Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
11007409 | Journal of Environmental Radioactivity | 2018 | 7 Pages |
Abstract
We examined the vertical 134Cs and 137Cs concentration profiles in the southwestern Okhotsk Sea in 2011, 2013, and 2017. In June 2011, atmospheric deposition-derived 134Cs from the Fukushima Dai-ichi Nuclear Power Plant (FDNPP) was detected at depths of 0-200â¯m (0.06-0.6 mBq/L). In July 2013, 134Cs detected at depths of 100-200â¯m (â¼0.05 mBq/L) was ascribed to the transport of low-level 134Cs-contaminated water and/or the convection of radioactive depositions (<0.03 mBq/L at depths of 0-50â¯m). In July 2017, 134Cs was detected in water samples at depths above 300â¯m (0.03-0.05 mBq/L), and the inventory, decay-corrected to the FDNPP accident date, exhibited its maximum value (85 Bq/m2) during this period. Combining temperature-salinity data with the concentrations of global fallout-derived 137Cs led to a plausible explanation for this observation, which is a consequence of re-entry of FDNPP-derived radiocesium through the Kuril Strait from the northwestern North Pacific Ocean to the Okhotsk Sea and subsequent mixing with the south Okhotsk subsurface layer until 2017.
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Authors
Mutsuo Inoue, Toshiki Morokado, Ken Fujimoto, Shizuho Miki, Hisaki Kofuji, Yutaka Isoda, Seiya Nagao,