| Atmospheric particulate matters, a main atmospheric pollutant that currently affect Chinese urban air quality, can bring important effects go global climate, urban visibility and human health. Because PM2.5 can enter human respiratory system, even penetrate through lung cells into the blood circulation, it bring worse harms to human health. Studies of epidemiology showed that polluted levels of PM2.5 were more significantly correlative with human deformity and mortality comparing to PM10. Due to the worse harms of PM2.5, it became the study object and chief pollutant for rigorous control in the world, especially in the developed countries, during recent years. But china does not build any PM2.5 control standard until now. In china, studies of PM2.5 are just underway, and the studies mainly focus no metropolises and seriously polluted cities. So, the research of this paper can roundly and objectively reflect the PM2.5 polluted situations of medium cities represented by Changsha. This study result can provide basics for controlling atmospheric fine particulate matters in Changsha, and it also provide database for China establishing control standard of PM2.5 in the future.This research focuses on the atmospheric particles of different areas and different seasons in Changsha city. Firstly, atmospheric PM2.5 were synchronous sampled in urban and suburban areas during June 2009 to October 2009. Concentrations of PM2.5 in Summer (June to August) and Autumn (September to October) were compared, and so were the concentrations of PM2.5 in urban and suburban area. Secondary,18 inorganic elements of PM2.5 samples were detected by EDXRF, and the elements of PM2.5 in different areas and different seasons were compared. Variational patterns of PM2.5 and its elements concentrations during October of 2009, which included National Day holidays and seriously polluted periods, were analyzed. Finally, based on the elements concentrations, source apportionments of PM2.5 of Changsha in different period were done by using PCA and APCA methods. The main conclusions of this paper were as followed:the average daily PM2.5 concentration of Changsha during sampling period was 92.3μg/m3, which largely exceeded American PM2.5 daily standard (35μg/m3) and European Union PM2.5 yearly standard. The Summer and Autumn daily concentrations were 57μg/m3 and 131μg/m3, respectively. PM2.5 and its major elements (except for As, Zn, Pb, Mn) daily concentration in Summer was lower than Autumn. The difference of average urban from suburban PM2.5 its major elements (except for K, Mn) daily concentrations was tiny, and the change of the average concentrations of elements in urban and suburban were similar with the change of PM2.5 concentrations. Comparing concentrations of S and K showed that increasing PM2.5 concentration during holidays of National Day was mainly due to the plentiful firecrackers and fireworks combustions. Increasing of PM2.5 during seriously polluted periods was due to more combustion sources.Source apportionment showed that six pollution sources of Changsha PM2.5 were soil dust, secondary aerosols, traffic emission, Motor vehicles, coal combustion and waste incineration, and their contributions were 38.2%,21.0%,11.6%,11.1%,10.8% and 7.2%. difference of source contribution between urban and suburban was tiny, and difference of source contribution between Summer and Autumn was on the secondary aerosol, and its contribution were 15.4% and 26.1%, respectively, during Summer and Autumn. During seriously polluted period, PM2.5 of Changsha mainly came from secondary aerosol and biomass burning (contributed 41.9%), which implied that biomass burning was the important reason of Changsha PM2.5 serious pollution.
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