Oxygen microprofiles measured in situ in sediments of Kermadec Trench and adjacent abyssal plains

Oxygen microprofiles were measured using an autonomous benthic lander system. Once the lander had stabilized at the seabed, an array of O2 microelectrodes was vertically moved across the sediment-water interface at a predefined resolution - measurements were recorded at each depth after a delay of a few seconds. When the array had reached the maximum measuring depth, sensors were retracted to the start position, and the array was moved horizontally before the measuring routine was repeated (Glud et al. 2021). Sensor signals were converted into O2 concentrations using a linear calibration curve that was based on measurements in the bottom water of known O2 concentration and measurements in the anoxic sediment layers.