WHAM - A CHEMICAL-EQUILIBRIUM MODEL AND COMPUTER CODE FOR WATERS, SEDIMENTS, AND SOILS INCORPORATING A DISCRETE SITE ELECTROSTATIC MODEL OFION-BINDING BY HUMIC SUBSTANCES

WHAM (Windermere Humic Aqueous Model) is designed to calculate equilib rium chemical speciation in surface and ground waters, sediments, and soils. The model is suitable especially for problems where the chemica l speciation is dominated by organic matter (humic substances). WHAM c ombines Humic Ion-Binding Model V with a simple inorganic speciation c ode for aqueous solutions. Precipitation of aluminum and iron oxides, cation-exchange on an idealized clay mineral, and adsorption-desorptio n reactions of fulvic acid also are taken into account. The importance of ion accumulation in the diffuse layers surrounding the humic molec ules is emphasized. Model calculations are performed with a BASIC comp uter code running on a Personal Computer.