At Site 1270 one rock interval, Sample 209-1270D-4R-1 (Piece 14, 112–131 cm), was collected to characterize the microbial community inhabiting this environment. The rock sample is a completely serpentinized harzburgite.
The outer surface was quickly flamed with a propane torch. The speed of this sterilization technique helped minimize the time (~20 min) the rock sample was exposed to oxygen. Our cruise sampling strategy was to characterize the microbiological community in serpentinized peridotite over the range of depths of penetration we achieved. At this site we hoped to collect a sample from ~30 mbsf. However, owing to poor recovery from previous holes at this site, we collected a sample from a shallower core with sufficient recovery to address all the cruise objectives. The sample was placed in the anaerobic chamber in a sterile container on ice for 2 hr, until the next core arrived on deck. Core 209-1270D-5R (encompassing our target depth interval) was only a few rounded pieces of gabbro and peridotite, so we elected to process the provisional sample taken from Core 4R. After being kept cool, samples were prepared for enrichment cultures, deoxyribonucleic acid (DNA) analysis, total organic carbon analysis, and scanning electron microscope studies as described in "Microbiology" in the "Explanatory Notes" chapter.
Aliquots of surface water were collected and prepared for DNA analysis and direct counts as described in "Seawater and Water Samples" in "Microbiology" in the "Explanatory Notes" chapter. One method was used to examine the type and extent of contamination caused by drill fluids that penetrated the interior of the rock sample used for microbial studies, perfluorocarbon tracer (PFT), as described in "Contamination Tests" in "Microbiology" in the "Explanatory Notes" chapter. The results of the PFT analyses confirm delivery of the tracer to the core. We could also detect PFT in samples from the interior of the core, but at a level lower than that measured in a blank (Table T12; Fig. F118).
Table T13 is a summary of atmospheric and surface water data for the period of 29 May to 4 June 2003. For surface water direct count data, 1 mL of water was stained as described in "Microbiology" in the "Explanatory Notes" chapter. One milliliter of funnel rinse water was used as a control. Salinity, temperature, and pH values for all surface waters varied; salinity ranged 36.0–37.0 psu, temperature 25.3°–25.8°C, and pH for all samples was 7.96. Surface water samples were collected between 1221 and 1440 hr. Air samples were collected for culture-based studies between 0630 and 0746 hr. Air sample volumes were 112–443.7 L per sample (two samples taken). Microbial growth (colony forming units) was for the total volume at 48 and 96 hr of incubation (Table T13). Air temperatures, humidity, wind speed, and wind direction ranged 24.9°–26.1°C, 68.2%–77.5%, 2.2–7.8 m/s, and 58°–110°, respectively. Samples for shore-based analysis of bacterial community DNA and bacteria and viral direct counts were collected daily and stored according to protocol.