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Electrochemical evaluation of iron-binding ligands along the Australian GEOTRACES southwestern Pacific section (GP13)

Citation

Cabanes, DJE and Norman, L and Bowie, AR and Strmecki, S and Hassler, CS, Electrochemical evaluation of iron-binding ligands along the Australian GEOTRACES southwestern Pacific section (GP13), Marine Chemistry, 219 Article 103736. ISSN 0304-4203 (2019) [Refereed Article]

Copyright Statement

2019 Elsevier B.V. All rights reserved.

DOI: doi:10.1016/j.marchem.2019.103736

Abstract

In this work, we performed electrochemical investigations of Fe-binding ligands in water samples collected in autumn 2011 along the Australian GEOTRACES southwestern Pacific section (GP13, between 153E and 170W longitude along the 30S line East of Australia, 0-1000m depth). We determined the capacity of the bulk organic ligands to complex Fe using competitive ligand exchange-adsorptive cathodic stripping voltammetry (CLE-AdCSV) with salicylaldoxime as the competing ligand. Two categories of organic ligands, humic substances (HS-like) and catalytically active polymers (Cat. P) were electrochemically quantified in order to better define the bulk of Fe-binding ligands. Finally, Fe speciation results have been linked to oceanographic data, phytoplankton biomass, and two groups of cyanobacteria (Prochlorococcus and Synechococcus) which are prominent members of the phototrophic community in the study region. Across the section, higher total ligand concentrations over dissolved Fe concentrations were observed, as well as the predominance of "weak" Fe-binding ligands (log KFeL<12). Highest "excess ligands" were mostly concentrated in the upper layer of the water column, suggesting a direct link with biological activity. None of the two groups of organic ligands measured (HS-like and Cat. P) accounted for the bulk of the total Fe-binding ligands concentration, hindering a better characterization of the nature of in-situ Fe-binding ligands. Cat. P concentrations showed statistically significant positive correlations with all biomarker pigments and the abundance of Prochlorococcus, suggesting that this material, resembling polysaccharides, could be a good parameter to probe organic compounds from specific biological origin. Amongst the biological parameters, only Prochlorococcus was related to Fe concentrations.

Item Details

Item Type:Refereed Article
Keywords:iron-binding ligands, Australian GEOTRACES, southwestern Pacific, iron, organic speciation, humic substances, polymers, phytoplankton
Research Division:Earth Sciences
Research Group:Oceanography
Research Field:Chemical Oceanography
Objective Division:Environment
Objective Group:Physical and Chemical Conditions of Water
Objective Field:Physical and Chemical Conditions of Water in Marine Environments
UTAS Author:Bowie, AR (Professor Andrew Bowie)
ID Code:136877
Year Published:2019
Funding Support:Australian Research Council (FT130100037)
Deposited By:Oceans and Cryosphere
Deposited On:2020-01-21
Last Modified:2020-03-20
Downloads:0

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