不同提取剂提取土壤中重金属能力的对比研究

为比较不同浸提剂的提取能力, 采用去离子水(DI)、硫酸-硝酸(AA)、二乙烯三胺五乙酸(DTPA)、醋酸缓冲溶液(TCLP)、氯化钙溶液(CC)对Cu、Ni、Pb、Cd复合污染土壤中的有效态重金属进行提取, 同时采用欧共体标准物质局提出的BCR连续提取法(BCR)和TESSIER提出的SEP连续提取法(Sequential Extraction Procedures)对污染土壤中的重金属进行形态分析, 探究了不同多级提取法中重金属形态分布的关系以及浸提剂浸出的重金属质量分数与多级提取法中重金属形态分布的关系.研究结果表明:各浸提剂的浸提能力从强到弱依次是:DTPA、TCLP、CC、AA、DI; 对于Cu和Ni元素, BCR法提取的活跃形态的质量分数与SEP法提取的活跃形态的质量分数相近; TCLP浸出重金属的质量分数与BCR连续提取法中重金属的形态存在紧密联系, TCLP浸提剂能提取出弱酸可提取态的重金属; DTPA浸出重金属的质量分数与SEP连续提取法中重金属的形态也存在紧密联系, DTPA浸提剂能提取出可交换态、碳酸盐结合态和铁锰氧化态的重金属.本研究结果可为重金属污染土壤修复评估标准提供参考依据.

A Comparative Study of the Capacity of Different Extractants to Extract Heavy Metals in Soil

The extraction capacity of different extractants, the species distribution of heavy metals in different multi-stage extraction methods, and the relationship between the extracted heavy metal content and the species distribution of heavy metal were investigated in detail. Several classical extractants, including deionized water (DI), sulfuric acid-nitric acid (AA), diethylenetriaminepentaacetic acid (DTPA), toxicity characteristic leaching procedure (TCLP), and calcium chloride (CC) were used to detect the content of available heavy metals in soil contaminated in combination with Cu, Ni, Pb and Cd. Furthermore, the BCR sequential extraction proposed by European Community Bureau of Reference and Sequential Extraction Procedures (SEP) were carried out to analyze the species distribution of heavy metals in the contaminated soil. The results showed that the extraction capacity of each extractant ranks from strong to weak as DTPA, TCLP, CC, AA, DI. The content of active components extracted with the BCR method is similar to that extracted with the SEP method. The content of heavy metals leached with TCLP is closely related to the form of heavy metals in BCR. The availability of heavy metals in TCLP extraction was an acid extractable fraction. The content of heavy metals leached with DTPA is also closely related to the form of heavy metals in SEP. The availability of heavy metals in DTPA extraction was exchangeable, bound to carbonates and Fe-Mn oxide-bound. This study can improve the evaluation methodology of soil heavy metal pollution.