Department of Civil Engineering, Graduate School of Engineering, Gifu University, 1-1, Yanagido, Gifu 501-1193, Japan.
Department of Civil Engineering, Faculty of Engineering, Gifu University, 1-1, Yanagido, Gifu 501-1193, Japan.
J Environ Manage. 2019 Mar 1;233:89-96. doi: 10.1016/j.jenvman.2018.12.033. Epub 2018 Dec 17.
The Great East Japan Earthquake and subsequent tsunami in 2011 generated massive amounts of disaster waste and tsunami deposits, one-third of which comprised soil and sediment, which are expected to be re-used; however, there has been no previous experience or knowledge of recovered soil. In this study, up-flow column leaching tests were conducted to investigate the elemental leaching behavior in this soil and sediment following its separation and treatment (hereafter termed "recovered soil") to assess whether it can be safely re-used without posing any environmental risk. The pH of the leaching water was slightly alkaline throughout the test period, regardless of the source of the recovered soil. Concentrations of calcium and sulfate ions in the leaching water varied in a similar way to the electrical conductivity (EC), with a stable state being observed initially followed by a rapid decrease until typical concentrations were reached, whereas sodium and chloride ions derived from seawater made a relatively small contribution to the EC. In terms of toxic elements, zinc and copper concentrations decreased as the volume of leaching water increased, whereas lead, fluoride, and arsenic concentrations increased as the concentration of calcium and sulfate ions decreased, indicating that the dissolution of large quantities of compounds such as calcium sulfate controlled the toxic element behavior in the recovered soils. Consequently, there is a need for continuous and careful monitoring of areas where recovered soil is re-used or treatment of the recovered soil prior to its re-use.
2011 年东日本大地震及随后的海啸产生了大量灾害废物和海啸沉积物,其中三分之一为土壤和沉积物,预计将被再利用;然而,对于回收的土壤,此前没有任何经验或知识。在这项研究中,进行了上向流柱浸出试验,以研究这种土壤和沉积物在分离和处理(以下称为“回收土壤”)后的元素浸出行为,以评估其是否可以安全再利用而不会带来任何环境风险。在整个测试期间,浸出水中的 pH 值均呈弱碱性,而与回收土壤的来源无关。浸出水中钙和硫酸盐离子的浓度与电导率(EC)的变化方式相似,最初观察到稳定状态,随后迅速下降,直到达到典型浓度,而来自海水的钠离子和氯离子对 EC 的贡献相对较小。就有毒元素而言,锌和铜浓度随着浸出水量的增加而降低,而铅、氟化物和砷浓度随着钙和硫酸盐离子浓度的降低而升高,这表明大量化合物(如硫酸钙)的溶解控制了回收土壤中有毒元素的行为。因此,需要对回收土壤再利用或再利用前对回收土壤进行持续和仔细的监测。