Pollution Characteristics of Heavy Elements in Nanchang, China Street Dust

Heavy elements are always the major pollutants in urban areas, and their pollution levels and spatial distributions vary among various land use types. In this study, we investigated the concentrations, pollution levels, spatial-temporal distributions, and health risks of 23 elements in street dusts (<63 mu m) along the urban expansion in metropolitan Nanchang. The average concentrations of Cu, Zn, Cd, Pb, Sr, Te, Ba, Sn, Sb, and Bi were distinctly higher than their background values, and most of their enrichment factor (Ef) >2, indicating anthropogenic inputs as the major sources. The majority of elements in dust had high spatial heterogeneities and area characteristics. Seasonality had a minor effect on the variation of element concentrations, but had a significant effect on the modified degree of contamination index (mC(d)) of elements. The quantity of elements with characteristics of anthropogenic fingerprint (Ef>2) was identified as an indicator of urban expansion due to it being consistent with the distributions of population density and traffic flow. The enrichment of Cd, Sr, and Sb contributed 36.38-46.96% to the mC(d). The mC(d) values decreased significantly along urban expansion, which happened only in summer. Most elements in street dusts had multiple sources and were highly related to the traffic input due to their close correlation with the recognized anthropogenic-related elements such as Cd and Pb. The HI values for all the elements were below the safe level, suggesting a non-carcinogenic risk to inhabitants. The exposure for As and Cd in dusts caused significant carcinogenic risk to inhabitants. High concentration, Ef value, and HI value of Sb possibly caused adverse health risks and requires more attention.