The GeoMICROBE instrument sled—designed to conduct real-time and time-series microbial geochemical sampling of the deep (basaltic) crustal biosphere—is setting the bar higher for “clean” operation . To limit sample contamination, this advanced instrument system exploits new features of the CORK (Circulation Obviation Retrofit Kit) observatories that are installed in scientific ocean drilling program boreholes. Key developments in the new instrument generation are fluid delivery lines (FDLs) and the use of greatly improved materials for intake gratings and casings. The FDLs, which run exterior to CORK casing as continuous 1/8- to 1/2-inch (inside diameters) tubing, allow discrete depth horizons that are vertically separated by packer-seals to be individually sampled.
The GeoMICROBE’s powerful pump can thoroughly flush the CORK FDLs prior to sampling and larger sample volumes permit reliable analyses of multiple complementary parameters requiring large fluid volumes, biomass or general particle mass, as well as providing adequate volumes for enrichment, metabolic or other experimental studies. The fluids pass a series of in-line sensors and an in situ filtration and collection system.
This constantly evolving system has been successfully connected to Integrated Ocean Drilling Program Hole 1301A on the eastern flank of the Juan de Fuca Ridge. The current article  presents preliminary results from 12-hour (July 2010) and year-long (August 2010 to July 2011) deployments. The improvements continue with more recent CORK installations (October/November 2011) at the IODP North Pond sites on the western flank of the Mid-Atlantic Ridge including up to three 1.3 cm sampling lines made of Tefzel which is essentially inert, providing no chemical contamination or potential energy sources.
Caption: GeoMICROBE instrument sled connected to CORK-II installation at IODP Hole 1301A (Courtesy: J. Cowen and WHOI Deep Submergence Group).