Based on fundamental principles transport equations are derived for components in sediment layers. These differ from the usual formulation by the fact that compaction of sediments is explicitly considered. Compaction without doubt plays a significant role in the processes of early diagenesis. As an effect of compaction changing porosity can be observed in sediment profiles. In the paper analytical solutions are derived for cases in which porosity logs show an exponential shape. Comparison with those solutions, which are obtained for the constant porosity (i.e., no compaction) situation, show the relevance of the theoretically rigorous formulation, which is therefore recommended for implementation in computational models.