A semi-analytical model for simulating two-dimensional multispecies reactive transport

Multispecies advection-dispersion equations coupled with sequential first-order decay reactions is widely to predict the plume migration behaviors of degradable or decaying contaminants such as radionuclides, nitrogen and chlorinated solvents in the groundwater system. Although researchers attempted to develop analytical solutions to coupled advection-dispersion equations, the available analytical solutions in the literature are mostly derived for a one-dimensional transport system. Analytical solutions for multi-dimensional coupled multispecies transport are important and needed for real world application, whereas only relatively rare analytical solutions for a finite-domain transport system were derived. The solutions for transport in a finite domain generally involves a summation of infinite series expansions, making numerical evaluations of the solutions always time-consuming and inefficient. This study presents a novel semi-analytical model for rapid simulating two-dimensional plume migrations of all the members in a decay chain. The verification of the developed model is established by an excellent agreement between the derived model and with an analytical model in the literature derived for a finite domain. Moreover, the computational time for numerical evaluations of the derived solution is only 1/7 of the computational time for the solution derived for a finite domain. The derived semi-analytical model is an accurate and computationally efficient tool for simulating plume behaviors of degradable and decaying contaminants.