My current PhD research is focused on understanding the biogeochemistry of organic sulfur formation using compound-specific stable isotope analysis. |
hopanoid thiophene - an organic sulfur compound
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The purpose of such research is to unravel some of the complexities of the sulfur cycle, paying particular attention to organic sulfur. Using new analytical capabilities to measure compound specific sulfur isotopes we will be able to elucidate the processes surrounding organic sulfur formation and what role environmental factors play in the cycling of sulfur in both aqueous and sedimentary environments. Ultimately, these measurements will establish a baseline of molecular organic sulfur isotopes which can then be used for understanding the coupled biogeochemical cycles of carbon and sulfur through geologic time, as well as the biogeochemistry of early Earth systems and origins of life.
This work is being completed under the direction of Dr. Josef P. Werne at the University of Pittsburgh and is supported by funds from the National Science Foundation (NSF) and the American Chemical Society Petroleum Research Fund (ACS - PRF).
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Sulfurization of organic matterLaboratory sulfurization of carbohydrates, lipids, and DOM will establish constraints on the sulfur isotopic signature of compounds found in natural systems. Laboratory results will be applied to natural samples from the Upper Jurassic Kimmeridge Clay Formation, where the preservation of carbohydrates through sulfurization has resulted in the extremely high organic carbon content (34%) of the Blackstone Band, in particular.
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Modern analog for Earth's early ocean - sulfur cyclingAnalysis of water column and sediment samples from two euxinic lake systems (Fayetteville Green Lake, NY, USA and Mahoney Lake, BC, Canada) will establish a baseline for the sulfur isotope values of organic sulfur compounds in natural environments. We will be looking for general patterns of fractionation among different types of molecules and how they may relate to environmental conditions. Fayetteville Green Lake is considered a modern analog to the ocean ca. 3 billion years ago and provides a unique opportunity to examine how Earth’s early ocean operated with respect to sulfur cycling dynamics.
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Split surface of a sediment core from Mahoney Lake, British Colombia, Canada
During my Masters, I worked to reconstruct (paleo)productivity trends in Lake Superior over the last 10,000 years using bulk organic carbon and nitrogen elemental abundances and stable isotopes, as well as compound-specific stable isotopes of carbon.
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Recent studies have documented changes in Lake Superior’s physical, chemical, and biological processes – including a 3.5°C warming of the surface waters over the last century. Such changes are often difficult to perceive as cause for concern when not placed within a historical context. The aim of this research was to reconstruct trends in primary productivity in Lake Superior over the last 10,000 years using bulk and molecular biomarker proxies of sedimentary organic matter, with an emphasis on changes in the last 200 years. Our efforts ultimately provided a historic baseline on which to assess anthropogenically induced changes in Lake Superior.
Publications forthcoming. |
