My current research focuses on nutrient and trace metal cycling in high-energy beaches. These beaches are characterized by organic matter and oxygen input via tide and wave induced seawater infiltration during high tide and exfiltration of modified pore waters during low tide. Within the sediment redox gradients develop as a consequence of organic matter degradation, which leads to nutrient release to the pore water and mobilization/immobilization reactions of trace metals (e.g., Fe, Mn, V, U, Mo). As beaches connect the terrestrial and marine realm, they further exhibit subterranean estuaries, i.e., fresh groundwater that exfiltrates at the land-sea boundary mixes with circulating seawater. Since high-energy beaches are very dynamic systems, I study the impact of transient boundary conditions (e.g., salinity, redox conditions) on trace metal (and nutrient) mobilization and immobilization in the shallow to tens of meters deep subsurface of a high-energy beach on Spiekeroog Island. This research will contribute to a better understanding of the (global) role of beach systems for nutrient and trace metal cycling.