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Full-Text Articles in Earth Sciences
Hydrogeologic Investigation Of A Covered Karst Terrain, Joseph Peter Honings
Hydrogeologic Investigation Of A Covered Karst Terrain, Joseph Peter Honings
LSU Doctoral Dissertations
Increasing demand for water for agricultural use within the Dougherty Plain of the Southeastern United States has depleted surface water bodies. In karstic landscapes, such as the Dougherty Plain in southwest Georgia where the linkages between surface and ground waters are close, there is a need to understand the physical characteristics of the subsurface that allow these close linkages. Having a better understanding of the subsurface characteristics will aid numerical modeling efforts that underpin policy decisions and economic analyses. Two common features on this karstic landscape are draws and geographically isolated wetlands. Using LiDAR, aerial imagery, and ground-penetrating radar, this …
Particulate Inorganic Carbon Flux And Sediment Transport Dynamics In Karst: Significance To Landscape Evolution And The Carbon Cycle., Randall Lee Paylor
Particulate Inorganic Carbon Flux And Sediment Transport Dynamics In Karst: Significance To Landscape Evolution And The Carbon Cycle., Randall Lee Paylor
LSU Doctoral Dissertations
Research focused on three areas of karst hydrogeology and sediment transport that have been poorly studied in the past: the role of particulate inorganic carbon transport in calculating carbon sink rates in karst; rapid changes in surface vs. subsurface sediment mixing in karst conduits; and comparison of landscape denudation calculations using dissolved carbonate load vs. total dissolved/sediment load. Carbonate bedrock weathering is a significant component of the atmospheric carbon sink. Particulate inorganic carbon (PIC) in bed and suspended sediment load of karst waters is frequently dismissed as insignificant for calculating denudation and carbon transport/sink rates, but PIC flux has not …
Tracing Sediment In The Subsurface Using Beryllium-7: Green River Basin, Ky, Caroline Adams Broderick
Tracing Sediment In The Subsurface Using Beryllium-7: Green River Basin, Ky, Caroline Adams Broderick
LSU Master's Theses
As water flows through areas of limestone, karst inevitably develops, creating sinking streams and sinkholes that transport alumino-silicate particles from the surface into the subsurface. Sediment budget studies on short term scales through karst are rare. Thus, a feasibility study using beryllium-7 (7Be), which attaches to soil particles and can be used as a short-term (2-3 month) tracer of the movement of fine-grained sediment in karst was investigated. Sediment samples were collected from a karstic catchment within Green River basin, Kentucky, both on the surface and in the subsurface along a cave stream. Samples were collected prior to and immediately …
A 2-D, Variable-Density Numerical Model Of Subsurface Fluid Flow Through The Edwards Aquifer, New Braunfels, Tx: Mechanisms Inhibiting Flow Across The Freshwater/Saline-Water Interface, Scott Ryan Tipple
LSU Master's Theses
The Edwards aquifer in south-central Texas, U.S., composed of faulted carbonate bedrock, contains freshwater and saline water. In aquifers that are used as a source of drinking water and that contain fresh and saline waters, saline-water intrusion can result in degradation of water quality. Yet, in the Edwards aquifer, limited saline-water intrusion has occurred. The questions addressed are “Why is the saline-water intrusion less than expected,” and “Is there a trigger that will result in saline-water intrusion into the freshwater reservoir?” Three hypotheses were tested. One: an extremely saline water density might prevent mixing across the interface. Two: faults could …
The Influences Of Microbial Diversity On Carbonate Geochemistry Across A Transition From Fresh To Saline Water In The Edwards Aquifer, Texas, Cassie Jo Gray
The Influences Of Microbial Diversity On Carbonate Geochemistry Across A Transition From Fresh To Saline Water In The Edwards Aquifer, Texas, Cassie Jo Gray
LSU Master's Theses
Microbially-mediated karstification through the production of metabolic byproducts has been well-documented in cave environments, but less is known about deep karstic settings. This research aimed to distinguish between microbial and geochemical influences on carbonate dissolution in the Edwards Aquifer, a prolific karst aquifer in central Texas, specifically from a transect of six wells across a transition from fresh to saline water in New Braunfels. For the first time, a portion of the aquifer’s bacterial diversity was examined from molecular 16S rRNA gene sequence analyses, which revealed that Alphaproteobacteria, Gammaproteobacteria, and Betaproteobacteria dominated the aquifer, with rare Bacteroidetes, Nitrospirae, and Firmicutes …