Researchers have been trying to determine why there’s so much mercury in seafood. They studied fish living in the North Pacific, which is in the path of winds coming from the parts of Asia with lots of coal-fired power plants. When scientists analyzed the chemical makeup of the toxins in fish tissue, they determined that the mercury was coming from the atmosphere—not volcanic eruptions or oceanic sediments, as some suggested. The mercury found in certain fish was “a near perfect match” with the atmospheric forms of mercury, which can travel long distances.
Once mercury lands on the water, bacteria on the surface convert it to a more toxic form—methylmercury. This is what accumulates in the tissues of fish. Unfortunately mercury levels are likely to rise in the future unless more countries institute emissions controls or begin to use less-polluting sources of energy.
“Why Is There Mercury In Fish? Blame Bacteria and Coal” by Emily Main, Rodale, www.rodalenews.com, 9/9/13