Program: Geoscience MS

Committee Chair: Anna Bergstrom

Committee: Anna Bergstrom, Ellyn Enderlin, Jim McNamara, Ruth Heindel

Abstract: In polar environments, glacial meltwater provides essential nutrients to downstream ecosystems. In the McMurdo Dry Valleys of Antarctica, surface melt from cold-based glaciers is an initial source of solutes. However, previous studies have primarily focused on cryoconite holes, which only contribute a small fraction to total meltwater production. As a result, the control of diffuse sediment weathering within glacial ice on meltwater chemistry remains less understood. To investigate controls on solute generation, we conducted cyclic freeze-thaw experiments on sediment collected from supraglacial ice and local bedrock. Major anions and cations were measured using ion chromatography.

Solute release increased with successive freeze-thaw cycles; however, the magnitude and composition of ions released were strongly influenced by lithology. Grain size further affected ion concentrations, with finer fractions generally producing higher concentrations of ions derived from less soluble minerals. These results indicate that sediment lithology is a primary control on meltwater chemistry, while freeze-thaw weathering influences the rate of solute generation. Diffuse sediment weathering within glacial ice is an important control of solute production and meltwater chemistry in polar glacial ecosystems.

View on site | Email this event

Program: Biomedical Engineering PhD

Committee Chair: Trevor Lujan

Committee: Trevor Lujan, Clare Fitzpatrick, Tyler Brown, Kirk Lewis

Abstract: The repetitive wear-and-tear of knee menisci plays a significant role in chronic knee pain and disability, yet little is understood about the mechanical factors that drive the pathomechanics of this degenerative process. This gap in knowledge is critical to developing strategies to prevent and delay the incidence of meniscal degeneration. To address this gap, this research examines how specific loading magnitudes and motion paths at the cartilage-meniscus interface influence meniscal wear behavior, including: material loss, extracellular matrix weakening, and fiber fraying. This body of work integrates highly-repeatable, novel 3D scanning techniques to quantify and visualize meniscus damage, while mechanical wear was simulated using custom-built pin-on-plate devices and a six-degree-of-freedom robotic joint simulator. Results demonstrate that meniscal wear is anisotropic and strongly influenced by compressive loading magnitude. These findings underscore the importance of joint loading environments on meniscal health and degeneration. Collectively, this work advances the understanding of meniscal pathomechanics and identifies key mechanical factors that can inform joint-preservation strategies to improve long-term knee health.

View on site | Email this event