A Novel Approach to Metal-Humic Complexation Studies by Lanthanide Ion Probe Spectroscopy

Naturally occurring humic substances are known to be potentially strong binders of metals in the environment. A sensitive spectroscopic technique, based on the unique luminescence properties of the tripositive lanthanide metal ions, has been developed to selectively probe metal binding sites in humic substances. A continuous, multiligand pH dependent ligand model is proposed to describe complexation of metals with humic materials in terms of mean binding strengths, distributions, and concentrations.