title: Fukushima-derived radiocesium in the western North Pacific in 2014.
abstract: In 2014, we measured activity concentration of radiocesium in the western North Pacific Ocean. In the north of Kuroshio Front high activity concentration of Fukushima-derived radiocesium in surface mixed layer in 2012 had been transported eastward by 2014. In the south of the front we found a radiocesium subsurface maximum in 200-600 m depth, which was similar to that observed in 2012. The subsurface maximum spread southward from 18°N to 15°N between 2012 and 2014, which suggests spreading of Fukushima-derived radiocesium into the whole western subtropical area by 2014 due to formation and subduction of the subtropical mode water.
authors.affiliation: Research and Development Center for Global Change, Japan Agency for Marine-Earth Science and Technology, 2-15 Natushima-cho, Yokosuka, Kanagawa 237-0061 Japan.
authors.forename: Yuichiro
authors.initials: Y
authors.lastname: Kumamoto
authors.affiliation: Institute of Environmental Radioactivity, Fukushima University, 1-1 Kanayagawa, Fukushima, Fukushima 960-1296 Japan.
authors.forename: Michio
authors.initials: M
authors.lastname: Aoyama
authors.affiliation: Low Level Radioactivity Laboratory, Kanazawa University, Wake, Nomi, Ishikawa 923-1224 Japan.
authors.forename: Yasunori
authors.initials: Y
authors.lastname: Hamajima
authors.affiliation: Department of Chemistry, College of Humanities and Sciences, Nihon University, 3-25-40 Sakurajousui, Setagaya Ward, Tokyo, 156-8550 Japan.
authors.forename: Hisao
authors.initials: H
authors.lastname: Nagai
authors.affiliation: Department of Chemistry, College of Humanities and Sciences, Nihon University, 3-25-40 Sakurajousui, Setagaya Ward, Tokyo, 156-8550 Japan.
authors.forename: Takeyasu
authors.initials: T
authors.lastname: Yamagata
authors.affiliation: Research and Development Center for Global Change, Japan Agency for Marine-Earth Science and Technology, 2-15 Natushima-cho, Yokosuka, Kanagawa 237-0061 Japan.
authors.forename: Yoshimi
authors.initials: Y
authors.lastname: Kawai
authors.affiliation: Atmosphere and Ocean Research Institute, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8564 Japan.
authors.forename: Eitarou
authors.initials: E
authors.lastname: Oka
authors.affiliation: Graduate School of Fisheries Sciences, Hokkaido University, 3-1-1 Minato-cho, Hakodate, Hokkaido 041-8611 Japan.
authors.forename: Atsushi
authors.initials: A
authors.lastname: Yamaguchi
authors.affiliation: School of Fisheries Sciences, Hokkaido University, 3-1-1 Minato-cho, Hakodate, Hokkaido 041-8611 Japan.
authors.forename: Keiri
authors.initials: K
authors.lastname: Imai
authors.affiliation: Research and Development Center for Global Change, Japan Agency for Marine-Earth Science and Technology, 2-15 Natushima-cho, Yokosuka, Kanagawa 237-0061 Japan.
authors.forename: Akihiko
authors.initials: A
authors.lastname: Murata
keywords: Fukushima Dai-ichi nuclear power plant accident; North Pacific Ocean; Radiocesium