How does it work?

Help us by mobilizing your community, school, or social networks to raise the money it takes to analyze 20 liters (about 5 gallons) of seawater for signs of radiation from Fukushima. We'll send you everything you need to take a sample and return it to us.

Find Out more

Educate Yourself

Should I be worried?

The ocean contains many small sources of naturally occurring radiation that in most places exceeds the dose provided by radioisotopes released from Fukushima. In addition, the remnants of nuclear weapons testing in the 1960s and 70s are also still detectable around the world. Except for locations on land in Japan and sites near the Fukushima Dai-ichi nuclear power plant, all of these sources combined pose little risk to human health. [ MORE ]

To describe the level of radiation in seawater samples, we use Bequerels (Bq), which equal the number of radioactive decay events per second, and report this number per cubic meter (1,000 liters or 264 gallons) of water. A typical sample will likely contain less than 10 Bequerels per cubic meter (Bq/m3) from cesium-137, thousands of times less than the radioactivity produced by naturally occurring isotopes such as potassium-40. By comparing the amount of cesium-137, which has a relatively long 30-year half life, and cesium-134, which has a much shorter, 2-year half life, we can “fingerprint” the contamination from Fukushima and estimate how much was released into the Pacific.

To understand exposure, we need to consider this number as well as the type of radiation produced (alpha particles, beta particles, or gamma rays) and the method of exposure (external or internal). Exposure is reported in Sieverts (Sv) or, more commonly, milli-Sieverts (mSv, or 0.001 Sv). Background radiation—the amount we receive from cosmic rays—amounts to 2 mSv at sea level. A single dental x-ray provides an exposure of as low as 0.005 mSv. [ LESS ]

Frequently Asked Questions

Find more Frequently Asked Questions about radiation from Fukushima HERE

How radioactive is our ocean?

View a guide to natural and man-made sources of radiation in the environment post-Fukushima.

How radioactive is our ocean?
How radioactive is our ocean?
How radioactive is our ocean?

impacts of radiation in the ocean

WHOI senior scientist Ken Buesseler discusses the presence and effect of radiation from Fukushima on the ocean and marine life.

Fukushima Plume predictions

Radioactive contaminants from Fukushima are carried across the Pacific Ocean by currents, the strongest of which is the Kuroshio, and spread along the West Coast of North America by complex coastal processes. Models predict that radionuclides from Fukushima will begin to arrive on the West Coast in early 2014, mainly in the north (Alaska and British Columbia) and then move further south in coming years before appearing in Hawaii in small amounts. The concentration of contaminants is expected to be well below limits set by the U.S. EPA for cesium-137 in drinking water (7,400 Bq/m3) or even the highest level recorded in the Baltic Sea after Chernobyl (1,000 Bq/m3).


The background level of radiation in oceans and seas varies around the globe. Measured in atomic disintegrations per second (Becquerels) of cesium-137 in a cubic meter of water, this variation becomes readily apparent. The primary source of cesium-137 has been nuclear weapons testing in the Pacific Ocean, but some regions have experienced additional inputs. The Irish Sea in 2008 showed elevated levels compared to large ocean basins as a result of radioactive releases from the Sellafield reprocessing facility at Seacastle, U.K. Levels in the Baltic and Black Seas are elevated due to fallout from the 1986 explosion and fire at the Chernobyl nuclear reactor. By comparison, EPA drinking water standard for cesium-137 is 7,400 Bq/m3. (Data courtesy of MARiS/IAEA and CMER; Illustration by Jack Cook, courtesy Coastal Ocean Institute, Woods Hole Oceanographic Institution)

What About Marine life?

Mouse over the numbers to learn more

Scientists are tracking the many pathways by which radioisotopes from the damaged nuclear reactors at Fukushima make their way into and out of seawater, marine life, and seafloor sediments. These depend on the behavior and metabolism of individual animal, the nature of complex coastal and open-ocean processes, and the physical and chemical properties of individual isotopes.

