| This paper is aim at the atmospheric particulate matter of PM2.5 and PM10 in the southern suburbs of Xi’an University Town, and the particulate matter samples of PM2.5 and PM10 were collected from October 2013 to October 2014. The mass concentrtions of all samples were detailed measured, and the concentrations of water-soluble inorganic ions and metallic elements in the PM2.5 and PM10 were analyzed. The main conclusions are as follows:(1) The annual characteristics of mass concentrations of PM2.5 and PM10 were as below:the annual average concentration of PM2.5 was 114.38 ± 97.87 μg/m3, and the annual average concentration of PM10 was 201.54 ±37.28 μg/m3; 55.43% of the PM2.5/PM10 values were higher than 0.5 and indicating that PM2.5 was an important component in PM10.The seasonal variations of the mass concentrations of PM2.5 and PM10 were both in a decreasing order of winter> autumn> spring> summer; and the PM2.5/PM10 average values of mass comcentration of four seasons were in a decreasing order of autumn> winter> spring> summer. The Day/Night average ratios of PM2.5 and PM10 were 1.00 and 0.96, respectively, and the ranges were 0.58～1.31 and 0.48～ 1.32, respectively; The variations of mass concentration of PM2.5 and PM10 during day and night were different.(2) The average concentrations of SO42-, NO3-, NH4+ and Ca2+ both in PM2.5 and PM10 were the highest four ions, and the average annual percentage of the total ion content of PM2.5 in the mass concentration of PM2.5 was 49.44%, while it was 49.92% in PM10; The results of the annual average values of the PM2.5/PM10 of the ions showing that the values of NH4+, SO42-, Cl-, NO3- and F- were higher than 0.5, while the values of K+, Mg+, Ca2+ and Na+ were lower than 0.5. The seasonal variations of total concentration of inorganic ions in the PM2.5 and PM10 were both in the order of winter> autumn> spring> summer; Meanwhile, the ions all presented a higher concentrations in autumn and winter, and a lower concentrations in spring and summer, except Ca2+ which presented a higher concentrations in spring and summer, and a lower concentrations in autumn and winter.(3) The results of combination modes of SO42-, NO3- and NH4+ both in PM2.5 and PM10 showed that (NH4)2SO4 and NH4NO3 were the main combination modes, in addition, NH4+ tended to combine with SO42- to generate (NH4)2SO4, then the rest of NH4+ combined with NO3- to generate NH4NO3. The sulfur oxidation ratio and the nitrogen oxidation ratio of the PM2.5 and PM10 were 0.29 and 0.14,0.34 and 0.21, respectively, indicating that there were obvious quadratic transformation process in the research period and the sulfur oxidation ratio was higher than nitrogen oxidation ratio; The results of correlation analysis indicating that the main meteorological factors which affecting the sulfur oxidation ratio was temperature, and nitrogen oxidation ratio was affected by temperature, relatively humidity and particulate matter concentration.(4) The concentration ranges of Cr, Cu, Mn, Ti, Zn, Pb and Cd were all large during the whole year, and the annual average concentrations of Zn both in PM2.5 and PM10 were the highest, while Cd both were the lowest; During the sampling time, the Cr and Zn in the PM10 were more likely exist in fine particles, while Cu, Mn, Ti, Pb and Cd were more enrichment in PM2.5-10.The seasonal variations of the seven metals were different, but they all presented the highest concentration level in winter, the lowest concentration level in summer; The PM2.5/PM10 values of the metals of Cr and Zn during four seasons were all higher than 0.5, and the seasonal differences were small. Except the average values of the Day/Night ratio of Zn in both PM2.5 and PM10, Pb in PM2.5 and Cd in PM10 were lower than 1, the values of other metals were all higher than 1; The diurnal variation of Ti was the most obvious among all the metals and the Pb was the least.(5) The results of the enrichment factor analysis showed that, during the whole sampling time, the PM2.5 and PM10 were polluted by Mn and Ti minimal, and most of the samples were non-polluted to moderate polluted by Mn and Ti; The pollution of Cr, Cu and Pb in PM2.5 and PM10 were between significant to high levels; While the PM2.5 and PM10 were polluted by Zn and Cd worst, and most of the samples were severe polluted by Zn and Cd. |
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