Geochemistry and ecological risk of metal(loid)s in overbank sediments near an abandoned lead/zinc mine in Central South China

The metal(loid) contamination in river sediments due to the legacy of abandoned mines has attracted wide attention. A total of 168 samples of water and overbank sediments from Xinqiang River near abandoned Taolin Pb/Zn mine were collected to reveal the migration and ecological risk of metal(loid)s in the river. The results showed that the overbank sediments were polluted by As, Cd, Cu, Pb, and Zn, which were 1.9-16.7 times higher than the background values due to historical mining and processing activities, while Ni and Cr mainly came from earth's crust. The distribution of metal(loid) pollution in the sediment profiles mainly covered in the mining district and the adjacent rural district. Resuspension of sediment particles is more likely to occur at the confluence of the rivers, and the secondary transportation of metal(loid) s was frequently found in the downstream of the confluence. The metals in sediments had different mobility with the water flow from the abandoned Pb/Zn mine to the downstream, following the migration order of Zn > Pb > Cd. Moreover, the potential ecological risk of Cd in the overbank sediments arrived to 503.2, a very high risk level; thus, the Cd contamination in the historical Pb/Zn mining area should be controlled with priority.