 |
| Titel |
A model of Fe speciation and biogeochemistry at the Tropical Eastern North Atlantic Time-Series Observatory site |
| VerfasserIn |
Y. Ye, C. Völker, D. A. Wolf-Gladrow |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
1726-4170
|
| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 6, no. 10 ; Nr. 6, no. 10 (2009-10-07), S.2041-2061 |
| Datensatznummer |
250004031
|
| Publikation (Nr.) |
 copernicus.org/bg-6-2041-2009.pdf |
|
|
|
|
|
| Zusammenfassung |
A one-dimensional model of Fe speciation and biogeochemistry,
coupled with the General Ocean Turbulence Model (GOTM) and a NPZD-type
ecosystem model, is applied for the Tropical
Eastern North Atlantic Time-Series Observatory (TENATSO)
site. Among diverse processes affecting Fe speciation, this
study is focusing on investigating the role of dust particles in
removing dissolved iron (DFe) by a more complex description of particle
aggregation and sinking, and explaining the abundance of organic
Fe-binding ligands by modelling their origin and fate.
The vertical distribution of different particle classes in the model shows high
sensitivity to changing aggregation rates. Using the aggregation
rates from the sensitivity study in this work, modelled particle
fluxes are close to observations, with dust particles dominating near the surface and
aggregates deeper in the water column. POC export at 1000 m is
a little higher than regional sediment trap measurements, suggesting
further improvement of modelling particle aggregation, sinking or
remineralisation.
Modelled strong ligands have a high abundance near the surface and decline
rapidly below the deep chlorophyll maximum, showing qualitative similarity
to observations. Without production of strong
ligands, phytoplankton concentration falls to 0 within the first 2 years
in the model integration, caused by strong Fe-limitation. A nudging of total weak
ligands towards a constant value is required for reproducing the
observed nutrient-like profiles, assuming a decay
time of 7 years for weak ligands. This indicates that weak ligands
have a longer decay time and therefore cannot be modelled adequately
in a one-dimensional model.
The modelled DFe profile is strongly influenced by particle
concentration and vertical distribution, because the most important
removal of DFe in deeper waters is colloid formation and
aggregation. Redissolution of particulate iron is required to
reproduce an observed DFe profile at TENATSO site. Assuming colloidal iron
is mainly composed of inorganic colloids, the modelled colloidal to
soluble iron ratio is lower that observations, indicating the
importance of organic colloids. |
| |
|
| Teil von |
|
|
|
|
|
|
|
|