[Environmental concerns on geochemical mobility of lead, zinc and cadmium from zinc smelting areas: western Guizhou, China].Huan Jing Ke Xue. 2009 Jul 15; 30(7):2065-70.HJ
Indigenous zinc smelting activity, widely spread in western Guizhou, China, had caused serious pollution of heavy metals of lead (Pb), zinc (Zn) and cadmium (Cd) in soil and water and posed risk to the local ecosystem. Geochemical distribution and mobility of Pb, Zn and Cd in soil, waste residue and waters were investigated in a small watershed in order to provide scientific base for the approach to pollution control and remediation. Concentrations of Pb, Zn and Cd in smelting residues averaged at 4 632 mg/kg, 8 968 mg/kg, and 58 mg/kg, respectively; whereas Pb 234 mg/kg, Zn 400 mg/kg and Cd 9.6 mg/kg in average in the soils around the smelting areas were measured. The sequential geochemical extraction test showed that Pb, Zn and Cd in the contaminated soils had high mobility and bioavailability for the metals, whereas smelting waste residues had lower mobility and bioavailability because their concentrations presented small percentages (all less than 0.2%) in the exchangeable fraction. Concentrations of Pb, Zn and Cd were high in the local stream water but low in groundwater. In the surface water, Pb, Zn and Cd were significantly concentrated in the suspended sediment. The results indicated that metal-rich erosion process of smelting residue and contaminated soil contributed to mobility of the metals into stream water.