Natural copper-binding ligands in the Arctic Ocean. The influence of the Transpolar Drift (GEOTRACES GN04)

Type Article
Date 2023-12
Language English
Author(s) Arnone Veronica1, Santana-Casiano J. Magdalena1, González-Dávila Melchor1, Planquette Helene2, Sarthou Geraldine2, Gerringa Loes J. A.3, González Aridane G.1
Affiliation(s) 1 : Instituto de Oceanografía y Cambio Global, IOCAG, Universidad de Las Palmas de Gran Canaria, ULPGC, Las Palmas de Gran Canaria, Spain
2 : univ Brest, CNRS, IRD, Ifremer, LEMAR, Plouzané, France
3 : Department of Ocean Systems, Royal Netherlands Institute for Sea Research, NIOZ, Den Hoorn, Netherlands
Source Frontiers In Marine Science (2296-7745) (Frontiers Media SA), 2023-12 , Vol. 10 , P. 1306278 (20p.)
DOI 10.3389/fmars.2023.1306278
Keyword(s) copper, copper-binding ligands, voltammetric method, Arctic Ocean, Transpolar Drift
Abstract

The Arctic Ocean is a unique biogeochemical environment characterized by low salinity surface waters, extensive sea-ice coverage, high riverine inputs, large shelf extension and the long residence time of deep waters. These characteristics determine the distribution of dissolved bio-essential trace metals, such as copper (Cu), and the dissolved organic-binding ligands capable of complexing it. This work reports the concentrations and conditional stability constants of dissolved Cu-binding ligands (LCu and log KcondCu2+L) measured in samples from the Polarstern (PS94) expedition, as part of the international GEOTRACES program (cruise GN04). Full-depth profile stations from the Barents Sea, Nansen Basin, Amundsen Basin and Makarov Basin were analysed by competitive ligand exchange-adsorptive cathodic stripping voltammetry (CLE-AdCSV). The basins and water masses presented a wide range of LCu concentrations (range: 1.40 – 7.91 nM) and log KcondCu2+L values (range: 13.83 – 16.01). The highest variability of Cu-binding ligand concentrations was observed in surface waters (≤200 m), and mean concentrations increased from the Barents Sea and Nansen Basin (2.15 ± 0.31 nM and 1.93 ± 0.35 nM, respectively) to the Amundsen (3.84 ± 1.69 nM) and Makarov Basins (4.40± 2.03 nM). The influence of the Transpolar Drift (TDP) flow path was observed in the Amundsen and Makarov Basins, especially on Cu-binding ligand concentrations (LCu range: 3.96 – 7.91 nM). In contrast, deep waters (>200 m) showed no significant differences between basins and water masses in terms of LCu concentrations (range: 1.45 – 2.78 nM) and log KcondCu2+L (range: 14.02 – 15.46). The presence of strong Cu-binding ligands (log KcondCu2+L>13) in surface waters stabilises the excess of dissolved copper (dCu) transported in the TPD and favours its export to the Fram Strait and Nordic Seas.

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Arnone Veronica, Santana-Casiano J. Magdalena, González-Dávila Melchor, Planquette Helene, Sarthou Geraldine, Gerringa Loes J. A., González Aridane G. (2023). Natural copper-binding ligands in the Arctic Ocean. The influence of the Transpolar Drift (GEOTRACES GN04). Frontiers In Marine Science, 10, 1306278 (20p.). Publisher's official version : https://doi.org/10.3389/fmars.2023.1306278 , Open Access version : https://archimer.ifremer.fr/doc/00869/98126/