Pollution Characteristics And Source Analysis Of PM_2.5 In Typical Dust Polluted City,Yinchuan

Fine participate matter (PM2.5) is the major air pollutant affecting urban air quality currently, also is the primary pollutants of air pollution in many cities.PM2.5 have important influence on visibility, climate and human health. The international community regarded PM2.5 as research objectives and the primary pollutant needed to be strict controlled recent years, and domestic researchers have carried lots of researches on formation mechanism、 composition characteristics、 source apportionment of PM2.5 also. In this paper, according to the pollution situation of PM2.5 in Yinchuan City, Carried out application research to distinguish the pollution characteristics and sources of PM2.5in 2013-2014. Based on thedata obtained, used lots of methods to research PM2.5 pollution characteristics and sources. The main research results are as follows:(1) Yinchuan’s annual PM2.5 mass concentration was 77.1ug/m3, The concentration of spring, summer, autumn and winter is 119.8ug/m3、40.0ug/m3、51.8ug/m3、94.0ug/m3 respectively, Spring and winter are the heavy pollution seasons while summer and autumn standard in good condition, The concentration difference between different urban functional areas is 20.1-80.2 μg/m3.(2) Composition analysis showed that:inorganic elements was the highest content of PM2.5 in Yinchuan, the relative proportion is 36%, followed by the carbon component, accounting for 33%, secondary water soluble ion accounted for minimum; inorganic element ratio up to 42% in spring and shows spring is dust season in Yinchuan, The ratio of secondary inorganic ion increased in summer and autumn, shows secondary sources of PM2.5 was strengthen in this two season, while secondary ion and carbon component concentrations were significantly increased in winter.(3) The same component group analysis showed that OC and EC have good correlation and their sources have great consistency; The SOR and NOR in spring and summer far higher than its in autumn and winter, because the dust have great impact on SO42- and NO3- in spring, while is mainly affected by atmospheric photochemical reaction; no machine elements in summer; Si is the highest content of inorganic elements, the mass concentration of 7.24 μg/ m3, correlation analysis among elements shows that Fe, Al, Ti have same source, The impact of Cu, Zn, Pb caused by soil dust is small.(4) The three kinds component correlation analysis showed that crustal elements, secondary inorganic ions and carbon content have correlation obviously in spring, because PM2.5 is mainly affected by the influence of dust, less affected by anthropogenic sources, composition analysis of dust composition also prove the conclusion; In winter, crustal elements and secondary ion, carbon component correlation is not obvious, but carbon content have significant correlation with secondary ion, it showed that anthropogenic sources increased in winter, and dust source contribution still exist obvious effect. Combine with the analysis of regional airflow and particle concentration, northwest transmission flow enhance the affect of dust particles in the spring and winter.Finally, using the receptor model CMB and PMF analyzed the source of PM2.5 inYinchuan, the results is:dust is the largest source, followed by coal combustion, mobile vehicle exhaust, and secondary particle, the contribution rate is 37%,18%,14%and 13% respectively. Sandy dust contribution rate is 37%, which in line with the results of qualitative analysis of PM2.5 composition, The contribution of building and metallurgical accounted for very small, the PMF analytical results tally with the CMB results.