Journal of Oceanography

, Volume 72, Issue 1, pp 67–76 | Cite as

134Cs and 137Cs in the North Pacific Ocean derived from the March 2011 TEPCO Fukushima Dai-ichi Nuclear Power Plant accident, Japan. Part two: estimation of 134Cs and 137Cs inventories in the North Pacific Ocean

  • Michio AoyamaEmail author
  • Mizuo Kajino
  • Taichu Y. Tanaka
  • Tsuyoshi Thomas Sekiyama
  • Daisuke Tsumune
  • Takaki Tsubono
  • Yasunori Hamajima
  • Yayoi Inomata
  • Toshitaka Gamo
Special Section: Original Article Oceanographic observations after the 2011 earthquake off the Pacific coast of Tohoku


We estimated the inventories of radiocaesium released by the Tokyo Electric Power Company Fukushima Dai-ichi Nuclear Power Plant (FNPP1) accident to the North Pacific Ocean by using compiled data and model simulations. By comparing the observed inventories with model-simulated results, we obtained 12–15 PBq of 137Cs for the atmospheric deposition released by the FNPP1 accident in the North Pacific Ocean. Before the Fukushima accident, 137Cs activity in the North Pacific Ocean was about 69 PBq. Therefore, the 12–15 PBq of 137Cs newly added by atmospheric deposition together with the 3.5 ± 0.7 PBq added by direct discharge increased the total 137Cs inventory in the North Pacific Ocean by 22–27 %. We also estimated the total amount of 137Cs released to the atmosphere to be 15–20 PBq, and the total amount of 137Cs released to the environment to be 19–24 PBq, respectively. Observed 134Cs to 137Cs activity ratio at the time of accident was close to 1 and extremely uniform, therefore, the total amount of 134Cs deposition in the North Pacific Ocean, that of released to the atmosphere, that of direct discharge to the ocean and that of released to the environment were the same amounts as those of 137Cs.


Fukushima Dai-Ichi Nuclear Power Plant accident Atmospheric release Direct discharge Inventory 134Cs 137Cs Radiocaesium Land deposition 



This study was supported in part by the radioactive survey and research fund of Ministry of Education, Culture, Sports, Science and Technology (MEXT), Japan (Houshanou-chousa-kenkyuhi, FY2011-2014), in part by the J-RAPID fund of the Japan Science and Technology Agency as part of a project entitled “Investigation and Prediction of Impacts of The 2011 off the Pacific coast of Tohoku Earthquake on Marine Environment, FY2011-2012”, and by a Grant-in-Aid for Scientific Research (A) (No. 23253001) from MEXT. The authors thank Yukiko Suda and Aoi Mori for preparing the tables and figures for this article.


