Coupled Reactive Transport Models

Coupled mass transport models can also include heat transport (e.g., Raffensperger and Garven, 1995) or fluid flow. Coupled reactive transport models represent the desired tools for evaluating fate and transport of contaminants. 

Theories of coupled reactive transport models can be found in Cederberg et al (1985), Lichtner (1996), Raffensperger and Garven (1995), Steefel and MacQuarrie (1996), Walsh (1983), Walter et al (1994), and Yeh and Tripathi (1989). Here, we only give a rudimentary introduction to the concept. 

As discussed in Chapter 2, we reserve the term coupled transport model to multiple component-multiple species reactive mass transport models such as phreeqc described above. In coupled models, two set of equations are solved together through some coupling schemes. In the case of coupled reactive transport models, two sets of mathe-... 

To illustrate the concept of coupled reactive transport models and differentiate them from static geochemical and solute transport models, we use a simple example modified from... 

The coupled reactive transport model is designed to simulate the acid plume migration under this cover and attenuate reclamation plan. An 800 m strip along cross-section A-A (Figure 6.2) was discretized into 200 cells (Figure 10.4). Each cell is 4 min length. The time step is 0.08 year. 

As discussed in previous sections, coupled reactive transport models generate numerous data and the predicted mass transport is complex. Here, we only give some basic information from this modeling exercise. Interested readers are referred to Zhu and Burden (2001) and Zhu et al. (2001a, 2002) for details. 

From the coupled reactive transport modeling results, the shortcomings of the Ad approach are obvious ... 

Figure 10.6. Breakthrough curves for sulfate at the 200th cell from (a) the coupled reactive transport model (surface adsorption reactions are added) and (b) the d-based model.

While the mechanistic treatment of chemical reactions in the coupled multi-component, multi-species mass transport has obvious advantages over the empirical isotherm-based transport models, we can also easily compile a long list of shortcomings for coupled reactive transport models. We choose a few and list them here. 

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