ICMGP 2022 – On-Demand / Poster Presentation

Abstract Information :

Late-1800's gold mining practices in Nova Scotia has led to mercury (Hg) and arsenic (As) contamination of wetlands. Environmental risks and financial liability associated with this unresolved issue remain high. Wetland settings are particularly challenging for risk management. Removal of contaminated sediments is disruptive and can re-mobilize contaminants. Physically isolating contaminated sediment using thick 'capping' layers of inert sand and clay would lead to a net loss of wetland ecosystems. Chemically-active amendment materials with higher contaminant sorptive capacities than traditional passive isolation caps are a potential alternative for restoring tailing-impacted wetlands. The thickness, function and longevity of traditional inert capping approaches can be improved through the use of carefully selected amendments, decreasing contaminants? mobility, toxicity, and bioavailability and offering both containment and treatment to contaminated sediment. The overall objective of this project was to test three proprietary reactive amendment blends including zero valent iron (ZVI) and zeolite with and without a thin protective capping. The reactive amendments and/or protective capping were added to 100 ml of contaminated sediment collected from the field and incubated in 1L beakers with water for 1 month before the start of the tests. Water and sediment ecotoxicity tests (Daphnnia magna and Hyalella azteca), bioaccumulation tests (Caridina multidentate and Cambarellus patzcuarensis), porewater and overlaying water analysis for dissolved contaminants, and sediment core testing for mineralogy were then completed. Results will be presented, including preliminary conclusions on the effectiveness of the reactive amendments and thin capping in reducing risks of Hg and As in these contaminated wetland areas.