DOI: 10.1002/2016GB005511
Scopus记录号: 2-s2.0-85013435774
论文题名: Thorium distributions in high- and low-dust regions and the significance for iron supply
作者: Hayes C ; T ; , Rosen J ; , McGee D ; , Boyle E ; A
刊名: Global Biogeochemical Cycles
ISSN: 8866236
出版年: 2017
卷: 31, 期: 2 起始页码: 328
结束页码: 347
语种: 英语
英文关键词: aerosol dust
; Amazon River
; Barbados
; Bermuda
; Hawaii
Scopus关键词: aerosol
; atmospheric deposition
; concentration (composition)
; dissolved matter
; dust
; estimation method
; isotopic composition
; nutrient dynamics
; outflow
; thorium isotope
; uranium isotope
; Amazon River
; Barbados
; Bermuda
; Hawaii [United States]
; Pacific Ocean
; Pacific Ocean (North)
; United States
英文摘要: Thorium and uranium isotopes (232Th, 230Th, 238U, and 234U) were investigated to refine their use for estimating mineral dust deposition and Fe delivery to the ocean. U concentrations and isotope ratios were consistent with conservative behavior and can safely be described using published U-salinity relationships and global average seawater isotopic composition. Near Barbados, waters affected by the Amazon outflow contained elevated 232Th. This signals one region where the thorium-dust method is inaccurate because of a confounding continental input. Dissolved 232Th fluxes in this region suggest that Amazonian Fe supply to the adjacent open ocean is much larger than local atmospheric deposition. The colloidal content of dissolved Th south of Bermuda was found to be quite small (2–6%), similar to that found north of Hawaii, despite the order of magnitude higher dust deposition in the Atlantic. This finding supports the assumption that dissolved 232Th and 230Th are scavenged at the same rate despite their different sources and also sheds light on the increase of dissolved 232Th fluxes with integrated depth. Outside the region influenced by Amazon River waters, dissolved 232Th fluxes are compared with Bermudan aerosol Fe deposition to estimate that fractional Th solubility is around 20% in this region. Finally, new dissolved and soluble Fe, Mn, and Cr data from the subtropical North Pacific support the idea that Fe concentrations in the remote ocean are highly buffered, whereas 232Th has a larger dynamic range between high- and low-dust regions. ©2017. American Geophysical Union. All Rights Reserved. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/77770
Appears in Collections: 气候变化事实与影响
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作者单位: School of Ocean Science and Technology, University of Southern Mississippi, Stennis Space Center, MS, United States; Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA, United States
Recommended Citation:
Hayes C,T,, Rosen J,et al. Thorium distributions in high- and low-dust regions and the significance for iron supply[J]. Global Biogeochemical Cycles,2017-01-01,31(2)