The University of Tokyo hosted a conference this week on the 12th and 13th of November, where researched presented data which revealed that the levels of radioactivity in the ocean waters around the crippled Fukushima Daiichi nuclear power plant remain stable around 1,000 becquerels, rather than falling as expected. Researchers believe that run-off from rivers, as well as continued leaks from the plant, may be partially to blame, but have shown research which may indicat that contaminated sediment and marine organisms are also involved.
A new model presented by scientists from Woods Hole Oceanographic Institution in Massachusetts estimates that 16.2 petabecquerels (1015becquerels) of radioactive caesium leaked from the plant — roughly the same amount that went into the atmosphere. Some experts worry that it could have long-term economic consequences for fishermen living on the east coast of Japan.
Researchers at the conference are convinced that something is preventing the radiation levels from dropping. “There must be a source,” says Scott Fowler, an oceanographer at Stony Brook University in New York.
Jota Kanda from the Tokyo University of Marine Science and Technology says the plant is still leaking around 0.3 terabecquerels (1012 becquerels) per month through the basements of the crippled reactors. Kanda says they have found some 95 terabecquerels of cesium accumulated on the ocean floor near the plant, and may have even been absorbed directly by the sand itself, or accumulated in the excrement of small marine organisms like plankton on the sea floor.