The sea around Fukushima has been dangerously contaminated

Radioactive releases from the nuclear accident did not have an observable impact on terrestrial and aquatic ecosystems beyond the immediate vicinity of the plant, and no impact is expected.

The Fukushima-Daiichi nuclear accident caused 3.5 PBq* of Cesium-137 and 134 to be released into the Pacific Ocean, leading to a temporary increase in radioactivity of the water near the plant. Releases into the atmosphere also led to an increase in radioactivity in the air.

The limited duration of these releases, the dilution of the Cesium and trapping of the element in sediments, allowed for a significant decrease in contamination levels. Moreover, natural decay means that today, compared to the initial quantity, only 36% of the total cesium released by the accident remains. Now, contamination has returned to levels similar to those prior to the accident in the water around the plant, and to negligible levels in the air.

In its 2015 report, the International Atomic Energy Agency (IAEA) states that no direct effects due to radioactivity could be observed on plants or animals, and indicates that, considering the exposure, it is very unlikely that biota or ecosystems would suffer significant radiological consequences.

* The Becquerel is a unit of measurement quantifying the activity of a certain amount of radioactive material. Becquerel multiples (such as peta becquerel, PBq, which is 10^15 becquerels) are used to quantify quantities of radioactive material rather than mass. 3.5 PBq is a significant amount, but it is 10 times less than that of Chernobyl releases.