WEKO3
アイテム
Vertical distributions of 230Th in mid-latitude of the Pacific Ocean
https://repo.qst.go.jp/records/69245
https://repo.qst.go.jp/records/69245a07260e3-7969-4fc0-8bd9-c03df9d49db1
| Item type | 会議発表用資料 / Presentation(1) | |||||
|---|---|---|---|---|---|---|
| 公開日 | 2007-12-21 | |||||
| タイトル | ||||||
| タイトル | Vertical distributions of 230Th in mid-latitude of the Pacific Ocean | |||||
| 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 |
Okubo, Ayako
× Okubo, Ayako× Obata, Hajime× Gamo, Toshitaka× Zheng, Jian× 大久保 綾子× 鄭 建 |
|||||
| 抄録 | ||||||
| 内容記述タイプ | Abstract | |||||
| 内容記述 | Thorium is one of the least soluble elements in seawater: its dissolved species is considered as Th(OH)n(4-n)+ [Turner et al., 1981]. Th-232 (t1/2 = 1.4 * 1010 years) in the oceans is almost entirely contributed by continental weathering, whereas 230Th (t1/2 = 75,200 years) is produced in situ within the water column through the decay of a parent nuclide 234U in the seawater. Vertical distributions of 230Th have been well described by reversible scavenging model in the Pacific Ocean [Nozaki et al., 1981; Bacon and Anderson, 1982; Nozaki, 1983; Nozaki and Nakanishi, 1985; Nozaki et al., 1987]. Scavenging-mixing models have been adopted in regions where horizontal advection is the dominant factor controlling 230Th distribution, such as in the Weddell Sea [Rutgers van der Loeff and Berger, 1993], the Atlantic Ocean [Vogler et al., 1998; Moran et al., 1997; 2001; 2002] and the Andaman Sea [Okubo et al., 2004]. Previous studies on thorium isotopes in seawater have elucidated scavenging processes in water columns in various oceans. Nevertheless, thorium isotope studies have not been performed sufficiently in mid-latitude of the Pacific Ocean. This study clarifies vertical distributions of thorium isotopes, especially 230Th, to study scavenging processes of thorium and trace metals in this region. We investigated the vertical distribution of thorium isotopes in mid-latitudes of the Pacific Ocean especially 230Th as a test case of scavenging of metals, and discuss the control factor of the distribution of 230Th. In comparison with previous studies in the Pacific Ocean [Nozaki et al., 1981; Nozaki and Nakanishi, 1985; Nozaki et al., 1987], the higher latitude stations show lower 230Th concentrations. This tendency corresponds to the primary productivity in surface oceans. The prominent feature is the depletion of 230Th concentrations compared with that estimated by reversible scavenging model calculations in deep water in BO-3 (30o N, 160oW, Depth: 5778 m) and BO-5 (19oN, 175o W, Depth: 5480 m). For these deficiencies, two possibilities were considered 1) lateral transport of re-suspended particles 2) enhanced scavenging effect in deep water. |
|||||
| 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 | American Geophysical Union 2007 Fall Meeting | |||||
| 発表年月日 | ||||||
| 日付 | 2007-12-14 | |||||
| 日付タイプ | Issued | |||||
