Leaching Characteristics and risk evaluation of heavy metals from recyle materials and contaminated soil with sequential extraction test

渗滤液中重金属的浸出量与废物中重金属的形态密切相关。几种顺序浸出试验已被用作澄清固体样品中重金属等微量元素可提取形式的工具。这些测定土壤和沉积物中可提取微量金属的方法于1992年被欧洲标准、测量和测试程序统一为BCR法。但是我们不能将BCR方法应用于碱样品，因为这种方法只适用于中性样品。在本研究中，我们改进了BCR顺序萃取法的条件，使其适用于碱样品。并将该改进的BCR顺序提取方法应用于回收材料和污染土壤，评价回收材料和污染土壤的可提取形态。结果表明，以蒸馏水提取和中和为前处理步骤，改进的BCR法可以得到碱样品中各组分中足够量的重金属。从试剂的结果来看，Pb、Cd、Cu和Zn的氧化物主要在酸溶部分提取，硫化物主要在可氧化部分提取。通过这些结果，可以明确改进的BCR法得到的各个馏分的特征。然而，铬的可提取形式无法评估。将改进的BCR方法应用于回收材料和污染土壤，从洗脱特征的角度对每个样品中的重金属进行分类。结果表明，重金属的洗脱风险较低。

Leaching amounts of heavy metals in the leachates are closely related to the forms of heavy metals in the wastes. Several kinds of sequential leaching tests have been used as a tool to clarify the extractable forms of trace elements like heavy metals in solid samples. These procedures for the determination of the extractable trace metals in soil and sediments were harmonized as the BCR method by the Standards, Measurements and Testing Programs in Europe in 1992. But we cannot apply the BCR method to alkali samples because this method is only for neutral samples.In this study, we improved the condition of the BCR sequential extraction method in order to apply to alkali samples. Moreover, this modified BCR sequential extraction method was applied to the recycle materials and contaminated soils in order to evaluate the extractable forms of recycle materials and contaminated soils.As the results, we could obtain the adequate amounts of heavy metals for each fraction from alkali samples by the modified BCR method, which had the distilled water extraction and neutralization procedures as pre-treatment steps. Judging from the results of the reagents, the oxides of Pb, Cd, Cu and Zn were mainly extracted in the acid soluble fraction, and sulfides were mainly extracted in the oxidisable fraction. From these results, the feature of each fraction obtained by the modified BCR method was able to be clarified. However, the extractable forms of Cr could not be evaluated. Furthermore, the modified BCR method was applied to the recycle materials and contaminated soils, and the heavy metals contained in each sample could be classified from a viewpoint of elution characteristics. These results showed that elution risk of heavy metal was low.