Vertical distributions of 226Ra, 228Ra, and 137Cs activities in the southwestern part of the Sea of Okhotsk
1 Institute of Nature and Environmental Technology Kanazawa University, Japan
2 Fisheries Research Agency, National Research Institute of Fisheries Science, Japan
3 Japan Marine Science Foundation - Aomori, Japan
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We collected 14 water column seawater samples in the southwestern part of the Sea of Okhotsk and employed low-background γ-spectrometry with convenient minimal radiochemical processing to determine the activities of 226Ra (half-life t1/2 = 1600 y), 228Ra (5.75y), and 137Cs (30.2 y) of the samples. All of these nuclides exhibited unique vertical profiles; 226Ra, 228Ra, and 137Cs activities exhibit small variations from 50–500 m depth (226Ra, ~ 2 mBq l−1; 228Ra, ~0.4 mBq l−1; 137Cs, ~ 1 mBq l−1); These profiles can be explained by convective mixing of surface water to this layer.
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