We sampled the Gotland Deep and Bornholm and Arkona basins the past few days. All sampling was successfully completed yesterday! We’re now entering the Kieler Canal and should arrive on Texel, the Netherlands, on Wednesday morning. It’s now rainy and cold, which is quite different from the sunny and warm weather that we have had most of the cruise.
Looking at the past few days, especially the lander deployment at Bornholm was eventful. The landers are used to measure the sediment-water exchange of nutrients by placing a chamber over the sediment and taking water samples with syringes from the chambers at fixed moments in time. The oxygen concentrations in the chambers are also measured. This gives us an idea of the uptake of oxygen by the sediment. We can compare this measured oxygen uptake to that calculated from profiles of oxygen measured in sediment cores with micro-electrodes.
Looking at the past few days, especially the lander deployment at Bornholm was eventful. The landers are used to measure the sediment-water exchange of nutrients by placing a chamber over the sediment and taking water samples with syringes from the chambers at fixed moments in time. The oxygen concentrations in the chambers are also measured. This gives us an idea of the uptake of oxygen by the sediment. We can compare this measured oxygen uptake to that calculated from profiles of oxygen measured in sediment cores with micro-electrodes.
Normally, the lander is deployed with a rope and a buoy so that at the end of the day, we can go to the buoy, take the rope and bring the lander back onto the ship again.
At Bornholm, however, the rope attached to one of the landers broke during the deployment. This meant that the lander fell to the seafloor without any further control and had to be brought to the surface with an acoustic release. This release allows the weight on the lander to drop to the seafloor and the lander subsequently will come to the sea surface. Because the lander did not have a flag or other marking, it took some moments for us to find it, even though it was near the ship. Once found, the lander was quickly brought on deck again.