Potential Impacts of Tailings and Tailings Cover Fertilization on Arsenic Mobility in Surface and Ground Waters

Abstract

A number of mining sites worldwide, particularly gold mines, have tailings management facilities (TMFs) that contain high levels of arsenic. Current closed mine site regulatory agencies tend to prefer revegetation of TMFs as part of the mandated reclamation activities. At many sites, often in polar regions, vegetation is difficult to establish either directly on the tailings or on the coarse-rock covers due to nutrient poor soils, phytotoxicity problems, and/or a less than optimum climate. Addition of phosphorus-based fertilizers to the tailings and/or cover material is commonly considered in order to promote the revegetation process and – ideally – allow the site owners to discharge their closure duties as rapidly as possible. However, due to the similar geochemistry of arsenic and phosphorus oxyanion species, this type of mine closure strategy may have unintended consequences regarding arsenic mobility on and off the site. This document reviews the current state-of-the-art regarding mobilization of arsenic by phosphate ions, and identifies relevant risks and opportunities of using this information to better manage closed mine sites