AsianScientist (Apr. 4, 2012) – An international research team is reporting the results of a research cruise they organized to study the radiation released into the ocean from the tsunami-crippled reactors in Fukushima, Japan.
Led by Ken Buesseler, a senior scientist and marine chemist at the Woods Hole Oceanographic Institution (WHOI), the team studied the concentrations and spread of radioactive substances released into the Pacific Ocean, a consequence of the explosion of the Fukushima power plant in March last year.
The researchers did this by collecting and analyzing samples of water and plankton, and measuring the ocean currents off the damaged reactor plant and further offshore along the Kuroshio current, a large, fast current that flows north near the coast of Japan before turning east along the shore of the Chiba Peninsula.
Initial findings from the paper published in the journal Proceedings of the National Academy of Sciences suggest that the Fukushima power plant disaster may account for the largest accidental release of radiation to the ocean in history.
Fortunately, after analyzing the samples collected from the researchers found that the amount of radiation in the ocean measured was lower than safe drinking water standards.
“Our goal was to provide an independent assessment of what the Japanese were reporting and also to get further off shore to sample in places where we thought the currents would be carrying most of the radionuclides,” said Buesseler.
“We also wanted to provide as wide ranging a look as possible at potential impacts on the marine system to give a better idea of what was going on in the region, but also to provide a stronger baseline from which to measure future changes.”
Another intriguing finding was that the location of samples with the highest level of radiation pointed to eddies, which are swirling water bodies that break off from strong ocean currents such as Kuroshio.
Though the radiation levels in an eddy was 1,000 times higher compared to levels prior to the accident, they still fell below levels of concern for humans and marine organisms and were approximately one-sixth the level of naturally occurring radionuclides such as potassium-40.
However, there are questions still left unanswered. An open question is why radiation levels in the waters around Fukushima have not decreased since the Japanese stopped emergency cooling operations. According to Buesseler, the ground surrounding the reactors may have become saturated with contaminated water that is slowly seeping out into the water.
Also, further studies would be needed to look for hotspots near the shore or the power plant to find contaminated marine species unsafe for consumption.
The article can be found at: Buesseler KO et al. (2012) Fukushima-derived radionuclides in the ocean and biota off Japan.
Source: Woods Hole Oceanographic Institution; Photo: WHOI.
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