Two-dimensional transport and fate of chemicals emitted by arbitrarily placed sources in confined aquifers

A two-dimensional mathematical model (TWODIMPL) is presented that describes the advective-dispersive transport and the transformations of chemicals leaking into confined aquifers. Linear equilibrium rules are assumed to apply to the sorbing soil components made up of weakly sorbing and strongly sorbing fractions and an organic matter fraction. First- or zero-order loss rates of compound due to microbial or other irreversible loss processes are included. Aquifers of rectangular shape and infinite in the transverse dimensions with constant strength sources of chemical, emitting uniformly across the finite vertical aquifer thickness are assumed. The linear parabolic transport equation is solved via the classical Green's function approach. The spatial distribution of chemical concentration at any time derived from any and all distributed sources is given as a time convolution integral. The integral is approximated numerically by a specialized Simpson's quadrature procedure. Several specific scenarios are evaluated and discussed.