Recent Research

Selenium Project

Uranium has been mined and milled for decades in northern Saskatchewan, one of the largest sources of Uranium in the world. Selenium (Se) co-occurs with the mined uranium ore deposits and has been found at elevated concentrations in sediment, benthic invertebrates and whole fish at the Key Lake milling operation (N. Saskatchewan). Given that Se can bioaccumulate in aquatic organisms and have toxic effects at higher trophic levels, this research was initiated to investigate the environmental impact of Se downstream of this milling operation.

Using a holistic, interdisciplinary approach in collaboration with David Janz and Canada Research Chair Ingrid Pickering, the broader goals of this project are to: (1) Establish spatial and temporal distribution of Se forms (species) through abiotic and biotic environmental compartments and their relationships and (2) Understand pathways of Se exposure to and uptake by benthic invertebrates, primary consumer and secondary consumer fish.

Oil Sands Research

Toxicity of Athabasca Oil Sands process-affected waters to aquatic organisms
The alkaline hot water extraction process used to separate bitumen from sand, at the Athabasca Oil Sands (AOS), produces tailings and process-affected waters.  The toxicity of these oil sands process affected waters (OSPWs) have been shown to be, at least partially, related to elevated levels of a relatively persistent group of dissolved organic acids known as naphthenic acids (NAs).  Research is currently underway to evaluate the potential for the degradation and associated reduction in aquatic toxicity of OSPWs in laboratory microcosms , which are being used to simulate natural wetland environments.

Thermal upgrading of oil sands bitumen in Alberta, Canada, produces an enormous volume of coke as a by-product. Research is currently underway to evaluate the leachability of trace metals associated with coke their potential toxicity to aquatic life.  Results from this research work will assist in planning and decision making process for oil sands coke reclamation strategies.

Metals bioavailability in Sediment Research
Various projects have investigated metals bioavailability in sediment. Excluding research associated with the Se Project, recent projects are briefly described below.

Alternative approaches to the derivation of sediment quality guidelines (ongoing)

Sediment quality values for uranium operations in Canada (located mainly in northern Saskatchewan) have been derived by the Canadian Nuclear Safety Commission for metals, metalloids, and radionuclides using the screening-level concentration approach . However, this approach may inappropriately label all elements found at a site as a potential cause of an effect, when in reality only one or two elements are likely causing toxicity. Using sediment chemistry and benthos data from sites near uranium operations in northern Saskatchewan, work is currently underway to develop a new no-effect value derivation approach for metals in sediment.  This research is also attempting to characterize the bioavailability of metals in sediment to benthic invertebrates using porewater measurements and chemical extractions.

Uranium Uptake, Accumulation and Physiological Adaptation in Aquatic Invertebrates (ongoing)

The uranium (U) mining and milling industry in northern Saskatchewan, Canada, can lead to localized increases of U in aquatic systems due to release of effluent. Delineating and quantifying the routes of metal uptake in freshwater invertebrates are important for understanding metal bioaccumulation and toxicity. However, the dietary route of metal accumulation and toxicity to freshwater invertebrates has, until recently, largely been overlooked. Research is currently underway to investigate the dietary bioaccumulation of U in aquatic invertebrates fed both absorbed and adsorbed U. Potential modifying factors such as dissolved oxygen concentration, osmotic concentration, and passive absorption though the cuticle and gills are also being evaluated.