230Th in the eastern South Pacific Ocean: Boundary scavenging and bottom scavenging by metal oxides derived from hydrothermal vents. (September 2018)

• Record Type: Journal Article
• Authors: Okubo, Ayako
• Is Part Of: Deep sea research. Volume 139(2018)
• Page Start: 79
• Page End: 87
• Publication Date: 2018-09
• Subjects: Thorium -- The eastern South Pacific Ocean -- Biological productivity -- Boundary scavenging -- Hydrothermal scavenging -- Bottom scavenging, equatorial zonal current, oxygen minimum zone; Oceanography -- Periodicals; Océanographie -- Périodiques; 551.4605
• DOI: 10.1016/j.dsr.2018.07.010
• Languages: English
• ISSNs: 0967-0637

Abstract

Abstract: The vertical distribution of total 230 Th was investigated in the eastern South Pacific Ocean. Among the stations studied, 230 Th inventories in the depth range 1000‒2500 m generally decrease with increasing net primary productivity and export production, which implies that the spatial variability of particle flux controls the 230 Th distribution. On the other hand, at equatorial stations, 230 Th inventories in the depth range 0‒1000 m were similar to those found at stations in lower productivity regions, and the effect of lateral input of 230 Th by equatorial zonal flow was considered. The large-scale bottom scavenging effect on 230 Th in deep layers arising from hydrothermal activity in the vicinity of the East Pacific Rise was observed at stations in the Southwest Pacific Basin and the Peru Basin. Corresponding to the pattern seen in the map of iron and manganese oxide content of surface sediment, the observed 230 Th depletion was higher in the Peru Basin than the Southwest Pacific Basin, suggesting that these oxides contribute to the observed bottom scavenging. Highlights: The local biological productivity controls the 230 Th inventories in deep layers. The characteristics of hydrography affect 230 Th inventories in upper 1000 m. The large-scale bottom scavenging effect is arising from hydrothermal activity.