Radioactive cesium in ocean plankton, from Fukushima

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

In the latest survey, the team also found cesium-134 — which has a two-year half-life — in plankton at the same levels as cesium-137, whose half-life is three decades.

Cesium found in plankton almost 375 miles from Fukushima nuclear plant, Boston Herald, By The Yomiuri Shimbun http://news.bostonherald.com/news/international/asia_pacific/view/20120318cesium found_in_plankton_almost_375_miles_from_fukushima_nuclear_plant/srvc=home&position=recent, March 18, 2012 – TOKYO — Radioactive cesium believed to have been released during the crisis at the Fukushima No. 1 nuclear power plant in Japan following last year’s major earthquake has been found in plankton about 600 kilometers (nearly 375 miles) 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 research team collected animal plankton at 17 locations between 30
kilometers (18.6 miles) and 600 kilometers (372.8 miles) east of the
plant in June last year, about three months after the March 11
earthquake and tsunami that triggered the nuclear crisis.

Cesium-137 was detected in all of the collected plankton, which in a
dry state was found to contain 0.3 to 56.4 becquerels per kilogram.
The farther away the plankton was collected, the less radiation it
contained, according to the team.

Results of a similar survey conducted by the team before the crisis
showed that plankton contained between 0.1 and 0.4 becquerels of
cesium-137 per kilogram.

In the latest survey, the team also found cesium-134 — which has a two-year half-life — in plankton at the same levels as cesium-137, whose half-life is three decades.