Study On The Characeteristic Of Meltallic Elements In PM_2.5 At Main City Of Kunming

In recent years, some major cities in China are suffering from continued haze. Domestic and international governments or research institutes are highly concerned of PM2.5. Metal elements are major components of PM2.5., analyzing their physical characteristics in PM2.5, content and form, and then studying the origin sources, distribution, migration and transformation is of great significance to better understand and assess hazards of PM2.5 to human health and the protect or control of ambient air quality.This study treats the city of Kunming as the research object, samples PM 2.5 from the urban environment clean air control point, industry-intensive area, and traffic-intensive area. Samples are analzed on mass concentration,34 kinds of metal elements concentration, and valence state concentration of 24 elements. Then using Muller index, enrichment factor, cluster analysis, Pearson product-moment correlation coefficient, and principal component analysis does PM2.5 source appointment and functional area analysis; calculating bio-availability coefficient and comparing the concentration levels does analysis on PM 2.5 metal elements valence state in the traffic intensive area; and drawing on particulate metal elements risk assessment methods recommended by U.S. Environmental Protection Agency dose evaluation of risk associated with Co and other nine mental elements in Kunming City’s PM2.5 samples.Research shows that the order of Kunming city PM2.5 mass concentration is the industrial-intensive area> the traffic intensive area> the clean area; in the control area (Clean) there are higher concentration levels of Mn, Co, Zn, Mo, Ag, Cd, Pb and other man-made sources of element; in the industrial area; V, As, W, Mn, Co, Ni, Cu, Zn, Ag, Cd, Pb and other elements,which are related metallurgical and chemical industrial production, have higher level; in urban traffic-intensive area there are higher sample concentration levels for V, Mn, Co and Ag; in Kunming city, PM2.5 of Sn, Ag, Cd, Pb, Bi, Ca and other elements of background concentration is high, mainly from human activities; urban sources of PM2.5 metal element is characterized by the mixed sources; in the traffic-intensive area Ti, V, Rb, Fe, mainly exists in the form of F4, As in the form of F1 and F3, Y, La, Sm, Cr in the form of F3, F4, Sb, Mn in the form of F1, F4, W in the form of F1, F3, F4, Co, Ni in the form of F2, F3, F4, Cu in the form of F3, Zn in the form of F2, F3, Sr in the form of F1, F2, Ag, Cd in the form of F2, Mn, Ba, T1 in all four forms evenly distributed; Sr, Zn are bioavailable elements, T1, Ba, Cd, Ag, Mn, Rb, As, Sb, W, Ni, Mo, Co, Pb are potential bioavailability of elements; PM2.5 of Cr, Mn, Cu, Pb, As and other elements in the main city of Kunming have an adverse impact on children’s health; risk of causing cancer for Co, Ni, As, Cd and other elements is far less than the recommended level, therefore they are less likely to cause cancer.