Distribution of copper-binding ligands in Fram Strait and influences from the Greenland Shelf (GEOTRACES GN05)

• Published in: Science of The Total Environment
• Main Authors: Arnone, Veronica, Santana-Casiano, J. Magdalena, González-Dávila, Melchor, Sarthou, Geraldine, Krisch, Stephan, Lodeiro, Pablo, Achterberg, Eric P., González, Aridane G.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Elsevier 1481
• Subjects: Arctic; Arctic Ocean; Climate change; Fram Strait; Greenland; Nordic Seas; North Atlantic; Phytoplankton; Sea ice
• Online Access: https://oceanrep.geomar.de/id/eprint/59392/; https://oceanrep.geomar.de/id/eprint/59392/7/1-s2.0-S004896972306789X-main.pdf; https://doi.org/10.1016/j.scitotenv.2023.168162

Highlights • Cu complexation was measured for the first time in the Fram Strait region. • Cu-binding ligand concentrations and binding strength varied longitudinally in the Fram Strait. • More than 99 % of dCu was organically complexed by strong ligands. • On the Greenland shelf the Transpolar Drift and the coastal processes were the main sources of Cu ligands. Abstract The Fram Strait represents the major gateway of Arctic Ocean waters towards the Nordic Seas and North Atlantic Ocean and is a key region to study the impact of climate change on biogeochemical cycles. In the region, information about trace metal speciation, such as copper, is scarce. This manuscript presents the concentrations and conditional stability constants of copper-binding ligands (LCu and log KcondCu2+L) in the water column of Fram Strait and the Greenland shelf (GEOTRACES cruise GN05). Cu-binding ligands were analysed by Competitive Ligand Exchange-Adsorptive Cathodic Stripping Voltammetry (CLE-ACSV) using salicylaldoxime (SA) as competitive ligand. Based on water masses and the hydrodynamic influences, three provinces were considered (coast, shelf, and Fram Strait) and differences were observed between regions and water masses. The strongest variability was observed in surface waters, with increasing LCu concentrations (mean values: Fram Strait = 2.6 ± 1.0 nM; shelf = 5.2 ± 1.3 nM; coast = 6.4 ± 0.8 nM) and decreasing log KcondCu2+L values (mean values: Fram Strait = 15.7 ± 0.3; shelf = 15.2 ± 0.3; coast = 14.8 ± 0.3) towards the west. The surface LCu concentrations obtained above the Greenland shelf indicate a supply from the coastal environment to the Polar Surface Water (PSW) which is an addition to the ligand exported from the central Arctic to Fram Strait. The significant differences (in terms of LCu and log KcondCu2+L) between shelf and coastal samples were explained considering the processes which modify ligand concentrations and binding strengths, such as biological activity in sea-ice, phytoplankton bloom in surface waters, ...