[Physicochemistry and bioreactivity characterization of fine particles (PM(2.5)) in Shanghai air]

PM(2.5) was collected at Shanghai urban and suburban sites during spring and autumn. PIXE (Proton Induced X-ray Emission) was used to investigate mass concentration of 15 elements (S, K, Ca, Ti, Cr, Mn, Fe, Ni, Cu, Zn, As, Se, Br, Sr, Pb) in Shanghai PM(2.5). The total mass concentration of the 15 chemical elements was higher in spring (5 038.6 ng x m(-3)) than in summer (3 810.6 ng x m(-3)). In spring, mass concentrations of these elements in urban and suburban samples were in the same level. In summer, concentration of the elements in urban samples were lower than in suburban samples, however, the elements which were originated from anthropogenic resources were in higher level in urban samples. The results of FESEM showed that Shanghai PM(2.5) was consisted of soot aggregates, coal fly ashes, minerals, bio-particles and unidentified particles. The result of Plasmid DNA assay demonstrated bioreactivity of urban PM(2.5) was more reactive than that of suburban PM(2.5), this phenomenon probably was explained by higher mass level of heavy metals and more proportion of soot aggregates in urban PM(2.5).