Woods Hole Q&A on #Fukushima Radiation and Fish

Ken Buesseler at Woods Hole Oceanographic Institution has been researching the marine life and how it is affected by the Fukushima I Nuclear Power Plant accident that has released significant amount of radioactive materials into the Pacific Ocean.

He has a page with questions that he gets from people concerned about the radiation in marine life and his answers.

From Q&A by Ken Buesseler at Woods Hole Oceanographic Institution (emphasis in the answers is mine):

What is the state of fisheries off Japan and along U.S. West Coast?

The coastal fisheries remain closed in Japan near Fukushima, where there is a concern for some species, especially the bottom dwelling ones, which are being tested and many have been found to be above the Japanese government's strict limits for cesium in seafood. These contaminated fish are not being sold internally in Japan or exported. Because of the dilution that occurs even a short distance from Fukushima, we do not have a concern about the levels of cesium and other radionuclides in fish off the West Coast of the U.S.

More about the state of Japanese fisheries (pdf).

Are fish such as tuna that might have been exposed to radiation from Fukushima safe to eat?

Seawater everywhere contains many naturally occurring radionuclides, the most common being polonium-210. As a result, fish caught in the Pacific and elsewhere already have measurable quantities of these substances. Most fish do not migrate far from home, which is why fisheries off Fukushima remain closed. But some species, such as the Pacific bluefin tuna, can swim long distances and could pick up cesium in their feeding grounds off Japan. However, cesium is a salt taken up by the flesh that will begin to flush out of an exposed fish soon after they enter waters less affected by Fukushima. By the time tuna are caught in the eastern Pacific, cesium levels in their flesh are 10-20 times lower than when they were off Fukushima. Moreover, the dose from Fukushima cesium is considered insignificant relative to the dose from naturally occurring polonium-210, which was 1000 times higher in fish samples studied, and both of these are much lower relative to other, more common sources, such as dental x-rays.

More about the dose and associated risk (pdf) of radiation from Fukushima to marine life and humans.

Is there concern about other radionuclides, such as strontium-90?

The continued release of radionuclides from groundwater and leaking tanks at Fukushima nuclear power plants site needs to be watched closely, as the character or mix of radionuclides is changing. One example is the higher levels of strontium-90 contained in groundwater and storage tanks that are leaking into the ocean. Because strontium-90 mimics calcium, it is taken up by and concentrated in bones, where it remains for long periods of time (it has a half-life of 30 years and calcium/strontium is not replaced as quickly in the body as cesium). If leaks of strontium-90 continue, this radionuclide could become a larger concern in small fish such as sardines, which are often eaten whole. So far, however, evidence suggests that levels in fish of strontium-90 remains much lower than that of cesium-137.

Is radiation exposure still a concern?

I stood on a ship two miles from the Fukushima reactors in June 2011 and as recently as May 2013, and it was safe to be there (I carry radiation detectors with me) and collect samples of all kinds (water, sediment, biota). Although radioactive isotopes in the samples and on the ship were measurable back in our lab, it was low enough to be safe to handle samples without any precautions. In fact, our biggest problem is filtering out natural radionuclides in our samples so we can measure the trace levels of cesium and other radionuclides that we know came from Fukushima.

Where does radiation from Fukushima go once it enters the ocean?

The spread of cesium once it enters the ocean can be understood by the analogy of mixing cream into coffee. At first, they are separate and distinguishable, but just as we start to stir the cream forms long, narrow filaments or streaks in the water. The streaks became longer and narrower as they moved off shore, where diffusive processes began to homogenize and dilute the radionuclides. In the ocean, diffusion is helped along by ocean eddies, squirts, and jets that broaden, mix, and continue to dilute the cesium as it travels across the ocean. With distance and time, radionuclide concentrations become much lower in the ocean, something that our measurements confirm.

More information about our oceanographic studies off Fukushima (pdf).

Are the continued sources of radiation from the nuclear power plants of concern?

The site of the Fukushima Dai-ichi nuclear power plant is an ongoing source of radionuclides (pdf) in to the ocean—something I've seen evidence of in my data and published about since 2011. Although the numbers sound large (300,000 gallons of water leaked or 20 trillion bequerels [sic] per liter), we calculated in 2011 when radiation levels were much higher than today that the dose to someone on a ship or in the ocean was not of concern. For the workers at the site, direct exposure from leaking storage tanks is of greater health concern because exposure from these concentrated sources is much higher. For the general public, it is not our direct exposure, but uptake by the food web and, hence, the potential for human consumption of contaminated fish that is the main health concern.

