Wednesday, August 26, 2009

Mercury found in every fish tested!

US Geological Survey press release: Mercury contamination is widespread. Mercury was detected in all fish sampled from 291 streams across the U.S. Concentrations in about a quarter of the fish sampled exceeded the criterion for the protection of humans who consume average amounts of fish, established by the U.S. Environmental Protection Agency (0.3 parts per million, wet weight).
  • Most rivers and streams across the U.S. receive mercury predominantly via atmospheric deposition. However, atmospheric deposition of mercury alone does not explain mercury contamination in fish in our Nation’s streams. Naturally occurring watershed features, like wetlands, forests, and organic-rich soils, can enhance the conversion of mercury to the most toxic form of mercury (methylmercury). Methylmercury is a form of mercury that is readily available for uptake by aquatic organisms, and biomagnifies to high concentrations in fish….
  • Once in the food web, methylmercury biomagnifies at a fairly consistent rate from algae to invertebrates to fish—even among diverse stream ecosystems. In the ecosystems studied, foodweb characteristics have less impact on the amount of mercury in fish than do methylmercury levels in water.
A brook trout, not a thermometer

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