Grant: Strategic Projects - Group

Gold mines frequently have high natural arsenic concentrations in tailings and nearby streams and ground water. The optimal remediation(clean-up) plan should protect the local population from health risks associated with ingesting arsenic-rich solids or waters. In the case of publicly accessible sites in Nova Scotia, where arsenic is present at concentrations hundreds to thousands times the recommended soil guideline, placing a cover on the tailings seems like an obvious solution. However, this may trigger dissolution of the arsenic-bearing minerals and lead to a pulse of arsenic being released to local streams and groundwater. The situation is complicated because the stability of the arsenic-bearing minerals is not well-known.Conventional remediation designs such as flooding, removal or fencing are problematic because of the high solubility of the As minerals, dust hazards and expense associated with removal and community resistance regarding fencing. We propose to conduct experiments and field tests investigating the biogeochemical stability of different tailings types in order to design the best plan to protect downstream surface and groundwaters and reduce risk to human health for individuals using the area for recreatio- nal purposes. Our experiments will use new equipment to test the effect of environmental conditions and advanced analytical techniques that can determine whether arsenic is dissolved in groundwater or moves as colloidal particles. If most of the As is colloidal, the risk is assessed differently since mobility depends on mineral stability. Two large environmental consulting companies support the project by sharing their expertise and helping to train students. These companies will be exposed to the state-of-the-art knowledge in remediation research. The NS government has indicated that they will use our results to help in the ongoing developing of public policy related to the historic and new gold mine. The results of our research will provide experimentally-tested recommendations applicable to many of the thousands of abandoned mine sites in Canada. It will produ- ce three PhD and two MSc graduates as well as one postdoctoral fellow.