Concentration and pollution assessment of heavy metals within surface sediments of the Raohe Basin, China.

Surface sediment samples were collected from four areas (the Jingdezhen Industrialized Area (JDZ), Upstream (UP), the Dexing Mining Area (DX), and Downstream (DM)) to investigate the concentration and chemical composition of heavy metals. The sediments were analysed for Cu, Zn, Pb, Cd, Cr, As, and Ni using a sequential extraction scheme according to the improved BCR (European Community Bureau of Reference) method. The obtained results show that the maximum values of Cu (793.52 μg·g), Zn (72.09 μg·g), Pb (222.19 μg·g), and Cd (1.60 μg·g) were collected from the DX sampling area, while the JDZ area had the highest concentrations of Cr (97.09 μg·g), As (318.05 μg·g), and Ni (66.35 μg·g). The majority of metal values far exceeded their corresponding background values. The risk analysis of geo-accumulation index (I) indicated that the heavy metals Cu and As were the main pollution factors and each element of the pollution degree followed the order of: Cu > As > Pb > Cd > Cr > Zn. Metal partitioning characteristics were also considered and more than 80% of metals show potential bioavailability and toxic effects.