  1. Adachi K, Kajino M, Zaizen et al (2013) Emission of spherical cesium-bearing particles from an early stage of the Fukushima nuclear accident. Sci Rep 3:2554. doi: 10.1038/srep02554 Google Scholar
  2. Bailly du Bois P, Laguionie P, Boust et al (2012) Estimation of marine source-term following Fukushima Dai-ichi accident. J Environ Radioact 114:2–9. doi: 10.1016/j.jenvrad.2011.11.015 CrossRefGoogle Scholar
  3. Buesseler K, Aoyama M, Fukasawa M (2011) Impacts of the Fukushima nuclear power plants on marine radioactivity. Environ Sci Technol 45:9931–9935. doi: 10.1021/es202816c CrossRefGoogle Scholar
  4. Charette M, Breier C, Henderson P et al (2013) Radium-based estimates of cesium isotope transport and total direct ocean discharges from the Fukushima Nuclear Power Plant accident. Biogeosciences 10:2159–2167CrossRefGoogle Scholar
  5. Chino M, Nakayama H, Nagai H et al (2011) Preliminary estimation of release amounts of131I and137Cs accidentally discharged from the Fukushima Daiichi Nuclear Power Plant into the atmosphere. J Nucl Sci Technol 48:1129–1134. doi: 10.1080/18811248.2011.9711799 CrossRefGoogle Scholar
  6. Draxler R, Arnold D, Chino M et al (2015) World Meteorological Organization’s model simulations of the radionuclide dispersion and deposition from the Fukushima Daiichi nuclear power plant accident. J Environ Radioact 139:172–184. doi: 10.1016/j.jenvrad.2013.09.014 CrossRefGoogle Scholar
  7. Estournel C, Bosc E, Bocquet M et al (2012) Assessment of the amount of cesium-137 released into the Pacific Ocean after the Fukushima accident and analysis of its dispersion in Japanese coastal waters. J Geophys Res 117:C11014. doi: 10.1029/2012JC007933 CrossRefGoogle Scholar
  8. Kajino M (2011) MADMS: modal aerosol dynamics model for multiple modes and fractal shapes in the free-molecular and near-continuum regimes. J Aerosol Sci 42:224–248. doi: 10.1016/j.jaerosci.2011.01.005 CrossRefGoogle Scholar
  9. Kajino M, Kondo Y (2011) EMTACS: development and regional-scale simulation of a size, chemical, mixing type, and soot shape resolved atmospheric particle model. J Geophys Res 116:D02303. doi: 10.1029/2010JD015030 Google Scholar
  10. Kajino M, Inomata Y, Sato K, Ueda et al (2012) Development of the RAQM2 aerosol chemical transport model and predictions of the Northeast Asian aerosol mass, size, chemistry, and mixing type. Atmos Chem Phys 12:11833–11856. doi: 10.5194/acpd-12-13405-2012 CrossRefGoogle Scholar
  11. Kanda J (2013) Continuing 137Cs release to the sea from the Fukushima Dai-ichi Nuclear Power Plant through 2012. Biogeosciences Discuss 10:3577–3595. doi: 10.5194/bg-10-6107-2013 CrossRefGoogle Scholar
  12. Katata G, Terada H, Nagai H et al (2012) Numerical reconstruction of high dose rate zones due to the Fukushima Dai-ichi Nuclear Power Plant accident. J Environ Radioact 111:2–12. doi: 10.1016/j.jenvrad.2011.09.011 CrossRefGoogle Scholar
  13. Katata G, Chino M, Kobayashi T et al (2015) Detailed source term estimation of the atmospheric release for the Fukushima Daiichi Nuclear Power Station accident by coupling simulations of an atmospheric dispersion model with an improved deposition scheme and oceanic dispersion model. Atmos Chem Phys 15:1029–1070. doi: 10.5194/acp-15-1029-2015 CrossRefGoogle Scholar
  14. Kawamura H, Kobayashi T, Furuno A et al (2011) Preliminary numerical experiments on oceanic dispersion of131I and137Cs discharged into the ocean because of the Fukushima Daiichi Nuclear Power Plant Disaster. J Nucl Sci Technol 48:1349–1356. doi: 10.1080/18811248.2011.9711826 CrossRefGoogle Scholar
  15. Kobayashi T, Nagai H, Chino et al (2013) Source term estimation of atmospheric release due to the Fukushima Dai-ichi Nuclear Power Plant accident by atmospheric and oceanic dispersion simulations. J Nucl Sci Technol 50:255–264. doi: 10.1080/00223131.2013.772449 CrossRefGoogle Scholar
  16. Large WG, Yeager SG (2004) Diurnal to decadal global forcing for ocean and sea-ice models: The data sets and flux climatologies. National Center for Atmospheric Research. NCAR/TN-460 + STRGoogle Scholar
  17. Large WG, McWilliams JC, Doney SC (1994) Oceanic vertical mixing: a review and a model with a nonlocal boundary layer parameterization. Rev Geophys 32:363–403CrossRefGoogle Scholar
  18. Mathieu A, Korsakissok I, Quelo D et al (2012) Atmospheric dispersion and deposition of radionuclides from the Fukushima Daiichi Nuclear Power Plant Accident. Elements 8:195–200. doi: 10.2113/gselements.8.3.195 CrossRefGoogle Scholar
  19. Miyazawa Y, Masumoto Y, Varlamov et al (2013) Inverse estimation of source parameters of oceanic radioactivity dispersion models associated with the Fukushima accident. Biogeosciences 10:2349–2363. doi: 10.5194/bg-10-2349-2013 CrossRefGoogle Scholar
  20. Mizuta R, Oouchi K, Yoshimura H et al (2006) 20-km-Mesh global climate simulations using JMA-GSM Model—mean climate states. J Meteorol Soc Jpn 84:165–185. doi: 10.2151/jmsj.84.165 CrossRefGoogle Scholar
  21. Morino Y, Ohara T, Nishizawa M (2011) Atmospheric behavior, deposition, and budget of radioactive materials from the Fukushima Daiichi nuclear power plant in March 2011. Geophys Res Lett 38. doi: 10.1029/2011GL048689
  22. Oza R, Indumati S, Puranik V et al (2013) Simplified approach for reconstructing the atmospheric source term for Fukushima Daiichi nuclear power plant accident using scanty meteorological data. Ann Nucl Energy 58:95–101CrossRefGoogle Scholar
  23. Rypina II, Jayne SR, Yoshida S et al (2013) Short-term dispersal of Fukushima-derived radionuclides off Japan: modeling efforts and model-data intercomparison. Biogeosciences Discuss 10:1517–1550. doi: 10.5194/bg-10-4973-2013 CrossRefGoogle Scholar
  24. Saunier O, Mathieu A, Didier D et al (2013) An inverse modeling method to assess the source term of the Fukushima nuclear power plant accident using gamma dose rate observations. Atmos Chem Phys 13:11403–11421. doi: 10.5194/acp-13-11403-2013 CrossRefGoogle Scholar
  25. Shamarock W, Klemp J, Dudhia J et al (2008) A description of the advanced research WRF version 3. NCAR technical note NCAR/TN/u2013475 + STRGoogle Scholar
  26. Shchepetkin AF, McWilliams JC (2005) The regional oceanic modeling system (ROMS): a split-explicit, free-surface, topography-following-coordinate oceanic model. Ocean Model 9:347–404. doi: 10.1016/j.ocemod.2004.08.002 CrossRefGoogle Scholar
  27. Shibata K, Yoshimura H, Ohizumi M et al (1999) A simulation of troposphere, stratosphere and mesosphere with an MRI/JMA98 GCM. Pap Meteorol Geophys 50:15–53CrossRefGoogle Scholar
  28. Smith G (2014) UNSCEAR 2013 report. Volume I: Report to the General Assembly, Annex A: Levels and effects of radiation exposure due to the nuclear accident after the 2011 great east-Japan earthquake and tsunami. J Radiol Prot Off J Soc Radiol Prot 34:725Google Scholar
  29. Stohl A, Seibert P, Wotawa G et al (2012) Xenon-133 and caesium-137 releases into the atmosphere from the Fukushima Dai-ichi nuclear power plant: determination of the source term, atmospheric dispersion, and deposition. Atmos Chem Phys 12:2313–2343. doi: 10.5194/acp-12-2313-2012 CrossRefGoogle Scholar
  30. Tanaka TY, Orito K, Sekiyama TT et al (2003) MASINGAR, a global tropospheric aerosol chemical transport model coupled with MRI/JMA 98 GCM- Model description. Pap Meteorol Geophys 53:119–138. doi: 10.2467/mripapers.53.119 CrossRefGoogle Scholar
  31. Terada H, Katata G, Chino et al (2012) Atmospheric discharge and dispersion of radionuclides during the Fukushima Dai-ichi Nuclear Power Plant accident. Part II: verification of the source term and analysis of regional-scale atmospheric dispersion. J Environ Radioact 112:141–154. doi: 10.1016/j.jenvrad.2012.05.023 CrossRefGoogle Scholar
  32. Tsumune D, Aoyama M, Hirose K et al (2011) Transport of 137Cs to the Southern Hemisphere in an ocean general circulation model. Prog Oceanogr 89:38–48. doi: 10.1016/j.pocean.2010.12.006 CrossRefGoogle Scholar
  33. Tsumune D, Tsubono T, Aoyama M et al (2012) Distribution of oceanic 137Cs from the Fukushima Dai-ichi Nuclear Power Plant simulated numerically by a regional ocean model. J Environ Radioact 111:100–108. doi: 10.1016/j.jenvrad.2011.10.007 CrossRefGoogle Scholar
  34. Tsumune D, Tsubono T, Aoyama M et al (2013) One-year, regional-scale simulation of 137Cs radioactivity in the ocean following the Fukushima Daiichi Nuclear Power Plant accident. Biogeosciences 10:5601–5617CrossRefGoogle Scholar
  35. Winiarek V, Bocquet M, Duhanyan N et al (2014) Estimation of the caesium-137 source term from the Fukushima Daiichi nuclear power plant using a consistent joint assimilation of air concentration and deposition observations. Atmos Environ 82:268–279CrossRefGoogle Scholar
  36. Yukimoto S, Yoshimura H, Hosaka M et al. (2011) Meteorological Research Institute-Earth System Model Version 1 (MRI-ESM1)—model description. Technical reports of The Meteorological Research Institute No. 64. doi:10.11483/mritechrepo.64Google Scholar

