PHREEQC files for geochemical simulations in Horn Creek, Grand Canyon, AZ

PHREEQC files included in this ScienceBase product include the input (.pqi) and output (.pqo) files formatted for use in PHREEQC and as basic text files, and the information regarding samples used in the simulations. The files were used to interpret changes in water quality between 2018 and 2022 within the Horn Creek watershed of Grand Canyon for the associated publication (add citation here when available). PHREEQC is a publicly available software for geochemical modeling and the software can be downloaded at https://www.usgs.gov/software/phreeqc-version-3. An accompanying report (Parkhurst and Appelo, 2013) serves as the formal documentation for PHREEQC.  The wateq4f database (Ball and Nordstrom, 1991) was used, without modification, for the PHREEQC simulation. 

Parkhurst, D.L., and Appelo, C.A.J., 2013, Description of input and examples for PHREEQC version 3—A computer program for speciation, batch-reaction, one-dimensional transport, and inverse geochemical calculations: U.S. Geological Survey Techniques and Methods, book 6, chap. A43, 497 p., available at http://pubs.usgs.gov/tm/06/a43/.
Ball, J.W., and Nordstrom, D.K., 1991, Users WATEQ4F—User’s manual with revised thermodynamic data base and test cases for calculating speciation of major, trace and redox elements in natural waters: U.S. Geological Survey Open-File Report 90–129, 185 p.