Organic Fe speciation in the Eurasian Basins of the Arctic Ocean and its relation to terrestrial DOM

The bio-essential trace metal iron (Fe) has poor inorganic solubility in seawater, and therefore dissolution is dependent on organic complexation. The Arctic Ocean is subject to strong terrestrial influences which contribute to organic solubility of Fe, particularly in the surface. These influences...

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Bibliographic Details
Published in:Marine Chemistry
Main Authors: Slagter, H. A., Reader, H. E., Rijkenberg, M. J. A., van der Loeff, M. Rutgers, de Baar, H. J. W., Gerringa, L. J. A.
Format: Article in Journal/Newspaper
Language:English
Published: 2017
Subjects:
CATHODIC STRIPPING VOLTAMMETRY
SOUTHERN-OCEAN
PERMAFROST CARBON
HUMIC SUBSTANCES
COASTAL WATERS
NATURAL-WATERS
COMPLEXING LIGANDS
OPTICAL-PROPERTIES
IRON-LIMITATION
DISSOLVED IRON
Arctic
Arctic Ocean
Makarov Basin
Southern Ocean
Fram Strait
makarov basin
Nansen Basin
permafrost
Online Access:https://hdl.handle.net/11370/39988644-860d-4e0a-82f5-aef9f6dd56cf
https://research.rug.nl/en/publications/39988644-860d-4e0a-82f5-aef9f6dd56cf
https://doi.org/10.1016/j.marchem.2017.10.005
https://pure.rug.nl/ws/files/58454086/1_s2.0_S0304420317301901_main.pdf
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Summary:The bio-essential trace metal iron (Fe) has poor inorganic solubility in seawater, and therefore dissolution is dependent on organic complexation. The Arctic Ocean is subject to strong terrestrial influences which contribute to organic solubility of Fe, particularly in the surface. These influences are subject to rapid changes in the catchments of the main contributing rivers. Here we report concentrations and binding strengths of Fe-binding organic ligands in relation to spectral properties of Dissolved Organic Matter (DOM) and concentrations of humic substances. Full-depth profiles of Fe and Fe-binding organic ligands were measured for 11 stations, good agreement to previous studies was found with ligand concentrations between 0.9 and 2.2 equivalent nM of Fe (Eq. nM Fe) at depths > 200 m. We found nutrient-like profiles of Fe in the Atlantic-influenced Nansen basin, surface enrichment in the surface over the Amundsen and Makarov basins and scavenging effects in the deep Makarov basin. A highly detailed surface transect consisting of two sections crossing the surface flow from the Siberian continental shelf to the Fram Strait, the TransPolar Drift (TPD), clearly indicates the flow path of the riverine contribution to Fe and Fe-binding organic ligands with concentrations of 0.7 to 4.4 nM and 1.6 to 4.1 Eq. nM Fe, respectively. This is on average 4.5 times higher in DFe and 1.7 times higher in Fe-binding organic ligands than outside the TPD flow path. Conditional binding strengths of ligands in the entire dataset were remarkably similar at 11.45

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