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| Titel |
A global compilation of dissolved iron measurements: focus on distributions and processes in the Southern Ocean |
| VerfasserIn |
A. Tagliabue, T. Mtshali, O. Aumont, A. R. Bowie, M. B. Klunder, A. N. Roychoudhury, S. Swart |
| 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. 6 ; Nr. 9, no. 6 (2012-06-29), S.2333-2349 |
| Datensatznummer |
250007135
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| Publikation (Nr.) |
 copernicus.org/bg-9-2333-2012.pdf |
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| Zusammenfassung |
| Due to its importance as a limiting nutrient for phytoplankton growth in
large regions of the world's oceans, ocean water column observations of
concentration of the trace-metal iron (Fe) have increased markedly over
recent decades. Here we compile >13 000 global measurements of
dissolved Fe (dFe) and make this available to the community. We then conduct
a synthesis study focussed on the Southern Ocean, where dFe plays a
fundamental role in governing the carbon cycle, using four regions, six
basins and five depth intervals as a framework. Our analysis highlights
depth-dependent trends in the properties of dFe between different regions
and basins. In general, surface dFe is highest in the Atlantic basin and the
Antarctic region. While attributing drivers to these patterns is uncertain,
inter-basin patterns in surface dFe might be linked to differing degrees of
dFe inputs, while variability in biological consumption between regions
covaries with the associated surface dFe differences. Opposite to the surface,
dFe concentrations at depth are typically higher in the Indian basin and the
Subantarctic region. The inter-region trends can be reconciled with similar
ligand variability (although only from one cruise), and the inter-basin
difference might be explained by differences in hydrothermal inputs
suggested by modelling studies (Tagliabue et al., 2010) that await
observational confirmation. We find that even in regions where many dFe
measurements exist, the processes governing the seasonal evolution of dFe
remain enigmatic, suggesting that, aside from broad Subantarctic –
Antarctic trends, biological consumption might not be the major driver of dFe
variability. This highlights the apparent importance of other processes such
as exogenous inputs, physical transport/mixing or dFe recycling processes.
Nevertheless, missing measurements during key seasonal transitions make it
difficult to better quantify and understand surface water replenishment
processes and the seasonal Fe cycle. Finally, we detail the degree of
seasonal coverage by region, basin and depth. By synthesising prior
measurements, we suggest a role for different processes and highlight key
gaps in understanding, which we hope can help structure future research
efforts in the Southern Ocean. |
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