Evaluating the biogeochemistry of oil sands tailings in end pit lakes

油砂是加拿大经济的重要组成部分；然而，油砂作业对环境的影响也在不断增加。尾矿库几乎完全用于废物管理，总占地面积超过220平方公里。经过处理的油砂矿石产生的尾矿浆排放到沉淀池中，最终必须被回收并整合到关闭矿井的景观中。然而，由于尾矿的固形物/粘土含量较低，脱水速度较慢，这使得油砂尾矿的回收特别具有挑战性。一种拟议的复垦方法是尾矿湖(EPLs)，它涉及在退役的露天矿坑中沉积厚厚的尾矿层，上面覆盖着水。从理论上讲，EPL是一种合适的回收策略，因为尾矿可以缓慢脱水，而水帽则是水生生态系统的栖息地。然而，第一次全规模示范EPL表明，这一策略存在几个挑战，包括浑浊产生和水帽质量。因此，建议在EPLs中沉积混凝剂明矾和絮凝剂处理的尾矿(聚丙烯酰胺，PAM)，以改善尾矿的脱水和减少浊度的产生。这项技术被称为永久水上储存结构(PASS)。到目前为止，将经过PASS处理的尾矿存放在EPLs中的生物地球化学影响尚不清楚，PAM、PAM降解产物和铝的生物降解和环境命运也不清楚。该项目将阐明EPLs中未处理和已处理尾矿的生物地球化学行为，并将评估EPLs是否是一种合适的、对环境负责的尾矿回收策略。这些研究的目的是研究PAM在处理后的油砂尾矿中的生物降解，并评估未处理和处理后的油砂尾矿在EPLs中的生物地球化学演化。对油砂尾矿固有微生物的微观研究将调查PAM处理的尾矿在好氧和厌氧条件下的生物降解性。我之前的研究现在已经发展成为研究复杂的厌氧生物修复系统的几十年的知识，并使我们能够处理同样复杂的PAM生物修复系统。随着未来50年油砂矿即将关闭，了解当前尾矿回收做法的长期影响至关重要。拟议的研究将提供关于使用环境保护油类进行回收所产生的生物地球化学影响的重要信息。从这项研究中获得的知识将有助于查明和减少关闭地雷做法对环境的长期影响，并将指导今后的研究和发展。加拿大人的既得利益是，确保拟议的研究项目向油砂行业提供所需的信息，以便作出健全的尾矿管理和矿山关闭规划决定。

The oil sands are a vital component to the Canadian economy; however, the environmental impacts of oil sands operations are also growing. Tailings impoundments are used almost exclusively for waste management with a combined footprint more than 220 km2. Processed oil sands ore yields tailings slurries that are discharged into a settling basin and must eventually be reclaimed and integrated into mine closure landscapes. However, due to the low solids/high clay content of tailings, they are slow to dewater, making reclamation of oil sands tailings particularly challenging. One proposed reclamation method is end pit lakes (EPLs), which involve depositing thick layers of tailings capped with water in decommissioned open pits. Theoretically, EPLs are a suitable reclamation strategy because the tailings can slowly dewater while the water cap serves as habitat for an aquatic ecosystem. However, the first full-scale demonstration EPL showed that there are several challenges with this strategy, including turbidity generation and water cap quality. As such, depositing coagulant- (alum) and flocculant-treated (polyacrylamide, PAM) tailings in EPLs was proposed to improve tailings dewatering and reduce turbidity generation. This technology is called permanent aquatic storage structure (PASS). To date, the biogeochemical implications of depositing PASS-treated tailings in EPLs remain unknown, and the biodegradation and environmental fate of PAM, PAM degradation products, and aluminum are not well understood. This program will elucidate the biogeochemical behavior of untreated and treated tailings in EPLs and will evaluate whether EPLs are a suitable, environmentally responsible tailings reclamation strategy. The objectives of these studies are to investigate PAM biodegradation in treated oil sands tailings, and evaluate the biogeochemical evolution of untreated and treated oil sands tailings in EPLs. Microcosm studies with microorganisms indigenous to oil sands tailings will investigate biodegradation in PAM-treated tailings under aerobic and anaerobic conditions. My previous research has now developed into decades worth of knowledge in studying complex anaerobic bioremediation systems and uniquely positions us to tackle this equally complex PAM bioremediation system. With upcoming oil sands mine closures over the next 50 years, it is vital to understand the long-term effects of current tailings reclamation practices. The proposed research will provide critical information on the biogeochemical implications of using EPLs for reclamation. The knowledge gained from this research will assist in identifying and reducing the long-term environmental impacts of mine closure practices and will guide future research and development. Canadians have a vested interest in ensuring the proposed research project provides the oil sands industry with information needed to make sound tailings management and mine closure planning decisions.