Diffusive oxygen uptake rates measured during POLARSTERN cruise PS94 (TransArcII) to the Barents Sea and central Arctic

We assessed diffusive oxygen uptake rates by measuring ex situ porewater oxygen microprofiles. Sediment cores were placed in a water bath and a stirring device was implemented in each core to homogenize the overlying water column and, to create a diffusive boundary layer (DBL) that was similar to in situ conditions. Microprofiles were measured using fiber-optical needle sensors (OXR50 & OXR230) constructed at Pyroscience® (Germany). After two-point calibration (0 % & 100 %) with bottom water taken from the rosette at the same station, the sensors were connected to a Firesting O2 oxygen meter (Pyroscience®) and controlled by using a computer-run micromanipulator. Vertical resolution was programmed to 100 μm, with resting time per data point of 5 seconds. Profile length was programed to be 6.5 cm.