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

19世纪末，新斯科舍省的黄金开采活动给该省的湿地和浅水环境留下了严重的汞(Hg)和砷(As)污染。与这些矿场相关的环境风险和财务责任很高，不仅在新斯科舍省，而且在加拿大和世界其他地区，也使用了类似的黄金开采做法。湿地和浅水环境对补救和风险管理尤其具有挑战性。清除受污染的沉积物是破坏性的，可以重新动员污染物。使用厚厚的沙层和粘土层物理隔离受污染的沉积物将导致湿地生态系统的净损失，还需要昂贵的补偿要求。理想情况下，补救策略将具有成本效益，可在湿地地点使用，以管理砷和汞的风险，并确保湿地特征得到保留和改善。2019年，圣玛丽大学(SMU)完成了一项概念验证研究，研究表明，在湿地沉积物中添加活性沸石和纳米零价铁(NZVI)的泥浆混合物，可能会在不影响敏感湿地功能的情况下限制遗留金矿尾矿污染的风险。本提案中概述的项目的总体目标是在这些发现的基础上，为湿地中高污染的遗留金矿废物制定一种创新、安全和具有成本效益的风险管理战略。这一战略将由SMU、里贾纳大学(URegina)、麦卡勒姆环境有限公司和大西洋矿业新斯科舍公司共同制定。如果成功，这项反应性修正案申请将支持湿地的完整性和自然功能，开垦具有潜在价值的海滨地产，以及改善偏远地区的娱乐、旅游、捕鱼、狩猎和贝类捕捞。

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.