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| Titel: |
Dust deposition: iron source or sink? A case study |
| Auteur: |
Y. Ye T. Wagener C. Völker C. Guieu D. A. Wolf-Gladrow |
| Verschenen in: |
Biogeosciences discussions |
| Paginering: | Jaargang 7 (2010) nr. 6 pagina's 9219-9272 |
| Jaar: |
2010 |
| Inhoud: |
A significant decrease of dissolved iron (DFe) concentration has been observed after dust addition into mesocosms during the DUst experiment in a low Nutrient low chlorophyll Ecosystem (DUNE), carried out in the summer of 2008. To understand the processes regulating the observed DFe variation, we simulated the experiment by a one-dimensional model of the Fe biogeochemical cycle, coupled with a simple ecosystem model. Different size classes of particles and particle aggregation are taken into account to describe the particle dynamics. DFe concentration is regulated in the model by dissolution from dust particles and adsorption onto particle surfaces, biological uptake, and photochemical mobilisation of particulate iron. The model reproduces the observed DFe decrease after dust addition well, choosing particle adsorption rates of 30, 150 and 750 m<sup>3 kg<sup>−1 d<sup>−1 for particles of different size classes. These adsorption rates range between the measured adsorption rates of soluble iron and those of colloidal iron, indicating both processes controlling the DFe removal during the experiment. Sensitivity studies reveal that initial DFe concentration before dust addition was crucial for the net impact of dust addition on DFe during the DUNE experiment. From the balance between sinks and sources of DFe, a critical DFe concentration, above which dust deposition acts as a net sink of DFe, rather than a source, has been estimated for the DUNE experiment. Taking into account the role of excess iron binding ligands, this concept of a critical DFe concentration might be applied to explain the short-term variability of DFe after natural dust deposition. |
| Uitgever: |
Copernicus GmbH (provided by DOAJ) |
| Bronbestand: |
Elektronische Wetenschappelijke Tijdschriften |
Details van artikel 37 van 146 gevonden artikelen
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