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dc.contributor.authorHorner, Tristan J.  Concept link
dc.contributor.authorKinsley, Christopher W.  Concept link
dc.contributor.authorNielsen, Sune G.  Concept link
dc.date.accessioned2015-09-01T17:25:36Z
dc.date.available2015-09-01T17:25:36Z
dc.date.issued2015-07-09
dc.identifier.urihttps://hdl.handle.net/1912/7511
dc.descriptionAuthor Posting. © The Author(s), 2015. This is the author's version of the work. It is posted here by permission of Elsevier for personal use, not for redistribution. The definitive version was published in Earth and Planetary Science Letters, 430 (2015): 511-522, doi:10.1016/j.epsl.2015.07.027.en_US
dc.description.abstractThe marine biogeochemical cycle of Ba is thought to be controlled by particulate BaSO4 (barite) precipitation associated with the microbial oxidation of organic carbon and its subsequent dissolution in the BaSO4-undersaturated water column. Despite many of these processes being largely unique to Ba cycling, concentrations of Ba and Si in seawater exhibit a strong linear correlation. The reasons for this correlation are ambiguous, as are the depth ranges corresponding to the most active BaSO4 cycling and the intermediate sources of Ba to particulate BaSO4. Stable isotopic analyses of dissolved Ba in seawater should help address these issues, as Ba-isotopic compositions are predicted to be sensitive to the physical and biogeochemical process that cycle Ba. We report a new methodology for the determination of dissolved Ba-isotopic compositions in seawater and results from a 4, 500 m depth profile in the South Atlantic at 39.99 S, 0.92 E that exhibit oceanographically-consistent variation with depth. These data reveal that water masses obtain their [Ba] and Ba-isotopic signatures when at or near the surface, which relates to the cycling of marine BaSO4. The shallow origin of these signatures requires that the substantial Ba-isotopic variations in the bathypelagic zone were inherited from when those deep waters were last ventilated. Indeed, the water column below 600 m is well explained by conservative mixing of water masses with distinct [Ba] and Ba-isotopic compositions. This leads us to conclude that large scale oceanic circulation is important for sustaining the similar oceanographic distributions of Ba and Si in the South Atlantic, and possibly elsewhere. These data demonstrate that the processes of organic carbon oxidation, BaSO4 cycling, and Ba-isotopic fractionation in seawater are closely coupled, such that Ba-isotopic analyses harbor great potential as a tracer of the carbon cycle in the modern and paleo-oceans.en_US
dc.description.sponsorshipT.J.H. acknowledges support from Makoto A. Saito (Gordon and Betty Moore Foundation; Project # 3782) and the Postdoctoral Scholar Program at the Woods Hole Oceanographic Institution, with funding provided by the Doherty Foundation. Development of Ba-isotopic protocols at NIRVANA was made possible with funding from The Andrew W. Mellon Foundation Endowed Fund for Innovative Research (T.J.H. and S.G.N.).en_US
dc.format.mimetypeapplication/pdf
dc.language.isoen_USen_US
dc.relation.urihttps://doi.org/10.1016/j.epsl.2015.07.027
dc.subjectBariumen_US
dc.subjectIsotopic fractionationen_US
dc.subjectBariteen_US
dc.subjectSeawateren_US
dc.subjectBiogeochemistryen_US
dc.titleBarium-isotopic fractionation in seawater mediated by barite cycling and oceanic circulationen_US
dc.typePreprinten_US


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