Pore water pressure maintaining sampler for deployment on deep-sea ROV-Jellyfish

Abstract

Obtaining high-quality pore water samples is of great importance for marine resource investigations. We describe a deep-sea in-situ pore-water pressure-maintaining sampler aboard the heavy-duty ROV-Jellyfish. It can operate at water depths up to 3000 m and acquire 24 different pore-water pressure-holding samples of seafloor sediments with a sampling depth resolution of 2 cm. In this study, the working capacity of the pore water sampler is initially analyzed through structural design and theoretical calculation. The force changes of the integrated system of sampling Rhizons during the penetration of sediments and the extraction of pore water were simulated by the CEL-coupled Euler method in ABAQUS to determine the material and working speed of the integrated system.Meanwhile, the interaction and diffusion effects at the interface between the sample and deionized water during the pore water sample storage under pressure retention were investigated by the laminar flow and dilute matter diffusion methods in COMSOL. Laboratory experiments were conducted to analyze the effect of 2 cm depth resolution on the maximum sampling volume when obtaining pore water samples at different depths during the sampling process, thus reducing the mutual contamination between pore water samples from adjacent layers. Finally, the sea trials prove the sampler's pressure-holding sealing performance and application performance. Thus, the pore water sampler can carry out more in-depth scientific applications.