Characterization of metal binding sties in fulvic acids 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 luminescent properties of the tripositive lanthanide metal ions, has been developed to selectively probe metal binding sites in humic substances. A continuous multiple site ligand model is proposed to describe complexation of metals with humic materials in terms of mean binding strengths, distributions, and concentrations. Experimental results as well as a simulation study that uses this model are also presented