INFLUENCE OF HUMIC SUBSTANCES ON THE AQUATIC ADSORPTION OF HEAVY-METALS ON DEFINED MINERAL PHASES

The distribution of heavy metals in the aqueous phase of aquifers is s trongly dependent on the kind of solid phase and on the presence of di ssolved organic matter. Batch experiments were performed to investigat e the phase distribution of Cd, Pb, and Cu using Quartz, Potassium Fel dspar, Sodium Feldspar, Kaolinite, Calcite, and Fe/Mn-coated Quartz sa nd as mineral phases. Natural organic matter (NOM) from a brown water lake was used to study its influence on the phase distribution of the metals. From the experimental results, Freundlich isotherms were calcu lated. They turned out to be suited for a description of the heterogen eous systems. Despite the obvious limitations of mechanistic interpret ation, NOM increased the dissolved fraction of Cu and Pb, and decrease d that of Cd.