Distribution of 137Cs and 134Cs in the North Pacific Ocean: impacts of the TEPCO Fukushima-Daiichi NPP accident

  • Michio Aoyama
  • Daisuke Tsumune
  • Yasunori Hamajima


Impact of the TEPCO Fukushima-Daiichi NPP accident, FNPP1, to the North Pacific Ocean occurred through two pathways, namely direct release and atmospheric deposition to wide ocean surface. We collected more than 100 seawater samples in the North Pacific Ocean in April and May 2011 by seven commercial ships as VOS. Since the sample volume was 2 l each, we measured radiocaesium activity at Ogoya Underground Facility to obtain reliable activity. 137Cs was detected at all stations and 134Cs was detected at most of the stations in the North Pacific Ocean. The 137Cs activity ranged from around 1 to 1,000 Bq m−3 with activity ratios of 134Cs/137Cs close to 1 which is a signature of radiocaesium originated from the FNPP1 accident. At east of the International Date Line north of 40°N in the Pacific Ocean in April 2011, the 134Cs activity ranged from 2 to 12 Bq m−3.


137Cs 134Cs Fukushima North Pacific Ocean Underground facility 



The authors thank to Nippon Yusen Kaisha, NYK for their voluntary work to collect seawater samples. The authors also thank to Aoi Mori, Yukiko Yoshimura, Tomoko Kudo and Shoko Shimada for their work to create database, tables and figures.


  1. 1.
    The 2011 Tohoku Earthquake Tsunami Joint Survey Group (2011) J Jpn Soc Civil Eng Ser B2 67:63Google Scholar
  2. 2.
    Morino N, Takahashi T, Yasuda T, Yanagisawa H (2011) Geophys Res Lett. doi: 10.1029/2011GL049210 Google Scholar
  3. 3.
    Chino M, Nakayama H, Nagai H, Terada H, Katata G, Yamazawa H (2011) J Nucl Sci Technol. doi: 10.3327/jnst.48.1129 Google Scholar
  4. 4.
    Tsumune D, Tsubono T, Aoyama M, Hirose K (2011) J Environ Radioactivity. doi: 10.1016/j.jenvrad.2011.10.007 Google Scholar
  5. 5.
    Hirose K, Aoyama M, Igarashi Y, Komura K (2005) J Radioanal Nucl Chem 263:349–353Google Scholar
  6. 6.
    Aoyama M, Hirose K (2007) In: Povinec P (ed) Analysis of environmental radionuclides, 1st edn. Elsevier, Hungary, pp 137–162Google Scholar
  7. 7.
    Hamajima Y, Komura K (2004) Appl Radiat Isotop 61:179–183CrossRefGoogle Scholar
  8. 8.
    Aoyama M, Fukasawa M, Hirose K, Hamajima Y, Kawano T, Povinec PP, Sanchez-Cabeza JA (2011) Prog Oceanogr. doi: 10.1016/j.pocean.2010.12.003 Google Scholar
  9. 9.
    Povinec PP, Aoyama M, Fukasawa M, Hirose K, Komura K, Sanchez-Cabeza JA, Gastaud J, Ješkovský M, Levy I, Sýkora I (2011) Prog Oceanogr. doi: 10.1016/j.pocean.2010.12.004 Google Scholar
  10. 10.
    Cabeza JA, Levy I, Gastaud J, Eriksson M, Osvath I, Aoyama M, Povinec PP, Komura K (2011) Prog Oceanogr. doi: 10.1016/j.pocean.2010.12.005 Google Scholar
  11. 11.
    Aoyama M, Hirose K, Nemoto K, Takatsuki Y, Tsumune D (2008) Geophys Res Lett. doi: 10.1029/2007GL031964 Google Scholar
  12. 12.
    Aoyama M, Hirose K, Igarashi Y (2006) J Environ Monit 8:431–438CrossRefGoogle Scholar
  13. 13.
    Aoyama, unpublished dataGoogle Scholar
  14. 14.
    Buesseler K, Aoyama M, Fukasawa M (2011) Environ Sci Technol. doi: 10.1021/es202816c Google Scholar
  15. 15.
    Honda MC, Aono T, Aoyama M, Hamajima Y, Kawakami H, Kitamura M, Masumoto Y, Miyazawa Y, Takigawa M, Saino T (2012) Geochem J 46(1):e1–e9Google Scholar

Copyright information

© Akadémiai Kiadó, Budapest, Hungary 2012

Authors and Affiliations

  • Michio Aoyama
    • 1
  • Daisuke Tsumune
    • 2
  • Yasunori Hamajima
    • 3
  1. 1.Meteorological Research InstituteTsukuba-shiJapan
  2. 2.Environmental Science Research LaboratoryCentral Research Institute of Electric Power IndustryAbiko-shiJapan
  3. 3.Low Level Radioactivity LaboratoryKanazawa UniversityNomiJapan

Personalised recommendations