Life Sciences Commons^™

Characterizations Of Dissolved Organic Carbon At Hydrothermal Systems Of The Midcayman Rise, Aaron Mau

Theses and Dissertations

Marine dissolved organic carbon (DOC) is a carbon reservoir comparable in size to all atmospheric CO2 and is composed primarily of refractory material which can be thousands of years old. Circulation through hydrothermal systems has been demonstrated to profoundly alter this material, but the mechanisms that lead to addition, removal, and alteration of DOC are poorly understood. Consequently, the contribution of hydrothermal systems to organic carbon cycling in the deep ocean – and the biological and geochemical processes exhibited at different venting environments – remain highly uncertain.

In January 2020, samples were collected from two hydrothermal vent fields at the …

Influence Of Energy Availability On The Carbon Isotopes Of Methane And Biomarkers During Hydrogenotrophic Methanogenesis, Tran Nguyen

Theses and Dissertations

Signatures of organic molecules in the environment are widely used to identify microbial metabolic processes and to track the cycling of carbon. The lipid biomarkers of methane cycling archaea are of particular interest as they are unique, preserved over geologic time scales, and reflect processes that impact an important greenhouse gas. Their isotopic compositions have been used to distinguish regions where archaea produce and anaerobically consume CH4. Previous work has demonstrated that energy availability impacts the stable carbon isotopes of CH4 during microbial synthesis from H2 and CO2. Here, we investigated whether this relationship could be extended to lipids and …