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

新斯科舍省从19世纪末开始的金矿开采活动给全省的湿地和浅淡水环境留下了严重的汞和砷污染。与这些地点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方，类似的金矿开采方法已经使用。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具有破坏性，可能使污染物重新流动。用厚厚的沙子和粘土“覆盖”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，还需要昂贵的赔偿要求。理想情况下，补救策略将具有成本效益，可以在湿地现场使用，以管理砷和汞的风险，也将确保湿地的特点得到保留和改善。2019年，圣玛丽大学（SMU）完成了一项概念验证研究，该研究表明，向湿地沉积物中添加活性沸石和纳米零价铁（nZVI）的浆料混合物可以限制遗留金矿尾矿污染物的风险，而不会影响敏感的湿地功能。本提案中概述的项目总体目标是在这些调查结果的基础上，为湿地中高度污染的遗留金矿废物制定一项创新、安全和具有成本效益的风险管理战略。该战略将由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省公司合作制定。如果成功的话，这种反应性修正案的应用将支持湿地的完整性和自然功能，回收潜在的有价值的海滨财产网站，以及改善娱乐，旅游，捕鱼，狩猎和贝类收获的偏远网站。

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.