JpGU-AGU Joint Meeting 2017

Presentation information

Print

[EJ] Oral

M (Multidisciplinary and Interdisciplinary) » M-AG Applied Geosciences

[M-AG34] [EJ] Dynamics of radionuclides emitted from Fukuchima Dai-ichi Nuclear Power Plant in the environment

Thu. May 25, 2017 1:45 PM - 3:15 PM Convention Hall A (International Conference Hall 2F)

convener:Kazuyuki Kita(Faculty of Science, Ibaraki University), Yuichi Onda(Center for Research on Isotopes and Environmental Dynamics, University of Tsukuba), Yasuhito Igarashi(Atmospheric Environment and Applied Meteorology Research Department, Meteorological Research Institute), Masatoshi Yamada(Institute of Radiation Emergency Medicine, Hirosaki University), Chairperson:Michio Aoyama(Institute of Environmnetal Radioactivity, Fukushima University), Chairperson:Yayoi Inomata(Kanazawa University)

2:15 PM - 2:30 PM

[MAG34-15] Oceanic dispersion of radioactive cesium derived from Fukushima Dai-ichi Nuclear Power Plant accident in the North Pacific during six years

*Hideki Kaeriyama1 (1.Japan Fisheries Research and Education Agency)

Keywords:Fukushima Dai-ichi Nuclear Power Plant accident, Radioactive cesium, North Pacific, Mode water

After the Fukushima Dai-ichi Nuclear Power Plant (FDNPP) accident, many data on radioactive cesium (134Cs and 137Cs) in seawater had been collected and published. Present study summarizes details the radioactive cesium dispersion pattern in the North Pacific based on observational data obtained by FRA. Briefly, the Fukushima-derived radioactive cesium dispersed eastward as surface water, and was also observed via a southward intrusion to subsurface waters as Subtropical Mode Water and Central Mode Water. The radioactive cesium movement related to mode water is important in terms of the circulation of cesium into the ocean interior. The concentration of Fukushima-derived radiocesium in Subtropical Mode Water and water column inventory of 137Cs were gradually decreased between 2012 and 2015.
The most remarkable temporal changes of Fukushima-derived radioactive cesium off the coast near the FDNPP site were observed during the first six months of 2011. After that, continuous decreasing trend has been observed until 2016. Although higher concentrations of radioactive cesium than the background levels measured before the accident are still detected. Continued monitoring is still necessary.