Investigation and assessment of heavy metals in surface sediments of Ganjiang River, China.

Surface sediment samples were collected from four sampling areas (Ganzhou nonferrous metal processing zones (GZ), Jian city sewage discharge areas (JA), Non city areas (NC) and Zhangshu middle-city areas (ZS)) to investigate the degree and chemical partitioning of heavy metals. Samples were analyzed for Cu, Zn, Pb, Cd, Cr, As and Ni using sequential extraction scheme. Based on geo-statistics analyses, the results showed maximum values of Cu (131.84 μg g(-1)), Zn (290.68 μg g(-1)), Cd (99.57 μg g(-1)), Cr (53.75 μg g(-1)), As (25.58 μg g(-1)) and Ni (64.75 μg g(11)) were in sediments dated at GZ areas, while ZS areas had the highest concentrations of Pb (128.51 μg g(-1)). Almost all metal values were higher than their corresponding background values in the following order: Ni < Cr < Zn < Pb < As < Cu < Cd. Meanwhile, sediments showed that heavy metals were predominantly occured in Fe-Mn oxide, residual, organic, exchangeable and carbonate fractions respectively. It was found that concentration in carbonate fractions were generally low for most of the studied metals. The geo-accumulation index and sediment quality values were used to determine the potential risk of heavy metal contamination. The results of geo-accumulation index indicated that contamination degree ranged from uncontaminated to extremely contaminated degrees. When metal partitioning characteristics were also considered, over 60% of metals showed potential bioavailability and toxic effects were probable.