SGER: New Scales of Measuring Organic Carbon Diagenesis in Marine Sediments

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AbstractOCE-0129555A principal investigator from the University of Southern California will take advantage of two cutting-edge technologies for an investigation of benthic organic carbon cycling. Initially, the PI will create oxygen profiles utilizing genetically engineered bacteria (Shewanella sp.) which can be modified to perform carbon oxidation using either oxygen, or manganese oxide, or any combination of electron acceptors. Using these bacteria will allow the PI to construct oxygen profiles with control over organic substrate type/distribution, oxidant availability/distribution and bacterial community abundance/distribution. The goal of this research is to provide a direct relationship between solute profiles observed in sediments and the type and abundance of bacteria needed to carry out the redox reactions to yield a given profile. In addition, the PI also will use a profiling X-ray fluorescence scanner in collaboration with a scientist from Germany, to determine Fe, Ca, Mn and Ti in laminated sediments from low-oxygen-sites off Southern California and Mexico at 2-3 mm intervals or 3-6 years of resolution. The objective of this study is to obtain high resolution images of changes in solid phase Fe, Mn and Ti and carbonate as a function of time to identify diagenetic fronts and interpret changes in ocean productivity.