Abstract:

This study aims to discuss the combined pollution of cadmium and lead in soils around smelters in central and southern China, and reduce the risk of soil pollution around the smelter. Three compound passivation materials were selected and soil culture experiments were conducted to investigate the passivation effect of compound materials on heavy metal contaminated soil around Zhuzhou Smelter. The results showed that under the same experimental conditions, the concentrations of cadmium and lead in the soil leaching solution treated with three passivation materials (C1, C2 and C3) did not exceed the Class IV standard in the Environmental Quality Standards for Surface Water (GB 3838—2002), the content of heavy metals in soluble soil conformed to the environmental quality standards. According to the passivation effects of the three materials on Cd and Pb in the soil around Zhuzhou smelter in Hunan Province on the 7th, 15th and 30th days, the addition of 1.0% C1 (clay mineral + TMT) material had the best passivation effect on cadmium and lead. The highest reduction rate of cadmium acid leaching state content reached 97.02%, and the highest reduction rate of lead acid leaching state content reached 99.37%. The effect of C1 passivation materials on cadmium and lead in soil gradually shifted from the exchangeable state and the bound state of iron and manganese oxides to the residual state with the passage of time, which reduced the migration ability of cadmium and lead heavy metals, reduced the cadmium and lead risk around the smelter to the environment. This experiment screened out the conditioning passivation materials for the combined pollution of cadmium and lead in soils, which provided a reference for solving the pollution control around smelters in central and southern China.

Key words: around smelters in central and southern China, cadmium and lead, 2,4,6-trimercapto-s-triazine trisodium (TMT), clay minerals, compound materials