Will radiation be of concern along U.S. and Canadian coasts?

Levels of any Fukushima contaminants in the ocean will be many thousands of times lower after they mix across the Pacific and arrive on the West Coast of North America some time in late 2013 or 2014. This is not to say that we should not be concerned about additional sources of radioactivity in the ocean above the natural sources, but at the levels expected even short distances from Japan, the Pacific will be safe for boating, swimming, etc.

Is debris washing ashore on the US/Canadian West Coast of concern?

Debris washed out to sea by the tsunami does not carry Fukushima radioactive contamination—I’ve measured several samples in my lab. It does, however, carry invasive species, which will be of serious concern to coastal ecosystems on the West Coast.

Have there been increased deaths as a result of radiation from Fukushima?

Reports of increased deaths are simply not true. Read this reasoned response in Scientific American to the most often-cited "scientific" paper about erroneously linking deaths to radiation from Fukushima. That article ends “This is not to say that the radiation from Fukushima is not dangerous (it is), nor that we shouldn’t closely monitor its potential to spread (we should).” I agree with that statement.

Where can people go for reliable information?

Here are some other links I have passed to others.
Fukushima's Radioactive Water Leak: What You Should Know
http://news.nationalgeographic.com/news/energy/2013/08/130807-fukushima-radioactive-water-leak/
Latest Radioactive Leak at Fukushima: How Is It Different?
http://news.nationalgeographic.com/news/energy/2013/08/130821-fukushima-latest-leak-how-is-it-different/
See also following article from the Woods Hole Oceanographic Institution (w/ links to many others)
http://www.whoi.edu/oceanus/viewArticle.do?id=167749&sectionid=1000
From the special issue of Oceanus Magazine devoted to the cause and impacts of Fukushima:
http://www.whoi.edu/oceanus/series/fukushima
Consider supporting our new Center for Marine and Environmental Radioactivity and check out CMER public education links, such as ABCs of radioactivity
http://www.whoi.edu/page.do?pid=119836

(I wish he didn't mention the dental x-rays...)

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Woods Hole Scientist's Latest View on Ocean Contamination from Fukushima Accident: "We Haven't Gone Very Far" in Assessing the Extent, Damage

Wood's Hole Oceanographic Institute researcher Ken Buesseler wrote a special article for CNN on March 11, 2012 about the effect that radioactive materials released from Fukushima I Nuclear Power Plant have had on the ocean and marine life. He led a team of international researchers last June to survey the ocean where the contaminated water was dumped by TEPCO.

He seems more concerned now than when the initial report of the June survey was released (see my previous post).

From CNN (3/11/2012):

What Fukushima accident did to the ocean
By Ken Buesseler, Special to CNN

(CNN) -- One year ago, a series of events began with an earthquake off the cost of Japan that culminated in the largest accidental release of radioactivity into the ocean in history.

We have to be careful and say "accidental" because in the late 1950s and early 1960s, 50 to 100 times more radioactivity was released worldwide as fallout from the intentional testing of nuclear weapons. The word "ocean" is also important, since Chernobyl in 1986 was hundreds of miles inland, so it had a smaller impact on the concentrations of radionuclides in the sea than was measured directly off Japan in 2011.

One year later, we have to ask, what do we know about Fukushima's impact on the ocean and levels of radioactive contaminants in water and fish?

In many ways we were fortunate that impacts were largely confined to the ocean. Certainly, the Japanese people continue to feel devastating effects of so large a release within their country, and many people may never be able to return to their homes. But in general the winds during the height of the accident at the Fukushima Daiichi nuclear power plant were blowing offshore. As a result, more than three-quarters of the radioactivity fell on the ocean. This is important, as any that lands on soil remains in place, resulting in the potential for greater human exposure and increased chances of contamination to food supplies and property.

In the Pacific, however, the strong Kuroshio Current (similar to the Atlantic Gulf Stream) helped move any contamination quickly away from shore and diluted it by mixing it into deeper water.

