Saturday, October 27, 2012

福島の魚と西海岸の魚 Fukushima fish & West Coast fish


Fukushima fish 'may be inedible for a decade'

Marine scientist finds levels of radioactivity in fish near stricken Fukushima nuclear plant are higher than expected

Fiona Harvey, environment correspondent,

Thursday 25 October 2012 19.00 BST

Fish from the waters around the Fukushima nuclear plant in Japan could be too radioactive to eat for a decade to come, as samples show that radioactivity levels remain elevated and show little sign of coming down, a marine scientist has warned.

According to a paper published in the journal Science on Thursday, large and bottom-dwelling species carry most risk, which means cod, flounder, halibut, pollock, skate and sole from the waters in question could be off limits for years, .


Sample fish caught in waters near the stricken reactors suggest there is still a source of caesium either on the seafloor or still being discharged into the sea, perhaps from what is left of the cooling waters. As the levels of radioactive isotopes in the fish are not declining as fast as they should have, the outlook for fishing in the area is likely to be poor for the next 10 years, the paper's author told the Guardian.

"These fish could have to be banned for a long time. The most surprising thing for me was that the levels [of radioactivity] in the fish were not going down. There should have been much lower numbers," said Ken Buesseler, senior scientist at the Woods Hole Oceanographic Institution in the US, who wrote the paper titled Fishing For Answers Off Fukushima.


He said his findings – taken in part from Japanese research and sampling of fish in the area – showed how difficult it was to predict the outcome of a nuclear incident such as that at Fukushima. In 2011, after the earthquake and tsunami that struck Japan on 11 March and killed nearly 20,000 people, the nuclear reactors suffered a series of serious radiation leaks as their cooling systems failed, and workers fought frantically to try to shut them down. It was the world's worst nuclear accident since Chernobyl, in Ukraine in 1986.

In the wake of the incident, the Japanese government sought to calm public fears by lowering the levels of radioactivity that would mean a fish was deemed unsafe for human consumption. As of April 2012, fish can only be sold in Japan if it contains less than 100 becquerels of caesium 134 and 137 in seafood per kilogram of wet weight, down from a previous limit of 500 becquerels.


Buesseler said this was not because scientific advice had changed, but because the government wanted to reassure people. "This is not lethal – I'm not trying to be alarmist," he said. "But the levels [of radioactivity in the fish] are measurable and consistent. It's a small increase in risk."

However, eating large quantities of such fish over a long period could be harmful, he said. Fish is a more important part of the Japanese diet than in countries such as the US and the UK.



...The finding suggests that the region's coastal-dwelling fish are still being exposed to new sources of cesium, possibly from the seafloor or from contaminated groundwater that's flowing into the ocean. And even though most fish sampled in the new study had levels of cesium below safe limits for consumption, some fish contained surprisingly large amounts.

..."If (the cesium) is in the seafloor, it could be many years or even decades for that to go away," said Ken Buesseler, an oceanographer at the Woods Hole Oceanographic Institution in Mass. "That implies we're going to have an issue in coastal fisheries for a long time to come in Japan. We certainly can't say we're out of the woods yet."

..."Just because you haven't read about it in the news" lately, he added, "doesn't mean it has gone away."

...He was immediately struck with the realization that radiation levels in fish had not dropped in the past year. Fish naturally lose a few percent of their concentrations of cesium if they are not re-exposed, Buesseler said, suggesting that the animals are still facing new inputs of the radioactive material.

...More than 40 percent of fish in the region contained levels greater than the new safe-consumption limit of 100 units per kg. Two greenling fish collected this August contained a surprisingly high level of 25,000 units.


For his part, Buesseler ate all of the seafood he was offered on a trip to Japan in July.



Green Oregon: Tuna shows only trace radiation from Japanese nuclear disaster; offers clues to migration

By The Oregonian

October 25, 2012 at 7:39 AM, updated October 25, 2012 at 5:17 PM

Albacore tuna caught off the West Coast show only traces of radiation from the Fukushima nuclear disaster, according to scientists from Oregon State University and the National Oceanic and Atmospheric Administration.

And what radiation is detected is far below anything that would pose a risk to humans who consume the fish, the research team said in a press release Wednesday. The findings are preliminary with additional fish to be tested.

People are constantly exposed to radiation from the natural environment, said Delvan Neville, a graduate researcher with OSU's Radiation Health Physics program and a co-investigator on the project. "To increase their normal annual dosage of radiation by just 1 percent, a person would have to eat more than 4,000 pounds of the highest (radiation) level albacore we've seen."
人々は常に自然環境から被曝しているのだ、とオレゴン大学の放射線保健物理学の新卒調査員であり、このプロジェクトの共同調査員Delvan Neville氏は言いました。「通常の年間放射線被曝量を1%上げるためには、私たちが調べたビンナガマグロで最も高かった放射能レベルのものを4000ポンド(1014kg)以上食べなければなりません。」

Neville will present the team's preliminary findings Monday at the Heceta Head Coastal Conference in Florence.
Neville氏は、この予備検査の結果を、月曜日にフローレンスで行われるHeceta Head Coastal会議で発表します。

The OSU team's findings are consistent with those of California researchers who announced in May traces of Fukushima-linked radionuclides in bluefin tuna.

But finding the trace radiation in albacore is giving clues to the fish and its elusive migration patterns.


The researchers first identified two Fukushima-linked isotopes - Cesium-137 (Cs-137) and Cesium-134 (Cs-134) - this July, in samples of fish caught and frozen in 2011. Cs-134, in particular, is considered key to the Fukushima nuclear "fingerprint."
As more fish were tested, the results were consistent with the initial findings: No Cs-134 in fish caught before the disaster, but traces of the isotope in a significant number of fish caught since, according to the announcement.

"What we can say is that we have detected Cs-134 in fish thousands of miles from where that Cs-134 came from, and over a year since it was released," Neville added. "It's very interesting scientifically, and it can tell us more about tuna migration and what happens to radioactive releases, but it's nowhere near enough to be concerned about food safety."

-- The Oregonian

The Associated Pressの関係記事より抜粋

...Albacore tuna is a $41 million business in the Pacific Northwest, and fishermen from the region caught about 10,000 tons last year, according to the U.S. Department of Commerce.

Washington fishermen accounted for about 53 percent of the haul, and the remainder came through Oregon docks.


The U.S. Environmental Protection Agency, Food and Drug Administration and NOAA have jointly stated they have "high confidence" in the safety of U.S. seafood products because the radiation levels are so low.

The News Line onlineより抜粋

...Anglers at the Port of Ilwaco said they don't expect the news will cut into business because the amount is so small.

"Everything in the ocean has some type of contaminant in it. It's such a miniscule amount that you get more radiation walking by an X-ray machine," said Milt Gudgell, owner of Pacific Salmon charters, which operates four charter tuna boats during the tourist season.
「海のものは全て何かしら汚染されています。そのようにあまりにも少ない量で、レントゲンをかける方がよっぽど多くの放射線を浴びるのです。」とパシフィックサーモンチャーターズのオーナー、Milt Gudgell氏は言いました。観光シーズンには、4隻のマグロ釣りボートを運航しています。


注: 健康被害を問題ない、とする報告は、一般市民を守るためではなく、他の大きな勢力を守るためであることが多いことを、心に留めておきましょう。

Note: Please keep it in mind that the announcement reassuring people about the safety of small amount of radiation exposure is generally not aiming to protect their citizen or someone vulnerable, but to protect someone very strong with huge power.

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