Book contents
- Frontmatter
- Contents
- Preface
- 1 Introduction
- 2 Model Concepts
- 3 Thermodynamic Background
- 4 Computer Programs for Geochemical Modeling
- 5 Preparation and Construction of a Geochemical Model
- 6 Speciation and Solubility Modeling
- 7 Modeling Surface Adsorption
- 8 Reaction Path Modeling
- 9 Inverse Mass Balance Modeling
- 10 Coupled Reactive Transport Models
- 11 Kinetics Modeling
- Appendix
- References
- Index
10 - Coupled Reactive Transport Models
Published online by Cambridge University Press: 27 March 2010
- Frontmatter
- Contents
- Preface
- 1 Introduction
- 2 Model Concepts
- 3 Thermodynamic Background
- 4 Computer Programs for Geochemical Modeling
- 5 Preparation and Construction of a Geochemical Model
- 6 Speciation and Solubility Modeling
- 7 Modeling Surface Adsorption
- 8 Reaction Path Modeling
- 9 Inverse Mass Balance Modeling
- 10 Coupled Reactive Transport Models
- 11 Kinetics Modeling
- Appendix
- References
- Index
Summary
Introduction
The fate and transport of contaminants in subsurface environments are known to be controlled by complex physical, chemical, and biological processes that are coupled in nature. However, most models described in the preceding chapters only simulate geochemical reactions in a static system, resembling the contents of a beaker. Hydraulic effects, such as advection and dispersion, are not taken into account. In reality, the transport processes bring about mass fluxes between spatial domains, which disturb the equilibrium or chemical steady state and result in chemical reactions. Therefore, the direction and extent of chemical reactions can be determined by transport processes in addition to thermodynamics and chemical kinetics. As discussed before, the regulatory environment requires predictions of concentration distribution in space and time. Because static geochemical models are unable to deal with chemical reactions on temporal and spatial coordinates, they are of little direct use to the end results that are sought.
A natural response to the limitations of both geochemical equilibrium models and the solute transport models (see §10.3 for a discussion) is to couple the two. Over the last two decades, a number of models that couple advective–dispersive–diffusive transport with fully speciated chemical reactions have been developed (see reviews by Engesgaard and Christensen, 1988; Grove and Stollenwerk, 1987; Mangold and Tsang, 1991). In the coupled models, the solute transport and chemical equilibrium equations are simultaneously evaluated.
These models, however, are mostly at the research and development stage, and most model applications are “example” calculations demonstrating code capability. Applications as a part of the fulfilment of regulatory requirements are just beginning to appear at the time of writing.
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- Environmental Applications of Geochemical Modeling , pp. 199 - 229Publisher: Cambridge University PressPrint publication year: 2002
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