Input of 129I into the western Pacific Ocean resulting from the Fukushima nuclear event
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We present an initial characterization of the input of 129I into the Pacific Ocean resulting from the 2011 Fukushima nuclear accident. This characterization is based primarily on 129I measurements on samples collected from a research cruise conducted in waters off the eastern coast of Japan in June 2011. These measurements were compared with samples intended to reflect pre-Fukushima background that were collected during a May 2011 transect of the Pacific by a commercial container vessel. In surface waters, we observed peak 129I concentrations of ~300 μBq/m3 which represents an elevation of nearly three orders of magnitude compared to pre-Fukushima backgrounds. We coupled our 129I results with 137Cs measurements from the same cruise and derived an average 129I/137Cs activity ratio of 0.442 × 10−6 for the effluent from Fukushima. Finally, we present 129I depth profiles from five stations from this cruise which form the basis for future studies of ocean transport and mixing process as well as estimations of the total budget of 129I released into the Pacific.
Keywords129Iodine Fukushima Environmental radioactivity Accelerator mass spectrometry Ocean tracers
This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. This publication was funded by the Gordon and Betty Moore Foundation through Grant GBMF3007 to Ken Buesseler and the National Science Foundation. We wish to thank Paul Quay and Hilary Palevsky (University of Washington) for collecting samples from the May 2011 OOCL Tokyo crossing (funding provided by the National Oceanic and Atmospheric Agency’s Global Carbon Cycle Program).
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