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
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
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.
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