Cycling of redox-sensitive trace metals in barrier island freshwater lenses.

Freshwater lenses connect the terrestrial and marine realm via groundwater discharge at the edges of islands and serve as drinking water resources. We studied the redox-sensitive metals U, Mo, V, and Tl along the redox gradient of fresh groundwater lenses on Spiekeroog Island, northern Germany. Groundwater solute concentrations were linked to groundwater age and redox characteristics.

Iron sulfide formation in young and rapidly-deposited permeable sands at the land-sea transition zone.

Organic-poor, permeable quartz sands are often present at land-sea transition zones in coastal regions. Yet, the biogeochemical cycles of carbon, sulfur, and iron are not well studied here. The aim of this work was, therefore, to improve our understanding regarding the chemical processes in these prominent coastal sediments.