Freshwater Contaminants
Southwest Alaska Network. 2020. Freshwater Contaminants. Southwest Alaska Network
Mercury is a toxic element with no known essential biological function. It occurs naturally as a solid in various minerals and as a gas in volcanic eruptions. It is also released into the environment as a gas by human activities, particularly mining and coal burning. Gaseous elemental mercury can be transported atmospherically to areas far from original sources, after which it can be oxidized and deposited on the earth’s surface in the form of rain or snow. Under anaerobic conditions, typically in wetland sediments, bacteria can convert this deposited inorganic mercury to organic methylmercury. Methylmercury may then accrue in aquatic organisms through the intake of water and food. In fish, methylmercury both bioaccumulates and biomagnifies, meaning it increases over time within an individual and it increases up the food chain across individuals. For this reason, long-lived top-predator species, like lake trout, have a high risk of mercury contamination, and diet is a key pathway by which contamination occurs.
- Type
- Resource Brief
- Authors
- Southwest Alaska Network
- Date of Issue
- 2020-03
- Publisher
- Southwest Alaska Network
- Units
- KATM , LACL , SWAN
- Keywords
- lake trout, mercury, methylmercury, sockeye salmon, water quality
- Subjects
- Ecological Framework: Water | Water Quality | Toxics , Ecological Framework: Biological Integrity | Focal Species or Communities | Fishes , Ecological Framework: Human Use | Consumptive Use | Consumptive Use