Biomarker evidence for bacterial oxidation of oil-derived hydrocarbons at seeps in the southern Gulf of Mexico
- 1Institute for Geology, Center for Earth System Research and Sustainability, Universität Hamburg, 20146 Hamburg, Germany
- 2Institute for Geology, Universität Wien, 1090 Wien, Austria
- 3Institute for Mineralogy and Crystallography, Universität Wien, 1090 Wien, Austria
- 4Key Laboratory of Ocean and Marginal Sea Geology, South China Sea Institute of Oceanology, Innovation Academy of South China Sea Ecology and Environmental Engineering, Chinese Academy of Sciences, Guangzhou 510301, China
- 5Shanghai Engineering Research Center of Hadal Science and Technology, College of Marine Sciences, Shanghai Ocean University, Shanghai 201306, China
- 6Laboratory for Marine Mineral Resources, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266061, China
- 7MARUM – Center for Marine and Environmental Sciences and Department of Geosciences, University of Bremen, 28334 Bremen, Germany
Hydrocarbon seepage is a widespread phenomenon at continental margins around the world. The composition of the ascending fluids can be variable, consisting of short- and long-chain hydrocarbons as well as crude oil. A prominent site of oil seepage is the Bay of Campeche in the southern Gulf of Mexico. The seepage of petroleum is known to have an inhibiting effect on life at seeps, but short- and long-chain hydrocarbons have been shown to be degraded by a range of heterotrophic sulfate-reducing bacteria. Here we present lipid biomarker and carbon isotope data from authigenic carbonates from the Campeche Knolls in the southern Gulf of Mexico. The Campeche carbonates display d13C values in the range of -31.3‰ to -21.9‰, which is in accord with carbon derived from oil-derived hydrocarbons. Interestingly, the Campeche carbonates contain particularly high amounts of bacterial non-isoprenoidal ether lipids (DAGEs) with a wide variety of alkyl chain lengths. The bacterial biomarkers show heavier carbon isotopic signatures than their counterparts at methane seeps. These data allow for the characterization of bacterial oxidation of oil-derived hydrocarbons in modern and, in cases of moderate to good biomarker preservation, ancient environments, permitting the assessment of the influence of different fluid chemistries on the composition of chemosynthesis-based communities at seeps.
How to cite: Krake, N., Birgel, D., Smrzka, D., Zwicker, J., Huang, H., Feng, D., Bohrmann, G., and Peckmann, J.: Biomarker evidence for bacterial oxidation of oil-derived hydrocarbons at seeps in the southern Gulf of Mexico, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-7597, https://doi.org/10.5194/egusphere-egu22-7597, 2022.
