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Titel |
Imprint of a dissolved cobalt basaltic source on the Kerguelen Plateau |
VerfasserIn |
J. Bown, M. Boye, P. Laan, A. R. Bowie, Y.-H. Park, C. Jeandel, D. M. Nelson |
Medientyp |
Artikel
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Sprache |
Englisch
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ISSN |
1726-4170
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Digitales Dokument |
URL |
Erschienen |
In: Biogeosciences ; 9, no. 12 ; Nr. 9, no. 12 (2012-12-19), S.5279-5290 |
Datensatznummer |
250007470
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Publikation (Nr.) |
copernicus.org/bg-9-5279-2012.pdf |
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Zusammenfassung |
Processes of cobalt (Co) entrainment from shelf sediments over the Kerguelen
Plateau were studied during the KEOPS (Kerguelen Ocean Plateau compared
Study) in order to explain the exceptionally high dissolved cobalt
concentrations that have been measured in the surface waters above the
Kerguelen Plateau, and in intermediate and deep waters above its eastern
slope. Lateral advection and dissolution of Co contained in basalt sediments
around Heard Island, a main source of lithogenic Co in the study area, were
shown to imprint the process of surface enrichment over the plateau.
Dissolved Co enrichment was strongest at the intercept of the eastern slope
with intermediate and deep waters, probably due to more efficient
mobilisation of the sediments in the slope current, in addition to advection
of Co-enriched and low-oxygenated ocean water masses.
In surface waters, the strong sedimentary Co inputs were estimated to be
much higher than biological Co uptake in phytoplankton blooms, underlining
the potential use of dissolved cobalt as tracer of the natural iron
fertilization above the Kerguelen Plateau. Based on a simple steady-state
balance equation of the external input of dissolved iron over the plateau,
the fertilization of iron inferred by using dissolved Co as a tracer of
basalt sources is estimated to be 28 × 102 ± 21 × 102 t yr−1
in surface waters of the Kerguelen Plateau. This estimate is
consistent with preceding ones (Zhang et al., 2008; Chever et al., 2010), and
the calculated iron supply matches with the phytoplankton demand (Sarthou et
al., 2008). |
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