The roles of celestine and barite in modulating strontium and barium water column concentrations in the northeast Pacific Ocean
Steiner, Zvi (Helmholtz Centre for Ocean Research Kiel)
Turchyn, Alexandra V. (University of Cambridge. Department of Earth Sciences)
Ziveri, Patrizia (Universitat Autònoma de Barcelona. Institut de Ciència i Tecnologia Ambientals)
Shiller, Alan M. (University of Southern Mississippi)
Lam, Phoebe J. (University of California)
Paytan, Adina (University of California)
Achterberg, Eric P. (Helmholtz Centre for Ocean Research Kiel)

Data:	2025
Resum:	The water column distributions of the alkaline earth metals strontium (Sr) and barium (Ba) were studied along a transect from Hawaii to Alaska. Despite similarity in the chemical properties of Sr and Ba, we find that changes in their concentrations along the transect are governed by different chemical and biological processes, meaning that these elements can be treated as independent variables in modern and ancient environments. Alaskan margin sediments are a particularly important source of dissolved Ba to the North Pacific, likely through a combination of saline submarine groundwater discharge and reductive dissolution of manganese (Mn) oxides. Abyssal North Pacific sediments are also a source of Ba to the bottom waters but a sink for Sr. We find that over 90 % of the water column variability in Sr concentrations is driven by precipitation and dissolution of the celestine (SrSO4) skeletons of Acantharia. However, the high Ba content of Acantharia celestine accounts for only 5-8 % of the global ocean variability in Ba concentrations in the water column. Similarly, the effects of barite (BaSO4) precipitation and/or dissolution on the marine Sr cycle is negligible, accounting for <1 % of the water column concentration structure for Sr and ∼3 % of the sedimentary Sr burial. The Sr-Ba-PO4 concentration distributions in the North Pacific are inconsistent with significant export of barite to the deep ocean and sediment. This suggests most of the barite formed at intermediate depths dissolves at similar horizons to its formation. The Ba content of phytoplankton organic matter is too low to constitute a major source for particulate Ba in the mesopelagic North Pacific, which suggests Ba is concentrated in marine aggregates by heterotrophic micro-organisms.
Nota:	Unidad de excelencia María de Maeztu CEX2019-000940-M
Drets:	Aquest document està subjecte a una llicència d'ús Creative Commons. Es permet la reproducció total o parcial, la distribució, la comunicació pública de l'obra i la creació d'obres derivades, fins i tot amb finalitats comercials, sempre i quan es reconegui l'autoria de l'obra original.
Llengua:	Anglès
Document:	Article ; recerca ; Versió publicada
Matèria:	Acantharia ; Barite ; Barium ; Celestite ; North Pacific ; Strontium
Publicat a:	Geochimica et Cosmochimica Acta, Vol. 388 (January 2025) , p. 182-194, ISSN 0046-564X

DOI: 10.1016/j.gca.2024.10.003

13 p, 2.1 MB

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