The role of redox biogeochemistry in oxic zone development in the oil sands first reclamation end pit lake, Syncrude Canada's Base Mine Lake.

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Reclamation of oil sands tailings in the Alberta Oil Sands Region is a key industry and Canadian priority. The industry partner in the proposed research, Syncrude Canada Ltd., ranked as the world's largest producer of synthetic crude from oil sands and the biggest single source in Canada, is actively developing innovative strategies to reclaim their tailings. In 2012, Syncrude commissioned Base Mine Lake (BML) to assess water capped tailings technology (WCTT) as a means of tailings disposal. It is expected that in the long term, the lake will develop an oxygenated surface zone with the potential to support higher trophic levels. Based on evidence from existing tailings ponds, there is evidence that microbial biogeochemical cycling of oxygen consuming compounds (OCC) contributed from the tailings layer may reduce BML water cap oxic zone development. However, as this is the first commercial-scale end pit lake (EPL) in the oil sands, the developmental trajectory and outcome in BML are uncertain. The proposed three-year, field-based research will directly address this important knowledge gap. It will characterize (1) BML water cap depth dependent oxygen concentrations, (2) in situ oxygen consumption rates (OCR) and (3) the OCC and biogeochemical processes involved in OCR over spatial, seasonal and annual time scales. The results will identify important microbial and chemical constituents affecting oxic zone early development in BML and determine their impact. Results will thus inform Syncrude's BML research goal to sufficiently understand processes affecting BML's development and ultimate incorporation in the closure landscape such that future EPL applications are well informed. It will benefit Canada through improved environmental management and increased sustainability of oil sands activities and the training of 13 HQP in leading edge, applied environmental sciences. These HQP will develop the critical skills and experience in tailings reclamation that will needed for the future of the oil sands in Canada