我国几个工矿与污灌区土壤重金属污染状况及原因探讨

矿产品堆场土壤中重金属在环境中富集，随着元素的迁移、转化及地下水的循环，成为环境污染问题。本文将改进的顺序提取法（BCR）应用于矿产品堆场土壤中Cd、As、Pb的化学形态分析，结合这三种元素的性质，将堆场土壤中Cd、As、Pb分为可交换态、可还原态、可氧化态和残渣态，并利用电感耦合等离子体发射光谱法测定其含量。采用形态分析标准参考物质GBW 07436验证了三步提取态的准确性，并对6个矿产品堆场土壤中Cd、As、Pb形态含量进行了分析，三步提取态加上残渣态质量分数之和与重金属总量进行了比较，回收率在85%~103%之间。通过对矿产品堆场土壤实际样品分析，Cd、As、Pb三种元素非残渣态含量顺序为Cd（79.40%~94.94%）>Pb（24.27%~37.73%）>As（22.89%~31.51%），表明Cd元素较为容易进入生物圈。该方法解决了港口堆场土壤中重金属化学形态提取问题，对污染土壤的治理具有指导意义。

Sequential extraction procedure for the speciation of particulate trace metals

Heavy metal elementals can be enriched in soil at mineral products yard, which become a problem of environmental pollution caused by elemental migration, transformation and circulation in underground water. In this experimentation the modified BCR sequential extraction method was applied to the chemical species analysis of Cd, As and Pb. Based on the properties of these three elementals, the chemical species of Cd, As and Pb were divided into four fractions: exchangeable, reducible, oxidizable and residual, and Inductively Coupled Plasma-Atomic Emission Spectrometry (ICP-AES) were used to measure the content of Cd, As and Pb. Morphological analysis standard reference material GBW 07436 was conducted to verify the accuracy of the three step extraction state. Contents of chemical species of Cd, As and Pb in soil from six mineral products yard were analyzed, including contents of three step extraction state plus the residual and the total contents of the desired metals elements. The recoveries were from 84.54% to 102.88%. The analysis results for actual samples demonstrated the contents of Cd, As and Pb in non-residual fraction were in order as Cd (79.40%-94.94%)>Pb(24.27%-37.73%)>As (22.89%-31.51%), which indicated Cd is easy to enter the biosphere. This method has resolved the problem to extract the chemical species of heavy metal elements in soil from port mineral products yard, and has profound significance to the treatment of contaminated soil.