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| Titel |
Carbon, oxygen and biological productivity in the Southern Ocean in and out the Kerguelen plume: CARIOCA drifter results |
| VerfasserIn |
L. Merlivat, J. Boutin, F. d'Ovidio |
| 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 ; 12, no. 11 ; Nr. 12, no. 11 (2015-06-09), S.3513-3524 |
| Datensatznummer |
250117975
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| Publikation (Nr.) |
 copernicus.org/bg-12-3513-2015.pdf |
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| Zusammenfassung |
| The Kerguelen Plateau region in the Indian sector of the Southern Ocean
supports annually a large-scale phytoplankton bloom which is naturally
fertilized with iron. As part of the second Kerguelen Ocean and Plateau
compared Study expedition (KEOPS2) in austral spring
(October–November 2011), one CARbon Interface OCean Atmosphere (CARIOCA) buoy was deployed east of the Kerguelen
Plateau. It drifted eastward downstream along the Kerguelen plume. Hourly
surface measurements of pCO2, O2 and ancillary observations were
collected between 1 November 2011 and 12 February 2012 with the aim of
characterizing the spatial and temporal variability of the biological net
community production, NCP, downstream the Kerguelen Plateau, assessing the
impact of iron-induced productivity on the biological inorganic carbon
consumption and consequently on the CO2 flux exchanged at the air–sea
interface. The trajectory of the buoy up to mid-December was within the
longitude range 72–83° E, close to the polar front and then in the
polar frontal zone, PFZ, up to 97° E. From 17 November to
16 December, the buoy drifted within the Kerguelen plume following a filament
carrying dissolved iron, DFe, for a total distance of 700 km. In the first
part of the trajectory of the buoy, within the iron plume, the ocean surface
waters were always a sink for CO2 and a source for O2, with fluxes of
respective mean values equal to −8 mmol CO2 and +38 mmol
O2 m−2 d−1. To the east, as the buoy escaped the iron-enriched
filament, the fluxes were in the opposite direction, with respective mean values
of +5 mmol CO2 and −48 mmol O2 m−2 d−1. These numbers
clearly indicate the strong impact of biological processes on the
biogeochemistry in the surface waters within the Kerguelen plume in
November–mid-December, while it is undetectable to the east in the PFZ from mid-
December to mid-February. While the buoy follows the Fe-enriched filament,
simultaneous observations of dissolved inorganic carbon (DIC) and dissolved
oxygen (O2) highlight biological events lasting from 2 to 4 days.
Stoichiometric ratios, O2 / C, between 1.1 and 1.4 are observed
indicating new and regenerated production regimes. NCP estimates range from
60 to 140 mmol C m−2 d−1. |
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