Understanding impacts of microbial methane ebullition in oil sands pit lakes: methane release and transport of petroleum hydrocarbons

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Petroleum in the Alberta Oil Sands Region (AOSR) is a key component of the Canadian economy. Currently reclamation of land impacted, and tailings produced, by surface mining operations in the AOSR is a central industry and environmental priority in Canada. Syncrude Canada Ltd. has commissioned the first example of oil sands reclamation by water capped tailing technology (WCTT) via the development of an 8 km2 pit lake (PL) Base Mine Lake (BML) in 2012. While PL reclamation is commonly employed for tailings management in hard rock mining, the AOSR is unique due to the organic rich nature of the tailings. Since 2012 Syncrude has supported an intensive research program aimed at understanding the development of BML This research program has identified ongoing bubbling, known as ebullition, of microbially produced methane from the tailings. In addition to its implications to greenhouse gas emissions, this methane ebullition represents a potential mechanism for the transport of residual petroleum hydrocarbons (PH) and naphthenic acids (NA) into the water column. Transport of these compounds has the potential to negatively impact biogeochemical cycling and ecosystem development within BML. This research program will focus on characterizing compounds that can drive ongoing microbial methane production within BML and will evaluate the potential for PH and/or NA to be transported to the water column during methane ebullition. This research will not only inform adaptive management of BML and future PL in the AOSR thereby contributing to the key priorities of tailings management and reclamation of the AOSR, but it will also provide fundamental insights into the processes controlling petroleum hydrocarbon transport and fate in organic rich environments that can be transferred to other impacted environments including harbours, industrial shorelines, and spill sites. It will also train a diverse team of highly skilled personnel capable of contributing to the petroleum industry, environmental remediation, government monitoring and academic research in understanding biogeochemical cycling in organic rich and petroleum impacted environments.