Tale of the Tuna

Most marine life that becomes contaminated with Fukushima radiation remains near the reactor, but some species, like Bluefin tuna, are far-ranging and even migrate across the Pacific. When these animals leave the Northeast coast of Japan, some isotopes remain in their body, but others, like cesium, naturally flush out of their system. (Credit: Madigan, Baumann, and Fisher )

News & Events


Previous Events

March - April 2019

Fukushima: A view from the ocean
Public Lecture series in Japan by Ken Buesseler

March 19, 2017 • 7:00 pm

Fukushima: A View from the Ocean
Temple University, Japan Campus


January 2018

Radioactivity in the Marshall Islands
BBC Interview

[ MORE ]

More Previous Events

Mon., December 19, 2016

Tests Find Lingering Radiation From Japan On Our Shores
The Jefferson Exchange, Southern Oregon University NPR

Sat., June 11, 2016 • 7:00 pm

Earth: Our Radioactive Home
Facts vs. Misconceptions

Xiamen University Science & Arts Center, China

Fri., July 1, 2016 • 3:30 pm

Fukushima and the Ocean - Five Years Later
Goldschmidt, Pacifico Yokohama, Japan

September 26-30, 2016

Our Radioactive Ocean - Citizen Science to track cesium from Fukushima Conference for Low-Level Radioactivity Measurement Techniques, Seattle, WA

Wed., March 23, 2016 • 6 - 8:30 pm

Tohoku 5th Anniversary Commemoration
U.S.-Japan Council, Boston, MA

Mon., March 1, 2016 • 1 pm

Reddit “Ask Me Anything” Science series with Ken Buesseler

September 14, 2015

Radioactivity In Our Ocean: Fukushima & Its Impact On The Pacific at the Vancouver Aquarium
» View video


October 19, 2015

Ken O. Buesseler: Fukushima Daiichi — a view from two sides of the Pacific
Temple University Japan
» View website

December 14, 2015 • 9-9:30 am

Fukushima: Ocean Impacts and Public Concern
AGU Fall Meeting San Francisco

July 27, 2015 • 9 am

WCAI Radio's Heather Goldstone of Living Lab interviews Ben Lacomte, Ken Buesseler and Linda Amaral Zettle.
» Listen

November 10, 2014 • 1 pm

Reddit "Ask me Anything" on Fukushima ocean impacts
» View website

November 13, 2014

Vancouver presentation on West Coast ORO sampling
» View poster (pdf)

June 18, 2014

Alaska Community Action on Toxics
» Audio presentation

June 5, 2014

Fukushima - A View From The Ocean
Public talk at Vancouver Aquarium
» View video

June 1, 2014

Ocean Sampling Fukushima Radiation at Bodega Head, CA
» View video

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About this Project

The world's oceans contain many of naturally occurring radioactive isotopes, as well as the remnants of nuclear weapons testing in the 1950s and 60s. Starting in 2011, fallout, runoff, and continued leaks from the Fukushima Dai-ichi nuclear power plant added to this baseline and sparked fears of wide-ranging impacts to the marine ecosystem and human health. Despite concerns, there is no U.S. government agency monitoring the spread of low levels of radiation from Fukushima along the West Coast and around the Hawaiian Islands—even though levels are expected to rise over coming years.

Whether you agree with predictions that levels of radiation along the Pacific Coast of North America will be too low to be of human health concern or to impact fisheries and marine life, we can all agree that radiation should be monitored, and we are asking for your help to make that happen.

The Woods Hole Oceanographic Institution has both the experience and facilities to monitor and track the spread of radionuclides released from Fukushima in the waters of the Pacific Coast of North America. The Institution and the Center for Marine and Environmental Radiation (CMER) are uniquely equipped to provide consistent, accurate assessment of both natural and manmade radiation in marine samples and is hosting this site to make this information readily available to everyone in a timely manner.

We live in a Sea of radioactivity.
The danger is in the dose.

- Ken Buesseler, Marine Chemist, Woods Hole Oceanographic Institution -