WEKO3
アイテム
Post-depositional Precipitation of Authigenic Uranium in Suboxic Sediments From the Okinawa Trough, Western Northwest Pacific Margin
https://repo.qst.go.jp/records/68316
https://repo.qst.go.jp/records/683160996e393-9b56-40bf-824b-10dd805e096c
| Item type | 会議発表用資料 / Presentation(1) | |||||
|---|---|---|---|---|---|---|
| 公開日 | 2006-02-27 | |||||
| タイトル | ||||||
| タイトル | Post-depositional Precipitation of Authigenic Uranium in Suboxic Sediments From the Okinawa Trough, Western Northwest Pacific Margin | |||||
| 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_c94f | |||||
| 資源タイプ | conference object | |||||
| 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× Wang, Zhong-Liang× Zheng, Jian× Kato, Yoshihisa× 山田 正俊× 王 中良× 鄭 建 |
|||||
| 抄録 | ||||||
| 内容記述タイプ | Abstract | |||||
| 内容記述 | Suboxic hemipelagic sediments cover only 7 - 10 % of the world's ocean area, however, the areally integrated removal of uranium into suboxic hemipelagic sediments is of greater magnitude than that into anoxic sulfate-reducing sediments. The East China Sea is one of the largest marginal seas in the world. Huge amounts of matter are supplied from the Asian continent mainly through the Yangtze River (Changjiang) and the Yellow River (Huanghe). In spite of the large amounts of riverine input, the behavior of redox sensitive uranium in the East China Sea and Okinawa Trough sediments and its significance in the geochemical budget have been poorly investigated. Concentrations of U and Th isotopes in Okinawa Trough and East China Sea sediment cores were determined by isotope dilution inductively coupled plasma mass spectrometry (ID-ICP-MS) to investigate the behavior of redox sensitive uranium in suboxic hemipelagic sediments and its significance in oceanic uranium balance. 238U concentrations and 238U/232Th activity ratios in the East China Sea sediments showed no remarkable variation with depth. However, 238U and 238U/232Th ratios in the Okinawa Trough sediments were low in the surface oxidizing layer but increased where the post-oxic condition was encountered. The distribution profiles of 230Th and 232Th concentrations were relatively constant with depth in both the Okinawa Trough and East China Sea sediment cores. These results suggested that there has been post-depositional precipitation of authigenic uranium within the suboxic Okinawa Trough sediment column. The post-depositional precipitation rates of authigenic uranium were estimated to be 47 to >62 ng cm-2 yr-1; these rates were comparable to those previously reported for several anoxic sediments. A mechanism controlling precipitation of uranium may be the downward diffusion of uranium U(VI), reduction to U(IV) and finally precipitation onto the solid phase. The accumulation rate of uranium for the Okinawa Trough sediments was approximately 8 times higher than the world average rate reported for suboxic sediments. This removal of uranium in the oceanic budget increases the importance of the suboxic sediment sink. |
|||||
| 会議概要（会議名, 開催地, 会期, 主催者等） | ||||||
| 内容記述タイプ | Other | |||||
| 内容記述 | 2006 Ocean Sciences Meeting | |||||
| 発表年月日 | ||||||
| 日付 | 2006-02-24 | |||||
| 日付タイプ | Issued | |||||
