MINTEQ model

Matrix extrapolation undertaken by this model means that the model calculates the free metal ion concentration as the toxic species, given a total metal concentration and site-specific conditions in terms of water hardness, DOC, salinity, and so on. As an example, according to the MINTEQ model, a type of water with a hardness of 10 mg/L CaC03, a DOC content of 10 mg/L, a total Zn concentration of 10 mg/L, and a variable pH gives a distribution of Zn species as given in Table 2.5. 

De Groot et al. (1998) also gave regression parameters for calculating the total metal concentration in pore water from the total concentration in the soil. If site-specific physicochemical pore water characteristics are also available, the predicted total metal concentration in pore water can be extrapolated to the bioavailable ion concentration in pore water by site-specific application of the MINTEQ model. 

A computer code is obviously not a model. A computer code that incorporates a geochemical model is one of several possible tools for interpreting water-rock interactions in low-temperature geochemistry. The computer codes in common use and examples of their application will be the main focus of this chapter. It is unfortunate that one commonly finds, in the literature, reference to the MINTEQ model or the PHREEQE model or the EQ3/6 model when these are not models but computer codes. Some of the models used by these codes are the same so that a different code name does not necessarily mean a different model is being used. 

From the results it appears that most of the Cd in the filtrate is labile and there was a good agreement between the three variants of sampler (DGT OP, DGT RP, and Chemcatcher ) and the spot samples. The estimates of concentrations of labile Cu and Ni were similar for all three samplers, and these were consistent with the output from the Visual MINTEQ model. Whilst these results for Cu and Ni are consistent with... 

MINTEQA2 http //www.epa.gov/ceampubl/mmedia/minteq/index.htm MINTEQA2 is an equilibrium speciation model that can be used to calculate the equilibrium composition of dilute aqueous solutions in the laboratory or in natural aqueous systems. The model is useful for calculating the equilibrium mass distribution among dissolved species, adsorbed species, and multiple solid phases under a variety of conditions including a gas phase with constant partial pressures. 

Allison J, Brown DS, Novo-Gradac K. US Environmental Protection Agency, Environmental Research Laboratory. 1991. MINTEQA2/PROEFA2 a geochemical assessment model for environmental systems, http //www.epa.gov/ceampubl/mmedia/minteq/ index.htm (accessed July 28, 2005). 

The thermodynamic equilibrium models, including surface complexation models, require the solution of a complex mathematical equation system. For this reason, many computer programs (e.g., CHEAQC, CHEMEQL, CHESS, EQ3/6, F1TEQL, Geochemist s Workbench, H ARPHRQ, JESS, MINTEQ and its versions, NETPATH, PHREEQC, PHRQPITZ, WHAM, etc.) have been developed to calculate the concentration and activity of chemical species, estimate the type and amount of minerals formed or dissolved, and the type and amount of sorbed complexes. 

These programs are able to model the geological systems soil/rock-aqueous solution systems that is the concentration and distribution of the thermodynamically stable species can be determined based on the total concentrations of the components and the parameters just mentioned. In addition, the programs can also be used to estimate thermodynamic equilibrium constants and/or surface parameters from the concentrations of the species determined through experiments. Thermodynamic equilibrium constants can be found in tables (Pourbaix 1966) or databases (e.g., Common Thermodynamic Database Project, CHESS, MINTEQ, Visual MINTEQ, NEA Thermodynamical Data Base Project (TDB), JESS, Thermo-Calc Databases). Some programs (e.g., NETPATH, PHREEQC) also consider the flowing parameters. 

Brown, D.S. and Allison, J.D. (1987). MINTEQAl Equilibrium Metal Speciation Model A user s manual. Athens, Georgia, USEPA Environmental Research Laboratory, Office of Research and Development... 

USEPA (1998, 1999) MINTEQA2/PRODEFA2, a geochemical assessment model for environmental systems. User manual supplement for version 4.0, online at epa.gov/ ceampubl/mmedia/minteq/supplei.pdf, 76pp. 

MINTEQ Geochemical MINTEQ is a geochemical model designed to estimate equilibrium compositions of dilute aqueous solutions. 

The surface capacitance for the constant capacitance model is 1.06 F/m, The intrinsic constants to be used in the constant capacitance model calculation are tabulated in Problem 9. Intrinsic constants for the double-layer model are listed in the MINTEQ file feo-dim.dbs. You can either enter them individually in PRODEFA2, or simply attach that file to your problem. Assign all phosphate adsorption to the high-energy SOI sites. 

Davis, A., and D. D. Runneli.s. 1987. Geochemical interactions between acidic tailings fluid and bedrock use of the computer model MINTEQ, A/jp/icrf Geoc7ie/n. 2 231-41. 

MINTEQ ( was the equilibrium mass-transfer code chosen to model the geochemical interaction between leachate and sandstone. The model was selected to perform three functions for which it is well-suited ... 

Speciation of the fluid was modeled using MINTEQ. The major inorganic species in the L2 leachate are listed in Thble II. The thermodynamic data base for MINTEQ was adapted from that of WATEQ3 (12 iA)- VAX version of the model used in this study was obtained from Battelle Pacific Northwest Laboratory and implemented at the University of Colorado by Davis (16). 

PHREEQC2 is distributed with different databases. The database Minteq.dat was chosen for the modelling of the column experiments. Constants of the protonation reactions for all oxoanions are included in this database. It also contains constants of various soluble phosphate and chromate species (complexes with all major cations and anions). The formation of soluble arsenate complexes is not considered because this seems not to be necessary (compare Cullen and Reimer, 1989). 

The constants for the surface complexation of calcium, sulphate, phosphate and arsenate are included in the file minteq.dat. This data was not sufficient for the modelling of the column experiments performed and had to be augmented. Surface complexation constants for magnesia and chromate for amorphous iron hydroxide were taken from Dzombak and Morel (1990) (see Table 12.3). Van Geen (1994) showed that also carbon dioxide has to be considered for the modelling of adsorption. Carbon dioxide is not mentioned in Dzombak and Morel (1990). The database used contains complexation constants derived from data of Van Geen et al. (1994) and were reoptimized by Dr. C. A. J. Appelo (Amsterdam) for use with PHREEQC2 and amorphous iron hydroxide. This data was transferred from the database file PHREEQC.dat to Minteq.dat. 

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