Summary of carbon, nitrogen, and iron leaching characteristics and fluorescence properties of materials considered for subseafloor observatory assembly

Abstract

To limit the potential for metal contamination in crustal subsurface borehole observatories, fiberglass and resin-coated steel pipe were used for the first time in scientific ocean drilling during Integrated Ocean Drilling Program (IODP) Expeditions 327 and 336. Here, we summarize the carbon, nitrogen, and iron leaching characteristics of the various materials used and considered for the observatory construction, as these substrates may potentially induce or inhibit in situ microbial growth. We also report on the fluorescence properties of several dopes and sealants used in observatory construction, as these may interfere with DNA-based fluorescence observations on observatory microbial colonization experiments.

Microbial activity in the marine deep biosphere: progress and prospects

“…Installation of new Circulation Obviation Retrofit Kits (CORKs) that have been redesigned and constructed using inert materials such as Teflon-like fluid delivery lines, titanium fittings, and fiberglass borehole casing (e.g., Fisher et al, 2011a; Edwards et al, 2012b; Orcutt et al, 2012) have allowed for collection of high-integrity fluid samples at the seafloor during ROV expeditions (see Wheat et al (2011) for recent review of CORK developments). Additionally, new seafloor instrumentation and subsurface observatory hardware has recently been deployed to enable microbiological investigations (Fisher et al, 2011a; Orcutt et al, 2011b; Edwards et al, 2012b), including an in situ electrochemical analyzer (e.g., Edwards et al, 2011a), in situ fluid pumping systems for collecting pristine fluids and particles from hydrothermal vents, plumes, and microbial mats (Breier et al, 2012), and new integrated sensor and sampling packages for ROVs during short-term sampling, and for automated instrument packages during year-long CORK deployments (Cowen et al, 2012).…”

2. Life in the Oceanic Crust

“…Newer CORK-II, A-CORK and CORK-Lite versions incorporate newer features such as sample intake ports positioned away from casing material and fluid delivery lines that are made of microbiologically-friendly polytetrafluoroethylene (PTFE) material and run external to the CORK casing. While there are clear advantages to conducting in situ experiments and obtaining relatively pristine samples from the newer CORK observatories [79], old CORK installations can provide samples useful for comparative microbiological analysis [80]. CORK observatories also facilitate the collection of samples at varying temporal resolution from the same basaltic crust environment [57], which is not possible with in situ coring methods.…”

Site 395

“…The deepest section of the CORK comprises (from the bottom up) a bullnose that is not restricted (terminates at 532.8 mbsf), six perforated 6 inch drill collars, a crossover, a section of perforated 5.5 inch casing, a crossover to fiberglass, three 4.5 inch slotted fiberglass casings, a single nonslotted fiberglass casing, a crossover, a landing seat (2.875 inch), and an inflatable packer. All steel portions are coated with either Xylan, TK-34XT, or Amerlock to reduce reactivity (Edwards et al, 2012;Orcutt et al, 2012). However, steel that was exposed as a result of handling operations was painted with a fast-drying epoxy paint (Alocit 28) that could dry in the water while the CORK was being lowered below the rig floor.…”