A critical comparison of studies of complex formation between copper(II) and fulvic substances of natural waters

The results obtained by various authors in discussing complex formation between copper(II) and fulvic substances in natural waters are compared; particular attention is given to results obtained in the natural pH range (6–9). The influence of the experimental conditions used for the complexation measurements is discussed, as well as the hypotheses used in interpretation of the data. The ligand concentration, and the possible formation of mixed complexes and precipitation of copper hydroxide, are considered. When these factors are taken into account, a better agreement may be found between the results of the various workers. Further, the relative importance of the various possible reactions may be defined from such a comparison. As a result, various recommendations are given about the features of the experimental conditions that must be considered to obtain meaningful data on complex formation.