Water Resources Applications Software Geochemical || Ground Water || Surface Water || Water Quality || General Summary of PHRQPITZ 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 - An interactive program for mass-balance calculations netpath - Interactive program for calculating NET geochemical reactions and radiocarbon dating along a flow PATH phreeqc - A program for aqueous geochemical calculations phreeqe - A program for geochemical calculations wateq4f - A program for calculating speciation of major, trace, and redox elements in natural waters The URL for this page is http://water.usgs.gov/cgi-bin/man_wrdapp?phrqpitz If you have any questions or comments about this page, contact Page created: 03/22/2000