广西刁江流域Cd和Pb复合污染稻田土壤的钝化修复

Remediation of Contaminated Paddy Soil by Immobilization of Pollutants in the Diaojiang Catchment,Guangxi Province

采用田间小区试验,研究施用海泡石、石灰和磷酸盐对广西刁江流域Cd和Pb复合污染稻田土壤的钝化修复效应,并通过土壤重金属形态分析探讨不同钝化剂的作用机理。结果表明,添加钝化剂可显著提高稻谷和秸秆产量,最大增产率分别可达25.4%和28.3%,其中海泡石与磷酸盐复配处理增产效果最佳。施用钝化剂可以有效降低水稻各部位重金属含量,水稻糙米Cd和Pb含量最大降幅可达65.12%和61.86%;钝化剂复配处理对水稻地上部Cd和Pb含量的降低效果明显优于单一处理,其中海泡石和磷酸盐或石灰复配处理糙米Cd含量符合GB2762—2005《食品中污染物限量》。不同钝化处理均能显著降低土壤TCLP(毒性特性浸出程序)提取态Cd和Pb含量,最大降幅分别为28.86%和45.60%,其中钝化剂复配处理对土壤TCLP提取态重金属的抑制效果优于单一钝化处理。总体而言,海泡石与磷酸盐复配处理对广西刁江流域重金属复合污染稻田土壤的钝化修复作用最佳。

Effects of sepiolite, lime and phosphate immobilizing cadmium and lead in contaminated paddy soil in the Di- aojiang catchment, Guangxi were investigated through a field experiment, and mechanisms of the effects were analyzed through fractionation of the pollutants in the soil. Results show that the use of these amendments markedly increased yield of the crop, both grain and straw, to the greatest extent, by 25.4% and 28.3% , respectively. The effect of combined ap- plication of sepiolite and phosphate was the most significant. The application of these immobilizers significantly decreased Cd and Pb concentrations in all the parts of the plant. Especially in brown rice, the drop reached 65.12% and 61.86% , respectively. The effect of combined application of the immobilizers was more significant than that of the application of only one kind of immobilizer in the above-ground part of the plant. The brown rice produced in the treatment of combined appli- cation of sepiolite and phosphate or lime met Maximum Levels of Contaminants in Foods （ GB 2762 - 2005 ） in Cd concen- tration. The application of immobilizers, combined or single, significantly reduced the concentrations of TCLP-extractable Cd and Pb （TCLP, i.e. toxicity characteristic leaching procedure ）, with the maximal possible reduction reaching 28.86% and 45. 60% , respectively. Combined application was obviously more effective than the application of only one. To sum up, combined application of sepiolite and phosphate is the most effective recommendation for remediation of Cd and Pb contaminated paddy soil by immobilizing the pollutants in Diaojiang catchment, Guangxi.