Acetate and hydrogen concentrations in pore fluids were measured in samples taken at seven sites from southern Hydrate Ridge (SHR) offshore Oregon, USA. Acetate concentrations ranged from 3.17 to 2515 µM. The maximum acetate concentrations occurred at Site 1251, which was drilled on a slope basin to the east of SHR at depths just above the bottom-simulating reflector (BSR) that marks the boundary of gas hydrate stability. Acetate maxima and localized high acetate concentrations occurred at the BSR at all sites and frequently corresponded with areas of gas hydrate accumulation, suggesting an empirical relationship. Acetate concentrations were typically at a minimum near the seafloor and above the sulfate/methane interface, where sulfate-reducing bacteria may consume acetate. Hydrogen concentrations in pressure core samples ranged from 16.45 to 1036 parts per million by volume (ppmv). In some cases, hydrogen and acetate concentrations were elevated concurrently, suggesting a positive correlation. However, sampling of hydrogen was limited in comparison to acetate, so any relationships between the two analytes, if present, were difficult to discern.
1Lorenson, T.D., Colwell, F.S., Delwiche, M., and Dougherty, J.A., 2006. Data report: Acetate and hydrogen concentrations in pore fluids associated with a large gas hydrate reservoir, southern Hydrate Ridge, offshore Oregon, USA. In Tréhu, A.M., Bohrmann, G., Torres, M.E., and Colwell, F.S. (Eds.), Proc. ODP, Sci. Results, 204: College Station, TX (Ocean Drilling Program), 1–20. doi:10.2973/odp.proc.sr.204.126.2006
2U.S. Geological Survey 345 Middlefield Road, Menlo Park CA 94025, USA. Correspondence author: tlorenson@usgs.gov
3Idaho National Laboratory, 2525 North Fremont Avenue, Idaho Falls ID 83415, USA. Present address: 104 COAS Admin Building, College of Oceanic and Atmospheric Sciences, Oregon State University, Corvallis OR 97331-5503, USA.
Initial receipt: 16 May 2005
Acceptance: 21 December 2005
Web publication:
11 September 2006
Ms 204SR-126