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Competitive Sorption And Transport Of Heavy Metals In Soil And Mn Oxide-Coated Sand, Joshua Tyler Padilla

LSU Doctoral Dissertations

This study investigated the competitive sorption of Ni, Pb, and Zn as well as synergistic interactions between Ni and phosphate (P) in soils and Mn oxide-coated sand. During stirred-flow experiments, the sorption of heavy metal cations by Olivier soil was mutually reduced when applied simultaneously. When applied consecutively, the cation of higher affinity was able to displace the cation of lower affinity from the soil surface, however, no evidence for the reverse case was observed. A novel general exchange kinetics model was able to correctly describe such displacement. Competition between Ni and Zn mutually increased mobility in Olivier and Windsor …

Soil Organic Matter Accretion, Complexity, And Degradation In Eroding Coastal Wetlands, Yadav Sapkota

LSU Doctoral Dissertations

Coastal wetlands are one of the most productive ecosystems on the earth. They are increasingly recognized and valued for atmospheric carbon sequestration and storage for a long time. However, coastal wetlands acreage is shrinking, across the globe, due to several factors including sea-level rise, local subsidence, edge erosion, extreme weather events, and anthropogenic activities. The coastal wetlands in the Mississippi River Deltaic Plain experience high relative sea-level rise, limited sediment supply, and high marsh edge erosion, leading to substantial land loss. These wetlands require restoration and conservation to slown down land loss and continue providing ecosystem services. The coastal restoration …

Water-Energy Nexus: Studies On Salinity Gradient Energy Harvest And Desalination, Guangcai Tan

LSU Doctoral Dissertations

Water and energy are fundamentally linked, and both are important for the development of human society. The demand for renewable energy and freshwater are two global challenges in the 21^st century. Herein, a novel chloride-ion (Cl⁻) concentration flow cell (CFC) based on two symmetrical electrodes (BiCl₃, CoCl₂, VCl₃, or BiOCl) separately by a cation-exchange membrane was used as an efficient method to recover salinity gradient (SG) energy. The CFC with metal chloride electrodes (BiCl₃, CoCl₂, and VCl₃) was based on Cl⁻ extraction/insertion, and that …

Effect Of Biosurfactant And Biochar On Ecosystem Functions And Oil Remediation In Crude Oil Contaminated Wetland Soils, Zhuo Wei

LSU Doctoral Dissertations

Decontamination of oil spill from coastal wetland soils requires a delicate approach. Remediation strategies using biochar, biosurfactant, and nutrient additions have been proposed. However, there is little information on application of these with combination for treatment of crude oil-contaminated wetland soil. Therefore, incubation studies were carried out to investigate the impact of biochar and rhamnolipid (RL) biosurfactant along with nitrogen (N) application on petroleum hydrocarbon degradation in a Louisiana coastal saline marsh and their impacts on greenhouse gas (GHG) emission. Additionally, the toxicity of crude oil as well as remediation materials on coastal wetland ecosystem were assessed at three levels: …

Using Poultry Litter Ash As A Fertilizer Source For Bermudagrass (Cynodon Dactylon) Establishment And Loblolly Pine (Pinus Taeda) Plantation, Crystal L. Vance

LSU Doctoral Dissertations

Lower solubility of P in poultry litter ash (PLA) than conventional phosphorus (P) fertilizers such as triple superphosphate (TSP) may reduce P losses in drainage and runoff; however, lower P solubility may reduce its efficacy as a P source. A laboratory experiment was conducted to examine the effect of acidity on P release and the effect of different combustion temperatures on P solubility as a prerequisite to the following studies. The first research objective was to determine the effect of soil pH on the efficiency of PLA relative to TSP for establishment of common bermudagrass (Cynodon dactylon L.) and …

Development Of A Tunable Platform For The Study Of Geomacromolecular Matrices Using Controlled Radical Polymerization, Arjun Pandey

LSU Doctoral Dissertations

Soil is an important environmental component, and the study of soil processes have many practical implications such as improvement in agriculture, mitigation of climate change etc. The widespread use of Agricultural Chemicals (ACs) in modern agriculture has resulted in adverse effects in environment and human health mostly through contamination into food and water sources. Study of fate, bioavailability, and transport of ACs involves molecular level understanding of their interactions with soil. This can be challenging due to complex and heterogeneous nature of soil. One common approach used is the correlation of macroscopic properties of soil, (e.g. sorption) with empirical parameters …

Silicon Fertilization In Rice And Wheat: Dynamics With Trace Elements And Effect Of Silicate Slag Granular Size On The Release Pattern Of Monosilicic Acid In Soil, Wooiklee S. Paye

LSU Doctoral Dissertations

Studies were conducted to evaluate the impact of silicon (Si) fertilization on the uptake of harmful trace elements in Louisiana rice production system, and document the effect of silicate slag granular size on its ability to supply Si in wheat. The influence of silicate slag and lime on the uptake and translocation of harmful trace elements in rice grain was determined. Results showed that both slag and lime had similar effects on pH at five of the nine sites investigated. Soil Si was significantly (P <0.001) increased with application of silicate slag at all sites. Lime and silicate slag had no effect on the concentration of trace elements in soil. However, increasing Si rates were negatively correlated with arsenic (As) and cadmium (Cd) concentration in rice grain. The release pattern of monosilicic acid (H₄SiO₄) from wollastonite and silicate slag was compared in a wheat greenhouse …

