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| Titel |
Labile Fe(II) concentrations in the Atlantic sector of the Southern Ocean along a transect from the subtropical domain to the Weddell Sea Gyre |
| VerfasserIn |
G. Sarthou, E. Bucciarelli, F. Chever, S. P. Hansard, M. González-Dávila, J. M. Santana-Casiano, F. Planchon, S. Speich |
| 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 ; 8, no. 9 ; Nr. 8, no. 9 (2011-09-06), S.2461-2479 |
| Datensatznummer |
250006113
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| Publikation (Nr.) |
 copernicus.org/bg-8-2461-2011.pdf |
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| Zusammenfassung |
| Labile Fe(II) distributions were investigated in the Sub-Tropical South
Atlantic and the Southern Ocean during the BONUS-GoodHope cruise from 34 to
57° S (February–March 2008). Concentrations ranged from below the
detection limit (0.009 nM) to values as high as 0.125 nM. In the surface
mixed layer, labile Fe(II) concentrations were always higher than the
detection limit, with values higher than 0.060 nM south of 47° S,
representing between 39 % and 63 % of dissolved Fe (DFe). Apparent
biological production of Fe(II) was evidenced. At intermediate depth, local
maxima were observed, with the highest values in the Sub-Tropical domain at
around 200 m, and represented more than 70 % of DFe. Remineralization
processes were likely responsible for those sub-surface maxima. Below 1500
m, concentrations were close to or below the detection limit, except at two
stations (at the vicinity of the Agulhas ridge and in the north of the
Weddell Sea Gyre) where values remained as high as ~0.030–0.050 nM.
Hydrothermal or sediment inputs may provide Fe(II) to these deep waters.
Fe(II) half life times (t1/2) at 4°C were measured in the upper and
deep waters and ranged from 2.9 to 11.3 min, and from 10.0 to 72.3 min,
respectively. Measured values compared quite well in the upper waters with
theoretical values from two published models, but not in the deep waters.
This may be due to the lack of knowledge for some parameters in the models
and/or to organic complexation of Fe(II) that impact its oxidation rates.
This study helped to considerably increase the Fe(II) data set in the Ocean
and to better understand the Fe redox cycle. |
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