High-affinity metal binding by isolated humic acids has been observed for both copper and calcium in metal titration experiments. Results of titrationsof humicacids with a single metal (either calcium or copper) are consistent with a discrete ligand site model of humate-metal binding. However, copper titrations in thepresence of excess calcium do not show competitive effects predicted by such a model. Hence, different ligand sites mustbe involved in calcium and copper binding, or a binding mechanism other than discrete ligand binding must be operative.
All Science Journal Classification (ASJC) codes
- Environmental Chemistry