Numerical Evaluation of Breakthrough Curves

In order to evaluate the reaction function, simulations of one-dimensional advective-reactive transport expressed in terms of the travel time rmust be conducted. A series of concentration profiles with respect to t calculated at distinct times ij (i = 1,2. ) approximate the reaction function F (Fig. 7.4). The length of the streamtube is given 

If the assumption of a representative streamtube is valid, the normalised breakthrough curve (BTC) of a reactive tracer at the control surface (Fig. 7.5) is then given by  

If a separate consideration of an ensemble of single streamtubes should be required due to large-scale physico-chemical heterogeneities, the model discretisation must be chosen in accordance with the residence times of a conservative tracer in the homogeneous sub-regions (zones) of the aquifer domain considered (Fig. 7.6). In this case, a definite value of the total travel time rQ, , k) of a conservative tracer along each 

In case of nonequilibrium conditions or a complex system of reactive processes, each reaction function T(T ,(,fcO has to be evaluated by means of a numerical simulation. A special case is given if no inter-solute and no kinetic reactions have to be taken into account, e.g. in case of fast or equilibrimn sorption. In this case the reaction function Ccan be calculated analytically by 

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Modelling Reactive Transport of Organic Solutes in Groundwater 7.2.3 Numerical Evaluation of Breakthrough Curves... 

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