Groundwater pollution by organic compounds: a two-dimensional analysis of contaminant transport in stratified porous media with multiple sources of non-equilibrium partitioning

Abstract

Transport of pollutants in soil and groundwater often occurs in stratified media under non-equilibrium conditions. Confined aquifers are usually bounded by low-permeability layers of soil which have been shown to exert a significant influence on the fate of contaminants in groundwater. Numerical solutions of transport equations have usually been restricted to single layers and have included single sources of non-equilibrium processes or none at all. The effect of soil stratification itself has sometimes been reduced to a transport-based non-equilibrium process. A boundary element solution of the transport equations in the Laplace domain is extended to include multiple sources of non-equilibrium processes in saturated media under the assumption of rate-limited mass transfer. Green functions accurately model infinite and semi-infinite domains such as soils and Laplace transforms remove the need for time-stepping and the associated numerical complexity. The proposed numerical technique is validated by comparing its results to analytical solutions. Its scope is illustrated through a case study of a sand aquifer bounded by less permeable layers of silt, and infiltrated by pollutants from a neighbouring lake. Copyright © 1999 John Wiley & Sons, Ltd.