A DATABASE MANAGEMENT TOOL FOR THE PHREEQC AND MINTEQA2 GEOCHEMICAL MODELS

An MS Excel application has been developed to allow users of the geochemical models PHREEQC and MINTEQA2 to more easily review and edit the databases of geochemical reactions pertaining to these models. PHREEQC (distributed by the USGS) and MINTEQA2 (distributed by the US EPA) are two programs that model the equilibrium behavior of species in groundwater under varying conditions. Both modeling programs rely on a database of components, species, reactions, and associated thermodynamic parameters to perform the necessary computations. However, previous databases for these models lack efficient and secure editing functions that could benefit the users of the models. This Excel application allows the user to scroll through the database, displaying each component (master species) in a window for editing, as well as allowing new components to be added. In the same manner, the reaction database is accessible via a window where each reaction species is displayed as the user scrolls. Changes to reaction species can easily be made, but only when the species is displayed in the window, as the underlying spreadsheet is not directly accessible. The user may change a reaction’s equilibrium constant or enthalpy of reaction, supply or update documentation of the source of these parameters, add new reaction species, or delete species. The Excel application has the ability to format the database to be read by either model with a simple selection from the user. This allows users of either model to efficiently change or customize the model’s database and enhances the flexibility of the MINTEQA2 and PHREEQC models. The database management application is available free from the authors.