The Fate of As and Heavy Metals in the Flooded Paddy Soil Stabilized by Limestone and Steelmaking Slag

Abstract

The characteristics of As and heavy metals depend on the oxidation/reduction condition of the soil environment. The most heavy metals are immobilized by the reduction condition whereas As, Fe and Mn become more soluble. Therefore this study estimated the stabilization efficiency of the agricultural paddy soil in the vicinity of the abandoned mine using a flooded column test including analysis of the soil solution, contaminants fractionation and rice grain. Limestone and steelmaking slag were used as amendments for stabilization of the contaminated soil. In an analysis of the soil solution, the mobile characteristics of Fe and Mn, which were used as electron acceptors of the microorganisms, were controlled by increasing the pH by adding alkali amendments. This means that the contaminants combined with Fe and Mn can be stable under flooded reduction condition. However, the concentrations of cationic heavy metals (Cd, Pb, and Zn) were also decreased without amendments because the carbonates produced from microbial respiration increased the pH of the soil solution. In the amended soil, the specific sorbed fraction of As and carbonates fraction of heavy metals were increased when compared to the control soil at the end of the column test. Especially in heavy metals, the increase of carbonates fraction seems to be influenced by alkali amendments rather than microbial respiration. Because of the stabilization effect in the flooded paddy soil, the contents of As and Zn in rice grain from amended soil were lower than that of the control soil. But additional research is needed because of the relatively higher Pb content identified in the rice grain from the amended.

Stabilization of Agricultural Soil Contaminated by Arsenic and Heavy Metals using Biochar derived from Buffalo Weed

“…영향을 최소화 하는 것이다 Kim et al, 2003). 따라서 안정화 공법은 오염된 농경지 토양에 대해 물리적 특성을 유지하면서 생산성을 고려한 위해성 기반의 토양처리에 있어서 현실적으로 가장 타당한 방안 이라 할 수 있다 (Koh et al, 2015a).…”