Transport paths of contaminants around the Japanese Archipelago from distributions of soluble radionuclides

• Project/Area Number: 18K11615
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 63010:Environmental dynamic analysis-related
• Research Institution: Kanazawa University
• Principal Investigator: Inoue Mutsuo 金沢大学, 環日本海域環境研究センター, 准教授 (60283090)
• Co-Investigator(Kenkyū-buntansha): 長尾 誠也 金沢大学, 環日本海域環境研究センター, 教授 (20343014)
• Project Period (FY): 2018-04-01 – 2021-03-31
• Project Status: Completed (Fiscal Year 2020)
• Budget Amount: ¥4,290,000 (Direct Cost: ¥3,300,000、Indirect Cost: ¥990,000); Fiscal Year 2020: ¥1,300,000 (Direct Cost: ¥1,000,000、Indirect Cost: ¥300,000); Fiscal Year 2019: ¥1,560,000 (Direct Cost: ¥1,200,000、Indirect Cost: ¥360,000); Fiscal Year 2018: ¥1,430,000 (Direct Cost: ¥1,100,000、Indirect Cost: ¥330,000)
• Keywords: 放射性セシウム / ラジウム / ガンマ線計測 / 福島原子力発電所事故 / 物質循環 / 放射性核種 / ガンマ線測定 / 日本海

Outline of Final Research Achievements

Soluble radionuclides (Cs-134, Cs-137, Ra-226, and Ra-228) in seawater have been used as powerful tracers to investigate geochemical cycles in marine environments. By employing low-background gamma-spectrometry, we conduct fine-resolution observations of spatial variations of these radionuclides in the Sea of Japan, East China Sea, and Okhotsk Sea, and assess the circulation patterns of water masses. Particularly, FDNPP accident-derived Cs-134 explained circulation paths of soluble components around the Japanese Archipelago. Furthermore, the migration of Ra-228 readily explained the circulation patterns of Cs-134.

Academic Significance and Societal Importance of the Research Achievements

溶存放射性核種の分布から、日本列島近辺にもたらされる海水循環に関する情報を議論した。本海域における溶存成分循環の時間軸設定は、汚染問題を考えるうえで極めて重要であるにも関わらず、環境中に放出された時期・地域の明らかな放射性セシウムをトレースする以外の手法では困難である。これら放射性核種の空間分布の充実は、海水循環の解明のみならず、今後の有事の際の溶存汚染物質循環の対策にも有効である。さらに本研究で得られる日本列島を取り巻く海水のCs-134およびCs-137濃度の分布は、風評被害対策にも重要である。

