2020 Volume 25 Issue 2 Pages 31-40
A long-term osmotically pumped fluid sampler, OsmoSampler, consists mainly of an osmotic pump with a semipermeable membrane and sampling coil, which allows for sequential fluid sampling for years without an electric power supply. We reviewed the theoretical/technical properties of the OsmoSampler and three studies that analyzed fluids collected with the OsmoSampler system in marine environments: Juan de Fuca ridge (2656 mbsl [624 mbsf] at ~64°C for three years), Gulf of Mexico (540 mbsl at ~8°C for one year), and eastern margin of the Japan Sea (904 mbsl at ~0°C for one year). These studies reliably obtained continuous fluid samples and pointed to the time-series changes of fluid geochemistry due to the migration of deep hydrothermal fluid, the active fluid migration in near-seafloor methane-rich systems, and the oscillation of water/gas composition in response to gas hydrate formation/dissolution near the seafloor. The OsmoSampler could provide new insights for long-term monitoring of environmental changes in deep sea conditions.