High concentrations of radioactive cesium have been found in plankton from the sea near the Fukushima Daiichi Nuclear Power Plant.
Researchers from Tokyo University of Marine Science and Technology collected plankton in waters up to 60 kilometers from the coast of Iwaki City in July. They found 669 becquerels per kilogram of radioactive cesium in animal plankton from waters 3 kilometers offshore.
They say a wide range of fish feed on animal plankton and that the contamination could accumulate in the food chain and have a more serious impact when it gets into relatively large fish.
The research group's leader, Professor Takashi Ishimaru, says the plankton were so heavily contaminated because sea currents continuously carried contaminated water southward from the nuclear plant. He says detailed studies are needed to determine how long the effect on fish will continue.
NHK Plankton Story