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- Hinrichs Lab - VOFAS
Hinrichs Lab - VOFAS
VOFAS: Carbon isotopic compositions of volatile fatty acids as proxies for biogeochemical processes in the deep marine biosphere (IODP Exp. 301)
| Duration: | July 2004 - June 2005 |
| Funding: | Deutsche Forschungsgemeinschaft (DFG) Schwerpunktprogramm 527 "Integrated Ocean Drilling Program/Ocean Drilling Program (IODP/ODP)" (Project HI 616/5-1) |
| Principal Investigator(s): | Kai-Uwe Hinrichs |
| Involved scientists in the Hinrichs Lab: | Verena Heuer |
| Partners: | Dr. B. Engelen (Institute for Chemistry and Biology of the Marine Environment, Carl-von-Ossietzky University, Oldenburg), Dr. T.G. Ferdelmann (Max Planck Institute for Marine Microbiology, Bremen), Dr. N. Finke (Max Planck Institute for Marine Microbiology, Bremen), Dr. M. Krummen (ThermoElectron, Bremen), Prof. K. Küsel (Friedrich-Schiller-Universität, Jena), Dr. M. Lever (Universtiy of North Carolina Chapel Hill, NC, USA), Prof. A. Teske (Universtiy of North Carolina Chapel Hill, NC, USA) |
Abstract
By demonstrating the existence of an extensive deep marine biosphere the Ocean Drilling Program has posed some fundamental questions for biogeochemistry, namely: (1) How can bacterial populations survive on buried, recalcitrant organic material for millions of years? (2) Is acetate of biogenic or thermogenic origin an alternative substrate for theses organisms? (3) Do chemoautotrophic microbes act as primary producers at great sediment depth?
This project was driven by the hypothesis that carbon-isotopic investigations of volatile fatty acids (VFA), most importantly acetate, will shed more light on the cycling of carbon within the deep biosphere. VFAs are key intermediates in microbially mediated processes. Their abundance and isotopic composition are controlled by a balance of biological sinks and sources. Here we aimed to decipher the information encoded in the carbon isotopic signatures of VFAs with the aim to develop a biogeochemical proxy that aids in the identification of in situ diagenetic processes in the deep biosphere. Our study seeked to fill the vast gap in knowledge on the extent of and underlying processes causing the isotopic variability of VFAs in marine sediments and elucidate the processes that cause extremely high acetate concentrations in some deeply buried sediments.
We investigated pore-waters from IODP Expedition 301 (Juan de Fuca Ridge Flank) as well as pore-waters from a range of sediments with various biogeochemical conditions to test the following working hypothesis: The isotopic signatures of VFAs exhibit a great range and are in a certain, yet unknown manner linked to the predominant biogeochemical processes in the sediment horizon. With complementary laboratory studies, we simulated the presumed temperature-dependent biological production of acetate at great burial depth in order to characterize and track this pool isotopically.
By demonstrating the existence of an extensive deep marine biosphere the Ocean Drilling Program has posed some fundamental questions for biogeochemistry, namely: (1) How can bacterial populations survive on buried, recalcitrant organic material for millions of years? (2) Is acetate of biogenic or thermogenic origin an alternative substrate for theses organisms? (3) Do chemoautotrophic microbes act as primary producers at great sediment depth?
This project was driven by the hypothesis that carbon-isotopic investigations of volatile fatty acids (VFA), most importantly acetate, will shed more light on the cycling of carbon within the deep biosphere. VFAs are key intermediates in microbially mediated processes. Their abundance and isotopic composition are controlled by a balance of biological sinks and sources. Here we aimed to decipher the information encoded in the carbon isotopic signatures of VFAs with the aim to develop a biogeochemical proxy that aids in the identification of in situ diagenetic processes in the deep biosphere. Our study seeked to fill the vast gap in knowledge on the extent of and underlying processes causing the isotopic variability of VFAs in marine sediments and elucidate the processes that cause extremely high acetate concentrations in some deeply buried sediments.
We investigated pore-waters from IODP Expedition 301 (Juan de Fuca Ridge Flank) as well as pore-waters from a range of sediments with various biogeochemical conditions to test the following working hypothesis: The isotopic signatures of VFAs exhibit a great range and are in a certain, yet unknown manner linked to the predominant biogeochemical processes in the sediment horizon. With complementary laboratory studies, we simulated the presumed temperature-dependent biological production of acetate at great burial depth in order to characterize and track this pool isotopically.