Copper speciation in glacial stream waters of Rutor Glacier (Aosta Valley, Italy)

The chemical speciation of copper in stream waters from Rutor Glacier was determined by cathodic stripping voltammetry with ligand competition against salicylaldoxime. The complexation of salicylaldoxime was calibrated at various calcium concentrations, the major competing cation in these waters. Copper concentrations ( 3 - 7 nM) were approximately ten-fold lower than typical for rain waters in this region, indicating that copper had been removed by adsorption onto rock and other particles. Strong copper binding ligands, with log K'(CuL) = 12.5 - 12.9, were detected in all samples, including waters emerging from beneath the glacier, with no detectable change in the ligand composition down stream. The results suggest that the ligands could originate from in situ production from algae in snow and ice, or directly from the precipitation.