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- Title
- Late Neogene to quaternary soil evolution across relict terraces in Northwest Florida.
- Author
- Randall, Chelsea Joel
- Abstract/Description
-
Delineation of relict terraces along the Northwest Florida coast can facilitate investigation of soil development within the Gulf of Mexico (GOM) coastal plain. Previous work to define terraces has primarily relied on topographic studies with little consensus on the number and extent of terraces. Research investigating soil development within the GOM coastal plain is also limited. The present study utilizes Geographic Information Systems (GIS) and a LiDAR derived Digital Elevation Model (DEM)...
Show moreDelineation of relict terraces along the Northwest Florida coast can facilitate investigation of soil development within the Gulf of Mexico (GOM) coastal plain. Previous work to define terraces has primarily relied on topographic studies with little consensus on the number and extent of terraces. Research investigating soil development within the GOM coastal plain is also limited. The present study utilizes Geographic Information Systems (GIS) and a LiDAR derived Digital Elevation Model (DEM) to apply a Surface Classification Model (SCM) for selection of terrace surfaces based on slope and surface roughness. The SCM output was analyzed for peaks in pixel count by elevation. Five terraces were defined between the following elevation ranges: 0-3.6 m, 4-9 m, 16-27 m, 29.5-51 m, and 57-64 m. Soil properties known to exhibit time related trends were analyzed across the delineated terraces. At increasing elevations, and presumably ages, soils exhibited a thickening of both the solum and Bt horizon, an increase in clay content, and a decrease in organic matter content. Bt horizons were observed at increasingly greater depths, with the exception of terrace 5, which was at shallower depth. Likely due to erosion associated with the high elevation and greater exposure of the surface.
Show less - Date Issued
- 2019, 2019
- Identifier
- 1153152792, WFE0000697
- Format
- Document (PDF)
- Title
- Measuring stable isotopes to trace groundwater transport of dissolved nitrogen in seagrass beds.
- Author
- McQueen, Haley Anne
- Abstract/Description
-
Submarine groundwater discharge (SGD) connects terrestrial groundwater to coastal surface waters through porous sediments. This research tracked dissolved nutrients as they traverse the subterranean estuary by measuring nitrogen stable isotope ratios in association with SGD inputs to nearshore beds of Thalassia testudinum. Variations of SGD-transported nutrients into the local environment (including porewaters and bottom waters) in which Thalassia is growing was investigated. Analysis was...
Show moreSubmarine groundwater discharge (SGD) connects terrestrial groundwater to coastal surface waters through porous sediments. This research tracked dissolved nutrients as they traverse the subterranean estuary by measuring nitrogen stable isotope ratios in association with SGD inputs to nearshore beds of Thalassia testudinum. Variations of SGD-transported nutrients into the local environment (including porewaters and bottom waters) in which Thalassia is growing was investigated. Analysis was carried out for variations in elemental abundance and stable isotope composition of seagrass in areas receiving SGD compared to control areas in which no SGD is measured. Eight site locations were sampled within Florida's Gulf Islands National Seashore's Naval Like Oaks (NALO) Preserve for bottom-water nitrate, nitrite, ammonium and phosphate; physical water quality parameters (dissolved oxygen, specific conductivity, temperature, pH, and turbidity); δ15N in pore-waters and groundwater transect; and dissolved radon. Additionally, Thalassia testudinum IRMS analysis for δ15N to investigate SGD influences on N ratios and stable isotope composition in the local seagrasses, including spatial and tidal controls on any variability in water column chemistry and seagrass biogeochemistry. Overall, there was not a significant correlation between SGD inputs and the stable isotope values found in Thalassia. However, significant findings linking SGD to atmospheric precipitation and isotope ratios to seagrass growing seasons were unearthed. The results of this research could prove advantageous for policymakers and environmental managers as they deal with pollution and conservation efforts surrounding seagrasses.
Show less - Date Issued
- 2020, 2020
- Identifier
- 1202267186, WFE0000721
- Format
- Document (PDF)
- Title
- Temporal variation of groundwater nutrient flux dynamics into Santa Rosa Sound, North West Florida.
- Author
- Leach, Dana J.
- Abstract/Description
-
Submarine groundwater discharge (SGD) is a pathway of nutrient loading into marine systems. SGD is described as the direct discharge of fresh or recirculated groundwater into the near-shore environment. This study aims to qualitatively identify nutrient transformation within the subterranean estuary (STE), which is a point of mixing between fresh groundwater and seawater where several chemical reactions occur. The biogeochemical conditions in porewater were identified using a push point...
Show moreSubmarine groundwater discharge (SGD) is a pathway of nutrient loading into marine systems. SGD is described as the direct discharge of fresh or recirculated groundwater into the near-shore environment. This study aims to qualitatively identify nutrient transformation within the subterranean estuary (STE), which is a point of mixing between fresh groundwater and seawater where several chemical reactions occur. The biogeochemical conditions in porewater were identified using a push point piezometer. A pieozomanometer survey was conducted to determine the nutrient flux into Santa Rosa Sound, Gulf Breeze, Florida. Nutrient concentration data were obtained by analyzing porewater samples from two sampling dates, June 16, 2019, and September 29, 2019. Upward velocity measurements were made on January 27, 2020. When comparing the two sampling dates, the subterranean estuary shifts from freshwater input into the system and salinity plots mimic the distribution of nitrogen within the STE. Phosphorus, pH, and oxidation-reduction potential (ORP) profiles were compared. In areas with low ORP and low pH, they indicate the possibility of iron oxidation and the possible presence of an "iron curtain". In this area, dissolved phosphorus is likely to precipitate from solution. Total dissolved inorganic nitrogen from porewater averaged 0.7 mmol d-1 per m shoreline. Upward velocity measurements showed that velocity increased with distance offshore, a trend that could be explained by a change of hydraulic conductivity and the patchiness of porewater substrate, where preferential flow through SGD favors sediments further offshore.
Show less - Date Issued
- 2020, 2020
- Identifier
- 1202025463, WFE0000718
- Format
- Document (PDF)