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| Titel |
The influence of iron and light on net community production in the Subantarctic and Polar Frontal Zones |
| VerfasserIn |
N. Cassar, P. J. DiFiore, B. A. Barnett, M. L. Bender, A. R. Bowie, B. Tilbrook, K. Petrou, K. J. Westwood, S. W. Wright, D. Lefèvre |
| 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. 2 ; Nr. 8, no. 2 (2011-02-01), S.227-237 |
| Datensatznummer |
250005437
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| Publikation (Nr.) |
 copernicus.org/bg-8-227-2011.pdf |
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| Zusammenfassung |
| The roles of iron and light in controlling biomass and primary productivity
are clearly established in the Southern Ocean. However, their influence on
net community production (NCP) and carbon export remains to be quantified.
To improve our understanding of NCP and carbon export production in the
Subantarctic Zone (SAZ) and the northern reaches of the Polar Frontal Zone
(PFZ), we conducted continuous onboard determinations of NCP as part of the
Sub-Antarctic Sensitivity to Environmental Change (SAZ-Sense) study, which
occurred in January–February 2007. Biological O2 supersaturation was derived
from measuring O2/Ar ratios by equilibrator inlet mass spectrometry.
Based on these continuous measurements, NCP during the austral summer 2007
in the Australian SAZ was approximately 43 mmol O2 m−2 d−1.
NCP showed significant spatial variability, with larger values
near the Subtropical front, and a general southward decrease. For shallower
mixed layers (<50 m), dissolved Fe concentrations and Fe sufficiency,
estimated from variable fluorescence, correlated strongly with NCP. The
strong correlation between NCP and dissolved Fe may be difficult to
interpret because of the correlation of dissolved Fe to MLD and because the
concentration of iron may not be a good indicator of its availability. At
stations with deeper mixed layers, NCP was consistently low, regardless of
iron sufficiency, consistent with light availability also being an important
control of NCP. Our new observations provide independent evidence for the
critical roles of iron and light in mediating carbon export from the
Southern Ocean mixed layer. |
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