*Olivier Evrard¹, Roxanne Durand¹, Seiji Hayashi², Hideki Tsuji², Yoshifumi Wakiyama³, Yuichi Onda⁴, Irène Lefèvre¹, Atsushi Nakao⁵, J. Patrick Laceby⁶ (1.Laboratoire des Sciences du Climat et de l'Environnement (LSCE, joint laboratory CEA-CNRS-UVSQ), University Paris-Saclay, France, 2.National Institute of Environmental Studies (NIES), Fukushima Branch, Japan, 3.Institute of Environmental Radioactivity (IER), Fukushima University, Japan, 4.Center for Research in Isotopes and Environmental Dynamics (CRIED), University of Tsukuba, Japan, 5.Graduate School of Life and Environmental Sciences, Kyoto Prefectural University (KUP), Japan, 6.Environmental Monitoring and Science Division (EMSD), Alberta Environment and Parks (AEP), Calgary, Alberta, Canada)