A multi-tracers approach to quantifying Shield brines mixing and migration from deep to shallow aquifer systems

前寒武纪盾牌含水层由火成岩和变质岩组成，可能是加拿大大部分地区等人口的重要水源。盾构含水层的地球化学特征是在深处(&gt；1000米)存在卤水，这是一种地下水，总溶解固体含量超过100,000毫克/L(TDS；海水约35,000毫克/L)。20世纪80年代，S在放射性废物储存库现场调查的推动下，对屏蔽卤水进行了开创性的研究，利用地球化学来表征这些复杂的系统。在加拿大最大的地形区加拿大地盾，在浅层发现了微咸水(1,000-10,000毫克/L TDS)(该计划的目的是开发追踪微咸水来源的方法，并对卤水混合和迁移到浅含水层的可能性进行模拟。该项目有几个地下矿场，其中一个矿场深度超过3000米，目标是魁北克西北部的Abitibi矿区。短期目标是：1)利用稳定氯和溴同位素等新的同位素示踪剂识别不同来源的水和混合动力学；2)通过研究Barlow-Ojibway粘土孔隙水的稳定同位素来确定更新世冰川融水；3)通过分析裂隙流动地球化学和裂隙矿物，研究裂隙和水/岩相互作用对盐度来源和地下水演化的作用。每个目标都将通过博士(2)、硕士(1)和学士学生(3)的项目来实现。他们将在加拿大面临专业人员短缺的领域获得宝贵的、最先进的培训。这项研究的结果将为科学界和工业(采矿、地热、核能)提供新的知识，以减轻深层卤水和浅层地下水引起的迁移和混合的潜在影响。随着矿山变得越来越深，该行业面临着巨大的挑战，因为咸水地下水的开采，以及由于腐蚀性极强的流体导致的设备迅速恶化。随着加拿大通过可持续利用自然资源促进北方的发展，全面了解盾牌卤水的来源和迁移的长期愿景是必要的，以确保北部和原住民社区的安全饮用水，并向该行业提供知识，使其适应其作业，并减轻对浅层地下水资源的潜在影响。

Precambrian Shield aquifers, composed of igneous and metamorphic rocks, may represent a vital source of water for population, such as the large parts of Canada. The geochemistry of Shield aquifers is characterized by the presence at depth (> 1000 m) of brines, a groundwater with more than 100,000 mg/L total dissolved solids (TDS; seawater about 35,000 mg/L). Pioneering studies on Shield brines in the 1980's, driven by radioactive waste repository site investigations, used geochemistry to characterize these complex systems. In the Canadian Shield, the largest physiographic region in Canada, brackish groundwater (1000-10,000 mg/L TDS) was identified at shallow depths ( of this program is to develop approaches to trace the origin of brackish groundwater and to model the potential mixing and migration of brines into shallow aquifers. With several underground mines, including one site more than 3000 m deep, this program targets the Abitibi mining region, northwestern Quebec. The short-term objectives are 1) to identify water of various origin and mixing dynamics using innovative isotopic tracers as stable chlorine and bromine isotopes, 2) to define the Pleistocene glacial meltwater by studying water stable isotopes of Barlow-Ojibway clay pore water, and 3) to investigate the role of fractures and water/rock interaction on sources of salinity and groundwater evolution by analyzing fracture flow geochemistry and fracture minerals. Each objective will be addressed through projects of doctorate (2), master (1), and bachelor students (3). They will gain valuable, state of the art training in a field that faces a shortage of professionals in Canada. The results from this research will provide new knowledge to the scientific community and industry (mining, geothermal, nuclear) to mitigate potential impacts of induced migration and mixing of deep brines with shallow groundwater. As mines are getting deeper, the industry faces major challenges with the pumping of saline groundwater, and with the quick deterioration of equipment due to the very corrosive fluids. With Canada fostering the development of the North through sustainable use of natural resources, such a long-term vision to get a comprehensive understanding of the origin and migration of Shield brines is mandatory to assure safe drinking water to northern and First Nations communities, as well as to provide the industry with knowledge to adapt their operations, and to mitigate potential impacts on shallow groundwater resources.