WHOI marine chemist Ken Buesseler. (Photo: Tom Kleindinst, WHOI)n)
'Harmless' radiation found off Japanese coast
Friday, February 24, 2012, 03:10 (GMT + 9)
Scientists have detected radioactive elements from the stricken Fukushima nuclear power plant in seawater and marine organisms as far as 600km from Japan. However, this radioactivity has not been deemed dangerous, they said.
"Just because we can measure radioactivity doesn't mean it's harmful," WHOI's Ken Buesseler said. "There's a pretty good news story in here - that the levels [of radioactivity] offshore are not of significance to human health in terms of exposure, or even if you were to eat the seafood offshore."
The findings resulted from a research cruise in June 2011 led by the Woods Hole Oceanographic Institution (WHOI). The cruise carried researchers from the US, UK, France, Spain and Japan who started this work just three months after the Fukushima crisis began in March, as an "independent check" on Japanese Government-funded research and the data made public by Tepco, the owners of the damaged Daiichi plant in Fukushima.
The Research Vessel KOK sailed gathered thousands of samples of seawater and the organisms living in it, such as plankton and small fish. It also deployed "drifters" into the water to study the activity of local currents and eddies, BBC News reports.
|WHOI physical oceanographer Steven Jayn. (Photo: Tom Kleindinst, Woods Hole Oceanographic Institution)
Analysis showed elevated levels of radioactive elements -- including caesium-137 and caesium-134 -- possibly linked to releases from the nuclear power station.
Radioactivity readings in the seawater across the track ranged from less than 3 Bq per m3 up to 4,000 Bq per m3.
The maximum of these readings is about 1,000 times what could be measured in the water under normal conditions but they were about one-tenth the levels generally considered harmful, Buesseler noted, AP reports.
The cruise did not find these highest detections in areas sampled closest to Fukushima because swirling ocean currents formed concentrations of the radioactive compounds. At the same time, the researchers were not permitted any closer than 30km to the coast.
When examining plankton and fish, the researchers even identified a radioactive form of silver for the first time in the open ocean.
Regardless, all measured levels of the Fukushima-related radioactivity were much lower than those of potassium-40, a naturally occurring radioisotope.
"The concentration of potassium-40 was five to six times greater than all of the [elements from Fukushima] combined," explained Professor Nicholas Fisher from Stony Brook University. "I would not hesitate eating any of the organisms we sampled."
Moreover, the scientists established that Fukushima-related radioactivity levels in seawater are not diminishing as fast as many had hoped.
"The reactor site still seems to be leaking; it hasn't shut off completely, and at those levels right on the coast you could still have these concentration factors that we measured that would indicate some organisms would be at levels unfit for human consumption," Buesseler said.
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By Natalia Real