Review of the composition and toxicity of oil sands process-affected water

The objective of this review was to summarize the aquatic environmental research through time in the oil sands to provide an understanding of the composition and toxicity of oil sands process-affected water (OSPW) as reported in the published literature and to propose future research directions. Literature from the results of two search engines using key words that contained oil sands tailings pond water, oil sands process water, and oil sands process-affected water over the period of 1975-2013 was examined. Results indicate that process water, while referred to using similar terminology (OSPW), included many different water types. In some cases, the description of the waters was absent in the papers reviewed. Inconsistent terminology and variance in the water types assessed confounded comparisons of OSPW composition and toxicity. Of the 342 articles sourced in this review, 105 focused on raw OSPW; that is, OSPW collected from active settling basins. Of the 35 studies that conducted exposures to assess raw OSPW toxicity, only 18 studies reported toxicity concurrent with chemistry. Of these, eight studies reported Microtox as the only toxicological endpoint. Thus, only 10 of the 342 papers reviewed (2.9%) included chemical analysis concurrent with standard acute and chronic bioassay assessments of fish and invertebrate toxicity. Some of the papers provided limited information on sampling procedures and method QA/QC. Differences in methodology for naphthenic acids also confounded interpretation or comparison across studies. These results suggest that future research must better elucidate the composition and toxicity of OSPW with consideration of (i) clear differentiation and reporting of different OSPW types and sources; (ii) use of consistent terminology for process waters;(iii) providing detail on mine type and processing that can affect raw OSPW composition (e.g., source, froth treatment, tailings management practices, etc.); (iv) the use of consistent and standardized chemical and toxicological methods; (v) concurrent chemical and toxicological analysis; and (vi) toxicological assessments at environmentally relevant exposure concentrations.