Temporal Variation of Radionuclide Contamination of Marine Plants on the Fukushima Coast after the East Japan Nuclear Disaster.

As a result of the Great East Japan Earthquake and associated tsunami in March 2011, the Fukushima Daiichi Nuclear Power Plant (FDNPP) released a large amount of radioactive material into the environment, resulting in contamination of many marine organisms. In this study, 15 marine algal species and a seagrass species were collected from the sublittoral zone of the Iwaki Coast of Fukushima Prefecture from May 2012 to June 2015 and analyzed for variations in Ag, Cs, and Cs over time. The results indicated that (1) Ag, Cs, and Cs were present in all marine plants collected in May 2012, (2) the concentration of Ag in the seagrass decreased significantly over time while the ecological half-life of Ag in was longer at locations closer to the FDNPP, and (3) the Ag/Cs radioactivity ratio of was remarkably high until 2015, indicating that detectable Ag was present in the coastal environment 4 years after the accident.