Journal cover Journal topic
Biogeosciences An interactive open-access journal of the European Geosciences Union
Biogeosciences, 10, 3067-3078, 2013
© Author(s) 2013. This work is distributed
under the Creative Commons Attribution 3.0 License.
Research article
07 May 2013
Surface pathway of radioactive plume of TEPCO Fukushima NPP1 released 134Cs and 137Cs
M. Aoyama1, M. Uematsu2, D. Tsumune3, and Y. Hamajima4 1Meteorological Research Institute, Tsukuba, Japan
2Atomosphere and Ocean Research Institute, The University of Tokyo, Kashiwa, Japan
3Environmental Science Research Laboratory, Central Research Institute of Electric Power Industry, Tokyo, Japan
4Institute of Nature and Environmental Technology, Kanazawa University, Kanazawa, Japan
Abstract. 134Cs and 137Cs were released to the North Pacific Ocean by two major likely pathways, direct discharge from the Fukushima NPP1 accident site and atmospheric deposition off Honshu Islands of Japan, east and northeast of the site. High density observations of 134Cs and 137Cs in the surface water were carried out by 17 cruises of cargo ships and several research vessel cruises from March 2011 till March 2012. The main body of radioactive surface plume of which activity exceeded 10 Bq m−3 travelled along 40° N and reached the International Date Line on March 2012, one year after the accident. A distinct feature of the radioactive plume was that it stayed confined along 40° N when the plume reached the International Date Line. A zonal speed of the radioactive plume was estimated to be about 8 cm s−1 which was consistent with zonal speeds derived by Argo floats at the region.

Citation: Aoyama, M., Uematsu, M., Tsumune, D., and Hamajima, Y.: Surface pathway of radioactive plume of TEPCO Fukushima NPP1 released 134Cs and 137Cs, Biogeosciences, 10, 3067-3078, doi:10.5194/bg-10-3067-2013, 2013.
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