Remediation Opportunities for Arsenic-Contaminated Gold Mine Waste

Abstract

Arsenic (As)-contaminated gold mine waste is a global problem and poses a significant risk to the ecosystem and community (e.g., carcinogenic, toxicity). Arsenic concentrations of 77,000 mg/kg and 22,000 mg/kg in mine waste have been reported for Canada and Australia, respectively. Research is investigating environmentally sustainable techniques to remediate As-rich mine waste. Biological techniques involving plants (phytoremediation) and soil amendments have been studied to bioaccumulate As from soil (phytoextraction) or stabilise As in the rhizosphere (phytostabilisation). Identified plant species for phytoremediation are predominately fern species, which are problematic for arid to semi-arid climates, typical of gold mining areas. There is a need to identify native plant species that are compatible with arid to semi-arid climates. Arsenic is toxic to plants; therefore, it is vital to assess soil amendments and their ability to reduce toxicity, enhance plant growth, and improve soil conditions. The effectiveness of a soil-amending phytoremediation technique is dependent on soil properties, geochemical background, and As concentrations/speciation; hence, it is vital to use field soil. There is a lack of studies involving mine waste soil collected from the field. Future research is needed to design soil-amending phytoremediation techniques with site-specific mine waste soil and native plant species.

Mine Site Restoration: The Phytoremediation of Arsenic-Contaminated Soils

“…Mining activities-for example, gold mining-represent one of the main anthropogenic sources of As. Gold (Au) extraction methods, such as refractory ores and free-milling ores, produce As wastes in the form of gas, leachate, and calcinated soil, which pose significant environmental risks [3,4]. It has been reported that, globally, the cumulative As production as a result of mining activities increased from 0.06 to 3.29 million tonnes between 1900 and 2000 [5]; numerous studies indicate increasing As pollution as a result of mining in many countries [6,7].…”