Radiation rises in sea

Japanese authorities have been taking samples from the ocean right off the coast and also 30 kilometers off the coast. While experts are concerned, Dr. Paul Johnston, head of the Greenpeace Research Laboratories at Exeter University in the UK, says the measurements aren’t enough:

"What is happening at the moment is a series of samples have been taken over a period of time, which indicate that there is a problem taking shape – there is a problem evolving there, but we don’t know much about the dimensions of this particular problem because the sampling frequency and intensity simply have not been sufficient to be able to pin that sort of thing down with any degree of resolution."

4,000 times higher than normal

Traces of radioactive iodine 131 have now been found in the sea which are more than 4,000 times higher than permitted levels.

Johnston says iodine itself is not the problem. "The situation is I think at the moment that what has been detected is iodine 131, which is less a concern than the other isotopes because of its shorter half-life. But of course, where there’s iodine 131, its very likely there are going to be other radionuclides as well, things like caesium 137 and possibly some of the plutonium isotopes as well because some of those have been found on the land. So we need to find out what is going on there." He adds, "It may be that there is no threat to human health but that will have to be decided on the basis of some comprehensive monitoring."

Johnston says it would not be good if caesium were found, as studies on radiation poisoning in Sellafield in the northern UK and the French Cap de la Hague have shown that the isotopes can travel very far.

"In fact, the discharges from Sellafield can be detected all the way up to the arctic regions so the caesium 137 which will tend to stay dissolved in the seawater, could be transported really quite long distances." Johnston points out the difference with other radioactive substances: "Things like the plutonium isotopes, if they are ultimately detected, are likely to remain much more localized with the sediments in the region and that might lead to a much more regional problem taking shape there.

Diluted radioactive material

Günter Kanisch of Hamburg’s Thünen Research Institute does not believe any radioactivity measured off the coast of Fukushima will have an impact on fish stocks further away, like in the Bering Sea, for example.

"Surely radioactive materials will move to other places, like to the Bering Sea, but it will take years and in the meantime, the concentration of radioactive materials will be so diluted until it reaches the Bering Sea, that it does not seem likely that there will be any trace of it in the fish there."

But Johnston is not so sure and says that experts and authorities will have to keep an eye on the situation, as it is still developing. He points out that the radiation can pose a real threat to human health if large quantities of contaminated fish or shellfish are consumed locally.

Author: Irene Quaile (sb)
Editor: Thomas Bärthlein