EQ3NR: a computer program for geochemical aqueous speciation-solubility calculations. User`s guide and documentation
EQ3NR is a geochemical aqueous speciation-solubility FORTRAN program developed for application with the EQ3/6 software package. The program models the thermodynamic state of an aqueous solution by using a modified Newton-Raphson algorithm to calculate the distribution of aqueous species such as simple ions, ion-pairs, and aqueous complexes. Input to EQ3NR primarily consists of data derived from total analytical concentrations of dissolved components and can also include pH, alkalinity, electrical balance, phase equilibrium (solubility) constraints, and a default value for either Eh, pe, or the logarithm of oxygen fugacity. The program evaluates the degree of disequilibrium for various reactions and computes either the saturation index (SI = log Q/K) or thermodynamic affinity (A = -2.303 RT log Q/K) for minerals. Individual values of Eh, pe, equilibrium oxygen fugacity, and Ah (redox affinity, a new parameter) are computed for aqueous redox couples. Differences in these values define the degree of aqueous redox disequilibrium. EQ3NR can be used alone. It must be used to initialize a reaction-path calculation by EQ6, its companion program. EQ3NR reads a secondary data file, DATAl, created from a primary data file, DATA0, by the data base preprocessor, EQTL. The temperature range for the thermodynamic data in the file is 0 to 300{sup 0}C. Addition or deletion of species or changes in associated thermodynamic data are made by changing only the file. Changes are not made to either EQ3NR or EQTL. Modification or substitution of equilibrium constant values can be selected on the EQ3NR INPUT file by the user at run time. EQ3NR and EQTL were developed for the FTN and CFT FORTRAN languages on the CDC 7600 and Cray-1 computers. Special FORTRAN conventions have been implemented for ease of portability to IBM, UNIVAC, and VAX computers.
- Research Organization:
- Lawrence Livermore National Lab., CA (United States)
- DOE Contract Number:
- W-7405-ENG-48
- OSTI ID:
- 59277
- Report Number(s):
- UCRL--53414; ON: DE84001842
- Country of Publication:
- United States
- Language:
- English
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