Chapter 13 - Phytostabilization of mine tailings

Abstract

Mine tailings and mill wastes, characterized by high concentration of metal(loids) toxicants from abandoned and active mining sites, have adverse impact on the entire ecosystem and is a worldwide environmental and social concern. Mine tailings is the residuum after the extraction and beneficiation of ores, composed of mostly fine-grained material, and high concentration of metals and salts. These are deficient in soil organic matter content and nutrients to promote natural growth of vegetation canopy. Mine spoil is detrimental primarily due to extreme low pH and high concentrations of toxic metals. Due to the loose nature of tailing dams, during precipitation there is always a chance of release of acidic water and toxic soil loaded with heavy metal contaminants. This results in metal leaching and acid mine drainage, which poses a major threat to soil and water resources besides human health. Most of the traditional methodologies used for remediation of these metallic contaminants are expensive, and besides being a further cause of environmental destruction, are also impractical. In order to achieve long-term aesthetic solution use of live plants or microorganisms/biomass, which can be implemented in situ to remediate tailings and mill wastes is proving to be a promising suitable strategy, which requires more attention on global basis. In this recent phenomenon phytostabilization has emerged as an alternative reclamation technique for stabilization of environmental toxins by using green plants, which proves to be cost effective, self-sustaining, and with an aim to rehabilitate entire terrestrial as well as aquatic ecosystem. Primarily it focuses on establishment and development of metal excluder plants supported by various amendments making the soil enriched with organic matter, immobilizing metals within the mine tailings itself into a less soluble form, thus enabling biological activity and restoring its natural quality. In this study background, concepts and various applications of phytostabilization, along with some case studies are discussed. Furthermore, basic characteristic of mine tailings and its impact on the biodiversity are also reviewed.