Thursday, March 29, 2012

Woods Hole's Study of Radioactivity in Pacific Ocean in June 2011: "Not Likely to Be Direct Threat" to Marine Life

(UPDATE: The researcher seems to have had a change of heart somewhat since December. See my latest post.)


Woods Hole Oceanographic Institute did the only marine survey by international researchers approved by the Japanese government in June 2011. The summary of the survey result, I just found out, was posted on their website on December 6, 2011.

Their conclusion:

Their study finds the levels of radioactivity, while quite elevated, are not a direct exposure threat to humans or marine life, but cautions that the impact of accumulated radionuclides in marine sediments is poorly known.

From Woods Hole Oceanographic Institute press release (12/6/2011; emphasis is mine):

Researchers Assess Radioactivity Released to the Ocean from the Fukushima Dai-Ichi Nuclear Power Facility

With news this week of additional radioactive leaks from Fukushima nuclear power plants, the impact on the ocean of releases of radioactivity from the plants remains unclear. But a new study by U.S. and Japanese researchers analyzes the levels of radioactivity discharged from the facility in the first four months after the accident and draws some basic conclusions about the history of contaminant releases to the ocean.

The study, conducted by Woods Hole Oceanographic Institution chemist Ken Buesseler and two Japanese colleagues, Michio Aoyama of the Meteorological Research Institute and Masao Fukasawa of the Japan Agency for Marine-Earth Science and Technology, reports that discharges from the Fukushima Dai-Ichi nuclear power plants peaked one month after the March 11 earthquake and tsunami that precipitated the nuclear accident, and continue through at least July. Their study finds the levels of radioactivity, while quite elevated, are not a direct exposure threat to humans or marine life, but cautions that the impact of accumulated radionuclides in marine sediments is poorly known.

The release of radioactivity from Fukushima—both as atmospheric fallout and direct discharges to the ocean—represent the largest accidental release of radiation to the ocean in history. Concentrations of cesium-137, an isotope with a 30-year half life, at the plants's discharge point to the ocean, peaked at over 50 million times normal/previous levels, and concentrations 18 miles off shore were much higher than those measured in the ocean after the Chernobyl accident 25 years ago. This is largely due to the fact that the Fukushima nuclear power plants are located along the coast, whereas Chernobyl was several hundred miles from the nearest salt water basins, the Baltic and Black Seas. However, due to ocean mixing processes, the levels are rapidly diluted off the Northwest coast of Japan.

The study used publically available data on the concentrations of cesium-137, cesium-134, and iodine-131 as a basis to compare the levels of radionuclides released into the ocean with known levels in the sea surrounding Japan prior to the accident. Impacts of the Fukushima Nuclear Power Plants on Marine Radioactivity is published in the latest issue of Environmental Science & Technology and is available on the journal's website. Buesseler received funding support for this work from the Gordon and Betty Moore Foundation and the National Science Foundation’s Chemical Oceanography program.

The investigators compiled and analyzed data on concentrations of cesium and iodine in ocean water near the plants’s discharge point made public by TEPCO, the electric utility that owns the plants, and the Japanese Ministry of Culture, Sports, Science and Technology (MEXT). The team found that releases to the ocean peaked in April, a fact they attribute to “the complicated pattern of discharge of seawater and fresh water used to cool the reactors and spent fuel rods, interactions with groundwater, and intentional and unintentional releases of mixed radioactive material from the reactor facility.” They also found that the releases decreased in May by a factor of 1000, “a consequence of ocean mixing and a primary radionuclide source that has dramatically abated,” they report.

While concentrations of some radionuclides continued to decrease, by July they were still 10,000 times higher than levels measured in 2010 off the coast of Japan. This indicates the plants “remain a significant source of contamination to the coastal waters off Japan,” they report. “There is currently no data that allow us to distinguish between several possible sources of continued releases, but these most likely include some combination of direct releases from the reactors or storage tanks, or indirect releases from groundwater beneath the reactors or coastal sediments, both of which are likely contaminated from the period of maximum releases.

Buesseler says that at levels indicated by these data the releases are not likely to be a direct threat to humans or marine biota in the surrounding ocean waters, but says there could be concern if the source remains high and radiation accumulates in marine sediments. “We don’t know how this might impact benthic marine life, and with a half-life of 30 years, any cesium-137 accumulating in sediments or groundwater could be a concern for decades to come,” he said.

In June, Buesseler led the first international, multidisciplinary assessment of the levels and dispersion of radioactive substances in the Pacific Ocean off the Fukushima Dai-Ichi nuclear power plants—a major research effort also funded by the Gordon and Betty Moore Foundation. During the research expedition, a group of 17 researchers and technicians spent two weeks aboard the University of Hawaii research vessel R/V Kaimikai-O-Kanaloa examining many of the physical, chemical, and biological characteristics of the ocean that determine the fate of radioactivity in the water and potential impact on marine biota. The results of their initial assessments will be presented in Salt Lake City in February 2012 at the Ocean Sciences Meeting, an international gathering of more than 4,000 researchers sponsored by The Oceanography Society, the American Society of Limnology and Oceanography, and the American Geophysical Union.

While international collaborations for comprehensive field measurements to determine the full range of isotopes released are underway, it will take some time before results are available to fully evaluate the impacts of this accident on the ocean.

"However, due to ocean mixing processes, the levels are rapidly diluted off the Northwest coast of Japan." - Uh... northwest? Fukushima I Nuclear Power Plant is in the northeast part of Japan.

