*li WENSHUAI¹、Yoshio Takahashi¹、Akira Usui²、Ryoichi Nakada³、Teruhiko Kashiwabara⁴、Hajime Obata⁵、Naoya Kanna⁵、Yoshihiro Asahara⁶、Hirofumi Tazoe⁷、Masato Tanaka¹ (1.Department of Earth and Planetary Science, Graduate School of Science, The University of Tokyo, Tokyo, Japan. 、2.Center for Advanced Marine Core Research, Kochi University, Kochi, Japan. 、3.Kochi Institute for Core Sample Research, Japan Agency for Marine-Earth Science and Technology (JAMSTEC), Kochi, Japan. 、4.Submarine Resources Research Center (SRRC), Japan Agency for Marine-Earth Science and Technology (JAMSTEC), Yokosuka, Japan. 、5.Atmosphere and Ocean Research Institute, The University of Tokyo, Japan. 、6.Department of Earth and Environmental Sciences, Graduate School of Environmental Studies, Nagoya University, Nagoya, Japan. 、7. Institute of Radiation Emergency Medicine, Hirosaki University, Honcho, Hirosaki, Aomori, Japan)