With growth of the Canadian oil sands industry, concerns have been raised about possible seepage of toxic oil sands process-affected water (OSPW) into the Athabasca River (AR). A sampling campaign in fall 2015 was undertaken to monitor for anthropogenic seepage while also considering natural sources. Naphthenic acids (NAs) and thousands of bitumen-derived organics were characterized in surface water, groundwater, and OSPW using a highly sensitive on-line solid phase extraction-HPLC-Orbitrap mass spectrometry (SPE-HPLC/Orbitrap MS) method. Elevated NA concentrations and bitumen-derived organics were detected in McLean Creek (30.1 µg/L) and Beaver Creek (190 µg/L), two tributaries that are physically impacted by tailings structures. This was suggestive of OSPW seepage, but conclusive differentiation of anthropogenic and natural sources remained difficult. High NA concentrations and bitumen-derived organics were also observed in natural water located far north of the industry, including exceedingly high concentrations in AR groundwater (A5w-GW, 2000 µg/L) and elevated concentration in a tributary river (Pierre River, 34.7 µg/L). Despite these evidence for both natural and anthropogenic seepage, no evidence of any bitumen-derived organics were detected at any location in AR mainstem surface water. The chemical significance of any bitumen-derived seepage to the AR was therefore minimal, and focused monitoring in tributaries will be valuable in future.

Characterization of naphthenic acids and other dissolved organics in natural water from the Athabasca Oil Sands Regions, Canada by using ultra-high resolution Orbitrap mass spetrometry

255th National Meeting (2018)

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