Seasonal variations of 228Ra/226Ra and 228Th/228Ra ratios in surface water from the eastern East China Sea
1 Institute of Nature and Environmental Technology, Kanazawa University, Japan
2 Fisheries Research Agency, Seikai National Fisheries Research Institute, Japan
3 Fisheries Research Agency, National Research Institute of Fisheries Science, Japan
4 Mutsu Marine Laboratory, Japan Marine Science Foundation, Aomori, Japan
A total of 30 surface water samples were collected at 2 sites on the east side of the East China Sea (ECS) during 2008–20f0, and 226Ra, 228Ra, and 228Th activities were measured using low-background γ-spectrometry. The 228Ra/226Ra and 228Th/228Ra activity ratios of the samples exhibited notable seasonal variations (228Ra/226Ra = 0.2–3.3; 228Th/228Ra = < 0.1–0.4) accompanying salinity changes (31.0–34.6). These changes are hypothesized to cause the change by altering the mixing ratio of 228Ra-rich and particle-rich continental shelf water within the ECS.
© Owned by the authors, published by EDP Sciences - SIF 2012