The Japanese government reported that approximately 1.22 trillion becquerels (Bq) of radioactive materials were released into the ocean, primarily through groundwater and rainwater runoff from the damaged nuclear power plant. The majority of the released substances were short-lived radionuclides, such as iodine-131 and cesium-137.
However, a subsequent study conducted by scientists from the Woods Hole Oceanographic Institution estimated that the amount of radioactivity released could be much higher, potentially reaching 25 trillion Bq. This discrepancy in estimates is largely attributed to the challenges of measuring radioactivity levels in the vast and dynamic ocean environment.
The released radioactive substances were dispersed by ocean currents and diluted over time, resulting in a gradual decline in their concentrations. Monitoring efforts by various organizations and governments have detected traces of radioactive materials in the Pacific Ocean, including the coastal waters of Japan and neighboring countries.
The levels of radioactivity detected in the ocean have generally been considered low and unlikely to pose a significant immediate threat to human health or the marine environment. However, long-term effects and potential impacts on certain marine species and ecosystems are still being studied.
