Determination of complexing capacities of ligands in natural waters and conditional stability constants of the copper complexes by means of manganese dioxide

A dispersion of manganese dioxide is used as a weak ion exchanger in the determination of the complexing capacities of natural waters for copper and in the estimation of the stability constants of the complexes formed, at the concentration and pH at which the ligands occur in natural waters. Experiments were done at 25°C and 0.01 M ionic strength. Stability constants varied from 10 7.8 to 10 8.8 at pH 7.6 for ligands in lakes and rivers. The constant for the copper—fulvic acid complex was estimated as 10 7.8 at pH 7.6. Only one complexing site of major importance for natural water environments was observed.