• Online Version of ᴘʜʀᴇᴇǫᴄ
• Version 3 Documentation by Parkhurst and Appelo (2013)
• Example Input Files
• USGS Software User Rights Notice

ᴘʜʀᴇᴇǫᴄ is a geochemical modeling software distributed by the U.S. Geological Survey and developed by David Parkhurst and Tony Appelo. The version here, modified by David Parkhurst, is capable of calculations at elevated temperatures and pressures (up to the T-P limits in the accompanying thermodynamic datasets, e.g., 1000 °C and 5000 bars).

In the pulldown menu, you can find the thermodynamic datasets distributed with ᴘʜʀᴇᴇǫᴄ by the USGS. We have added the library of BASIC language RATES blocks for about 100 minerals from Zhang et al. (2019) into these two datasets:

• phreeqc-kinetics.dat
• llnl-kinetics.dat

We added log K values for related phases in the PHASES block. All else in phreeqc.dat and llnl.dat were not changed.

The following thermodynamic datasets in the pulldown menu are consistent with thermodynamic properties in Zimmer et al. (2016) and updates documented in the SUPCRTBL log.

diagenesis.dat follows the framework of phreeqc.dat and covers the T-P range of 0.01-100 °C at 1 bar and 100-200 °C at PSAT. More specifically:

• All mineral, gas, and aqueous species have the analytical formula for the log K covering the T-P range of 0.01-100 °C at 1 bar and 100-200 °C at PSAT. Note that not all species in phreeqc.dat have parameters for calculations above 25 °C.
• It has molar volume parameters for solids and aqueous species for estimating the effect of pressure change on log K (suitable up to ~ 1000 bar and 200 °C, cf. Appelo et al., 2014)
• It contains Peng-Robinson equation parameters, critical temperature, pressure, and acentric factor for calculating gas fugacity (cf. Appelo et al., 2014);
• It contains “-gamma” parameters for use of the WATEQ activity coefficient equation for concentrated solutions. See the logfile for the coverage of ions and gamma values.
• It uses thermodynamic properties of SiO2°(aq) from Apps and Spicer (2004) and HSiO3- from Sverjensky et al. (1997) because they are more consistent with the 0-300 °C experimental data.
• It has a library of BASIC language RATES blocks for about 100 minerals and log K for related PHASES.

geothermal.dat takes the framework of llnl.dat and covers the T-P range of 0.01-100 °C at 1 bar and 100-300 °C at PSAT. It uses the B-dot equation parameters for activity coefficients of aqueous species:

• It uses thermodynamic properties of SiO2°(aq) from Apps and Spycher (2004) and HSiO3- from Sverjensky et al. (1997) because they are more consistent with 0-300 °C experimental data.
• It also has a library of BASIC language RATES blocks for about 100 minerals and log K for related PHASES.

Additionally, these datasets below use the thermodynamic properties of SiO2°(aq) from Miron et al. (2016):

• bl-0.5kb.dat: 65 – 350 °C, 0.5kb
• bl-1kb.dat: 110 – 600 °C, 1kb
• bl-2kb.dat: 180 – 940 °C, 2kb
• bl-5kb.dat: 300 – 1000 °C, 5kb

Users can generate databases at P-T ranges of your interest using the program SupPʜʀᴇᴇǫᴄ.

Note that we do not advocate any dataset over others. Here we provide a utility to facilitate teaching and research.

Appelo, C.A.J., Parkhurst, D.L., Post, V.E.A., 2014. Equations for calculating hydrogeochemical reactions of minerals and gases such as CO2 at high pressures and temperatures. Geochimica et Cosmochimica Acta 125, 49-67.

Parkhurst, D.L., Appelo, C., 2013. Description of input and examples for ᴘʜʀᴇᴇǫᴄ version 3--A computer program for speciation, batch-reaction, one-dimensional transport, and inverse geochemical calculations. Techniques and Methods 6-A43, U.S. Geological Survey, Reston, VA., 497.

Miron, G.D., Wagner, T., Kulik, D.A. and Heinrich, C.A. (2016) Internally consistent thermodynamic data for aqueous species in the system Na–K–Al–Si–O–H–Cl. Geochim. Cosmochim. Acta 187, 41-78.

Zimmer, K., Zhang, Y.L., Lu, P., Chen, Y.Y., Zhang, G.R., Dalkilic, M. and Zhu, C. (2016) SUPCRTBL: A revised and extended thermodynamic dataset and software package of SUPCRT92. Computer and Geosciences 90:97-111. DOI

Zhang YL, Hu B, Teng YG, Zhu C (2019) A library of BASIC scripts of rate equations for geochemical modeling using ᴘʜʀᴇᴇǫᴄ. Computers & Geosciences, v133. DOI

Zhang GR, Lu P, Zhang YL, Tu K, *Zhu C (2020) SupPHREEQC: A program to generate customized ᴘʜʀᴇᴇǫᴄ thermodynamic database based on Supcrtbl. Computer and Geosciences v143. DOI

This material was prepared, in part, sponsored by an agency of the United States Government or Indiana University. Neither the United States Government, nor Indiana University, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights.