At Site 1268 one rock interval (Sample 209-1268A-2R-1 [Piece 7B, 38–47 cm]) was collected to characterize the microbial community inhabiting this environment. The sample is a dunite that has been serpentinized and subsequently altered to talc along talc-oxide-sulfide veins.
The outer surface was quickly flamed with a propane torch, which is a simple and fast sterilization method to minimize drilling-induced and handling contamination of the outer sample surface. The speed of the sterilization technique helped minimize the time (~20 min) the rock sample was exposed to oxygen. After sterilization, enrichment cultures, samples for deoxyribonucleic acid (DNA) analysis, total organic carbon analysis, and scanning electron microscope studies were prepared as described in "Igneous Rocks" in "Microbiology" in the "Explanatory Notes" chapter.
Two methods were 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) and fluorescent microspheres. Both methods were deployed and analyzed as described in "Contamination Tests" in "Microbiology" in the "Explanatory Notes" chapter. The results of the perfluorocarbon tracer analyses confirm the delivery of PFT to the cores. Samples taken from the interior show the presence of PFT but at levels one to two orders of magnitude less than on the exterior of cores. The amount of PFT reported for the interior pieces is at or slightly above values reported for blanks analyzed at other sites during Leg 209 (Table T12; Fig. F96). The rock sample was rinsed in nanopure water, and the collected water was filtered and examined under a fluorescence microscope. An interior piece of the sample and a thin section were both examined under a fluorescence microscope to detect microsphere penetration. The fluorescent microsphere results showed that the microspheres reached the exterior of Piece 7B but did not penetrate to the interior of the core (Table T13).
Aliquots of surface and bottom water samples were collected and prepared for DNA analysis and direct counts (Table T14) as described in "Seawater and Water Samples" in "Microbiology" in the "Explanatory Notes" chapter.
Table T15 is a summary of atmospheric and surface water data for the period of 22–28 May 2003. Data were obtained in order to investigate the relationship of atmospheric microbial transport and nutrient loading of the water column to atmospheric dust impacting the sample sites. 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 water values varied; salinity ranged 36.0–36.5 psu, temperature 25.5–25.8°C, and pH 7.95–7.96. Surface water samples were collected between 1302 and 1356 hr. Air samples were collected for culture-based studies between 0630 and 0800 hr. Air sample volumes were 112–135 L per sample (two samples were taken). Microbial growth (colony forming units) was for the total volume at 48 and 96 hr of incubation (Table T15). Air temperatures, humidity, wind speed, and wind direction ranged 25.1°–27.3°C, 68.1%–81.8%, 5.1–8.2 m/s, and 82°–113°, respectively. Samples for shore-based analysis of bacterial community DNA and bacteria and viral direct counts were collected daily and stored according to protocol.