Iron-Sulfur Cluster Biosynthesis In Methanogens, Cuiping Zhao

LSU Doctoral Dissertations

Methanogens live in a syntrophic consortium with bacteria, taking advantage of the metabolic abilities of their syntrophic partners to overcome energetic barriers and break down compounds that they cannot digest by themselves. Interspecies electron transfer, which is a major type of microbial communication in syntrophic processes, improves methanogenesis and anaerobic oxidization of methane (AOM) processes involved in syntrophic consortia. These processes have a significant impact on the global carbon cycle. Most of the essential enzymes involved in methanogenesis are iron-sulfur proteins. Iron-sulfur clusters are one of the oldest and most versatile cofactors present in all domains of life. To date, …

The Use Of Cellulose Nanofibers In Polymer Matrix Composites Via 3d Printing, Ju Dong

LSU Doctoral Dissertations

Filament fused fabrication (FFF) is an extrusion-based 3D printing technology for manufacturing thermoplastic polymers. A major obstacle of 3D printed thermoplastic is the limited crystallinity resulting from a fast quench while material leaving the hot nozzle and solidifying quickly at the low-temperature platform. As a result, the mechanical performances of 3D printed thermoplastic is normally inadequate in comparison with conventionally manufactured ones (e.g., from injection molding). In this work, we developed two strategies for reinforcing and functionalizing 3D printed thermoplastic composites using cellulose nanofibers (CNFs) as nanofillers. Firstly, L-lactide monomers were grafted onto CNFs via ring-opening polymerization. The synthesized poly(lactic …

The Effects Of Biochar And Nitrogen Stabilizers Application On Forage Crop Growth, Greenhouse Gas Emission And Soil Quality, Joseph Elias Rodrigues Mikhael

LSU Doctoral Dissertations

ABSTRACT

Forage systems are important for animal production. Nitrogen fertilization and herbicides use has led to a significant increase in forage production. Therefore, this study aimed to investigate the effects of biochar and N-(n-butyl) thiophosphoric triamide + dicyandiamide (NBPT+DCD) application on manure and urea fertilized soil by focusing on nitrogen fertilizer efficiency use, greenhouse gases emissions, microbial community, soil aggregate stability, and organic carbon functional groups. In addition, herbicides effect on greenhouse gases emission was assessed. Biochar and NBPT+DCD increased nitrogen use efficiency of both fertilizers managements and reduced the N₂O emissions following manure fertilization. However, NBPT+DCD was …

Effect Of Increasing Levels Of Monosilicic Acid On Arsenic And Phosphorus Sorption In Soil, Flávia Bastos Agostinho

LSU Doctoral Dissertations

Arsenic (As) accumulation in rice (Oryza sativa) grains has increased human’s daily intake. Studies have shown that arsenite is taken up through known silicon (Si) transporters in rice. Moreover, the availability of As in soil is affected by chemically similar ligands that have high affinity to oxides surfaces, such as Si and phosphorus (P). Studies were conducted to: (I) investigate the role of elevated levels of Si on the concentration of different As fractions in soil and on As uptake by rice; (II) evaluate the effect of increasing monosilicic acidconcentrations on As sorption and kinetics in soil; and …

An Investigation Of Environmentally Persistent Free Radical (Epfr) Formation In Contaminated Soils Using Surrogate-Based Model Systems, Ugwumsinachi Godwin Nwosu

LSU Doctoral Dissertations

Environmentally persistent free radicals (EPFRs) have recently attracted attention due to their properties that detrimental to the health of living organisms. Earlier studies devoted to the formation of combustion generated particulate matter (PM) showed that EPFRs formed as a result of the association of aromatic chlorinated hydrocarbons with transition metal centers. Based on our previous studies, the amounts of EPFRs formed at Superfund soil sites contaminated with pentachlorophenol (PCP) are ~30 times higher compared to those formed at the neighboring uncontaminated soil sites, showing that EPFR formation is not confined to combustion generated particle. In order to design viable remediation …

Application Of Biomass Derived Materials In Nanocomposites And Drilling Fluids, Kunlin Song

LSU Doctoral Dissertations

Tar is inevitably produced from biomass thermochemical processes, and is often disposed as an industrial waste, leading to environmental pollution. As a result of its high carbon content, tar was expected to be a promising precursor for manufacturing carbon materials. Consequently, low-cost porous carbon nanofibers (CNFs) using tar, polyacrylonitrile (PAN), and silver nanoparticles was fabricated through electrospinning and subsequent stabilization and carbonization processes. The continuous electrospun nanofibers were obtained with diameters ranging from 392 to 903 nm. The addition of biomass tar resulted in increased fiber diameters, reduced thermal stabilities, and slowed cyclization reactions of PAN in the as-spun nanofibers. …

Fabrication And Evaluation Of Specialty Nonwoven Materials, Nan Jiang

LSU Doctoral Dissertations

The present work is to develop multifunctional materials with high performance on chemical absorption, adsorption and on acoustic absorption and insulation using natural fiber nonwovens via carbonization and activation. Evaluation of these textile materials includes tensile strength, thermogravimetric analysis, sound absorption and transmission loss, scanning electronic microscopy and surface properties. Carbonization of cotton nonwoven was carried out in a high temperature oven with nitrogen between 300 °C and 500 °C. The physical activation was undertaken using CO2. The N2 adsorpton isotherm curves of the cotton nonwoven showed the presence of micropores and macropores. High BET surface area and average pore …