In this section
Ocean Topics
- Climate & Weather
- How the Ocean Works
- Ocean & Human Lives
- Ocean Life
- Sustainable Ocean
- Ocean Tech

Radiation in the ocean comes from both natural and human-made sources. Naturally occurring radioactive elements have been present in seawater since the formation of Earth. But events like nuclear weapons testing and nuclear power plant accidents have added additional radioactive materials to the marine environment.
A well-known example is the 2011 Fukushima Daiichi nuclear disaster in Japan. After a powerful earthquake and tsunami damaged the power plant, radioactive substances like cesium-137 were released into the Pacific Ocean. Since then, scientists have worked to monitor, study, and explain the effects of this release on ocean ecosystems and human health. Their research helps us better understand how radioactive materials move through and break down in the ocean.
Scientists also investigate areas affected by older sources of contamination, such as the Cold War-era nuclear tests at Bikini Atoll in the Marshall Islands. This work is crucial for long-term monitoring and assessing the health of ocean environments worldwide.
Radiation in seawater is typically measured in becquerels (Bq) per cubic meter. This unit indicates the rate at which radioactive atoms decay. Understanding these measurements helps scientists determine what levels are safe for marine life and for people who depend on the ocean for food and economic activities.
All Topics on Radiation
Fukushima Radiation
On March 11, 2011, a magnitude 9.0 earthquake 80 miles off the northeast coast of Japan triggered a series of tsunamis that struck nearby shorelines and the Fukushima Daiichi nuclear power plant.
Articles Related to Radiation
From Oceanus Magazine
Fukushima and the Ocean: A decade of disaster response
Back to Bikini
Radioactivity Under the Beach?
Communication in the Fukushima Crisis
Radiation Health Risks
Seafood Safety and Policy
Tale of the Tuna
Radioisotopes in the Ocean
ABCs of Radioactivity
Japan’s Triple Disaster
Lessons from the 2011 Japan Quake
Fukushima’s Fallout and Marine Life
News Releases
Mapping the potential path of nuclear wastewater
WHOI’s Ken Buesseler named Geochemistry Fellow
Higher Levels of Fukushima Cesium Detected Offshore
Examining the Fate of Fukushima Contaminants
Fukushima Radioactivity Detected Off West Coast
Radioactive Ocean Website a Success
How Radioactive is Our Ocean?
Fishing for Answers off Fukushima
Sampling the Pacific for Signs of Fukushima
News & Insights
What happens to natural gas in the ocean?
WHOI-assisted study finds ocean dumping of DDT waste was “sloppy”
How Long Does Plastic Persist in the Ocean?
The many lifetimes of plastics
Forged in fire: WHOI recalls the Deepwater Horizon crisis
Summer’s coming: Will Cape Cod beaches be safe?
Fifty years later, the West Falmouth oil spill yields lasting contributions to remediation efforts
Rapid Response at Sea
Putting the ‘nuclear coffin’ in perspective
WHOI in the News
It’s not just toxic chemicals. Radioactive waste was also dumped off Los Angeles coast
Japan says it’s safe to release radioactive Fukushima water—so why are its neighbors freaking out?
Five Isotopes Found in Pilgrim Water Samples
WHOI Scientist Weighs In On Risks Of Radioactive Wastewater
A decade after Fukushima nuclear disaster, contaminated water symbolizes Japan’s struggles
How safe is the water off the coast of the San Onofre nuclear plant?
Environmental groups will do their own tests of radioactive wastewater from San Onofre
Should Japan dump radioactive water from Fukushima into the ocean?
Looks Like Japan Is Going Ahead With Plan to Dump Radioactive Fukushima Water Into the Ocean
Features
On March 11, 2011, a magnitude 9.0 earthquake 80 miles off the northeast coast of Japan triggered a series of…
On March 11, 2011, a magnitude 9.0 thrust-fault quake 80 mi east of Honshu, Japan, ruptured the subducting Pacific plate,…
Fukushima's 2011 nuclear accident released radioactive isotopes into the ocean; levels have since decreased but ongoing monitoring continues. Learn more…














Fukushima Radiation