| Autor: |
Inomata Y; 1Institute of Nature and Environmental Technology, Kanazawa University, Kanazawa, 920-1192 Japan., Aoyama M; 2Institute of Environmental Radioactivity, Fukushima University, 1 Kanayagawa, Fukushima, 960-1192 Japan., Tsubono T; Environmental Science Research Laboratory, Central Research Institute of Electronic Power Industry, 1646, Abiko, 270-1194 Japan., Tsumune D; Environmental Science Research Laboratory, Central Research Institute of Electronic Power Industry, 1646, Abiko, 270-1194 Japan., Kumamoto Y; 4Japan Agency for Marine-Earth Science and Technology, 2-15 Natsushima-cho, Yokosuka, 237-0061 Japan., Nagai H; 5Nihon University, 40-25-3 Sakurajosui, Setagaya, Tokyo, 156-8550 Japan., Yamagata T; 5Nihon University, 40-25-3 Sakurajosui, Setagaya, Tokyo, 156-8550 Japan., Kajino M; 6Meteorological Research Institute, 1-1 Nagamine, Tsukuba, 305-0052 Japan., Tanaka YT; 6Meteorological Research Institute, 1-1 Nagamine, Tsukuba, 305-0052 Japan., Sekiyama TT; 6Meteorological Research Institute, 1-1 Nagamine, Tsukuba, 305-0052 Japan., Oka E; 7Atmosphere and Ocean Research Institute, The University of Tokyo, Kashiwa, 277-8564 Japan., Yamada M; 8Institute of Radiation Emergency Medicine, Hirosaki University, Hirosaki, 036-8564 Japan. |
| Abstrakt: |
Distributions of radiocaesium ( 134 Cs and 137 Cs) derived from the Tokyo Electric Power Company (TEPCO) Fukushima Dai-ichi Nuclear Power Plant (FNPP1) accident in the North Pacific Ocean in the summer of 2012 were investigated. We have estimated the radiocaesium inventory in the surface layer using the optimal interpolation analysis and the subducted amount into the central mode water (CMW) by using vertical profiles of FNPP1- 134 Cs and mass balance analysis as the first approach. The inventory of the 134 Cs in the surface layer in the North Pacific Ocean in August-December 2012 was estimated at 5.1 ± 0.9 PBq on 1 October 2012, which corresponds to 8.6 ± 1.5 PBq when it was decay corrected to the date of the FNPP1 accident, 11 March 2011. It was revealed that 56 ± 10% of the released 134 Cs into the North Pacific Ocean, which was estimated at 15.3 ± 2.6 PBq, transported eastward in the surface layer in 2012. The amount of 134 Cs subducted in the CMW was estimated to be 2.5 ± 0.9 PBq based on the mass balance among the three domains of the surface layer, subtropical mode water, and CMW. |
