phreeqe(1) U.S. Geological Survey (wrdapp) phreeqe(1) NAME phreeqe - A program for geochemical calculations SYNOPSIS phreeqe [infile [ outfile [ database]]] OPTIONS infile - The name of the file in PHREEQE input format. outfile - The name of the file that will contain PHREEQE results. database - The name of the PHREEQE data base. If no arguments are specified, the program prompts for the input, output, and database file names. If only infile is specified, then outfile defaults to infile.out and the database to phreeqe.dat in the phreeqe2.4/bin_data directory. If only infile and outfile are specified, then the database defaults to phreeqe.dat in the phreeqe2.4/bin_data directory. NOTE PHREEQE is now obsolete and has been replaced with the program PHREEQC. ABSTRACT PHREEQE is a Fortran 77 computer program designed to model the chemical evolution of the aqueous phase as the result of specified geochemical reactions. Based on an ion-pairing aqueous model, PHREEQE can calculate pH, redox potential, concentration of elements, molalities and activities of aqueous species, and mineral or gas mass transfer as a function of reaction progress. The program is capable of simulating reactions due to mixing, titrating, net irreversible reaction, temperature changes, and mineral- or gas- phase equilibration. The aqueous model, including elements, aqueous species, and mineral and gas phases, is exterior to the computer code and is completely user definable. PHREEQE has been incorporated into several transport codes, including PHREEQM (Appelo and Willemsen, 1987, and Appelo and Postma, 1993). METHOD PHREEQE is a thermodynamic ion-association model. Individual-ion activity coefficients and formation of aqueous complexes are used to account for deviations from a thermodynamically ideal solution. Extensions of the Debye-Huckel theory are used to calculate individual-ion activity coefficients. The formation of each aqueous complex is defined by a mass-action expression with the appropriate association constant. Equilibrium between the aqueous phase and a mineral or gas is defined by a mass action expression and a dissociation constant. The program solves a simultaneous set of nonlinear equations that include some or all of the following equations: an activity-coefficient equation for each aqueous species, a mass-action equation for each aqueous complex, mass- balance equations for each element in solution (except hydrogen and oxygen), a charge-balance equation, a redox-balance equation, a 7 Jul 1998 1 phreeqe(1) U.S. Geological Survey (wrdapp) phreeqe(1) mass-action expression for each phase that is in equilibrium with the aqueous phase, an equation for ionic strength, and an equation for the activity of water. The program primarily uses a Newton- Raphson approach to iteratively refine a solution to the simultaneous nonlinear equations. HISTORY Version 2.4 1994/06/27 - WRDAPP tape 2.1 update release with enhancement that permits user to interactively page through output after execution is completed. Version 2.3 1994/05/20 - WRDAPP tape 2 release. Version January 1993 - Current version. Inconsistencies with standards or programming style were identified by Fortran syntax- and structure-checking programs and corrected. Changes included variable typing, structure of common blocks, use of generic functions, elimination of unused variables. Version August 1, 1990 - The linear equation solver was streamlined, parameter statements were added to facilitate redimensioning of the code, and unit numbers were stored in variables to facilitate installing the programs on PC's and other machines. An interactive program, PHRQINPT, was published to facilitate data entry. A high-ionic-strength version of the program was published, PHRQPITZ, that uses the specific-ion interaction approach to calculate activity coefficients. Version January 14, 1985 - Fortran 77 used. Numerical method modified to correct an error in the formulation of the Jacobian matrix. KNOBS keyword was added. A new unit of concentration was accepted, mmol/kg solution. An additional term in analytical expressions for log K was added. The aqueous model for carbonate minerals and aqueous species was updated. Version November 1980 - Original release of program in Fortran 66. DATA REQUIREMENTS Proper use of the program requires adequate knowledge of geochemistry and a proper formulation of the