Civil and Environmental Engineering Commons^™

The Ecological Responses To Hydroperiod Of Wetland Plant Species Determined By Manipulated Soil Surface Elevation (Marsh Organs), Brandon Wolff

LSU Master's Theses

As sea level rise, subsidence, and abandonment of natural deltaic processes due to a highly engineered Mississippi River continue to threaten Louisiana’s coastal wetlands, the need for a system-wide understanding of natural wetland land-building and preservation processes has never been greater. A key component of any wetland is the ever-changing water environment that periodically floods and dries the marsh platforms. The flooding depth, duration, and frequency, known as the hydroperiod, along with salinity and soil fertility are key determining factors of vegetation and marsh types at a particular location. Different types of vegetation will have different growth characteristics such as …

Wetland Soil Development Along Salinity And Hydrogeomorphic Gradients In Active And Inactive Deltaic Basins Of Coastal Louisiana, Amanda Fontenot

LSU Master's Theses

Coastal wetlands provide an abundance of ecosystem services that benefit society, such as essential habitat for commercial species, storm protection, nutrient cycling, and carbon storage. Louisiana faces rapid rates of relative sea level rise (natural subsidence and eustatic sea levels) that threaten wetland survival, which are amplified by a reduction of riverine sediment input. An important determining factor of marsh survival is the formation of wetland platform elevation, known as vertical accretion, which is determined by several processes including sediment deposition & erosion, below ground biomass (BGB) productivity, decomposition of organic matter, shallow & deep subsidence, and soil compaction. Feldspar …

Assessment Of Endogenous Biomass Decay As A Source Of Precursors For Microbially-Mediated Toluene And P-Cresol Production, Samuel J. Reynolds

LSU Master's Theses

The research reported in this thesis was conducted to investigate whether protein hydrolysis associated with endogenous decay of biomass produced following the addition of a readily fermentable substrate is a potential source of precursors that can ultimately be transformed to toluene and p-cresol in environments undergoing enhanced bioremediation.

A packed column intended to represent a laboratory-scale section of an aquifer was seeded with groundwater and then supplied with molasses-amended groundwater for a two-day interval. The injected molasses concentration and surface loading rate were selected to be representative of conditions in the vicinity of injection wells at a Superfund Site …

Isolation And Characterization Of Bacteria In A Toluene-Producing Enrichment Culture Derived From Contaminated Groundwater At A Louisiana Superfund Site, Madison Mikes

LSU Master's Theses

In an effort to better understand the role that various microbes may play in toluene production, bacteria from a toluene-producing enrichment culture derived from contaminated groundwater at a Superfund site were cultivated and isolated on low nutrient solid media. A total of 14 solid medium formulations containing varying pH ranges, carbon sources, solidifying agents, and incubation gas headspaces were used to obtain 278 isolates in pure culture. Isolated bacteria, identified using partial 16S rRNA gene sequences, were most closely related with the genera Anoxybacillus, Azospira, Bacillus, Bradyrhizobium, Cellulosimicrobium, Micrococcus, and Propionicimonas.

Further attempts …

Physical And Biological Factors Controlling The Fate Of Nitrate In A Louisiana Coastal Deltaic Floodplain, Alexandra Christensen

LSU Doctoral Dissertations

The Mississippi River Delta is threatened by a growing pressure to support large human populations in the United States both with food production, navigation systems, and urban development in the Mississippi River Basin. Nitrate-nitrogen load in the Mississippi River, up to 100 Tg N yr^-1 from agricultural and urban runoff, leads to phytoplankton blooms and hypoxia across the Louisiana continental shelf, creating dead zones of low dissolved oxygen threatening a significant commercial fishery. Along the coast and river corridors, floodplain ecosystems have the capacity to retain and remove nitrate. This dissertation explores the role of productive, actively growing coastal …

The Tensile Root Strength Of Emergent Coastal Macrophytes, Lauris Olivia Hollis

LSU Doctoral Dissertations

Spartina patens is a dominant emergent macrophyte in fresh, intermediate, and brackish marshes along the Atlantic and Gulf coasts of United States where its biomechanical properties are a key component of wetland health and resilience. Its root biomass and tensile root strength are essential for anchorage, erosion protection, and are important determinants of soil strength. Nutrients and the herbicide atrazine are suspected of negatively impacting this wetland plant and others. The objectives of this study were to: 1) ascertain the tensile root strength of five emergent coastal macrophytes in coastal estuaries, and 2) test the effects of nutrient addition, atrazine …

Rice Hull Bioreactor For Recirculating Aquaculture, Marlon A. Greensword

LSU Doctoral Dissertations

The engineering of floating media biofilters has been optimized over the years. The backwashing process has made them more energy and water efficient. Likewise, moving bed bioreactors (MBBR) are gaining interest and popularity because they are relatively affordable to build. Yet, developing countries’ aquaculture production remains largely excluded from the advances made in recirculating aquaculture systems (RAS). This discrepancy is partially driven by the high costs of media such plastic beads and Kaldnes (KMT) media, commonly used in MBBR.

This dissertation evaluates the usability and profitability of rice hulls (RH), an abundant by-product in many developing nations, as a sinking …