MODELING SOLUTE TRANSPORT INFLUENCED BY MULTIPROCESS NONEQUILIBRIUM AND TRANSFORMATION REACTIONS

We present an advective-dispersive solute transport model that explicitly accounts for multiple sources of nonequilibrium and transformation reactions during steady state flow in porous media. The multiprocess nonequilibrium with transformation (MPNET) model is formulated for cases where nonequilibrium, caused by a combination of transport-related and sorption-related processes, and abiotic/biotic transformations can be described as first-order processes. The impact of the coupling of nonequilibrium and transformation reactions on solute transport is examined using selected illustrative examples. The performance of the model is evaluated by comparing predictions obtained with the model, where values for all model parameters are obtained independently, to a data set obtained from the literature. The prediction obtained with the MPNET model matched the data very well, much better than did the predictions obtained with the MPNET model assuming no degradation and with a model that does not account for rate-limited sorption.