*Yuichi Kurihara¹, Hikaru Miura¹, Toshihiro Kogure¹, Noriko Yamaguchi², Shogo Higaki³, Aya Sakaguchi⁴, Yuichi Onda⁵, Masayoshi Yamamoto⁶, Kazuya Tanaka⁷, Jota Kanda⁸, Takashi Ishimaru⁸, Yoshio Takahashi¹ (1.Department of Earth and Planetary Science, Graduate School of Science, The university of Tokyo, 2.National Institute for Agro-Environmental Sciences, 3.Radioisotope Center, The university of Tokyo, 4.Faculty of Pure and Applied Science, University of Tsukuba, 5.Center for Research in Isotopes and Environmental Dynamics, University of Tsukuba, 6.Low Level Radioactivity Laboratory, Kanazawa University, 7.Japan Atomic Energy Agency, 8.Tokyo University of Marine Science and Technology)

*Yuichi Kurihara¹, Hikaru Miura¹, Toshihiro Kogure¹, Noriko Yamaguchi², Shogo Higaki³, Aya Sakaguchi⁴, Yuichi Onda⁵, Masayoshi Yamamoto⁶, Kazuya Tanaka⁷, Jota Kanda⁸, Takashi Ishimaru⁸, Yoshio Takahashi¹ (1.Department of Earth and Planetary Science, Graduate School of Science, The university of Tokyo, 2.National Institute for Agro-Environmental Sciences, 3.Radioisotope Center, The university of Tokyo, 4.Faculty of Pure and Applied Science, University of Tsukuba, 5.Center for Research in Isotopes and Environmental Dynamics, University of Tsukuba, 6.Low Level Radioactivity Laboratory, Kanazawa University, 7.Japan Atomic Energy Agency, 8.Tokyo University of Marine Science and Technology)