Freshwater Contaminants
Southwest Alaska Network. 2018. 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 its original emission sources. Then 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, which is five to ten times more toxic. Methylmercury tends to accumulate to greater concentrations in aquatic (rather than terrestrial) organisms. In fish, methylmercury readily crosses biological membranes, excretes slowly relative to its rate of uptake, and accumulates to concentrations vastly exceeding those in surface waters.
- Type
- Resource Brief
- Authors
- Southwest Alaska Network
- Date of Issue
- 2018-03
- 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