Focusing on different processes of the dynamic deep bioreactor, the scientific subprojects P1-P6 will share field methods, sampling approaches and experimental work as well as mathematical models. Morphodynamics and related subsurface flow and solute transport will be studied in P1, delivering baseline information on the flow field, fluxes, mixing and salinity distribution to the biogeochemical projects P2-P5: These subprojects focus on metabolic rates under varying redox conditions (P2), related abiotic transformations and microbial interactions with organic matter (P3), transformation and fractionation of trace elements and metal isotopes (P4) as well as on diversity and metabolic functioning of microbial communities (P5). Together, all subprojects will conceptualize the dynamic deep bioreactor within the subsurface of high-energy beaches, whose integrated functioning will be studied in reactive transport models (P6). Using numerical modelling, conceptual models will iteratively be improved by all project partners thus providing a quantitative framework for the interpretation of laboratory and field observations. The entire project is coordinated in the Z-project.