A MULTIPLE-TRACER APPROACH TO LABEL AND TRACE INDUSTRIAL WASTE AND GROUNDWATER: A CASE STUDY FROM CANADIAN OIL SANDS

The Athabasca oil sands in Northern Alberta represents an important oil reserve for Canada and the world. One of many environmental challenges of developing this natural resources is to monitor and evaluate impacts of developments on the aquatic ecosystem in the Athabasca Oil Sands Region (AOSR). This requires understanding and characterizing variations of multiple natural end-members including groundwaters, lakes and streams, as well as oil sands processes-affected water (i.e., industrial waste), in the AOSR. The efforts to distinguish industrial impacts from natural variations are further complicated by the fact that Athabasca River and its tributaries are incised directly into the bitumen bearing McMurray Formation, as well as other saline Cretaceous and Devonian Formations. High salinity and bitumen-derived organics not only can be attributed to wastes of industrial developments, but also can be linked to natural processes such as seepages along the river. Using single tracers for example chloride concentration or δ¹⁸O signatures to trace and identify industrial waste is usually hampered by this complications.

Here we compiled an integrated dataset, including isotopes, geochemistry and organic profiling data, from various industrial projects. Geophysical surveys along the Athabasca River were also conducted to identify the most likely area where the Athabasca River are impacted by inputs with high salinity. The dataset was used to characterize range and variability of individual geochemical/isotopic tracers in the region, and demonstrate the capacity and potential of individual tracers to trace and differentiate two particular types of end-members. However, there is no single 'silver bullet' indicator to differentiate industrial waste from all possible natural sources in the region. As a result, a multiple-tracer approach have been applied to interpret the source of water, salinity and organics in a complementary manner. The understanding of hydrogeological setting in a region context is also important to evaluate the sources and pathway of the high salinity inputs impacting water quality in the Athabasca River.