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

• Published in: Frontiers in Marine Science
• Main Authors: Arnone, Veronica, Santana Casiano, Juana Magdalena, González Dávila, Melchor, Planquette, Hélène, Sarthou, Géraldine, Gerringa, Loes J.A., González González, Aridane
• Other Authors: NO DATA, 57195278718, 57265678700, 6603931257, 22836555200, 6603306739, 34770314700, 37031064100, BU-BAS
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2023
• Subjects: 251002 Oceanografía química; Arctic Ocean; Copper; Copper-Binding Ligands; Transpolar Drift; Voltammetric Method; Arctic; Barents Sea; Makarov Basin; Amundsen Basin; amundsen basin; Fram Strait; makarov basin; Nansen Basin; Nordic Seas; Sea ice
• Online Access: http://hdl.handle.net/10553/128257; https://doi.org/10.3389/fmars.2023.1306278

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. 20 1,355 5,247 Q1 Q1 SCIE 10,3