The freshwater seawater mixing zone is a critical region for chemical
activity. Yet, little is known about the influence of ever present
spatial heterogeneity on the dynamics of mixing and calcite dissolution,
which play a key role in the understanding of Karst development. We
analyse the impact of different heterogeneity structures and strengths
on the local and global response of mixing and dissolution rates across
the saltwater freshwater mixing zone. We find that the initial
heterogeneity structure significantly impacts on observed dissolution
and mixing patterns, which sheds some new light on Karst propagation in
coastal aquifers.