Spatial variations of <sup>226</sup>Ra, <sup>228</sup>Ra, and <sup>228</sup>Th activities in seawater from the eastern East China Sea
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- INOUE MUTSUO
- Low Level Radioactivity Laboratory, Institute of Nature and Environmental Technology, Kanazawa University
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- YOSHIDA KEISUKE
- Low Level Radioactivity Laboratory, Institute of Nature and Environmental Technology, Kanazawa University
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- MINAKAWA MASAYUKI
- Fisheries Research Agency, National Research Institute of Fisheries Science
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- KIYOMOTO YOKO
- Fisheries Research Agency, Seikai National Fisheries Research Institute
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- KOFUJI HISAKI
- Japan Marine Science Foundation
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- NAGAO SEIYA
- Low Level Radioactivity Laboratory, Institute of Nature and Environmental Technology, Kanazawa University
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- HAMAJIMA YASUNORI
- Low Level Radioactivity Laboratory, Institute of Nature and Environmental Technology, Kanazawa University
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- YAMAMOTO MASAYOSHI
- Low Level Radioactivity Laboratory, Institute of Nature and Environmental Technology, Kanazawa University
Bibliographic Information
- Other Title
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- Spatial variations of ²²⁶Ra, ²²⁸Ra, and ²²⁸Th activities in seawater from the eastern East China Sea
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Abstract
A total of 74 surface and subsurface water samples at depths shallower than 200 m were collected in the eastern East China Sea (ECS), and spatial and seasonal variations in 226Ra, 228Ra, and 228Th activities were examined by low-background γ-spectrometry. The 228Ra and 228Th activities (as well as 228Ra/226Ra and 228Th/228Ra activity ratios) on the surface exhibited notable seasonal and lateral variations (228Ra/226Ra = 0.2-3.4; 228Th/228Ra = 0.1-0.4). From the 228Ra activity (0.2-6 mBq/L) and salinity (27.2-34.5), fractions of the Kuroshio, shelf, and Yangtze River waters on the surface of the ECS were estimated to be 50-95%, 3-50%, and 2-8% in July, and 95-100%, 1-5%, and 0-1% in April, respectively, exhibiting a lower fraction of shelf water in winter-spring and on the Japan side of the ECS. While the surface waters had high 228Th activity (~0.1-0.6 mBq/L) in July, resulting from the high activity of the parent 228Ra, their 228Th/228Ra ratio (~0.1) was lower compared with that of waters in February-April (0.15-0.35). 228Th is considered to be preferentially removed from the surface in summer, reflecting a high flux of biogenic particles.
Journal
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- GEOCHEMICAL JOURNAL
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GEOCHEMICAL JOURNAL 46 (5), 429-441, 2012
GEOCHEMICAL SOCIETY OF JAPAN
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Details 詳細情報について
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- CRID
- 1390001204553026688
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- NII Article ID
- 10031137505
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- NII Book ID
- AA00654975
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- COI
- 1:CAS:528:DC%2BC38XhvFSns7nM
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- ISSN
- 18805973
- 00167002
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- NDL BIB ID
- 024025619
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- Text Lang
- en
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- Data Source
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- JaLC
- NDL
- Crossref
- CiNii Articles
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- Abstract License Flag
- Disallowed