Distribution and source identification of heavy metals in the sediments of a river flowing an urbanization gradient, Eastern China

Heavy metal contamination is of great concern in rapidly urbanizing areas. A basin-basis study on the impacts of urbanization on the heavy metal contamination in surface sediments from the Qinhuai River, Eastern China, was conducted, focusing on the spatial variation and source appointments. All of the sampling sites can be divided into three groups based on the hierarchical cluster analysis (HCA) results, which correspond well to the pollution levels of the studied heavy metals in the sediments of the rural, suburban, and urban sections of the Qinhuai River. The relationship between the heavy metal and the Al/Si ratio of sediments varied distinctly with the metal species and urbanization degree of the river sections. Correlation analysis and HCA highlighted that zinc appeared to be a fairly efficient geochemical signature of urban-related heavy metal contamination. The contributions derived from urban activities ranged from 35.9% for Ni to 96.1% for Cu, as estimated by a multilinear regression of the absolute principal component score method (MLR-ACPS). Agricultural activities had a clear impact on As, Pb, and Cu contamination of the sediment. Lithologic sources contributed a significant portion of Ni, Cr, and As to the sediment.