Levels of radiation in the seas surrounding the ruined Fukushima Daiichi power plant in Japan are showing no signs of dropping off as expected, according to new data presented last week at a conference in Tokyo.
Scientists believe that continued leaks from the plant in addition to run off from contaminated land and radiation-soaked sediment on the sea floor are responsible.
Scientists suspect that rainfall is washing radioactivity from the land into rivers, which then carry it down to the sea, helping to maintain the high radiation levels. The plant itself may also still be leaking radiation, they suggest.
But Jota Kanda, an oceanographer at the Tokyo University of Marine Science and Technology, told Nature that the main cause is most likely the sandy ocean floor, which contains around 95 terabecquerels of radioactive caesium.
The sediment may have absorbed the radioactive caesium directly, or the radioactivity may have been deposited there via the excretions of tiny marine organisms like plankton.
Source: The- Scientist