WATEQ4F is a program for the calculation of chemical equilibrium in natural waters. It models the thermodynamic speciation of major and important minor inorganic ions and complex species in solution for a given water analysis and in situ measurements of temperature, pH, and redox potential. From this model the states of reaction of the water with solid and gaseous phases are calculated. The examination of reaction states may suggest the origin of the dissolved constituents and assist in the prediction of the chemical effects of ground-water production, recharge, irrigation, and anorganic pollution. The original version (WATEQ) was written in 1973 by A.H. Truesdell and B.F. Jones in PL/1. WATEQ4F is the latest version of WATEQ and includes several revisions to the thermodynamic data base including the addition of selenium and uranium species as well as the recently published values of Nordstrom and others (1990).

The preprocessor WQ4FINPT is distributed with WATEQ4F which allows the user to create and modify input files of analytical data. The public domain program is distributed with source code, DOS-based executable image, and example data sets. The revised documentation for WATEQ4F by Ball and Nordstrom (1991) provides instructions for program operation, explanations of the input and output files, and all reactions and references for the thermodynamic data base.

SYSTEM REQUIREMENTS

Intel 80386/80486 based computer, 640 Kb RAM, DOS 3.0 or higher.

Authors: J.W. Ball and D. Kirk Nordstrom (U.S. Geological Survey).