Solute transport with multiprocess nonequilibrium: a semi-analytical solution approach

A semi-analytical solution for the simulation of one-dimensional subsurface solute transport incorporating multiple nonequilibrium processes is presen ted. The solution is based on the theory developed by Brusseau et al. (1992 ) [Brusseau, M.L., Jessup, R.E., Rao, P.S,C., 1992. Modeling solute transpo rt influenced by multiprocess nonequilibrium and transformation reactions, Water Resources Research 28 (1), 175-182.] which is a generalized combinati on of two-site and two-region model. In addition to developing a semi-analy tical complement to their numerical solution, we extend the range of bounda ry and initial conditions considered, The semi-analytical solution can repr esent domains of both finite and semi-infinite extent and accommodates nonz ero initial concentrations. The solution is derived in Laplace space and fi nal results are obtained using an accurate and robust numerical inversion a lgorithm. The solution is particularly well suited for interpreting experim ental results obtained under controlled laboratory conditions. Identificati on of the input parameters for the solution is examined by simulating a col umn experiment by van Genuchten (1974) [van Genuchten, M., 1974. Mass Trans fer Studies in Sorbing Porous Media. PhD thesis, New Mexico State Universit y, Las Cruces, NM.]. (C) 2000 Elsevier Science B.V. All rights reserved.