Publication Date

12-2023

Advisor(s) - Committee Chair

Chris Groves, Mike May, Pat Kambesis, Rick Toomey

Degree Program

Department of Earth, Environmental, and Atmospheric Sciences

Degree Type

Master of Science

Abstract

An increase in atmospheric CO2 since the Industrial Revolution has altered rates of global climate change and has motivated a need to better quantify the flux of carbon between Earth’s reservoirs. Attempts to quantify the exchange of atmospheric carbon between sources and sinks have led to an increasing interest in the terrestrial landscape, including the continental carbon sink associated with carbonate-mineral dissolution. This research sought to better inform an understanding of karst landscapes and their relationship with global climate change through carbon cycling. The study utilized high-resolution data collection of pH, temperature, and specific conductance of waters in the Cascade River within Great Onyx Cave collected at tenminute intervals over a thirteen month-long period from August 2022 to September 2023. Absolute water pressure, barometric pressure, and water temperature readings to calculate water level were also measured at ten-minute intervals to correlate to discharge measurements. Water samples collected on bi-weekly monitoring trips were analyzed for major cations, anions, and alkalinity. Using linear regression analysis, the study quantified the dissolved inorganic carbon (DIC) mass flux between the atmosphere and landscape for seasonal comparison. Results suggest the Cascade River system is influenced by atmospheric and soil CO2 concentrations in both the warm and cool seasons, with more CO2 available during the warm season. The waters of the study site are constantly undersaturated with respect to calcite and thus are continually dissolving. Dissolution rates are higher during storm events in both seasons. DIC values are likewise influenced by storm events, decreasing rapidly in response to rainfall and are suggestive that discharge is the dominant control on DIC flux rates. The study results also define the carbon sink potential for Cascade Spring and indicate CO2 is being removed from the atmosphere in both the cool and warm season, with heightened cool season sink values associated with discharge capacity.

Disciplines

Earth Sciences | Geochemistry | Geology | Hydrology | Physical Sciences and Mathematics

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