土壤重金属连续提取方法的优化

重金属在污染土壤中的形态分布决定着重金属的迁移性和危害的程度。土壤重金属形态分析应用最多的是Tessier和BCR连续提取法。Tessier和BCR连续提取法没有考虑土壤样品的特征。美国环保署危险废物浸出毒性鉴别标准法虽然考虑土壤pH值，但没有划分形态。采集不同pH土样，结合Tessier、BCR和毒性浸出鉴别方法的特征，优化出针对不同pH值土壤的连续提取方法，将土壤中重金属划分为活性态、次生碳酸盐结合态、次稳定态和稳定态。用优化的连续提取方法对土样进行连续提取，重金属回收率为85%~115%。优化连续提取方法的结果与Tessier和BCR结果对比显示优化连续提取方法克服了Tessier连续提取法对非石灰质土壤提取过量BCR连续提取法对石灰质土壤提取不足的缺点。优化后的连续提取方法数据稳定可靠，可作为重金属形态分析方法使用。

Optimization of Soil Heavy Metal Sequential Extraction Procedures

The environmental risks of heavy metals depend on its speciation distribution in contaminated soils. The chemical speciation analysis was one of the hot topics in environmental sciences. In recent years, the most popular sequential extraction procedures were Tessier and BCR. Nethier Tessier nor BCR sequential extraction methods considered the characteristics of soil samples. Although Toxicity Characteristic Leaching Procedure (TCLP) used two different extraction regent is based on the pH values of soil samples, it is a single step extraction method. In this paper, compared with Tessier, BCR and TCLP extraction techniques, the speciation extraction method was optimized in order to adapt soils with different pH values. The heavy metals in the soils were divided into active fraction, secondary carbonate fraction, secondary steady fraction and steady fraction. The results show that the optimized sequential extraction method is more stable, the recovery rate is 85% to 115% which could satisfy the soil speciation evaluation requirements. And the optimized sequential extraction method is suitable for soils with different pH values.