MINTEQ is a computer program for computation of geochemical equilibria. MINTEQ was developed for incorporation into the Metals Exposure Analysis Modeling System (MEXAMS), a modeling system for the assessment of the fate and migration of selected priority pollutant metals in aquatic systems. MINTEQ combines the best features of two existing geochemical models MINEQL and WATEQ3. The mathematical structure was taken from MINEQL. The WATEQ3 features were added to this basic structure. The main features obtained from WATEQ3 are the well referenced thermodynamic data base, temperature correction of equilibrium constants using either the Van't Hoff relationship or analytical expressions for the equilibium constants as a function of temperature and ionic strength correction using either the extended Debye-Huckel equation or the Davies equation. Six different adsorption algorithms: an 'activity' Kd, an 'activity' Langmuir equation, an 'activity' Freundlich equation, an ion exchange algorithm, a constant capacitance surface complexation model, and the triple layer surface complexation model. In addition, a large number of user oriented features such as the ability to handle alkalinity inputs, an initial mass of solid, and different analytical inputs were incorporated.

Bibliography: pages 53-69 Final report. Photocopy.