EPJ Web of Conferences (Apr 2012)

Seasonal variations of 228Ra/226Ra and 228Th/228Ra ratios in surface water from the eastern East China Sea

  • Hamajima Y.,
  • Nagao S.,
  • Kofuji H.,
  • Minakawa M.,
  • Kiyomoto Y.,
  • Inoue M.,
  • Yoshida K.,
  • Yamamoto M.

DOI
https://doi.org/10.1051/epjconf/20122404005
Journal volume & issue
Vol. 24
p. 04005

Abstract

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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.