![]() ![]() However, some species of bacteria do produce methylmercury, as a byproduct of their respiration. We know that fish don’t methylate mercury, and phytoplankton and zooplankton probably don’t either. So where and how does the conversion of mercury to methylmercury take place? Lamborg said the process is probably biotic-done by living things. “Something like a shellfish, which is a filter feeder, that’s very close to the bottom of the food chain, is generally not as high in methylmercury as something like a tuna or a mackerel or swordfish or striped bass-all the fish, actually, that we really like to eat,” Lamborg said. Large predator fish such as tuna, for example, contain about 10 million times as much methylmercury as the water surrounding them. This is not just a scourge of modern life Lamborg said a mercury mine in Slovenia has been dumping its wastewater into the Gulf of Trieste since Roman times.īut even large discharges such as that wouldn’t pose a major threat to human health if the mercury were not converted to methylmercury, which diffuses into phytoplankton and then passes up the food chain in ever-accumulating quantities. We also discharge mercury-laden industrial effluents directly into rivers or the ocean. From there, rainfall washes the mercury into the ocean. The biggest single source is the burning of fossil fuels, especially coal, which releases 160 tons of mercury a year into the air in the United States alone. About two-thirds comes from human activities. Some comes from natural sources such as volcanic eruptions. We also know the source of most of the elemental mercury in the ocean. And that might still be in play, because there’s worms and shellfish and things living in the mud, and they’re always sort of stirring it up.” The big questionĪt Minamata Bay, the source of the methylmercury was clear. “The buzzword that people use for that is ‘legacy mercury.’ Coastal sediments tend to be really elevated in mercury that was dumped there 30, 40, 50, 100 years ago as a result of some industry. “There was a lot of mercury dumped back in the day when folks were not sensitive to what was going on,” said Lamborg. Minamata Bay was one of the worst cases ever of methylmercury poisoning, but sadly, it was not unique. Eugene Smith, later withdrew this and other searing photos from public display at the request of the subjects and their families.) ![]() ![]() In one famous picture, originally published in Life magazine, a woman cradles her teenage daughter, who had been deformed by prenatal exposure to methylmercury. Fitzgerald, who was the third student to graduate from the MIT/WHOI Joint Program and the first in chemical oceanography, devoted his career to mercury after seeing photographs in the 1970s of people poisoned by methylmercury dumped from a chemical plant into Minamata Bay, Japan. at the University of Connecticut with Bill Fitzgerald, one of the foremost experts on mercury in the ocean. Lamborg got hooked on mercury as a master’s degree student at the University of Michigan and then pursued his Ph.D. That’s the puzzle Carl Lamborg, a biogeochemist at Woods Hole Oceanographic Institution (WHOI), is trying to solve. (Photo by Danielle Fino, Woods Hole Oceanographic Institution) WHOI biogeochemist Carl Lamborg studies how various forms of mercury get into and cycle through the ocean and freshwater lakes and rivers, focusing particularly on the toxic form of mercury that accumulates in fish.
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