NAME
phrqpitz - Geochemical calculations in brines
SYNOPSIS
phrqpitz [infile [ outfile]]
OPTIONS
infile - The name of the file in PHRQPITZ input format.
outfile - The name of the file that will contain PHRQPITZ results.
If no arguments are specified, the program prompts for the input,
output, and two database file names.
If only infile is specified, then outfile defaults to infile.out.
The database names default to phrqpitz.dat and pitzer.dat in the
phrqpitz/bin_data directory.
ABSTRACT
PHRQPITZ is a modification of the geochemical modeling code,
PHREEQE, to permit calculations of geochemical reactions in brines
and other highly concentrated electrolyte solutions using the Pitzer
virial-coefficient approach for activity-coefficient corrections.
Reaction-modeling capabilities include calculation of (l) aqueous
speciation and mineral-saturation index, (2) mineral solubility, (3)
mixing and titration of aqueous solutions, (4) irreversible
reactions and mineral-water mass transfer, and (5) reaction path.
The computed results for each aqueous solution include the osmotic
coefficient, water activity, mineral saturation indices, mean
activity coefficients, total activity coefficients, and scale-
dependent values of pH, individual-ion activities, and individual-
ion activity coefficients. A data base of Pitzer interaction
parameters is provided at 25 C (Celsius) for the system: Na-K-Mg-Ca-
H-Cl-SO4-OH-HCO3-CO3-CO2-H2O; and it is extended to include largely
untested literature data for Fe(II), Mn(II), Sr, Ba, Li, and Br with
provision for calculations at temperatures other than 25 C.
PHRQPITZ is accompanied by an interactive input code, PITZINPT.
METHOD
The aqueous ion-pairing model of PHREEQE (Parkhurst and others,
1980) has been replaced with the Pitzer virial-coefficient approach
(Pitzer, 1973; Pitzer and Mayorga, 1973, 1974; Pitzer and Kim, 1974;
Pitzer, 1975) in PHRQPITZ, while retaining most of the reaction-
modeling capabilities of the original PHREEQE code. The Pitzer
treatment of the aqueous model is based largely on the equations as
presented by Harvie and Weare (1980) and Harvie and others (1984).
An expanded data base of Pitzer interaction parameters is provided
that is identical to the partially validated data base of Harvie and
others (1984) at 25 C (Celsius) for the system Na-K-Mg-Ca-H-Cl-
SO4-OH-HCO3-CO3-CO2-H2O, and extended to include largely untested
literature data for Fe(II), Mn(II), Sr, Ba, Li, Br, and B with
provision for calculations at temperatures other than 25 C.
PHRQPITZ offers two scaling conventions based on the work of Harvie
and others (1984): (1) no scaling is performed, and (2) all
individual-ion activity coefficients are scaled according to the
MacInnes (1919) convention. Much of the structure of PHREEQE is
maintained in PHRQPITZ. PHRQPITZ still uses the Newton-Raphson
approach to solve a set of algebraic equations by generating
successively better estimates of the molalities and activity
coefficients of the aqueous species. Several new subroutines were
added to PHREEQE that calculate the activity coefficients and
activity of water using the Pitzer equations. The most fundamental
change from PHREEQE is that the master variables are the molalities
of the master species instead of the activities of the master
species. The Newton-Raphson equations rely primarily on the total
differential of the molality of each aqueous species with respect to
the master variables.
Because it was adapted from PHREEQE, PHRQPITZ retains some of the
limitations of the original code. All calculations are made
relative to one kilogram (kg) of water. As there is no mass balance
for the elements H and O, there is no formal provision for keeping
track of the amount of water used in reactions such as hydration and
dehydration of solids. This may be a source of error in simulation
of the evaporation of brines where many of the minerals precipitated
are often hydrated and remove water from solution. Geochemical
redox reactions may not be attempted in PHRQPITZ. Other precautions
include the likelihood of introducing error in calculated mean
activities and saturation indices (particularly for carbonates) when
the measured pH is on a different activity coefficient scale than
the aqueous model, and the need for internal consistency between
mixed-salt and single-salt interaction parameters. Although the
Harvie and others (1984) data base has been extended to include
Fe2+, Mn2+, Sr2+, Ba2+, Li+, and Br-, and limited temperature
dependence, the data base has not been validated beyond that of
Harvie and others (1984) at 25 C. Any changes to the single-salt
parameters of the Harvie and others (1984) data base will likely
require extensive revision of the mixed-salt parameters and mineral
free energies. Any new values of the mixed-salt parameters must be
internally consistent with the single-salt parameters in the model
and include the higher-order electrostatic terms. Any changes to
the mixed-salt parameters, even if consistent with the given single-
salt parameters, will likely require changes to the mineral free
energies. Because of the lack of Pitzer interaction parameters for
aqueous aluminum and silica species, calculations with a
aluminosilicates cannot be attempted in PHRQPITZ. The temperature
range for equilibria in the phrqpitz.dat file is variable and is
generally 0 to 60; however, the NaCl system is valid to
approximately 350 C, and the carbonate system is reliable to about
100 C. The temperature dependence of the solubility of many of the
minerals in phrqpitz.dat is not known and large errors could result
if calculations are made at temperatures other than 25 C for these
solids. Limited temperature-dependent data for single-salt
parameters are included in the pitzer.dat file.
HISTORY
Version 1.12 1994/06/01 - Improved file opening procedure and bug
fixes.
Version January 1992 - Version 0.2. Modified for UNIX and PC
applications.
Version 0.2 - December, 1989. Fortran 77. Modified to correct
error in MacInnes scaling convention. Enhanced to include boron
speciation of Felmy and Weare (1986).
