Why mercury poisoning is worse in oceans than freshwater

[FritzCat66]

From ScienceDaily: Why Mercury Is More Dangerous in Oceans

Short answer: Methylmercury binds more tightly to the chlorides in salt, while the organic compounds it binds to in freshwater make it more quickly and easily broken down by the environment; so even though the overall concentration is less in oceans than freshwater, the little that's there ends up being more permanent, and thus carried on up the food chain where it becomes concentrated in the bodies of larger predators.

 

[jenika]

The potentially harmful version of mercury known as methylmercury latches onto dissolved organic matter in freshwater.The most common ways nature turns methylmercury into a less toxic form is through sunlight.Sunlight does not break it down in seawaterand in the lifetime of methlymercury is much longer in the marine environment and the Food and Drug Administration and the Environmental Protection Agency do not distinguish between freshwater and seawater.Even though freshwater concentrations of mercury are far greater than those found in seawater.