Characteristics And Chemical Speciation Of Heavy Metals In PM_2.5 And PM_2.5 In The Southern Suburbs Of Xi’an

All data based on real-time monitoring and experimental test data from December1,2010to November30,2011in Xi’an University of Architecture and Technology ofsouthern suburbs of Xi’an. We studied the Characteristics and Chemical Speciation ofHeavy Metals in PM_2.5and PM_2.5.Followed is the main conclusion that there has got.In the southern suburbs of Xi’an, characteristics of the average concentration ofheavy metal by obvious seasonal variation: the highest level in winter, the lowest insummer for Fe,Pb,As,Cd in PM_2.5and PM₁₀; the highest level in autumn for Cr,and thelowest in autumn for Hg in PM_2.5and PM₁₀. Most of heavy metals exist in PM_2.5.The result of EF show: As, Pb, Hg, Cd are mainly from natural sources, Cr isfrom natural sources and human activities. As mainly came from coal activities, Cdhad quite high enrichment degree in winter, fine particulate has high enrichmentdegree.The Cd is distributed in soluble and exchangeable fraction, carbonate, oxide andreducible fraction （above66.2%and69.8%）; About35%of Hg is distributed incarbonate, oxide and reducible fraction. more than77.1%of Cr and Fe are foundbound to organic matter, oxidisable and sulphidic fraction, and residual fraction,and theAs is more carbonate, oxide and reducible fraction than others.Bioavailable coefficients revealed that Cd is aioavailable element and more harmfor people, Fe,Cr are non-available elements, As,Pb and Hg are harm for environmentand people. The releasing rates of heavy metals from PM_2.5are increased as the pH ofthe acid rain decreased.the releasing rates and time is different with pH in everyelement.