某污染场地土壤重金属生物可给性及其对修复目标的影响研究

Bioaccessibility of heavy metals in soil of a contaminated site and its impact on determination of clean-up levels

采用体外实验方法(in vitro)对中国西南部某遗留污染场地土壤中重金属进行了生物可给性(BA)测定,分析基于BA结果修正的土壤修复目标。结果表明:砷(As)、铅(Pb)、铜(Cu)、镍(Ni)等4种重金属在模拟胃液和小肠液中的溶解态浓度远小于土壤中的重金属总量,即土壤中的重金属不能完全被人体吸收;As和Pb在胃阶段的生物可给性高于小肠阶段,而Cu和Ni在胃阶段的生物可给性低于小肠阶段;影响重金属生物可给性的因素主要有土壤pH值、w(Fe)、w(Mn)和重金属总量。并运用试验测定的生物可给性因子对As、Cu、Ni的修复目标值进行了修正,在避免对人体造成危害的同时,使场地内待修复的Cu污染土壤方量减少了100%,Ni污染土壤方量减少了31%,节约了修复成本,避免了过度修复。

The in vitro method was used to investigate the heavy metals bioaccessibility in soil of a polluted by in a steel mill in southwest china. The results showed that the dissolved concentrations of four heavy metals(As,Pb,Cu,Ni)in the stomach and intestine were far less than the total amount of heavy metals in the soil. it’s meant that the heavy metals in the soil could not be completely absorbed by the human body.The bioaccessibility of As and Pb in stomach was higher than that in intestine,while that of Cu and Ni in stomach was lower than that in intestine. The main factors affecting the bioaccessibility of heavy metals were pH,w(Fe),w(Mn)and total amount of heavy metals. In this paper,the clean-up levels of As,Cu and Ni were modified by using the bioaccessibility factors measured in the test. While avoiding the harm to human body,the earthwork to be repaired contaminated by Cu and Ni decreased by 100% and 31% respectively,which saved the repair cost and avoided excessive repair.