AN INVESTIGATION OF COPPER COMPLEXATION IN THE SEVERN ESTUARY USING DIFFERENTIAL PULSE CATHODIC STRIPPING VOLTAMMETRY

Copper complexation in water samples from the Severn Estuary has been characterized by metal titrations using differential pulse cathodic stripping voltammetry. The titration results were interpreted using a single ligand model of complexation. In all samples, measured ligand concentrations were in excess of dissolved copper and ranged between 13.3 and 196 nM. The range of log conditional stability constants determined was 11.4-12.8. Both ligand concentration and dissolved copper appeared to behave conservatively in the estuary, with the river being the dominant source of both constituents. In all of the samples analysed, greater than 99% of dissolved copper was organically complexed, with calculated pCu2+ values ranging from 11.12 to 12.84. The results of this study strongly suggest that copper is transported to the oceans in the form of river-borne organic complexes. © 1990.