Copyright information

© The Oceanographic Society of Japan and Springer Japan 2015

Authors and Affiliations

  • Michio Aoyama
    • 1
    Email author
  • Mizuo Kajino
    • 2
    • 3
  • Taichu Y. Tanaka
    • 2
  • Tsuyoshi Thomas Sekiyama
    • 2
  • Daisuke Tsumune
    • 4
  • Takaki Tsubono
    • 4
  • Yasunori Hamajima
    • 5
  • Yayoi Inomata
    • 6
  • Toshitaka Gamo
    • 7
  1. 1.Institute of Environmental RadioactivityFukushima UniversityFukushimaJapan
  2. 2.Meteorological Research InstituteTsukuba-ShiJapan
  3. 3.RIKEN Advanced Institute for Computational ScienceKobeJapan
  4. 4.Environmental Science Research LaboratoryCentral Research Institute of Electric Power IndustryAbiko-ShiJapan
  5. 5.Low Level Radioactivity Laboratory, Institute of Nature and Environmental TechnologyKanazawa UniversityNomiJapan
  6. 6.Atmospheric Research DepartmentAsia Center For Air Pollution ResearchNiigataJapan
  7. 7.Atmosphere and Ocean Research InstituteThe University of TokyoKashiwa-shiJapan

Personalised recommendations