Date of Award

Fall 12-2025

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Chemistry & Biochemistry

Program/Concentration

Chemistry

Committee Director

Patrick G. Hatcher

Committee Member

John Donat

Committee Member

Sandeep Kumar

Committee Member

Jingdong Mao

Abstract

The most abundant source of fossil fuel-forming kerogen on Earth is classified as Type II kerogen, believed to originate from marine biomass. However, a significant amount of lacustrine and terrigenous carbon is transported to the ocean through fluvial discharge. Less than half of the exported organic carbon is observed in coastal regions and the open ocean. There is a great need for an explanation of what is happening to this organic carbon during transport and deposition. Traditionally, the marine organic matter in coastal regions accumulates to eventually be buried and transformed into petroleum over millions of years due to its overwhelming aliphatic character. One hypothesis is that most of the organic matter found in the oceans is comprised of terrigenous organic matter that has undergone oxidative transformations to appear marine-like in chemistry and petroleum-forming potential.

This Dissertation discusses novel processes to produce alternative hydrocarbon-based fuels from lacustrine algae and investigates the effect that oxidative degradation has on the elemental, isotopic, and molecular makeup of sediments found in oceanic abyssal depths that contain relatively high amounts of terrigenous organic matter. The first project describes a two-step hydrothermal liquefaction process to produce higher quality bio-oil from algal kerogen-precursor material called algaenan. The second project expands on this two-step strategy by utilizing an oxidative degradation process to achieve a similar algal intermediate residue that is then converted to a bio-oil. The third chapter focuses organic matter characterization of sediments from the highly terrigenous containing Congo fan system fed by the Congo River. The fourth project shows the effect that oxidation has on the anoxic distal sediments in the Congo fan, camouflaging them to appear marine-like and to potentially yielding a Type II source for petroleum during geologic maturation.

The results presented here aid in the search for methods of producing renewable energy sources and in the understanding of what happens to algal and terrigenous organic matter during and following transport and deposition in marine settings. This challenges current carbon cycle source determinations, potentially calling for a reexamination of global carbon cycle estimations and traditional kerogen classifications.

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DOI

10.25777/ejjx-w137

ISBN

9798276041049

ORCID

0000-0002-5970-8260

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