The impact of methane ebullition on internal mass loading in an oil sands end pit lake

Please join us for a graduate student seminar this Friday March 29 at 3:30 pm in rm 155 Geology presented by Daniel Francis, MSc candidate:

The impact of methane ebullition on internal mass loading in an oil sands end pit lake

Internal mass loading from fine tailings (FFT) to the overlying water cover of oil sands end pit lakes (EPLs) will influence water quality in these closure landscapes. Consequently, a thorough understanding of processes controlling mass transport across the tailings-water interface is critical for estimating the long-term trajectory of water quality. In this study, we build upon existing models of physical mass transport across this interface in Base Mine Lake (BML), which is the first full-scale demonstration EPL in the Athabasca Oil Sands Region. These models simulated transport of conservative tracers by invoking periodic mixing of the upper FFT driven by physical processes in the overlying water cover. However, ongoing research supports the hypothesis that methane ebullition is the principal driver of FFT mixing below the tailings-water interface. We test this hypothesis applying enhanced diffusion rates to mimic continuous mixing of the upper FFT by ebullition. We also develop a modelling framework to explore relationships between methane ebullition and chemical transport across the interface. We then refined these models to simulate physical and chemical data from BML collected between 2015 and 2017. This study improves our understanding of methane dynamics, processes controlling chemical mass transport across the tailings-water interface, and long-term chemical evolution of BML.