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Abstract

A competitive ligand equilibration adsorptive cathodic stripping voltammetry (CLEACS V) technique using salicylaldoxime as the added ligand was developed for the detennination of copper speciation in seawater. The CLE-ACSV technique has been shown to be applicable to the determination of total copper. The depth profile at station AVHS-1 in the Western North Pacific has been reproduced, and the concentration of copper in the standard reference material NASS-4 was determined to be 3.4 ± 0.4 nM in excellent agreement with the certified value of 3.6 ± 0.2 nM. The applicability of this technique to the measurement of copper speciation was inferred from the ability to accurately determine the value of the overall stability constant for the Cu(SA)₂ complex by calibration with EDTA. The measured value of β₂sa/cu²⁺ = 15.0 ± 0.2 in excellent agreement with the only literature value of β^lci+ = 14.88 ± 0.3. Cultures of the marine cyanobacteria Synechococcus PCC7002 produce a strong copperbinding ligand when exposed to gradual increases in copper. This ligand as been shown to have a log K^u, of 12.2, amongst the strongest copper complexing ligands investigated to date.