Distribution and risk assessment of heavy metals in soils from a typical Pb-Zn mining area

Abstract

This study focuses on soil heavy metal pollution and the potential ecological risks associated with mining activities. For this work we collected 83 topsoil samples and 11 soil profile samples from a typical abandoned Pb-Zn mining area in Hunan Province, China. Concentrations of Cd, Pb, Zn, Cu, and Ni were measured using Inductively Coupled Plasma Mass Spectrometry (ICP-MS), and As was analyzed by atomic fluorescence spectometry (AFS). The mean concentrations of As, Pb, Cd, and Zn in topsoil were 84.85, 802.58, 6.13, and 689.66 mg/kg, respectively much higher than Class III of Environmental Quality Standard for soils in China (GB 15618-1995). The most contaminated areas appeared in the vicinity of the mine, discarded smelter, and tailing pond. Heavy metal contents in soils around the tailing pond increased substantially with soil depth, while first increasing and then decreasing with the increased soil depth around the abandoned smelter. The overall potential ecological risks of soil heavy metals in this abandoned mining area were moderate. However, heavy metals in soils around the tailing pond indicated a severe potential ecological risk, which should give rise to widespread concerns.