Exact series solutions of reactive transport models with general initial conditions

•Existing analytical solutions of reactive transport are limited to simple initial conditions.•A new method to invert a Laplace transform is presented.•Can evaluate analytical solutions with more general initial conditions.•New method produces series solutions that are accurate and simple to implement.

SummaryExact solutions of partial differential equation models describing the transport and decay of single and coupled multispecies problems can provide insight into the fate and transport of solutes in saturated aquifers. Most previous analytical solutions are based on integral transform techniques, meaning that the initial condition is restricted in the sense that the choice of initial condition has an important impact on whether or not the inverse transform can be calculated exactly. In this work we describe and implement a technique that produces exact solutions for single and multispecies reactive transport problems with more general, smooth initial conditions. We achieve this by using a different method to invert a Laplace transform which produces a power series solution. To demonstrate the utility of this technique, we apply it to two example problems with initial conditions that cannot be solved exactly using traditional transform techniques.