PHREEQC
Criterion | Explanation | |||
Model name/version | PHREEQC (pH-REdox-Equilibrium) version 3 | |||
General Description | Geochemical model based on speciation between physical phases (water, solids, gas). Simulates chemical and kinetic reactions and 1D transport (dispersion, diffusion, solute movement in porous media) of processes in water, laboratory and industrial processesenvironments. Applicable for rainwater, soil-water, groundwater and surface water quality. Capabilities include speciation (saturation indices; distribution of aqueous species; density and specific conductance of solution), batch reaction calculations (equilibrium distribution in aqueous phase, pure phases, solid solutions, gas phase, exchange sites, and surface sites; non-equilibrium processes such as aqueous phase mixing, kinetically control reactionkinetical reactions), sorption and desorption (surface complexation; ion exchange), inverse modeling to account for changes along flow path. | |||
Model Domain | General | |||
Developer | United States Geological Survey (USGS) | |||
Hardware computing requirements | Dependent on version of program being used: 32-bit, 64-bit, or any processor. | |||
Code language | Visual C and C++ | |||
Original application | Original model (PHREEQE) used for simulating geochemical reactions of the system, which included mixing of water, net irreversible reactions in solution, equilibrium dissolution and precipitation and temperature effects. | |||
Public/proprietary and cost | Publicly available and modifiable with no fees. User rights can be found at https://water.usgs.gov/water-resources/software/PHREEQC/NOTICE.TXT. | |||
Physically or empirically based | Model uses both mechanistic and empirical components. | |||
Mathematical methods used |
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Input data requirements | Data input is free-format using chemical symbolism. Input, in the form of database files, can be built using provided graphical interface or Notepad++, arranged using keyword data blocks format. Input parameters may include, but is not limited to, elements, chemical formulas, chemical equations, charges, valance states, pH, pe, temperature, concentrations, physical states, equilibrium constants, volumes, partition coefficients, isotopes, uncertainty ranges, reaction rates, enthalpy and process time. Nine database files are inherently provided in the program: phreeqc.dat, amm.dat (decoupled ammonia data), wateq4f.dat, llnl.dat (thermodynamic data), minteq.dat, minteq.v4.dat, pitzer.dat (specific-ion interaction data), sit.dat (specific-ion interaction data), iso.dat (isotope data). Most input parameters can be obtained through chemical and kinetic databases, or from peer-reviewed literature. _GoBack | _GoBack | | |
Outputs | Output of graphs and table with user selected results such as concentration, activities, saturation indices, densities and transport distances. | |||
Pre-processing and post-processing tools | Model application file, Notepad++ interface | |||
Representation of uncertainty | Uncertainty accounted for in inverse modeling through user defined limits for all analytical data. | |||
Prevalence | Very common: extensively used by governmental, educational, private and public entities. Used in the Delta to simulated simulate subsurface and drain-water geochemical reactions (Deverel et al. 2007) | |||
Ease of use for public entities | Easy to moderate, official user guide available in addition to many tutorials available through various sources. | |||
Ease of obtaining information and availability of technical support | No commercial help desk available, many user groups and forums available online. User guide available at https://wwwbrr.cr.usgs.gov/projects/GWC_coupled/phreeqc/. | |||
Model and Source code availability | Model available for download from: https://wwwbrr.cr.usgs.gov/projects/GWC_coupled/phreeqc/. Source codes available upon request. | |||
Status of model development | Model developed and available for use. Model updates are ongoing, status of model updates can be found at https://wwwbrr.cr.usgs.gov/projects/GWC_coupled/phreeqc/status.htm. | |||
Challenges for integration | Specificity of biogeochemical outputs may be difficult to scale to larger spatial resolutions often used in other models. |
References
Deverel, Steven S.J.; , Leighton, David D.A.; & , and Finlay, Mark M.R.(, 2007). Processes Affecting Agricultural Drainwater Quality and Organic Carbon Loads in California's Sacramento–San Joaquin Delta. San Francisco Estuary and Watershed Science, 5(2). jmie_sfews_10988. Retrieved from: http://escholarship.org/uc/item/8db266mg.
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 (No. 6-A43). US Geological Survey.