| Molybdenum toxicity in aquatic ecosystems has not been well characterized thus many jurisdictions, including the province of Saskatchewan, have not developed surface water quality regulations or guidelines to govern industrial emissions of aqueous molybdenum. The purpose of this thesis was to characterize the risk of molybdenum exposure to aquatic ecosystems proximal to four uranium mines in northern Saskatchewan using Environment Canada's methodology for environmental risk assessment including tools such as hazard quotients and probabilistic risk assessment. The study results indicate a risk to organisms that spend most or all of their lives in aquatic ecosystems near the Key Lake, Rabbit Lake and McArthur River uranium mines. Adoption and enforcement of the Canadian Council of Ministers of the Environment interim guideline of 0.073 mg/L would provide adequate protection to aquatic life. More toxicity studies are needed, however, to calculate a full surface water quality guideline. |
