Current Research Interests and Projects
Isotopologues of Organic MoleculesWith new funding from NASA, we are exploring how biological, physical, and environmental processes are recorded within molecules. This work uses DFT and isotope models, state of the art isotope NMR and novel mass spectrometry methods, and as part of a multi-institution collaborative team. At PSU, we are employing new Orbitrap MS techniques for position-specific analyses of C, N, H, S isotopes. The focus of this work is method development, and our long-term focus is on applications in biosignatures, astrobiology, and paleoenvironment and climate. Figure credit: A. Gilbert
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Fire markersWe are studying polycyclic aromatic hydrocarbons (PAH) as indicators of fire in ancient terrestrial environments. We are interested in the occurrence and nature of fire as a possible source of carbon released during the PETM. We also are interested in relationships between fire and grassland expansion during the mid to late Miocene around the world, and as a response to Plio-Pleistocene climate variability in eastern Africa.
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Habitats of early humansWe have been collaborating with Gail Ashley (Rutgers) to study the molecular fossils in lake sediments and paleosols surrounding Olduvai Gorge, Tanzania. Our work has documented climate variability that is orbitally paced during the rise of early humans. We have been working with archaeological samples to map spatial patterns in vegetation associated with vertebrate remains and human artifacts.
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Microbial biogeochemistry and biosignaturesWe collaborate with microbiologists to study the lipid and isotopic signatures of microbes in anoxic environments. We are currently studying F430, a co-enzyme that is critical to methanogenesis, and possibly methane oxidation through reverse methanogenesis. We also are investigating hopane polar lipids of cyanobacteria and sulfur-oxidizing bacteria. These compounds are important in studies of petroleum, past oceans and early life on Earth. Yet, we still know little of their biochemical functions and microbial sources.
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Frontiers in Isotope Analyses: Pico-CSIA, Nano-EA/IRMSCompound-specific carbon isotope analyses were introduced over 25 years ago. Today, they are widely used in biogeochemistry, environmental, petroleum, flavor, and forensics applications. We have recently developed a new generation of instrumentation, which reduces sample size to picomoles for molecular isotope analyses; we have also reduced sample sizes to nanomoles for bulk organic C, N, and S isotopes.
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