Water-rock interaction modeling

Steefel, C. I. and A. C. Lasaga, 1992, Putting transport into water-rock interaction models. Geology 20, 680-684. 

Based on the previously described reaction mechanism, we were able to use a nunnerical water/rock interaction model to quantitatively evaluate data from our experimental system. 

Fig. 2.11. Configurations of reactive transport models of water-rock interaction in a system open to groundwater flow (a) linear domain in one dimension, (b) radial domain in one dimension, and (c) linear domain in two dimensions. Domains are divided into nodal blocks, within each of which the model solves for the distribution of chemical mass as it changes over time, in response to transport by the flowing groundwater. In each case, unreacted fluid enters the domain and reacted fluid leaves it.

Kharaka, Y. K., W. D. Gunter, P. K. Aggarwal, E. H. Perkins and J. D. DeBraal, 1988, Solmineq.88, a computer program for geochemical modeling of water-rock interactions. US Geological Survey Water Resources Investigation Report 88—4227. 

May, H., 1992, The hydrolysis of aluminum, conflicting models and the interpretation of aluminum geochemistry. In Y. K. Kharaka and A. S. Maest (eds.), Water-Rock Interaction. Balkema, Rotterdam, pp. 13-21. 

Steefel, C. I. and P. Van Cappellen, 1990, A new kinetic approach to modeling water-rock interaction, the role of nucleation, precursors, and Ostwald ripening. Geochimica et Cosmochimica Acta 54,2657-2677. 

Steefel, C. I., and Ph. Van Cappellen (1990), "A New Kinetic Approach to Modelling Water Rock Interaction The Role of Nucleation, Precursors, and Ostwald Ripening", Geochim. Cosmochim. Acta 54, 2657. 

Kaufmaim RS (1989) Equilibrium exchange models for chlorine stable isotope fractionation in high temperature environments. In Proc 6 Int S>mp Water-Rock Interaction. Miles DL (ed) p 365-368 Kaufmann RS, Frape SK, Fritz P, Bentley H (1987) Chlorine stable isotope composition of Canadian Shield brines. In Saline Water and Gases in Crystalline Rocks, Fritz P, Frq)e SK (eds) Geological Association of Canada Special Paper 33 89-93... 

The discussion on the application of dissolved ions as indicators of the rocks passed through by groundwater is of a generalized nature—to show the direction of hydrochemical thinking—and is useful in establishing the constrains needed to formulate phenomenological conceptual hydrological models (section 1.5). The topic of chemical water-rock interactions is discussed by Drever (1982), Erikson (1985), and Hem (1985). 

Models may be followed by a discussion of the scientific conclusions reached in the study for example, which elements and compounds tend to behave as conservative parameters which ions participate in secondary water-rock interactions or reliability of isotopically based calculations, such as recharge altitude (section 9.8) or r)l3C values as a tool to correct observed 14C values for water-rock interaction. 

Geochemical modeling has become a popular and useful tool for a wide number of applications from research on the fundamental processes of water-rock interactions to regulatory requirements and decisions regarding permits for... 

Models are applied to a system, or a portion of the observable universe separated by well-defined boundaries for the purpose of investigation. A chemical model is a theoretical construct that permits the calculation of chemical properties and processes, such as the thermodynamic, kinetic, or quantum mechanical properties of a system. A geochemical model is a chemical model developed for geologic systems. Geochemical models often incorporate chemical models such as ion association and aqueous speciation together with mineralogical data and assumptions about mass transfer to study water-rock interactions. 

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. 

Many different forms of models are utilized, usually dictated by the objectives of research. Conceptual models are the most fundamental. All of us have some kind of concept of water-rock interactions. For a groundwater interacting with the aquifer minerals during its evolution, one might conceive that most minerals would be undersaturated in the area of recharge but that some minerals (those that dissolve fastest) would become saturated at some point down gradient, having reached their equilibrium solubility... 

Alpers C. N. and Nordstrom D. K. (1999) Geochemical modelling of water-rock interactions in mining environments. In Reviews in Economic Geology, vol. 6A, The Environmental Geochemistry of Mineral Deposits Part A. Processes, Methods and Health Issues, (eds. G. S. Plumlee and M. J. Logsdon). Soc. Econ. GeoL, Littleton, CO, pp. 289-324. 

Perkins E. H., Kharaka Y. K., Gunter W. D., and Debraal J. D. (1990) Geochemical modelling of water-rock interactions using SOLMINEQ.88. In Chemical Modelling of Aqueous Systems II D, Symp. Ser. 416 (eds. C. Melchior and R. L. Bassett). American Chemical Society, Washington, DC, pp. 117-127. 

Johnson T. M. and DePaolo D. J. (1996) Reaction-transport models for radiocarbon in groundwater the effects of longitudinal dispersion and the use of Sr isotope ratios to correct for water-rock interaction. Water Resour. Res. 32, 2203-2212. 

The sources of the saline fluids are argued by some to be water-rock interaction based on the presence of abundant chloride in mineral phases, fluid inclusions, and the incorporation of water into minerals as ways to increase sahnity. The strong similarity of fluids and mineral chemistry, especially for parameters such as strontium isotopes, is cited as evidence for the water-rock model of origin. 

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