Version 0.1 - Initial release, 1988.
DATA REQUIREMENTS
The user-defined input to PHRQPITZ is nearly identical to that of
PHREEQE. The interactive input-construction program, PITZINPT,
facilitates data entry and explanation of data needed. PHRQPITZ is
designed to perform a sequence of simulations in a single computer
run. Each simulation consists of two separate problems: (1) process
an initial solution or solutions, and (or) (2) model a reaction
(starting from the initial solution(s)). Many pathways for a
simulation are accessible with a single input file. Required input
begins with a title line followed by a line of selected options.
Depending on the options selected, additional data are supplied
using various "keyword" data blocks. A data block consists of a
keyword followed by appropriate data. The keyword informs the
program of the type and format of the data to follow. ELEMENTS and
SPECIES, if they are used, should be the first two data blocks while
the other keyword blocks may follow in any order. The keyword END
denotes the end of the input data and is required once for each
simulation. See program documentation for definition of keywords
and input requirements.
OUTPUT OPTIONS
The computed results for each aqueous solution include the osmotic
coefficient, water activity, mineral saturation indices, mean
activity coefficients, total activity coefficients, and scale-
dependent values of pH, individual-ion activities and individual-ion
activity coefficients. If chemical reactions are simulated, the
output depends on the general types of reactions being simulated,
such as (1) mixing of two solutions, (2) titrating one solution with
a second solution, (3) adding or subtracting a net stoichiometric
reaction (changing total concentrations of elements in proportion to
a given stoichiometry), (4) adding a net stoichiometric reaction
until the phase boundary of a specified mineral is reached, (5)
equilibrating with mineral phases, or (6) changing temperature.
SYSTEM REQUIREMENTS
PHRQPITZ and PITZINPT 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 it is 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
Plummer, L.N., and Parkhurst, D.L., 1990, Application of the Pitzer
Equations to the PHREEQE geochemical model, in Melchior, D.C.,
and Bassett, R.L., eds., Chemical modeling of aqueous systems II:
American Chemical Society Symposium Series 416, Washington, D.C.,
American Chemical Society, p. 128-137.
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.
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.
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.)
Plummer, L.N., Prestemon, E.C., and Parkhurst, D.L., 1991, An
interactive code (NETPATH) for modeling NET geochemical reactions
along a flow PATH: U.S. Geological Survey Water-Resources
Investigations Report 91-4078, 227 p.
Plummer, L.N., Prestemon, E.C., and Parkhurst, D.L., 1994, An
interactive code (NETPATH) for modeling NET geochemical reactions
along a flow PATH--version 2.0: U.S. Geological Survey Water-
Resources Investigations Report 94-4169, 130 p.
REFERENCES
Felmy, A.R., and Weare, J.H., 1986, The prediction of borate mineral
equilibria in natural waters: Application to Searles Lake,
California: Geochimica Cosmochimica Acta, v. 50, p. 2771-2783.
Harvie, C.E., Moller, N., and Weare, J.H., 1984, The prediction of
mineral solubilities in natural waters: The Na-K-Mg-Ca-H-Cl-
SO4-OH-HCO3-CO3-CO2-H2O system to high ionic strengths at 25 C:
Geochimica Cosmochimica Acta, v. 48, p. 723-751.
Harvie, C.E., and Weare, J.H., 1980, The prediction of mineral
solubilities in natural waters: the Na-K-Mg-Ca-Cl-SO4-H2O system
from zero to high concentration at 25 C: Geochimica Cosmochimica
Acta, v. 44, p. 981-997.
MacInnes, D.A., 1919, The activities of the ions of strong
electrolytes: Journal American Chemical Society, v. 41, p.
1086-1092.
Pitzer, K.S., 1973, Thermodynamics of electrolytes. 1. Theoretical
basis and general equations: Journal Physical Chemistry, v. 77,
p. 268-277.
Pitzer, K.S., 1975, Thermodynamics of electrolytes. 5. Effects of
higher-order electrostatic terms: Journal Solution Chemistry, v.
4, p. 249-265.
Pitzer, K.S., and Kim, J.J., 1974, Thermodynamics of electrolytes.
4. Activity and osmotic coefficients for mixed electrolytes:
Journal American Chemical Society, v. 96, p. 5701-5707.
Pitzer, K.S., and Mayorga, G., 1973, Thermodynamics of electrolytes.
2. Activity and osmotic coefficients for strong electrolytes
with one or both ions univalent: Journal Physical Chemistry, v.
77, p. 2300-2308.
Pitzer, K.S., and Mayorga, G., 1974, Thermodynamics of electrolytes.
3. Activity and osmotic coefficients of 2-2 electrolytes:
Journal Solution Chemistry, v. 3, p. 539-546.
TRAINING
PHRQPITZ is not currently 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 80225
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 PHRQPITZ
software can be retrieved are, respectively:
http://water.usgs.gov/software/phrqpitz.html
--and--
/pub/software/geochemical/phrqpitz
If you would like to obtain the price of and (or) order paper copies
of USGS reports, contact the USGS Branch of Information Services at:
U.S. Geological Survey
Branch of Information Services
Denver Federal Center, Box 25286
Denver CO 80225-0286
To inquire about Open-File Reports or Water-Resources Investigations
Reports:
Tel: 303-202-4210; Fax 303-202-4695
To inquire about other USGS reports:
Tel: 303-202-4700; Fax 303-202-4693
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
phreeqe(1) - A program for geochemical calculations
wateq4f(1) - A program for calculating speciation of major,
trace, and redox elements in natural waters