factor in Nanjing.The correlation of PM2.5 concentrations and SO2,NOX,CO,O3, and its relation to meteorological factors were analyzed. The results show that the correlation of PM2.5 concentrations and gaseous pollutants is great, followed by the SO2,CO. The air pollution has close correlation to the large-scale weather system in Nanjing, The PM2.5 mass concentration often higher when Nanjing located at high-pressured, two high-pressured convergence area, or controlled by low-pressured control, which was bad for pollutant diffusion.
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