*JITHYA NAWODI WIJESINGHE¹、Jun Koarashi²、Mariko Atarashi Andoh²、Yoko Saito Kokubu³、Noriko Yamaguchi⁴、Takashi Sase⁵、Mamoru Hosono⁶、Yudzuru Inoue⁷、Yuki Mori¹、Syuntaro Hiradate¹ (1.Soil Science Laboratory, Faculty of Agriculture, Kyushu University, Fukuoka 819-0395, Japan、2.Nuclear Science and Engineering Center, Japan Atomic Energy Agency, Ibaraki 319-1195, Japan、3.Tono Geoscience Center, Japan Atomic Energy Agency,Gifu 509-5102, Japan、4.National Agriculture and Food Research Organization, Institute for Agro-environmental Sciences, 3-1-3 Kan-nondai, Tsukuba, Ibaraki 305-8604, Japan、5.Boreal Laboratory for Phytolith Research, Iwate 028-7302,Japan、6.Tokyo Natural History Research Structure,Tokyo 162-0052, Japan、7.Faculty of Applied Information Technology, Nagasaki Institute of Applied Science,Nagasaki 851-0193, Japan )