Characteristics of the Elemental Release from Recovered Soil Separated from Disaster Waste Generated by the Great East Japan Earthquake and Tsunami

The physicochemical characteristics of the recovered soil separated from disaster waste and tsunami sediment generated by the Great East Japan Earthquake can be significantly different from those of the non-affected soil because the recovered soil contains unavoidable contamination such as pieces of concrete and wood debris as well as sea water. This study investigated elemental release from the recovered soil with water percolation using a column leaching test in order to investigate changes in the elemental release characteristics of the recovered soil. The electrical conductivity (EC) in the leaching water was constant at the initial stage of testing and gradually decreased at the middle stage of the test. The main contributors to the high EC value were calcium and sulfate ions, and the effect of sea water on elemental release was limited. Copper and zinc concentrations were relatively high during the early part of the leaching test, and subsequently, the concentrations of these elements decreased. In contrast, low levels of fluoride, lead, and arsenic in the leaching water were detected initially; however, the concentrations dramatically increased with the decrease in calcium and sulfate concentrations. These results indicate that the characteristics of elemental release altered with water percolation.