Environmental Research Institute (ERIC), Chulalongkorn University, Bangkok, Thailand.
Research Program of Toxic Substance Management in the Mining Industry, Center of Excellence on Hazardous Substance Management (HSM), Chulalongkorn University, Bangkok, 10330, Thailand.
Environ Sci Pollut Res Int. 2018 Apr;25(12):11800-11811. doi: 10.1007/s11356-018-1495-3. Epub 2018 Feb 14.
The change in environmental conditions during the transportation of contaminated soil and sediment was expected to affect the transformation of heavy metal fractionation. This study disclosed the serious contamination of copper (Cu), lead (Pb), and zinc (Zn) in the sewer sediment of an e-waste dismantling community in Thailand which may be caused by flushed contaminated soil and e-waste fragments. Two environmental conditions were simulated to observe the transformation of heavy metal fractionation. The anoxic sewer condition was induced using high substrate and sulfate in a closed container. The aeration of anoxic contaminated sediment was applied to simulate the transformation to an oxidative environment. The BCR sequential extraction was applied for heavy metal fractionation in this study. The study results exhibited that when heavy metal contaminated soil was transferred into this induced anoxic condition, fractionation was redistributed based on the chemical change of system that tends to be associated into F3 (oxidizable fraction) > F2 (reducible fraction) > F1 (acid soluble/exchangeable fraction). Cu exhibited the outstanding capability association to F3. The iron sulfide was not observed as usual due to its lower capability than Cu, Pb, and Zn. When contaminated sediment was transported to a more oxidative environment, the heavy metals fractionation would be redistributed again among those new environment media. It is noteworthy that F3 of Cu was stable even in oxic conditions. F2 of Fe was not developed by this oxic condition, possibly because its dehydration process was limited. The redistribution under an oxic environment became F1 > F2 > F3 indicating their more available form. This transformation was imperative and should be taken into account in heavy metal contaminated site management and control.
在运输污染土壤和沉积物的过程中，环境条件的变化预计会影响重金属形态的转化。本研究揭示了泰国一个电子废物拆解社区下水道沉积物中铜（Cu）、铅（Pb）和锌（Zn）的严重污染，这可能是由于冲洗污染的土壤和电子废物碎片造成的。本研究模拟了两种环境条件，以观察重金属形态转化。在封闭容器中使用高基质和硫酸盐来诱导缺氧下水道条件。对缺氧污染沉积物进行曝气，以模拟向氧化环境的转化。本研究采用 BCR 连续提取法对重金属形态进行了分析。研究结果表明，当重金属污染土壤转移到这种诱导的缺氧条件下时，根据系统化学变化，形态会重新分配，倾向于与 F3（可氧化形态）>F2（可还原形态）>F1（酸可溶/可交换形态）相关联。Cu 表现出与 F3 良好的结合能力。由于其能力低于 Cu、Pb 和 Zn，通常不会观察到铁硫化物。当污染沉积物被输送到更氧化的环境中时，重金属形态将在新的环境介质中再次重新分配。值得注意的是，即使在有氧条件下，Cu 的 F3 也很稳定。F2 没有在这种有氧条件下形成，可能是因为其脱水过程受到限制。在有氧环境下的再分配为 F1>F2>F3，表明它们具有更高的可用性。这种转化是至关重要的，在重金属污染场地管理和控制中应予以考虑。
