Fukushima radiation tracked across Pacific Ocean
By Jesse Emspak, LiveScience Contributor
2 April 2012 Radioactive material from the Fukushima nuclear disaster has been found in tiny sea creatures and ocean water some 186 miles (300 kilometers) off the coast of Japan, revealing the extent of the release and the direction pollutants might take in a future environmental disaster. In some places, the researchers from Woods Hole Oceanographic Institution (WHOI) discovered cesium radiation hundreds to thousands of times higher than would be expected naturally, with ocean eddies and larger currents both guiding the “radioactive debris” and concentrating it. With these results, detailed today (April 2) in the journal Proceedings of the National Academy of Sciences, the team estimates it will take at least a year or two for the radioactive material released at Fukushima to get across the Pacific Ocean. And that information is useful when looking at all the other pollutants and debris released as a result of the tsunami that destroyed towns up and down the eastern coast of Japan. “We saw a telephone pole,” study leader Ken Buesseler, a marine chemist and oceanographer at WHOI, told LiveScience. “There were lots of chemical plants. A lot of stuff got washed into the ocean.” [Japan Nuclear Radiation Shows Up in US (Infographic)] […] The team also looked at the amounts of cesium isotopes in the local sea life, including zooplankton, copepods (tiny crustaceans), shrimp and fish. They found both cesium-137 and cesium-134 in the animals, sometimes at concentrations hundreds of times that of the surrounding water. Average radioactivity was about 10 to 15 Bq per kilogram, depending on whether it was zooplankton or fish (concentrations were lowest in the fish). Even so, Buesseler said, the radioactivity levels are still below what is allowed in food in Japan, which is 500 Bq per kilogram of “wet” weight. And while cesium was present in the fish, it doesn’t accumulate up the food chain the way polychlorinated biphenyls (PCBs) or mercury do. Mercury and PCBs tend to stay in an animal’s tissues for long periods, so when a tuna eats smaller fish, it takes in all the chemicals those small fish have eaten. Cesium tends to be excreted from animals much faster. The WHOI expedition calculated that some 1.9 petabecquerels — or 1.9 million billion becquerels total — were in the stretch of ocean studied. The total released by the Fukushima accident was much greater, but a lot of the radionuclides were dispersed by the time of the sampling in June 2011. […]
