Chemical characteristics and Pb isotopic compositions of PM2.5 in Nanchang, China

In mid-September 2013, PM2.5 samples were collected at six sites in Nanchang, Jiangxi Province, China, to quantify nine water-soluble ions (Ca2+, Mg2+, K+, Na+, NH4+, SO42-, Cl-, F-, NO3-), 29 trace elements (Ba, Zn, Pb, Ni, Mo, Cr, Cu, Sr, Sb, Rb, Cd, Bi, Zr, V, Ga, Li, Y, Nb, W, Cs, T1, Sc, Co, U, Hf, In, Re, Be, and Ta), and to characterize Pb isotopic ratios ((207) pb/(206) pb, (208)pb/(206)pb, and (207) pb/(204)pb) for identifying the main source(s) of Pb. The results showed that the average daily PM2.5 concentration (53.16 +/- 24.17) mu g/m(3) was within the secondary level of the Chinese ambient air quality standard. The combined concentrations of SO42-, NH4+, and NO3- to total measured water-soluble ion concentrations in PM2.5 ranged from 79.40% to 95.18%, indicating that anthropogenic sources were significant. Coal combustion and vehicle emissions were both contributors to PM2.5 based on the NO3-/SO42- ratios. Wushu School experienced the lowest concentrations of PM2.5 and most trace elements among the six sampling sites. Enrichment factor results showed that TI, Cr, In, Cu, Zn, Pb, Bi, Ni, Sb, and Cd in PM2.5 were affected by anthropogenic activities. Cluster analysis suggested that Cd, Sb, Pb, Re, Zn, Bi, Cs, T1, Ga, and In were possibly related to coal combustion and vehicle exhaust, while Ni, Nb, Cr, and Mo may have originated from metal smelting. Pb isotopic tracing showed that coal dust, cement dust, road dust and construction dust were the major Pb sources in PM2.5 in Nanchang. Combined, these sources contributed an average of 72.51% of the Pb measured, while vehicle exhaust accounted for 27.49% of Pb based on results from a binary Pb isotope mixed model. (C) 2017 Chinese Society of Particuology and Institute of Process Engineering, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved.