Characterizing spatial distribution and sources of heavy metals in the soils from mining-smelting activities in Shuikoushan,Hunan Province,China

The spatial variation of heavy metals in the soils in Shuikoushan mining-smelting area,Hunan Province,China,was investigated using multivariate and geo-statistic analysis.A total of 106 composite soil samples were collected in an area of about 100 km2. Concentrations of total As,Cd,Pb,Zn,Cu and Cr were measured using inductively coupled plasma mass spectrometry(ICP-MS) . Arsenic and Pb were found to have a common source,indicating the same sources and spreading processes,such as aerosols and airborne particulates from smelting chimneys.Airborne sources from smelting chimneys contributed greatly to Cd in the area,which demonstrated the same dispersion pattern as As and Pb.However,two hot spots of Cd around smelters were possibly enlarged by wastewaters,demonstrating another important source of Cd in Shuikouhsan.Geo-statistic interpolated mapping demonstrated that hotspots of Zn were only found proximal to the large smelters,suggesting that Zn primarily came from the chimneys of larger smelters. The major Cu hot-spots appeared closely to the tailing dam,indicating that weathering and leaching of tailings were the major sources of Cu contamination in Shuikoushan.Our findings indicated that airborne volatile particles and aerosols contributed the most to As,Cd,Pb,Zn and Cu contamination,while Cd and Cu may also derive from the discharge of wastewater from smelters and the leaching of tailings,respectively.