That aside, I am puzzled by their conclusion that the releases of radioactive materials into the seawater, which is on-going, are not likely to be a direct threat to marine life, when fish and abalones from the coastal water of northeast Japan have been found with high concentration of radioactive cesium and radioactive silver. Researchers have found plankton far off the coast of Fukushima with concentrated radioactive cesium.

Is it possible that all the Woods Hole researchers took as samples was ocean water, and not marine life (plankton, seaweeds, fish, shellfish, etc.)?

Or are they saying few hundred becquerels/kg of radioactive cesium won't affect the fish?


Anonymous said...

they took samples of marine life (plankton, seaweeds, fish, shellfish, etc.). Last report they published the radiation levels were quite high (mutliples of Chernobyl in Ocean) maybe quite far out & to deep ocean floor to measure it is lower. Also, probably had to do a catch22 and downplay in someway in order to survive.

Atomfritz said...

Most marine animals wander for long paths.
So maybe only one of thousand fish in the nets could be highly-radioactive.
It's unlikely that at the little number of samples the researchers will catch one of these radioactive fish.

You'll never know except if you have the equipment to check whether the fish you bought is a "bad" one.

It could even become worse if some earthquake makes the tank farms rip open, because then the "cesium indicator" for radiation will be missing.
And every fish that has been near Fuku-I could be an "internal nuclear bomb" to your health.

Anonymous said...

Poor all the radioactive water in the ocean then. The amount of contamination of the sea so far is extremelly high, if this causes no health problem then poor all the waste water in it. We can also dump all spent fuel rod in it as well, hey! it causes no danger.
The IAEA has been far over protecting everyone. Every nuclear wastes can actually be just put in water without risk.
Strange that was not accepted before Fukushima! Also because of Fukushima, we also now know that we can work, clean, eat, breath and drink radionuclides and radioactivity without risk. Thank you very mcuh IAEA, Japan, Cananda, US, France and UK. 5 leading countries killing children without raising an eyebrow.

Anonymous said...

To Laprimavera,

LINK FOR FULL TEXT/PDF OF WOODS HOLE PAPER: "Impacts of the Fukushima Nuclear Power Plants on Marine Radioactivity". Here:

Coverage of this research appeared in the news and science press a few months ago, in the US and Canada. I just located the full text of the paper and will read it shorty. FWIW, during the BP oil spill in the Gulf of Mexico, in 2010, some other Woods Hole scientists published several first-rate, peer-reviewed research papers on the problem. That being said, this paper may prove to be a different story.

Cheers, JP

Lawrence N. Allen said...

So why did a group of North Pacific whales brave the newly opened arctic ocean ans swim to the North Atlantic (with the help of Russian ice breakers) if there were not a sudden die off of plankton in their normal environment. I doubt they were sensitive to Cesium levels.

Yosaku said...

Off topic, but farfromhome, if you're out there, I thought you might be interested in yesterday's NYT op-ed regarding radon exposure in the US (

This picks up on our earlier discussions of why, from a pure radiological risk perspective, I feel my family is safer in Tokyo than if we were to move home.

One data point that struck me:

"The resulting study of 927 public schools concluded that over 70,000 classrooms in the United States were likely to have radon concentrations that equal or exceed the E.P.A.’s action level [of four picocuries per liter of air]." (4 pCi/L is about 150 Bq/m3)

To calculate the corresponding yearly effective dose, multiply 150 Bq/m3 by the applicable conversion factor of 9 nSv (Bq·h/m3)−1 and let's assume that your child spends 8 hours a day, 200 days a year in the classroom. That adds up to an extra 2.16 mSv per year.

Anonymous said...

To Laprimavera,

UPDATE: Woods Hole scientist Ken Buesseler just did an update for CNN, on March 11, 2012. TITLE: "What Fukushima Accident did to the Ocean". LINK:

Note that Buesseler did this update following the Ocean Sciences Meeting (an international gathering of marine scientists studying radioactive substances in the ocean originating from Fukushima), held in Salt Lake City, Utah, from February 20-24th, 2012. It appears Buesseler has changed his tune somewhat since last June when he took samples from seawater in Japan.

Here's an excerpt from Buesseler's CNN report:

..."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."

..."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."

..."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."


arevamirpal::laprimavera said...

Thanks JP for your information and update.

Anonymous said...

To Laprimavera,

I found a 534 page LIST OF ABSTRACTS from the recent Ocean Sciences Meeting regarding the impact of Fukushima radiation on the ocean. LINK:

It's pretty dense reading, as you might imagine. Maybe somebody around here will drill down on the contents. Note, the North American press didn't give this conference much coverage at all.



Anonymous said...

Hey Laprimavera,

Thanks for saying hello. From my perspective, Ken Buesseler is now speaking as if he believes his previous "no harmful effects" research paper was rather say the least. It's very regrettable: that paper got a ton of attention and probably has left many people with the lasting impression that there is nothing much to worry about when it comes to the global marine ecosystem. Bummer.


Chibaguy said...

@Yosaku - external exposure cannot be compared to internal exposure. I think you know this. If you live in Tokyo then you know why a day does not pass without sirens.

Anonymous said...

The report is a complete crock of shite!What a bunch of asses at Hole! Anyone who has been observing the increasing presence of radioactive isotopes (far more than just cesium, iodine),and the dead and dying marine life all along the west coast and elsewhere knows better, what a sad species we humans have evolved to be.

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