problem. Input is arranged in keyword data blocks, which can appear in any order. However, data fields for a keyword have a fixed format that is column dependent. Use of the interactive program PHRQINPT to ensure proper formatting is suggested. PHRQINPT has logic to ensure completeness of problem formulation and help for each item of input. The basic strategy for problem formulation is to define (1) a starting condition, that is a beginning solution composition(s) (SOLUTION keyword), (2) the irreversible reactions (IOPT(3), REACTION, STEPS keywords), and (3) reversible reactions (MINERALS keyword). SYSTEM REQUIREMENTS PHREEQE and PHRQINPT are written in Fortran 77 with the following extensions: use of include files and variable names longer than 6 7 Jul 1998 2 phreeqe(1) U.S. Geological Survey (wrdapp) phreeqe(1) characters. Each program requires a minerals data base (provided) to be present in the directory from which they are executed. Simple script programs are included to facilitate this. Generally, the program is easily installed on most computer systems. The code has been used on UNIX-based computers and DOS-based 386 or greater computers having a math coprocessor and 2 mb of memory. DOCUMENTATION Parkhurst, D.L., Thorstenson, D.C., and Plummer, L.N., 1980, PHREEQE--a computer program for geochemical calculations: U.S. Geological Survey Water-Resources Investigations Report 80-96, 195 p. (Revised and reprinted, 1990.) RELATED DOCUMENTATION Fleming, G.W., and Plummer, L.N., 1983, PHRQINPT--an interactive computer program for constructing input data sets to the geochemical simulation program PHREEQE: U.S. Geological Survey Water-Resources Investigations Report 83-4236, 108 p. Parkhurst, D.L., 1995, User's guide to PHREEQC--a computer program for speciation, reaction-path, advective-transport, and inverse geochemical calculations: U.S. Geological Survey Water-Resources Investigations Report 95-4227, 143 p. Plummer, L.N., Parkhurst, D.L., Fleming, G.W., and Dunkle, S.A., 1988, A computer program incorporating Pitzer's equations for calculation of geochemical reactions in brines: U.S. Geological Survey Water-Resources Investigations Report 88-4153, 310 p. REFERENCES Appelo, C.A.J., and Postma, D., 1993, Geochemistry, groundwater and pollution: Rotterdam, Netherlands, and Brookfield, Vermont, A.A. Balkema. (Contains description of input for PHREEQM.) Appelo, C.A.J., and Willemsen, A., 1987, Geochemical calculations and observations on salt water intrusions. I: A combined geochemical/mixing cell model: Journal of Hydrology, v. 94, p. 313-330. Parkhurst, D.L., and Plummer, L.N., 1993, Geochemical models, in Alley, W.M., ed., Regional ground-water quality: New York, Van Nostrand Reinhold, chap. 9, p. 199-225. Plummer, L.N., 1984, Geochemical modeling: A comparison of forward and inverse methods, in Hitchon, B., and Wallick, E.I., eds., Proceedings First Canadian/American Conference on Hydrogeology--Practical Applications of Ground Water Geochemistry, Banff, Alberta, Canada: Worthington, Ohio, National Water Well Association, p. 149-177. TRAINING PHREEQE is no longer taught in any of the USGS National Training Center courses. 7 Jul 1998 3 phreeqe(1) U.S. Geological Survey (wrdapp) phreeqe(1) CONTACTS Operation: U.S. Geological Survey David Parkhurst Denver Federal Center, MS 413 Lakewood, CO 80227 dlpark@usgs.gov Distribution: U.S. Geological Survey Hydrologic Analysis Software Support Program 437 National Center Reston, VA 20192 h2osoft@usgs.gov Official versions of U.S. Geological Survey water-resources analysis software are available for electronic retrieval via the World Wide Web (WWW) at: http://water.usgs.gov/software/ and via anonymous File Transfer Protocol (FTP) from: water.usgs.gov (path: /pub/software). The WWW page and anonymous FTP directory from which the PHREEQE software can be retrieved are, respectively: http://water.usgs.gov/software/phreeqe.html --and-- /pub/software/geochemical/phreeqe SEE ALSO balninpt(1) - An interactive program for mass-balance calculations netpath(1) - Interactive program for calculating NET geochemical reactions and radiocarbon dating along a flow PATH phreeqc(1) - A program for aqueous geochemical calculations phrqpitz(1) - A program for geochemical calculations in brines wateq4f(1) - A program for calculating speciation of major, trace, and redox elements in natural waters 7 Jul 1998 4