Spatial variability of total dissolved copper and copper speciation in the inshore waters of Bermuda

Total dissolved copper (Cu) and Cu speciation were examined from inshore waters of Bermuda, in October 2009 and July-August 2010, to determine the relationship between total dissolved Cu, Cu-binding ligands and bioavailable, free, hydrated Cu2+ concentrations. Speciation was performed using competitive ligand exchange-adsorptive cathodic stripping voltammetry (CLE-ACSV). Mean total dissolved Cu concentrations ranged from 1.4 nM to 19.2 nM, with lowest concentrations at sites further from shore, consistent with previous measurements in the Sargasso Sea, and localized Cu enrichment inshore in enclosed harbors. Ligand concentrations exceeded dissolved [Cu] at most sites, and [Cu2+] were correspondingly low at those sites, typically <10−13 M. One site, Hamilton Harbour, was found to have [Cu] in excess of ligands, resulting in [Cu2+] of 10−10.7 M, and indicating that Cu may be toxic to phytoplankton here.