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Biogeochemical and phylogenetic signals of Proterozoic and Phanerozoic microbial metabolisms
(Massachusetts Institute of Technology, 2018)
Life is ubiquitous in the environment and an important mediator of Earth's carbon cycle, but quantifying the contribution of microbial biomass and its metabolic fluxes is difficult, especially in spatially and temporally-remote ...
An investigation of basin-scale controls on upper ocean export and remineralization
(Massachusetts Institute of Technology, 2018)
The biological carbon pump (BCP) helps to moderate atmospheric carbon dioxide levels by bringing carbon to the deep ocean, where it can be sequestered on timescales of centuries to millennia. Climate change is predicted ...
Water and volatile element accretion to the inner planets
(Massachusetts Institute of Technology, 2018)
This thesis investigates the timing and source(s) of water and volatile elements to the inner solar system by studying the basaltic meteorites angrites and eucrites. In chapters 2 and 3, I present the results from angrite ...
Scavenging and transport of thorium radioisotopes in the North Atlantic Ocean
(Massachusetts Institute of Technology, 2018)
Many chemical constituents are removed from the ocean by attachment to settling particles, a process referred to as "scavenging." Radioisotopes of thorium, a highly particle-reactive element, have been used extensively to ...
Radium isotopes as tracers of boundary inputs of nutrients and trace elements to the coastal and open ocean
(Massachusetts Institute of Technology, 2018)
Nutrients and trace metals are vital for supporting life in the ocean, but the boundary processes that control the distributions of these elements are poorly constrained. Radium isotopes are well suited to studying inputs ...
Carbon and mineral transformations in seafloor serpentinization systems
(Massachusetts Institute of Technology, 2018)
This thesis examines abiotic processes controlling the transformation and distribution of carbon compounds in seafloor hydrothermal systems hosted in ultramafic rock. These processes have a direct impact on carbon budgets ...
Movements and oceanographic associations of large pelagic fishes in the North Atlantic Ocean
(Massachusetts Institute of Technology, 2018)
Highly migratory marine fishes support valuable commercial fisheries worldwide. Yet, many target species have proven difficult to study due to long-distance migrations and regular deep diving. Despite the dominance of ...
The marine biogeochemistry of chromium isotopes
(Massachusetts Institute of Technology, 2018)
In the ocean, chromium (Cr) is a redox-sensitive trace metal. The reduction of Cr(VI) to Cr(III) occurs in oxygen deficient zones (ODZs), and Cr reduction in general has been identified as a significant Cr isotope fractionation ...
Chaotic advection, mixing, and property exchange in three-dimensional ocean eddies and gyres
(Massachusetts Institute of Technology, 2018)
This work investigates how a Lagrangian perspective applies to models of two oceanographic flows: an overturning submesoscale eddy and the Western Alboran Gyre. In the first case, I focus on the importance of diffusion as ...