PROFILING STABLE ISOTOPES OF WATER SIGNATURES TO DEFINE MASS TRANSPORT MECHANISMS FROM WATER CAPPED FLUID FINE TAILINGS IN THE OIL SANDS INDUSTRY
Syncrude Canada Ltd. has initiated the first full-scale EPL (Base Mine Lake), and established a monitoring program to characterize the physical, geochemical, and biological processes occurring in this new system. The stable isotopes of water (δ2H and δ18O) signature of oil sands process affected water has been shown to be highly distinct from that of freshwater associated with snow melt or rainfall (Baer, 2014). As a result, the isotope composition of the lake water and FFT pore-water can potentially be used as a conservative tracer for mass transport. Samples were collected every 0.1 m across the FFT – lake water interface (2 m above, to 2 m below), at three locations in Base Mine Lake. Water from each sample was analyzed with a Picarro L-2120-i Cavity Ring Down Spectrometer based on the vapour equilibration technique used by Wassenaar et al. (2008) to determine δ2H and δ18O concentrations. These results were compared to δ2H and δ18O concentrations of the lake at multiple locations, as well as inflow and outflow water. Numerical modelling was used to interpret the measured isotope profiles across the FFT – lake water interface and elucidate mass transport mechanisms from the FFT to the lake water.