*Masanobu Yamamoto¹、Takafumi Kikuchi¹、Hiromichi Sakurai¹、Ryoma Hayashi²、Osamu Seki¹、Takafumi Omori³、Abdullah Sulaiman⁴、Hasrizal Shaari⁵、Lulie Melling⁶ (1.Faculty of Environmental Earth Science, Hokkaido University、2.Lake Biwa Museum、3.The University of Tokyo、4.Minerals and Geoscience Department Malaysia、5.Universiti Malaysia Terengganu、6.Tropical Peat Research Institute)