Developing an in-situ risk management strategy for enhancing natural recovery of highly contaminated gold-mine-tailing impacted wetlands

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Gold mining practices in Nova Scotia from throughout the late 1800s have left a legacy of serious mercury (Hg) and arsenic (As) contamination of wetlands and shallow freshwater environments across the province. Environmental risks and financial liability associated with these sites are high, not only in Nova Scotia but across Canada and the rest of the world where similar gold mining practices have been used. Wetland and shallow-water settings are particularly challenging for remediation and risk management. Removal of contaminated sediments is disruptive and can re-mobilize contaminants. Physically isolating contaminated sediment using thick 'capping' layers of sand and clay would lead to a net loss of wetland ecosystems and would also require expensive compensation requirements. Ideally, remediation strategies would be cost effective, could be used at the wetland sites to manage the risk of both As and Hg, and would also ensure that wetland characteristics are retained and improved. In 2019, Saint Mary's University (SMU) completed a proof-of-concept study which showed that a slurry blend of reactive zeolite and nanoscale zerovalent iron (nZVI) added to wetland sediments may limit risks of legacy gold mine tailing contaminants without impacting sensitive wetland functions. The overall objective of the project outlined in this proposal is to build on these findings and develop an innovative, safe, and cost-effective risk management strategy for highly contaminated legacy gold mine waste in wetlands. This strategy will be developed in collaboration between SMU, the University of Regina (URegina), McCallum Environmental Ltd, and Atlantic Mining Nova Scotia Inc. If successful, this reactive amendment application will support the integrity and natural-functioning of wetlands, reclaim potentially-valuable waterfront property sites, as well as improve remote sites for recreation, tourism, fishing, hunting and shellfish harvesting.