After Japan nuclear power plant disaster: How much radioactivity in the oceans?

After Japan Nuclear Power Plant Disaster: How Much Radioactivity in the Oceans?
Radiation level in the oceans in 1990, mostly from nuclear weapons testing, measured in Becquerels. Credit: Woods Hole Oceanographic Institution

Among the casualties of the March 11, 2011, earthquake and resulting tsunami in Japan was the country's Fukushima Daiichi nuclear power plant.

A result of the loss of electricity, overheating at the power plant led to significant releases of iodine, cesium and other radioisotopes to the environment.

Japanese officials recently raised the severity of the incident to level 7, the highest level on the international scale and comparable only to the Chernobyl incident 25 years ago, says Ken Buesseler, a chemical oceanographer at the Woods Hole Oceanographic Institution.

"When it comes to the oceans, however," says Buesseler, "the impact of Fukushima exceeds Chernobyl."

Radionuclides in seawater have been reported from the Fukushima plant's discharge canals, from coastal waters five to ten kilometers south of the plant, and from 30 kilometers offshore.

"Levels of some radionuclides are at least an order of magnitude higher than the highest levels in 1986 in the Baltic and Black Seas, the two water bodies closest to Chernobyl," says Buesseler.

After Japan nuclear power plant disaster: How much radioactivity in the oceans?
Satellite image from 160 kilometers (100 miles) north of the Fukushima nuclear power plant in Japan. Japan's two large ocean currents--the Kuroshio and the Oyashio--converge here. Credit: NASA

He has been awarded a rapid-response grant from the National Science Foundation's (NSF) Division of Ocean Sciences to establish baseline concentrations of several radionuclides in the Atlantic and Pacific Oceans.

"Finding this information early on is key to understanding the severity of the releases and related public health issues," says Buesseler.

He and colleagues will establish a baseline radionuclide data set for the Atlantic and Pacific Oceans, using an east-to-west network of sampling stations where the ability to retrieve samples already exists.

Researchers learned much from Chernobyl about the fate of delivered to the oceans, and about using that fallout as a "tracer" for how fast ocean waters mix and sediments accumulate.

"After Chernobyl, fallout was measured not only in samples close to the site, such as those in the Black Sea, but as far afield as the north Pacific Ocean," Buesseler says.

Because the atmosphere and oceans are linked, scientists would expect radionuclides present in the atmosphere also to appear in the ocean, albeit at very low levels, says chemical oceanographer Henrieta Dulaiova of the University of Hawaii.

Dulaiova has also been awarded a rapid-response grant from NSF's Division of Ocean Sciences to study the fallout.

She is monitoring ocean waters to establish baseline concentrations of radionuclides, and to determine the spreading of released radionuclides.

"Like the people of Japan--though certainly to a lesser degree--we are dealing with a radiochemical situation that will be with us for a long time," says Don Rice, director of NSF's chemical oceanography program.

"To understand how the ocean and atmosphere have handled this contamination in the years ahead, we must first get a snap-shot of the situation today," says Rice. "Buesseler and Dulaiova are doing just that."

After Japan nuclear power plant disaster: How much radioactivity in the oceans?
Human sources of radiation in the atmosphere, compared with natural radionuclides in the ocean. Credit: Jack Cook, Woods Hole Oceanographic Institution

Dulaiova's study is focused on the central Pacific Ocean, and includes coastal and offshore waters off Hawaii, Guam and the Midway Islands.

"Hawaii's proximity to Japan makes it an important monitoring point," says Dulaiova. "We're conducting weekly coastal and monthly offshore water sample collections."

Bi-weekly samples from Guam are also collected, and samples are obtained from ships cruising the western Pacific.

The samples are then analyzed for cesium isotopes, whose signature allows scientists to identify radionuclides released from .

Dulaiova is also planning to look at other radionuclides such as iodine, strontium and some actinides that were released.

"The information is needed," she says, "so that any subsequent efforts to understand the severity of the releases, the bioaccumulation of radionuclides in the ocean food web, and ocean processes and spreading patterns of the released radioisotopes, all have good baseline data."

The researchers hope to develop an understanding of marine radionuclides on a global scale.

Explore further

Researchers track Chernobyl fallout

Citation: After Japan nuclear power plant disaster: How much radioactivity in the oceans? (2011, May 19) retrieved 15 October 2019 from
This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.

Feedback to editors

User comments

May 19, 2011
"When it comes to the oceans, however, the impact of Fukushima exceeds Chernobyl."

I hope this frightening statement is not just an attempt to get more funding for NSF in the upcoming budget review.

Earth's actual radioactivity has decreased ever since our elements were ejected from the Sun ~5 Gyr ago:


Will levels of radioactivity in the ocean now go as high as they were:

a.) 4 Gyr ago?
b.) 1 Gyr ago?
c.) 0.001 Gyr ago?
d.) After nuclear weapons tests?
e.) After nuclear waste was dumped in the oceans?

Which radioactivity should we be most concerned about?

The radioactivity of biological active elements produced by fission, iodine (I) and strontium (Sr)?

Quantitative answers would be appreciated.

With kind regards.,
Oliver K. Manuel
Former NASA Principal
Investigator for Apollo

May 19, 2011
A question asked(in the title of this useless article), a question unanwered. This article is nothing but fluff, but interestingly, I've heard of this oliver guy and he seems to have worded it a little better.

You're not going to get reliable data just listen to the crap the mainstream media is spewing out and constantly back peddling on! The government of japan too! How on earth is raising radiation tolerances by a thousand fold? The US too. And how responsible is it to shut off almost all your radiation monitoring stations? Canada too!

My only response is this:
it doesn't matter how much radioactivity, it matters what kind first and foremost!

Cesium and strontime are great slow deaths!

May 19, 2011
Of course you sign non-disclosure with signing on to nuclear.

What are you talking about?


The IAEA has been tracking and releasing information to the public about the Fukushima situation and the radiation levels in the surrounding areas since the earthquake.

Just because you choose not to look for information doesn't mean it's not there.

May 19, 2011
My Japanese friend showed me a picture of a dandelion in his prefecture that had grown to one meter in height. He also says
that the government and news media downplay the gravity of the
situation, while few people believe anything they're told.

May 19, 2011
My Japanese friend showed me a picture of a dandelion in his prefecture that had grown to one meter in height. He also says that the government and news media downplay the gravity of the situation, while few people believe anything they're told.

Few people here now believe government reports too.


Is it because politicians have misused government science in the way that former President Eisenhower warned might happen one day?

May 19, 2011
Ok - radioactivity extremely important immediately after and up to a point after the disaster - but at what point bet. the half-life of the radiation and the amount of sea water dilluting it do we need to stop worrying about its effects- at what point would levels be low enough to stop worrying about it?

May 20, 2011
There. The three words in parenthesis has saved you the embarrassment of appearing sympathetic towards an unrestricted information flow between industry and organization.

Obviously some information was/is supplied by Tepco, but the IAEA sends its own surveyors and other radiation monitoring personnel to do the monitoring of the radiation levels in the environment and foods away from the plant.

The Tepco information is typically about the condition in the plant at any given time. They were relied on more in the early stages of the accident. The IAEA now has personnel stationed there as well. You should actually read what's on the website I linked you before you immediately dismiss it.

You can't say that no information is provided and then ignore the information you're given.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more