The bioavailability and migration of pollutant ions (for example, radionuclides or heavy metals) in soils is closely related to the presence of humic substances (HSs). Because they strongly bind cationic species, humic substances when solid or adsorbed on mineral surfaces can retard the transport of metal ions; or conversely, dissolved HSs can enhance the mobility of these ions [1-10]. To predict speciation of metal ions in soils one must first evaluate the binding properties of both the minerals and the organic matter towards the studied metal species. Binding properties of dissolved organic matter (DOM) have been studied with numerous analytical methods including potentiometric, voltammetric, spectroscopic or physical separation based methods [2].