Assessment of Fraction and Mobility of Arsenic in Soil Near the Mine Waste Dam

Arsenic (As) contamination in abandoned mining areas has been of concern in Korea; hence, the reclamation and restoration of these areas must be conducted. Since large contaminated areas have not been restored yet, post management of restoration sites would be insufficient. The aim of this study was to monitor the pollution of environments near the waste dam in mining areas and to assess the fraction and mobility of As. Chemical assessment was conducted using sequential extraction and single extraction methods [Mehlich-3, 1N HCl, the simple bioavailability extraction test (SBET), and the synthetic precipitation leaching procedure (SPLP)], whereas biological assessment was conducted with a bok choy (Brassica campestris L. ssp. chinensis Jusl.) cultivation experiment. The results showed that the waste rock soil, forest soil, and sediments near the dam were contaminated with As. As a result of sequential extraction, most of the As in the soil of the upper part of the dam were observed to be tightly adsorbed (well-crystallized hydrous metal oxides and residual phases), whereas As in the forest soil of the lower part of the dam were observed to be relatively weakly bound (amorphous and poorly-crystallized hydrous metal oxides). These results show that As could be re-dissolved from secondary contaminated forest soil and spread to nearby environments. For the sustainable management of soil environment, an assessment of the fraction and mobility of As coupled with continuous monitoring are required.