[Source: Scientific Reports, full page: (LINK). Abstract, edited.]

Scientific Reports | Article <ABBR>Open</ABBR>
<ABBR></ABBR>Southward spreading of the Fukushima-derived radiocesium across the Kuroshio Extension in the North Pacific

Yuichiro Kumamoto,<SUP>1 </SUP>Michio Aoyama,<SUP>2, 5 </SUP>Yasunori Hamajima,<SUP>3 </SUP>Tatsuo Aono,<SUP>4 </SUP>Shinya Kouketsu,<SUP>1 </SUP>Akihiko Murata<SUP>1 </SUP>& Takeshi Kawano<SUP>1</SUP>
Journal name: Scientific Reports / Volume: 4, Article number: 4276 / DOI: doi:10.1038/srep04276

Received 27 December 2013 - Accepted 17 February 2014 - Published 04 March 2014

The accident of the Fukushima Dai-ichi nuclear power plant in March 2011 released a large amount of radiocesium into the North Pacific Ocean. Vertical distributions of Fukushima-derived radiocesium were measured at stations along the 149E meridian in the western North Pacific during the winter of 2012. In the subtropical region, to the south of the Kuroshio Extension, we found a subsurface radiocesium maximum at a depth of about 300 m. It is concluded that atmospheric-deposited radiocesium south of the Kuroshio Extension just after the accident had been transported not only eastward along with surface currents but also southward due to formation/subduction of subtropical mode waters within about 10 months after the accident. The total amount of decay-corrected <SUP>134</SUP>Cs in the mode water was an estimated about 6 PBq corresponding to 1060% of the total inventory of Fukushima-derived <SUP>134</SUP>Cs in the North Pacific Ocean.



Subject terms: Geochemistry - Marine chemistry

Contributions: Y.K. and S.K. wrote the paper. T.K. supervised the project. Y.K. and A.M. designed the study and led the cruise. Y.K., M.A., Y.H. and T.A. performed the radiocesium measurements.

Competing financial interests: The authors declare no competing financial interests.

Corresponding author: Correspondence to: Yuichiro Kumamoto