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238U, Th isotopes, 210Pb and 239+240Pu in settling particles on the continental margin of the East China Sea: Fluxes and particle transport processes
https://repo.qst.go.jp/records/44467
https://repo.qst.go.jp/records/44467caef5138-8a4a-4ec1-b78c-7ab47e23f7dc
| Item type | 学術雑誌論文 / Journal Article(1) | |||||
|---|---|---|---|---|---|---|
| 公開日 | 2006-07-13 | |||||
| タイトル | ||||||
| タイトル | 238U, Th isotopes, 210Pb and 239+240Pu in settling particles on the continental margin of the East China Sea: Fluxes and particle transport processes | |||||
| 言語 | ||||||
| 言語 | eng | |||||
| 資源タイプ | ||||||
| 資源タイプ識別子 | http://purl.org/coar/resource_type/c_6501 | |||||
| 資源タイプ | journal article | |||||
| アクセス権 | ||||||
| アクセス権 | metadata only access | |||||
| アクセス権URI | http://purl.org/coar/access_right/c_14cb | |||||
| 著者 |
Yamada, Masatoshi
× Yamada, Masatoshi× Aono, Tatsuo× 山田 正俊× 青野 辰雄 |
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| 抄録 | ||||||
| 内容記述タイプ | Abstract | |||||
| 内容記述 | Settling particles were collected from four locations on the continental margin of the East China Sea using cylindrical and conical time-series traps. Total mass fluxes and activities of 238U, 232Th, 230Th, 228Th, 210Pb and 239+240Pu were determined for the particles to elucidate their transport processes on the margin. Surface sediment samples were also analyzed for 238U, 232Th, 230Th, 210Pb and 239+240Pu. The total mass fluxes from the cylindrical traps were significantly higher than those from the conical traps during nearly the same time interval. There was a tendency for 210Pb concentrations to increase almost linearly with depth from 72 m on the continental shelf edge to 1019 m in the Okinawa Trough; the apparent rate was 17.3 dpm/g per 100 m of the water column with the correlation coefficient of 0.93. In addition, there was a marked increase of 210Pb fluxes with depth, with an especially large increase near-bottom. The estimated scavenging effectiveness ranged from 99 to 85 % for shelf edge and middle continental slope sites, respectively, indicating that 210Pb was effectively removed from the water column at each site. Both total mass fluxes and 210Pb fluxes varied on a very short time scale (1/2 day). The ratios of measured versus expected 230Th fluxes for sediment traps were 183 and 222 in the deeper traps. The ratio of the observed 210Pb fluxes to the 210Pb deficiency fluxes in the near-bottom traps ranged between 8.9 and 46. These results suggest that the episodic lateral transport is a key process for particle transport on this continental margin. Concentrations of 238U, 232Th, 230Th, 228Th, 210Pb and 239+240Pu in the time-series traps at a middle continental slope site had little variations throughout the sampling period. In contrast, the radionuclide concentrations at an upper continental slope site varied inversely with the total mass fluxes. The radionuclide concentrations during high total mass flux events were close to those of the surface sediment. These results suggest that the high total mass flux events observed at an upper continental slope site are mainly due to resuspension of the underlying surface sediments. | |||||
| 書誌情報 |
Marine Geology 巻 227, 号 1-2, p. 1-12, 発行日 2006-04 |
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| ISSN | ||||||
| 収録物識別子タイプ | ISSN | |||||
| 収録物識別子 | 0025-3227 | |||||
