Quick Search:    advanced search

GSW Home   GeoRef Home   My GSW Alerts   Contact GSW   About GSW   Journals List   Help

Environmental Geosciences

This Article Figures Only Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Duffy, M. Articles by Clark, J. F. Search for Related Content GeoRef GeoRef Citation

Gaseous emission rates from natural petroleum seeps in the Upper Ojai Valley, California

¹ Department of Earth Science, University of California, Santa Barbara, California 93106; present address: 2100 Main St, Suite 150, Huntington Beach, California 92648; mduffy{at}geosyntec.com
² Graduate Program in Marine Science, University of California, Santa Barbara, California 93106; fkinnaman{at}gmail.com
³ Department of Earth Science and Marine Science Institute, University of California, Santa Barbara, California 93106; valentine{at}geol.ucsb.edu
⁴ Department of Earth Science and Institute for Crustal Studies, University of California, Santa Barbara, California 93106; keller{at}geol.ucsb.edu
⁵ Department of Earth Science and Institute for Crustal Studies, University of California, Santa Barbara, California 93106; jfclark{at}geol.ucsb.edu

Marlene Duffy is a senior staff geologist at Geosyntec Consultants. Duffy holds an M.S. degree in geological sciences from the University of California at Santa Barbara (2004). She currently works on a variety of projects involving groundwater evaluation.

Frank Kinnaman is a graduate student researcher in the Marine Sciences Department at University of California at Santa Barbara. His graduate research as a member of the Valentine Group is focused on the microbial geochemistry of hydrocarbon seep environments, particularly the consumption of natural gas in marine sediments.

David L. Valentine is an associate professor of earth science at the University of California at Santa Barbara. His research interests center on biogeochemical processes including those impacting hydrocarbons. Valentine holds a Ph.D. in earth systems science from the University of California at Irvine (2000).

Edward A. Keller is a professor at the University of California at Santa Barbara in the Department of Earth Science and Program of Environmental Studies. His research is focused on active tectonics centered on the western transverse ranges of southern California and hydrologic studies of basic river processes, high-magnitude flood deposits, channel form, and process, and river restoration and management.

Jordan F. Clark (B.S., Yale University; Ph.D., Columbia University) is an associate professor at the University of California at Santa Barbara in the Department of Earth Science and Program of Environmental Studies. His research is focused on understanding geochemical interactions that occur near the Earth's surface and the effects of external anthropogenic and climatic forcing on these interactions. For more than a decade, his research group at University of California at Santa Barbara has been examining the fate of methane and other gases emitted by natural hydrocarbon seeps.

The atmospheric fluxes of methane (CH₄), carbon dioxide (CO₂), and reactive organic gases (ROGs) were determined for natural terrestrial petroleum seeps in the Upper Ojai Valley, California, by measuring the emission rates from five vents and scaling these measurements with the known distribution of seeps within the valley. The Upper Ojai Valley seeps emit about 55 m³/day (1942 ft³/day) of gas, of which about 15 m³/day (529 ft³/day; 3.6 Mg/yr) is CH₄, about 40 m³/day (1412 ft³/day; 27 Mg/yr) is CO₂, and less than 0.05 m³/day (1.765 ft³/day; 0.04 Mg/yr) are ROGs. CH₄ and ROG fluxes in the Upper Ojai Valley are, respectively, three and five orders of magnitude less than at the well-characterized Coal Oil Point field, a large offshore seep field located approximately 70 km (43 mi) to the west of the valley. The CO₂ flux from these two fields is about the same. The compositions and ¹³C values of seep and reservoir gases were also quantified and indicate extensive biodegradation of gaseous hydrocarbons and the input of isotopically enriched CO₂ during ascent from the reservoir. Unlike the nearby CH₄-dominated marine seeps, the largest percentage of gas emitted by seeps in the Upper Ojai Valley is CO₂.

This article has been cited by other articles:

				R. H. Mariner, S. A. Minor, A. P. King, J. R. Boles, K. S. Kellogg, W. C. Evans, G. A. Landis, A. G. Hunt, and C. B. Till A landslide in Tertiary marine shale with superheated fumaroles, Coast Ranges, California Geology, December 1, 2008; 36(12): 959 - 962. [Abstract] [Full Text] [PDF]