EPJ Web of Conferences 24, 04001 (2012)
https://doi.org/10.1051/epjconf/20122404001

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

^* E-mail: mutsuo@llrl.ku-unet.ocn.ne.jp

Abstract

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 t_1/2 = 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.