Complexing of metal ions by humic substances

The interaction of metal ions with humic substances is being studied using two different techniques. UV-scanning ultracentrifugation is being used to determine molecular weights and to investigate changes in aggregation brought about by metal ion complexation. The relationship between cation charge and conformation of the humic ligands is also being investigated. The complexation of actinide elements (U, Np, Pu, Am) by humic substances from soils contaminated by both natural processes and by low-level effluent releases is also being studied. Gel permeation chromatography has been used to show both that different fractions of humic substances vary greatly in their effectiveness as ligands and that different actinide elements associate with different fractions. These studies have also shown that uranium desorption is kinetically controlled by humic substances