Uptake and release of heavy metals by minerals and rock coatings

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The financial wealth of many countries is tied to their resources and manufacturing industries. In Canada, the processing of mining materials and waste disposal are key sources of the release of heavy metals into the environment. Accumulations of these elements in air, water and soils have a severe impact on the health of the environment. Therefore, understanding the fate of a heavy metal in the environment is critical to predict the presence of contaminants in air, water and soil. Predictive understanding requires knowledge regarding the interaction of a specific element-bearing material with the environment and once the element is released, its interaction with geological and barrier materials. My research focuses on the characterization of the release and uptake of heavy metals by minerals and coatings on rocks and minerals. In my ongoing research, I examine the release of Uranium via the dissolution of secondary uranium minerals, a scenario that would likely occur when nuclear waste comes in contact with Oxygen-rich solutions. A short-term goal of this part of my research is a general understanding between the dissolution properties of a secondary uranium mineral (features and kinetic) and its structure and the crystal-chemical properties of the elements in solution. The major part of my future research will be the characterization of the uptake of heavy metals by coatings and alteration phases. The uptake of heavy metals by minerals was dominantly studied using non-altered surfaces. However, mineral surfaces exposed to the atmosphere can be altered or covered by coatings and their interaction with heavy metal thus depends on the composition and structural features of alteration layers or alteration phases in proximity to the "parent" minerals. These examinations will include laboratory experiments on the uptake of heavy metals by alteration layers on silicate minerals. Furthermore, coatings and alteration phases will be studied in mine tailings and acidic soils around Sudbury and in the U-deposits of Elliot Lake and Pena Blanca, Mexico. The results from the studies at the U-deposits will give a better understanding on the mobilization of Uranium in mine tailings or nuclear waste repositories that are hosted in silica-rich lithologies.