@article {Quistad2011,
	title = {{Anaerobic propane oxidation in marine hydrocarbon seep sediments}},
	journal = {Geochimica et Cosmochimica Acta},
	volume = {75},
	number = {8},
	year = {2011},
	pages = {2159{\textendash}2169},
	abstract = {Propane (C3H8) is an abundant hydrocarbon in subsurface reservoirs with significance to atmospheric chemistry and to marine biogeochemistry. The anaerobic oxidation of propane coupled to sulfate reduction may prevent sub-seafloor accumulations of propane from entering the ocean and atmosphere. Anaerobic oxidation of propane has recently been demonstrated in cultures of novel sulfate-reducing bacteria, but has not been directly demonstrated or quantified in nature. In this work we describe a method involving incubation with 13C-propane to quantify rates of anaerobic oxidation of propane in anoxic sediment, and we conclusively demonstrate the oxidation of propane under sulfidic conditions in fresh sediments of a marine hydrocarbon seep. Observed rates of anaerobic oxidation of propane adhere to first-order kinetic behavior, enabling the modification of this method for whole core rate determinations. Whole core rates in nine cores from two hydrocarbon seeps measured 0.04{\textendash}2100~nmoles C3H8~cm-3~day-1 by this method. The seep persistently supplied with more propane displayed substantially higher rates of anaerobic oxidation of propane, by 1{\textendash}2 orders of magnitude when averaged over the top 10-cm, suggesting the development of the microbial community is strongly modulated by the availability of propane. This work is the first to estimate rates for anaerobic oxidation of propane in any environment, and demonstrates the potential importance of the process as a filter for preventing propane from entering the ocean and atmosphere.},
	keywords = {HOV Alvin (Human Occupied Vehicle)},
	issn = {0016-7037},
	doi = {10.1016/j.gca.2011.02.001},
	url = {http://dx.doi.org/10.1016/j.gca.2011.02.001},
	author = {Quistad, S D and Valentine, D L}
}
@article {Valentine2010,
	title = {{Asphalt volcanoes as a potential source of methane to late Pleistocene coastal waters}},
	journal = {Nature Geoscience},
	volume = {3},
	number = {5},
	year = {2010},
	pages = {345{\textendash}348},
	abstract = {Every year, natural petroleum seepage emits 0.2{\textendash}2 Tg of oil to the ocean1. Significant oil seepage can build large underwater mounds, consisting of tar deposits with morphologies similar to volcanic lava flows, known as asphalt volcanoes2, 3. Such events are typically accompanied by large fluxes of the greenhouse gas methane4, 5. Marine sediments from the Santa Barbara basin, California, contain a record of elevated methane concentrations6, anoxia and tar deposition7 during the Pleistocene epoch that had been attributed to dissolution of methane hydrates. However, the region is known to have exhibited oil seepage in the past7. Here, we document the discovery of seven extinct asphalt volcanoes off the coast of southern California. The morphology of the deposits and geochemistry of samples taken from the two largest structures supports their classification as asphalt volcanoes, derived from a common source. We estimate that the two structures resulted from seepage of 0.07{\textendash}0.4 Tg of oil, accompanied by the emission of 0.35{\textendash}1.8 Tg of methane. Radiocarbon dating of carbonate deposits entrained with the asphalt indicates formation of the volcanoes between 44 and 31 kyr ago. The timing and volume of erupted hydrocarbons from the asphalt structures can explain some or all of the documented methane release and tar accumulation in the Santa Barbara basin during the Pleistocene.},
	keywords = {AUV Sentry (Autonomous Underwater Vehicle), HOV Alvin (Human Occupied Vehicle)},
	issn = {1752-0894},
	doi = {10.1038/ngeo848},
	url = {http://dx.doi.org/10.1038/ngeo848},
	author = {Valentine, D L and Reddy, C M and Farwell, C and Hill, T M and Pizarro, O and Yoerger, D R and Camilli, R and Nelson, R K and Peacock, E E and Bagby, S C and Clarke, B A and Roman, C N and Soloway, M}
}
