Assessing landscape and seasonal controls on CO2 fluxes in a karst sinkhole
Karst landscapes can serve as carbon sinks when carbon dioxide (CO2) reacts with water to form carbonic acid, which then weathers carbonate rocks. However, CO2 can also move through the subsurface via gas diffusion, a process that is not well-understood in karst systems. This study focused on quanti...
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ftvirginiatec:oai:vtechworks.lib.vt.edu:10919/107440 2024-05-19T07:38:54+00:00 Assessing landscape and seasonal controls on CO2 fluxes in a karst sinkhole Thompson, Taryn Karie Crop and Soil Environmental Sciences Stewart, Ryan D. McLaughlin, Daniel L. Schreiber, Madeline E. 2022-01-06 ETD application/pdf http://hdl.handle.net/10919/107440 en eng Virginia Tech vt_gsexam:32899 http://hdl.handle.net/10919/107440 Creative Commons Attribution 4.0 International http://creativecommons.org/licenses/by/4.0/ concentration gradient zero-flux plane gradient method diffusion coefficient Fick's Law Thesis 2022 ftvirginiatec 2024-04-24T00:47:36Z Karst landscapes can serve as carbon sinks when carbon dioxide (CO2) reacts with water to form carbonic acid, which then weathers carbonate rocks. However, CO2 can also move through the subsurface via gas diffusion, a process that is not well-understood in karst systems. This study focused on quantifying CO2 diffusion within a karst sinkhole. The objectives of this study were to: 1) identify the depth of the zero-flux plane (i.e., depths of local maximum CO2 concentrations), analyze the distributions of concentration gradients, and investigate the validity of a uniform concentration gradient throughout the profile; and 2) assess the influences of vertical position and seasonality on CO2 fluxes within this sinkhole. The study site contained three locations within the sinkhole, including shoulder, backslope, and toeslope locations. Each location had three soil CO2 and three soil water content/temperature sensors placed at 20, 40, and 60 cm depths. Zero-flux planes were seldom detectable during the warm season (April-September) but were frequently found near the surface (20 or 40 cm) during the cool season (October-March). The common assumption of a uniform concentration gradient was often invalid based on relative concentrations between sensor pairs. As for the second objective, CO2 fluxes generally followed a trend of upward fluxes in warmer months that was partially offset by downward fluxes during the cooler months. These study results provide new insight into CO2 dynamics in a karst system, and suggest that subsurface processes such as chemical weathering and cave ventilation affect the direction and magnitude of CO2 fluxes. Master of Science Carbon dioxide (CO2) within soils is a larger pool of CO2 than atmospheric CO2. Therefore, the movement of CO2 within soils is important to understand, as soil CO2 may eventually diffuse through the soil and into the atmosphere. Soil CO2 movement is dependent on many factors such as soil water content, porosity, and temperature. Soil CO2 movement may vary between ... Thesis Carbonic acid VTechWorks (VirginiaTech) |
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concentration gradient zero-flux plane gradient method diffusion coefficient Fick's Law |
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concentration gradient zero-flux plane gradient method diffusion coefficient Fick's Law Thompson, Taryn Karie Assessing landscape and seasonal controls on CO2 fluxes in a karst sinkhole |
topic_facet |
concentration gradient zero-flux plane gradient method diffusion coefficient Fick's Law |
description |
Karst landscapes can serve as carbon sinks when carbon dioxide (CO2) reacts with water to form carbonic acid, which then weathers carbonate rocks. However, CO2 can also move through the subsurface via gas diffusion, a process that is not well-understood in karst systems. This study focused on quantifying CO2 diffusion within a karst sinkhole. The objectives of this study were to: 1) identify the depth of the zero-flux plane (i.e., depths of local maximum CO2 concentrations), analyze the distributions of concentration gradients, and investigate the validity of a uniform concentration gradient throughout the profile; and 2) assess the influences of vertical position and seasonality on CO2 fluxes within this sinkhole. The study site contained three locations within the sinkhole, including shoulder, backslope, and toeslope locations. Each location had three soil CO2 and three soil water content/temperature sensors placed at 20, 40, and 60 cm depths. Zero-flux planes were seldom detectable during the warm season (April-September) but were frequently found near the surface (20 or 40 cm) during the cool season (October-March). The common assumption of a uniform concentration gradient was often invalid based on relative concentrations between sensor pairs. As for the second objective, CO2 fluxes generally followed a trend of upward fluxes in warmer months that was partially offset by downward fluxes during the cooler months. These study results provide new insight into CO2 dynamics in a karst system, and suggest that subsurface processes such as chemical weathering and cave ventilation affect the direction and magnitude of CO2 fluxes. Master of Science Carbon dioxide (CO2) within soils is a larger pool of CO2 than atmospheric CO2. Therefore, the movement of CO2 within soils is important to understand, as soil CO2 may eventually diffuse through the soil and into the atmosphere. Soil CO2 movement is dependent on many factors such as soil water content, porosity, and temperature. Soil CO2 movement may vary between ... |
author2 |
Crop and Soil Environmental Sciences Stewart, Ryan D. McLaughlin, Daniel L. Schreiber, Madeline E. |
format |
Thesis |
author |
Thompson, Taryn Karie |
author_facet |
Thompson, Taryn Karie |
author_sort |
Thompson, Taryn Karie |
title |
Assessing landscape and seasonal controls on CO2 fluxes in a karst sinkhole |
title_short |
Assessing landscape and seasonal controls on CO2 fluxes in a karst sinkhole |
title_full |
Assessing landscape and seasonal controls on CO2 fluxes in a karst sinkhole |
title_fullStr |
Assessing landscape and seasonal controls on CO2 fluxes in a karst sinkhole |
title_full_unstemmed |
Assessing landscape and seasonal controls on CO2 fluxes in a karst sinkhole |
title_sort |
assessing landscape and seasonal controls on co2 fluxes in a karst sinkhole |
publisher |
Virginia Tech |
publishDate |
2022 |
url |
http://hdl.handle.net/10919/107440 |
genre |
Carbonic acid |
genre_facet |
Carbonic acid |
op_relation |
vt_gsexam:32899 http://hdl.handle.net/10919/107440 |
op_rights |
Creative Commons Attribution 4.0 International http://creativecommons.org/licenses/by/4.0/ |
_version_ |
1799478402182283264 |