This allowed us to report that by June 2011, even when we sampled within sight of the nuclear power plants, levels of cesium-137 and cesium-134 in the ocean, two primary products of nuclear fission, were elevated, but still below those considered of concern for exposure to humans. They were also well below biological thresholds of concern to the small fish and plankton we sampled, even if these were consumed by humans.

Several other groups have now confirmed our findings about levels of radioactivity up to 400 miles offshore.

Other measurements show trends that are more worrisome. Levels of radioactivity found in fish are not decreasing and there appear to be hot spots on the seafloor that are not well mapped. There is also little agreement on exactly how much radioactivity was released or even whether the fires and explosions at the power plant resulted in more radioactive fallout to the ocean than did direct releases of radioactivity caused by dumping water on the reactors to keep them cool.

Japan is taking what some think of as a precautionary measure by lowering the limits of radioactive contaminants in drinking water and food supplies, including seafood, on April 1.The new level for fish will be one-tenth of the acceptable level in the United States. Will Japan's new limits build consumer confidence or raise fears and questions about why more fish are considered unsafe for consumption? And why were fish caught last year considered safe, but now are not?

Despite the announcement in December that operators of the power plant had achieved cold shut down, we know they are still using tons of water to cool the reactors and that not all the water has been collected or treated. As a result, the ground around the site is like a dirty sponge, saturated with contaminated water that is leaking into the ocean.

Marine sediments are also collecting radioactive contaminants, exposing bottom-dwelling fish, shellfish and other organisms on the sea floor to higher levels of contaminants than those in the waters above. Little is known, however, about the level of contamination in the groundwater and on the seafloor and whether these will be a source of contaminants long after levels in the ocean have become diluted to the point that only the most sensitive instruments can detect them.

We do know that we can detect cesium at very dilute levels, well below those considered harmful. Using these sensitive techniques we can track the Fukushima contaminants as ocean currents carry the peak releases across the Pacific where they are expected to reach the U.S. West Coast in 2013-2014 at levels that are much lower than we measured off Japan in 2011 and thus not of concern to human health.

Two weeks ago, we held the largest international gathering of marine scientists studying radioactive substances in the ocean originating from Fukushima. Although we shared freely what each of us has learned in the last year, what we need today is also what we needed on March 11, 2011 — greater international coordination of long-term studies of the fate and consequences of the radiation. We've done the initial assessments. Now we need to begin answering the tougher questions, building public confidence in scientific studies by having multiple, independent groups at work, and ensuring we have the resources to build comprehensive, long-term studies.

As a scientist and a marine radiochemist, I am trained to provide answers about radioactivity in the ocean—how much is out there, where it is, and what its fate is likely to be in the future. Today, we haven't gone very far beyond the first question, which was key on March 11, 2011, but hardly seems sufficient one year later.

We're no wiser one year after the accident, whether it is about:

• the Fukushima I Nuke Plant accident itself;
• how much radioactive materials have been released so far;
  
• degree of contamination on land or in the ocean;
  
• effect of radiation on heath of humans (the national government is not taking health statistics in Fukushima Prefecture), animals, and plants
  

The Japanese government and government researchers cannot deal with any of these effectively. The Kan administration turned down the offer for help from the US and other nations for the Fukushima I Nuke Plant accident, citing some "national security" concerns. Mr. Edano, current Minister of Economy, Trade and Industry and then-Chief Cabinet Secretary under PM Kan, still says he, as Chief Cabinet Secretary, did not turn down the offer but told the US and others "We will consider your offer". That is, as fans of Sir Humphrey Appleby know, a bureaucrat/politician speech for "get lost". Will this change? Not very likely.

As Mr. Buesseler would know, there are different movements of seawater depending on the depth and proximity to the coast in addition to a major move by a major current like "Kuroshio". Significant amount of radioactive materials moved south along the coast, creating ever-shifting hot spots along the way, contrary to what the government researchers had assured the public (that they would be carried away by Kuroshio and disperse rapidly and evenly in the Pacific Ocean).

Mr. Buesseler may also be interested to know that squid, crab, and abalone have been found to highly concentrate radioactive silver from the ocean environment with ND level of radioactive silver (see my post on abalone). The ND levels of radioactive materials can still become harmful, because of bioconcentration.

The Chinese survey ship was finding radioactive strontium in the firefly squid 800 kilometers off the coast of Fukushima, back in August 2011. They also found radioactive silver. (See my post from August 2011.)

(H/T reader JP for CNN article)

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