Distribution, contamination and source discrimination of heavy metals in sediments from dam reservoir at Changsha city along the Xiangjiang River, China

Many statistics methods are used to explore heavy metals distribution, contamination, and human health risks of the Xiangjiang dam sediment. Results showed that dam sediments (DS) and pre-dam fluvial sediments(FS) had similar major and some trace element compositions. Meanwhile, the distribution differences of trace metals Ni, Mn, Zn, Cd, Cu and Pb was characterized; for which Ni had distinctly higher (up to 7699.5 mg/kg), and others had lower concentrations in the DS than FS. Heavy metals contamination in DS arrived at high degree for Ni (average I _Geo of 10.2) and Cd (average I _Geo of 3.2), and low to moderate for Mn, Zn, Cu, and Pb (1.52 < I _Geo < 3.3). The degree of heavy metal contamination decreased in the DS relative to the FS.For adults and children, Metals Ni and Cd may have non carcinogenic risk in some dam sediment (HI > 1), and the health risk for child is higher than adult. The non carcinogenic risk of Ni for adult (HI = 3.2389) and child (HI = 4.9751) are mainly in YP9. The non carcinogenic risk of Cd to adult (HI = 1.2579) and child (HI = 2.4587) is mainly located in SC1. Source discrimination study showed that metals Mn, Zn, Cd, Cu and Pb in the DS were from mining activities, while Ni was from the waste discharges like agricultural, catering within the reservoir. Protection for metals (especially Ni, Cd) contamination in the dam reservoir should pay a great attention to the anthropogenic activities both in upper river areas and within the dam reservoir.