Assessment of Heavy Metals and Metalloids Contamination in the Surface Sediments of the Xiangjiang River, Hunan, China

In this study, the Qingshuitang District from the Shifeng Bridge to the Majiahe Bridge was selected as study areas to assess the contamination status and release amount of heavy metals from the surface sediments of the Xiangjiang River, Hunan Province, China. A sum of five surface sediment samples were collected, and the total contents of Cu,Pb,Zn,Cd,Cr,Mn,As and Hg in these samples were measured by the Inductively Coupled Plasma Mass Spectrometry (ICP-MS) and Atom Absorption Spectrophotometer (AAS). Results showed that the average contents of Cd and As in the sediments were higher than the Grade III of the China Environmental Quality Standard for Soils. Moreover, release experiments were carried out to study the effect of flow velocity and pH values on the release of heavy metals from the sediments. The results suggested that increased the flow velocity and decreased the pH of overlying water could promote the release of heavy metals, while the release amount of four heavy metals were too small and the largest release amount of Mn was only 7.50 μg/(g·d). It suggested that the release of heavy metals from the sediments into the overlying water is a slow and long-term process.