Scientists continue to study the effects of radioactive contaminants on the marine environment following the earthquake, tsunamis, and resulting radiation leads from the Fukushima Dai-ichi nuclear power plant in Japan. On March 11, 2011, a 9.0 magnitude earthquake 80 miles off the Northeast Coast of Japan triggered a series of tsunamis that struck nearby shorelines with only a few minutes’ warning. The disaster left dozens of villages along nearly 200 miles of coast heavily damaged or completely destroyed.
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Radioisotopes Tracking Tuna Migration
Bluefin tuna born before the Fukushima disaster did not have elevated levels of cesium-134, but those caught in August 2011 did.
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Cesium-137 movement from Fukushima in coastal saters
Radioactive cesium from Fukushima was carried by currents, trapped in beach sands, then released back to the ocean as saltwater conditions changed.
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Infographic measuring amount of radioisotopes at 3 different nuclear disasters
The Fukushima disaster resulted in an unprecedented release of radioisotopes into the ocean.
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June 2011 Cesium-134 levels in the Pacific
Researchers on the Kaimikai o-Kanaloa found the Kuroshio Current blocked the southward flow of radioisotopes, trapping high levels south of Fukushima.
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Anatomy of the Fukushima earthquake and tsunami
Before and after the Fukushima earthquake and tsunami.
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Radioactivity in the Ocean: Natural vs. Human Sources
Nuclear accidents released PBqs of radiation, but natural sources like potassium-40 far exceed them—15 million PBq already exist in seawater.
The waves, some of which measured more than 40 feet, also struck the Fukushima Dai-ichi nuclear power plant 150 miles north of Tokyo, disabling the plant’s emergency systems and causing emergency crews to use seawater to cool the damaged reactors. Because of the plant’s location along the coast, much of the water washed into the Pacific, resulting in the largest accidental release of radiation to the ocean in history. Additional airborne radioactive material from the explosions and fires at the plant fell onto the sea surface, where it too mixed into the water, as did subsequent leaks from tanks on the site holding treated water.
Frequently asked questions
FAQ: Japan Earthquake and Tsunami
On March 11, 2011, a magnitude 9.0 thrust-fault quake 80 mi east of Honshu, Japan, ruptured the subducting Pacific plate, triggering a massive tsunami.
Within months of the accident, Ken Buesseler, a senior scientist at the Woods Hole Oceanographic Institution (WHOI), assembled a research cruise and science party of 17 people from eight institutions to sample the waters surrounding the nuclear plant. The scientists found elevated levels of the nuclear by-product cesium but they were below the threshold of concern for direct human exposure. The levels of cesium had diminished quickly off shore because cesium is soluble in seawater and was therefore diluted by the Pacific ocean currents. They also measured cesium and other radionuclides in plankton and fish and, in subsequent cruises, collected sediments from the seafloor near the plant. To this date, important fisheries off Fukushima remain closed due to levels of cesium that are above Japanese limits for seafood.
Through the newly established Center for Marine and Environmental Radioactivity (CMER), Buesseler continues to promote public education, training in marine radiochemistry, and research and engineering related to Fukushima and other natural and human sources of radioactivity.
Frequently asked questions
FAQs: Radiation from Fukushima
Fukushima’s 2011 nuclear accident released radioactive isotopes into the ocean; levels have since decreased but ongoing monitoring continues. Learn more in this Q & A article.
References
Fukushima and Radiation in the Ocean: How much?
Interactive feature
Fukushima by the numbers
Infographic
5 years later, Fukushima radiation continues to seep into the Pacific Ocean
Op-Ed by Ken Buesseler featured on PBS NewsHour
How Radioactive is Our Ocean?
Citizen science campaign aims to collect ocean samples and fund radiation analysis.
Fukushima Radiation in the Pacific
June 3 – 17, 2011
Tsunamis
People educated about tsunamis can save their own lives and the lives of others.
Tsunami Information
NOAA
Earthquake Hazards Program
USGS
Pacific Tsunami Warning Center
NOAA
Fukushima and the Ocean
Thursday, May 9, 2013
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