Radioactive cesium from Fukushima found in tuna caught off U.S.
Trace amounts of radioactive cesium released from Japan's crippled Fukushima Daiichi nuclear power plant have been found in bluefin tuna caught off the western coast of the United States, according to a study in the Proceedings of the National Academy of Sciences published online Monday.
While the amounts are not considered a health hazard, the detection reflects the magnitude of the nuclear disaster, which resulted in the release of massive amounts of radioactive materials into the atmosphere and sea.
A Stanford University researcher and two others wrote that they have found "unequivocal evidence" that the tuna transported across the Pacific Ocean radioactive cesium released in the disaster triggered by the powerful earthquake and tsunami in March last year.
According to the study, cesium 134 and cesium 137 found in 15 bluefin tuna caught off the coast of San Diego, California, last August measured 4 bequerels per kilogram and 6.3 bequerels per kg, respectively.
The tuna are believed to have been off the Japanese coast when the disaster occurred and migrated to the U.S. coast due to ocean currents.
In comparison, no cesium 134 was found in tuna caught in 2008, while a tiny amount of cesium 137 that would naturally exist in the environment was found in them. Cesium 134 has a relatively short half-life of two years.
Tokyo Electric Power Co., which operates the power plant in Fukushima Prefecture on the Pacific coast, estimates that 900,000 terabequerels of radioactive materials were released into the atmosphere, 18,000 terabequerels of which are believed to have flowed into the ocean. A terabequerel is equal to 1 trillion bequerels.
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|Publication:||Japan Energy Scan|
|Date:||May 29, 2012|
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