Assessment on heavy metal partitioning in mine-affected soils after solidification

Abstract

Approximately 6,000 abandoned mines are located in Korea1. Tailings of abandoned mines may contain high levels of heavy metals and metalloid compounds. The poor management and neglect of abandoned mine could cause leaching of hazardous heavy metals into soil and groundwater. Due to their potential toxicity, soils contaminated with metals pose significant risks to human health and environment2. Unlike many organic contaminants, heavy metals and metalloids are not biodegradable3. Solidification/stabilization technology has been used to treat agricultural land which contaminated with heavy metals in Korea. Compared with other remediation technology like soil flushing, chemical treatment, bio-remediation, and thermal deposition, solidification/stabilization has the merits of relatively low cost, ease of use, comprehensive strength, and high resistance to biodegradation. Due to these merits, both geotechnical engineers and researchers are concerning this technology. After solidification/stabilization treatment, soil monitoring is necessary to verify that the remedy remains effective and protective of human health and the environment. Information of heavy metal mobility in soil and potential risk is required to evaluate performance of solidification/stabilization and clarify the pollution and migration characteristics of the possible risk of heavy metals. In this research, 1) characteristics of mine-affected soils, 2) determine the speciation distribution and mobility of heavy metals, 3) examine the behavior relationship of heavy metals and speciation in soil, and 4) risk assesment were investigated. XRD, XRF analysis were conducted to characteristics of soils, the concentration of heavy metals was determined by ICP. Mobility of heavy metals was determined using sequential extraction including Tessior, Wenzel, and BCR methods. Two stabilization sites were found to be re-contaminated by heavy metal(As 373.88 mg/kg).