Design and deployment of autoclave pressure vessels for the portable deep-sea drill rig MeBo ( Meeresboden-Bohrgerät )

Abstract. Pressure barrels for sampling and preservation of submarine sediments under in situ pressure with the robotic sea-floor drill rig MeBo ( Meeresboden-Bohrgerat ) housed at the MARUM (Bremen, Germany) were developed. Deployments of the so-called MDP (MeBo pressure vessel) during two offshore expeditions off New Zealand and off Spitsbergen, Norway, resulted in the recovery of sediment cores with pressure stages equaling in situ hydrostatic pressure. While initially designed for the quantification of gas and gas-hydrate contents in submarine sediments, the MDP also allows for analysis of the sediments under in situ pressure with methods typically applied by researchers from other scientific fields (geotechnics, sedimentology, microbiology, etc.). Here we report on the design and operational procedure of the MDP and demonstrate full functionality by presenting the first results from pressure-core degassing and molecular gas analysis.