Cesium found in plankton 600 km away

Radioactive cesium believed to have been released during the crisis at the Fukushima No. 1 nuclear power plant has been found in plankton about 600 kilometers east of the facility, according to a Japan-U.S. joint research team.

The amount of cesium detected in the plankton was far below the government's provisional limit of 500 becquerels per kilogram for marine products, according to the team led by Jun Nishikawa, research associate at the University of Tokyo's Atmosphere and Ocean Research Institute.

However, follow-up studies will be necessary because the radioactive cesium is likely to have accumulated in fish that eat plankton, the team said.

The findings will be reported to a conference of the Oceanographic Society of Japan set for Tuesday. The Yomiuri Shimbun.