Salt Lake City: Radioactive contamination from
the Fukushima power plant disaster has been detected as far as almost 643 kilometers off Japan in the Pacific Ocean, with
water showing readings of up to 1,000 times more than prior
levels, scientists reported.
But those results for the substance cesium-137 are far
below the levels that are generally considered harmful, either
to marine animals or people who eat seafood, said Ken
Buesseler of the Woods Hole Oceanographic Institution.
He spoke yesterday in Salt Lake City, Utah, at the annual
Ocean Sciences Meeting, attended by more than 4,000
researchers this week.
The results are for water samples taken in June, about
three months after the power plant disaster, Buesseler said.
In addition to thousands of water samples, researchers also
sampled fish and plankton and found cesium-137 levels well
below the legal health limit.
"We`re not over the hump" yet in terms of radioactive
contamination of the ocean because of continued leakage from
the plant, Buesseler said in an interview before Tuesday`s
talk. He was chief scientist for the cruise that collected the
The ship sampled water from about 32 kilometers about 400
miles off the coast east of the Fukushima plant.
Concentrations of cesium-137 throughout that range were 10 to 1,000 times normal, but they were about one-tenth the levels generally considered harmful, Buesseler said.
Cesium-137 wasn`t the only radioactive substance released
from the plant, but it`s of particular concern because of its
long persistence in the environment. Its half-life is 30
The highest readings last June were not always from
locations closest to the Fukushima plant, Buesseler said.
That`s because swirling ocean currents formed concentrations
of the material, he said.
Most of the cesium-137 detected during the voyage probably
entered the ocean from water discharges, rather than
atmospheric fallout, he added.
Hartmut Nies of the International Atomic Energy Agency
said Buesseler`s findings were not surprising, given the
vastness of the ocean and its ability to absorb and dilute
"This is what we predicted," Nies said after Buesseler
presented his research.