Distribution of copper-complexing ligands in Canadian Arctic waters as determined by immobilized copper(II)-ion affinity chromatography

• Published in: Marine Chemistry
• Main Authors: Nixon, Richard L., Sarah, Jackson, Cullen, Jay T., Ross, Andrew
• Format: Article in Journal/Newspaper
• Language: English
• Published: Marine Chemistry 2019
• Subjects: Marine organic ligands; Copper; Immobilized metal-ion affinity chromatography; Canadian Arctic; GEOTRACES; Arctic; Baffin Bay; Canada; Canadian Arctic Archipelago; Arctic Archipelago; Baffin; canada basin; Climate change; Phytoplankton
• Online Access: http://hdl.handle.net/1828/11469; https://doi.org/10.1016/j.marchem.2019.103673

Complexation by dissolved organic ligands affects the bioavailability and distribution of copper and other bioactive trace metals in seawater. However, relatively little is known about the origin and identity of marine copper-complexing ligands, particularly in Arctic waters. We used immobilized copper(II)-ion affinity chromatography (IMAC) to isolate dissolved (< 0.2 μm) copper ligands from seawater samples collected during the 2015 Canadian Arctic GEOTRACES expedition. UV detection at 254 nm was employed to monitor elution of the compounds retained by IMAC. The areas of the resulting peaks were used to generate depth profiles that show, for the first time, how copper ligands are distributed across the Canadian Arctic. Copper ligand concentrations ranged from 0.9 to 4.8 nM, the depth of highest ligand concentration often coinciding with the chlorophyll maximum depth. Correlations between ligand concentration and in situ chlorophyll-a fluorescence suggest that marine phytoplankton or cyanobacteria could be an important source of copper ligands. A correlation was also observed between copper ligand and dissolved copper concentrations in Baffin Bay. Comparison of these results with published data for humic substances and other dissolved organic matter suggests that terrestrial input contributes to the pool of ligands captured by IMAC, particularly in the Canada Basin and Canadian Arctic Archipelago. This work was supported by the NSERC Climate Change and Atmospheric Research (CCAR) program (Grant Number RGPCC 433848-2012) and Fisheries and Oceans Canada (AR) and by university and departmental graduate scholarships from the University of Victoria (RN). Faculty Reviewed