During PS85 (in 2014) and PS93.2 (in 2015) sediment cores were recovered by a Multiple corer. Sediment cores were stored at in situ temperature of -0.75°C and used to measure oxygen profiles across the sediment-water interface with needle type optodes (diameter: 50µm, Pyro Science). By using the profiles, the diffusive oxygen uptake was calculated via the decrease in the oxygen concentration in the Diffusive Boundary Layer (DBL). For a further description of the calculation, please check the related publication.