|
Titel |
Towards accounting for dissolved iron speciation in global ocean models |
VerfasserIn |
A. Tagliabue, C. Völker |
Medientyp |
Artikel
|
Sprache |
Englisch
|
ISSN |
1726-4170
|
Digitales Dokument |
URL |
Erschienen |
In: Biogeosciences ; 8, no. 10 ; Nr. 8, no. 10 (2011-10-31), S.3025-3039 |
Datensatznummer |
250006171
|
Publikation (Nr.) |
copernicus.org/bg-8-3025-2011.pdf |
|
|
|
Zusammenfassung |
The trace metal iron (Fe) is now routinely included in
state-of-the-art ocean general circulation and biogeochemistry models
(OGCBMs) because of its key role as a limiting nutrient in regions of the
world ocean important for carbon cycling and air-sea CO2 exchange.
However, the complexities of the seawater Fe cycle, which impact its
speciation and bioavailability, are simplified in such OGCBMs due to gaps in
understanding and to avoid high computational costs. In a similar fashion to
inorganic carbon speciation, we outline a means by which the complex
speciation of Fe can be included in global OGCBMs in a reasonably
cost-effective manner. We construct an Fe speciation model based on
hypothesised relationships between rate constants and environmental
variables (temperature, light, oxygen, pH, salinity) and assumptions
regarding the binding strengths of Fe complexing organic ligands and test
hypotheses regarding their distributions. As a result, we find that the
global distribution of different Fe species is tightly controlled by
spatio-temporal environmental variability and the distribution of Fe binding
ligands. Impacts on bioavailable Fe are highly sensitive to assumptions
regarding which Fe species are bioavailable and how those species vary in
space and time. When forced by representations of future ocean circulation
and climate we find large changes to the speciation of Fe governed by pH
mediated changes to redox kinetics. We speculate that these changes may
exert selective pressure on phytoplankton Fe uptake strategies in the future
ocean. In future work, more information on the sources and sinks of ocean Fe
ligands, their bioavailability, the cycling of colloidal Fe species and
kinetics of Fe-surface coordination reactions would be invaluable. We hope
our modeling approach can provide a means by which new observations of Fe
speciation can be tested against hypotheses of the processes present in
governing the ocean Fe cycle in an integrated sense |
|
|
Teil von |
|
|
|
|
|
|