Research Products

• [Journal Article] Kuroshio fractions in the southwestern Sea of Japan; implications from radium isotopes (2021)
  • Author(s): Inoue, M., Shirotani, Y., Morokado, T., Hanaki, S., Ito, M., Kameyama, H., Kofuji, H., Okino, A., Shikata, T., Yoshida, M., Nagao, S.
  • Journal Title: Continental Shelf Research Volume: 214 Pages: 104328-104328
  • DOI: 10.1016/j.csr.2020.104328
  • Peer Reviewed
• [Journal Article] Circulation paths of 134Cs in seawater southwest of Japan in 2018 and 2019 (2020)
  • Author(s): Inoue, M., Takehara, R., Takikawa, T., Shirotani, Y., Morita, T., Honda, N., Nagao, S.
  • Journal Title: Journal of Environmental Radioactivity Volume: 223-224 Pages: 106382-106382
  • DOI: 10.1016/j.jenvrad.2020.106382
  • Peer Reviewed
• [Journal Article] Distribution of radiocesium and radium isotopes in the western Bering Sea in 2018 (2020)
  • Author(s): Inoue, M., R. Takehara, S. Hanaki, H. Kameyama, J. Nishioka, S. Nago
  • Journal Title: Marine Chemistry Volume: 225 Pages: 103843-103843
  • DOI: 10.1016/j.marchem.2020.103843
  • Peer Reviewed
• [Journal Article] Radiocesium in Japan Sea associated with sinking particles from Fukushima Dai-ichi Nuclear Power Plant accident (2020)
  • Author(s): Kaeriyama, H. Fujimoto, K., Inoue, M., Minakawa, M.
  • Journal Title: Journal of Environmental Radioactivity Volume: 222 Pages: 106348-106348
  • DOI: 10.1016/j.jenvrad.2020.106348
  • Peer Reviewed / Open Access
• [Journal Article] Suspended Particle－Water Interactions Increase Dissolved 137Cs Activities in the Nearshore Seawater during Typhoon Hagibis (2020)
  • Author(s): Takata, H., Aono, T., Aoyama, M., Inoue, M., Kaeriyama, H., Suzuki, S., Tsuruta, T., Wada, T., Wakiyama, Y.
  • Journal Title: Environmental Science and Technology Volume: online Issue: 2 Pages: 615-630
  • DOI: 10.1007/s40710-020-00433-8
  • Peer Reviewed
• [Journal Article] Convection of surface water in the northeastern Japan Sea: Implications from vertical profiles of 134Cs concentrations. (2019)
  • Author(s): Inoue, M., Takehara, R., Yamashita, S., Senjyu, T., Morita, T., Miki, S., Nagao, S.
  • Journal Title: Marine Chemistry Volume: 214 Pages: 103661-103661
  • DOI: 10.1016/j.marchem.2019.05.004
  • Peer Reviewed
• [Journal Article] Low levels of Fukushima Dai-ichi NPP-derived radiocesium in marine products from coastal areas in the Sea of Japan (2012-2017) (2019)
  • Author(s): Inoue, M., Yamashita, S., Takehara, R., Miki, S., Nagao, S.
  • Journal Title: Applied Radiation and Isotopes Volume: 145 Pages: 187-192
  • DOI: 10.1016/j.apradiso.2018.12.029
  • Peer Reviewed
• [Journal Article] Preliminary investigation of 222Rn in the Yakumo Wind-hole, an algific talus deposits, from Izumo, southwest Honshu, Japan. (2019)
  • Author(s): Ritsuo Nomura, Mutsuo Inoue, Hisaki Kofuji
  • Journal Title: Journal of Environmental Radioactivity Volume: 197 Pages: 109-115
  • DOI: 10.1016/j.jenvrad.2018.12.008
  • Peer Reviewed / Open Access
• [Journal Article] Vertical profiles of Fukushima Dai-ichi NPP-derived radiocesium concentrations in the waters of the southwestern Okhotsk Sea (2011-2017) (2018)
  • Author(s): Inoue, M., Morokado, T., Fujimoto, K., Miki, S., Kofuji, H., Isoda, Y., Nagao, S.
  • Journal Title: Journal of Environmental Radioactivity Volume: 192 Pages: 580-586
  • DOI: 10.1016/j.jenvrad.2018.04.021
  • Peer Reviewed
• [Journal Article] Radiocesium in the swash zones off the coast of the Japan Sea. (2018)
  • Author(s): Takata, H., Inoue, M., Shirotani, Y., Kudo, N.
  • Journal Title: Applied Radiation and Isotopes Volume: 141 Pages: 64-69
  • DOI: 10.1016/j.apradiso.2018.08.012
  • Peer Reviewed
• [Presentation] Ra-228/Ra-226比とCs-134濃度からみた日本海南西域表層の物質動態 (2020)
  • Author(s): 花木祥太朗、井上睦夫、竹原亮成、諸角季生、城谷勇陛、滝川哲太郎、吉田真明、沖野晃、三木志津帆、長尾誠也
  • Organizer: 日本放射化学会第64回討論会
• [Presentation] 134Csの空間分布からみた北太平洋北西部における海水循環 (2020)
  • Author(s): 竹原亮成、井上睦夫、花木祥太朗、松中哲也、森田貴己、三木志津帆、黒田寛、谷内由貴子、葛西広海、長尾誠也
  • Organizer: 日本放射化学会第64回討論会
• [Presentation] 234Th/238U比の空間分布からみた日本海の粒子除去 (2020)
  • Author(s): 亀山紘旭、井上睦夫、花木祥太朗、諸角季生、城谷勇陛、竹原亮成、森田貴己、三木志津帆、本多直人、長尾誠也
  • Organizer: 日本放射化学会第64回討論会
• [Presentation] Cs-134の水平分布からみた北海道東部太平洋海域における海水循環 (2020)
  • Author(s): 竹原亮成、井上睦夫、松中哲也、長尾誠也、黒田寛、谷内由貴子、葛西広海、森田貴己、三木志津帆、西岡純
  • Organizer: 日本海洋学会秋季大会
• [Presentation] Introduction of latest researches in Low Level Radioactivity Laboratory, Kanazawa University, Japan. (2019)
  • Author(s): Inoue, M.
  • Organizer: 1st Integrated Conference on Joint research Program in Mongolia (ICJPM)
• [Book] ぶんせき (2019)
  • Author(s): 井上 睦夫
  • Total Pages: 2
  • Publisher: 日本分析化学会
• [Book] Trans-Boundary Pollution in North-East Asia (2018)
  • Author(s): M. Inoue
  • Total Pages: 18
  • Publisher: Nova Science Publishers
  • ISBN: 9781536141634