Physical Sciences and Mathematics Commons^™

Phosphorus Cycling In Tropical Carbonate Sediment-Seagrass Systems, Zachary Howerton

OES Theses and Dissertations

This thesis presents two studies focusing on phosphorus cycling in calcium carbonate sediments inhabited by seagrasses. Phosphorus is a major limiting nutrient for primary productivity in these sediments as well as in the overlying waters. In large part this is due to removal of phosphate from solution by adsorption and precipitation reactions.

In chapter II, the relationship between the size of the sedimentary phosphorus pool and the abundance of seagrass on the Great Bahama Bank, as well as the relationship between phosphorus content and grain size in the sediments, were examined to better understand the biogeochemistry of carbonate sediments and …

Hydrogeologic Variations Across A Barrier Island That Influence Inter-Dune Wetlands False Cape State Park, Virginia, Matthew Collier Richardson

OES Theses and Dissertations

False Cape State Park in southeastern Virginia Beach, Virginia contains a transgressive barrier island complex. Inter-dune swales located on the eastern coast of the barrier island contain soils that experience hydric conditions. However, these swales lack the prolonged presence of hydric soil indicators that are necessary for a site to be officially recognized as a jurisdictional wetland. The appearance and subsequent disappearance of redoximorphic wetland soil features in the young, sandy soils of the inter-dune swales here may stem from changes in the patterns of groundwater recharge and discharge across the island. These soils are being monitored by the Mid …

Evaluating The Contribution Of Groundwater To Wetland Water Budgets Central Piedmont Virginia, Kerby Morgan Dobbs

OES Theses and Dissertations

In the Piedmont region of Virginia, development pressures are increasing the demand for mitigation wetlands but appropriate construction sites are relatively scarce due to local topography and geology. Many existing water budget models used for planned mitigation sites exhibit considerable error when estimating groundwater fluxes, particularly for historical years that lack hydraulic head data. This difficulty has led many planners to neglect or underestimate the contribution of groundwater to wetland water budgets, resulting in mitigation sites that fail to create the appropriate hydrology for the desired vegetation community. However, reliable estimations of groundwater input contributing to wetland water budgets can …

Assessing The Release Of Bioactive Trace Elements From Coal Fly Ash Into Natural Fresh Waters, Candace E. Wall

OES Theses and Dissertations

Each year a significant amount of coal fly ash enters the environment, where it can potentially cause adverse effects by releasing a range of bioactive trace elements. In this context, environmental studies have largely focused on the leaching of trace elements from the coal ash in landfills by rainwater and groundwater, while there has been relatively little study of the release of bioactive trace elements from coal fly ash deposited in natural fresh waters such as rivers and lakes. Furthermore, the batch leaching methods that have been used to study the interaction of rainwater and groundwater with coal ash in …

Response Of Natural Estuarine Algal Communities To Nitrogen Additions, Christopher Schweitzer

OES Theses and Dissertations

Coastal eutrophication resulting from nutrient over-enrichment plagues coastal waterways worldwide. In addition to dissolved inorganic N, many marine microbes, including phytoplankton, have the capacity to use certain dissolved organic nitrogen (DON) compounds. However, while we know that many specific DON compounds are labile, the bulk of the DON pool in nature is uncharacterized. The bioavailability of DON to estuarine microbes currently remains unclear.

It is becoming evident that natural phytoplankton assemblages in estuarine waters are capable of using both inorganic and organic N compounds for growth, both of which are present in anthropogenic point and non-point source discharges. Methods for …

Modeling Studies Of Antarctic Krill (Euphausia Superba) Survival During Transport Across The Scotia Sea And Environs, Bettina Andrea Fach

OES Theses and Dissertations

The Antarctic krill (Euphausia superba) populations at South Georgia, which is in the eastern Scotia Sea, are hypothesized to be sustained by import of individuals from upstream regions, such as the western Antarctic Peninsula. To test this hypothesis a modeling framework consisting of the Harvard Ocean Prediction System (HOPS) and a time-dependent, size-structured, physiologically-based krill growth model was developed. The simulated circulation fields obtained from HOPS were used with drifter studies to determine regions and pathways that allow transport of Antarctic krill to South Georgia. Pelagic phytoplankton concentrations along the simulated drifter trajectories were extracted from historical Coastal …

Environmental And Physiological Influences On Productivity And Carbon Isotope Discrimination In Eelgrass (Zostera Marina L.), Meredith Leigh Mcpherson

OES Theses and Dissertations

A short-term longitudinal study was used to examine the relations of achievement motivation, general motivation, interest, and self-regulatory predictors to cognitive strategy use and academic performance. A total of 102 college undergraduates enrolled in their first college-level introductory psychology course completed an Achieving Tendency Scale of achievement motivation, the Motivated Strategies For Learning Questionnaire, and an Interest Profile in psychology during the first two weeks of the semester. At midterm they completed the Study Activity Survey of cognitive strategy use. At the end of the semester exam grades, total points earned in the course, and grade point average were obtained. …

Observations And Modeling Forcing Mechanisms For The Coastal Dynamics Of The Upper Gulf Of Thailand, Suriyan Saramul

OES Theses and Dissertations

A numerical model based on the Princeton Ocean Model (130M) with ∼1 km horizontal grid and 21 vertical layers has been used to study the influence of wind stresses, river discharges, surface heat fluxes and tides on the three-dimensional circulation of the upper Gulf of Thailand (UGOT). Analysis of observations, including sea level data, provided additional information to support the model simulations. The UGOT is a shallow coastal system, ∼1°×1° in size with the average depth of only 15 m. Sensitivity studies evaluate how the dynamics is affected by surface wind stresses, river discharges, and surface heat fluxes. The impact …