Physical Sciences and Mathematics Commons^™

Impacts Of U.S. Biofuels Mandates On Environmental And Energy Security, Mohammad Alshawaf

Graduate Doctoral Dissertations

Congress passed the Energy Policy Act of 2005 and the Energy Independence and Security Act (EISA) of 2007 to reduce dependency on foreign oil by increasing the use of biofuels. EISA mandates 36 billion gallons of biofuel production in 2022, representing an increase of 118% in eight years. Existing and new farmland are expected to be employed to produce corn and other feedstock necessary to fulfill the biofuel mandate. There is little research on the potential environmental impact on water resources of meeting the ESIA biofuel mandates.

The objectives of this EISA study were twofold. First, the study measured the …

Formation Of Polycyclic Aromatic Hydrocarbons And Nitrogen Containing Polcyclic Aromatic Compounds In Titan's Atmosphere, The Interstellar Medium And Combustion, Alexander Landera

FIU Electronic Theses and Dissertations

Several different mechanisms leading to the formation of (substituted) naphthalene and azanaphthalenes were examined using theoretical quantum chemical calculations. As a result, a series of novel synthetic routes to Polycyclic Aromatic Hydrocarbons (PAHs) and Nitrogen Containing Polycyclic Aromatic Compounds (N-PACs) have been proposed. On Earth, these aromatic compounds originate from incomplete combustion and are released into our environment, where they are known to be major pollutants, often with carcinogenic properties. In the atmosphere of a Saturn’s moon Titan, these PAH and N-PACs are believed to play a critical role in organic haze formation, as well as acting as chemical precursors …

Measuring The Angle-Dependent Photoionization Cross Section Of Nitrogen Using High-Harmonic Generation, Xiaoming Ren, Varun Makhija, Anh-Thu Le, Jan Troß, Sudipta Mondal, Cheng Jin, Vinod Kumarappan, Carlos A. Trallero-Herrero

Physics Faculty Research & Creative Works

We exploit the relationship between high harmonic generation (HHG) and the molecular photorecombination dipole to extract the molecular-frame differential photoionization cross section (PICS) in the extreme ultraviolet (XUV) for molecular nitrogen. A shape resonance and a Cooper-type minimum are reflected in the pump-probe time delay measurements of different harmonic orders, where high-order rotational revivals are observed in N₂. We observe the energy- and angle-dependent Cooper minimum and shape resonance directly in the laboratory-frame HHG yield by achieving a high degree of alignment, [SEE FORMULA IN ABSTRACT cos2 θ] 0.8. The interplay between PICS and rotational revivals is confirmed by simulations …

The Impact Of Nitrogen Contamination And River Modification On A Mississippi River Floodplain Lake, Indu Karthic, Richard B. Brugam Ph.D., William A. Retzlaff, Kevin Johnson

SIUE Faculty Research, Scholarship, and Creative Activity

Anthropogenic nitrogen contamination has increased in ecosystems around the world (frequently termed the “nitrogen cascade”). Coke production for steel manufacturing is often overlooked as a source of nitrogen to natural ecosystems. We examined sediment cores from a Horseshoe Lake, a floodplain lake located just East of St. Louis Missouri (USA) to test whether a coking plant effluent could be traced using stable isotopes of nitrogen and diatom microfossils. The distribution of δ¹⁵N values in surface sediment samples from the lake shows the highest values near the coking plant effluent. Analysis stable isotopes of nitrogen from sediment cores using …

Decomposition And Nutrient Release Of Different Cover Crops In Organic Farm Systems, Jianru Shi

School of Natural Resources: Dissertations, Theses, and Student Research

Cover crops act as green manure adding organic matter to agricultural-soils. For legume green manures to be an effective nitrogen (N) source for organic farming systems, their N release must be in synchrony with crop N demand. The objectives of this study were 1) determine the decomposition rates of three common cover crops (white clover, (Trifolium repens,L ) red clover (Trifolium pratense L.) and soybean (Glycine max L) in order to determine when most N was released and its synchrony with subsequent corn crop uptake; 2) we focused on the effect of cover crops on soil …

Atmospheric Pressure He-Air Plasma Jet: Breakdown Process And Propagation Phenomenon, Asma Begum, Mounir Laroussi, Mohammad Rasel Pervez

Electrical & Computer Engineering Faculty Publications

In this paper He-discharge (plasma jet/bullet) in atmospheric pressure air and its progression phenomenon has been studied experimentally using ICCD camera, optical emission spectroscopy (OES) and calibrated dielectric probe measurements. The repetitive nanosecond pulse has applied to a plasma pencil to generate discharge in the helium gas channel. The discharge propagation speed was measured from the ICCD images. The axial electric field distribution in the plasma jet is inferred from the optical emission spectroscopic data and from the probe measurement. The correlation between the jet velocities, jet length with the pulse duration is established. It shows that the plasma jet …

An Approach For Dealing With Statuses Of Non-Statistically Significant Interactions Between Treatments, Zakaria M. Sawan

Journal of Modern Applied Statistical Methods

A field experiment on cotton yield resulted in a non-statistically significant interaction. An approach for follow-up examination between treatments based on least significant difference values was suggested to identify the effect regardless of insignificance. It was found that the classical formula used in calculating the significance of interactions suffers a possible shortage that can be eliminated by applying a suggested revision.

Uncoupling Between Dinitrogen Fixation And Primary Productivity In The Eastern Mediterranean Sea, Eyal Rahav, Barak Herut, Noga Stambler, Edo Bar-Zeev, Margaret R. Mulholland

OES Faculty Publications

In the nitrogen (N)-impoverished photic zones of many oceanic regions, prokaryotic organisms fixing atmospheric dinitrogen (N₂; diazotrophs) supply an essential source of new nitrogen and fuel primary production. We measured dinitrogen fixation and primary productivity (PP) during the thermally stratified summer period in different water regimes of the oligotrophic eastern Mediterranean Sea, including the Cyprus Eddy and the Rhodes Gyre. Low N₂ fixation rates were measured (0.8-3.2μmol N m-2 d-1) excluding 10-fold higher rates in the Rhodes Gyre and Cyprus Eddy (~20μmol N m^-2 d^-1). The corresponding PP increased from east to west (200-2500μmol …

Biogenic Nitrogen Gas Production At The Oxic–Anoxic Interface In The Cariaco Basin, Venezuela, E. Montes, M. A. Altabet, F. E. Muller-Karger, M. I. Scranton, R. C. Thunell, Claudia R. Benitez-Nelson, L. Lorenzoni, Y. M. Astor

Faculty Publications

Excess nitrogen gas (N2xs) was measured in samples collected at six locations in the eastern and western sub-basins of the Cariaco Basin, Venezuela, in September 2008 (non-upwelling conditions) and March 2009 (upwelling conditions). During both sampling periods, N2xs concentrations were below detection in surface waters, increasing to ~ 22 μmol N kg−1 at the oxic–anoxic interface ([O2] < ~ 4 μmol kg−1, ~ 250 m). Below the oxic–anoxic interface (300–400 m), the average concentration of N2xs was 24.7 ± 1.9 μmol N kg−1 in September 2008 and 27.5 ± 2.0 μmol N kg−1 in March 2009, i.e., N2xs concentrations within this depth interval were ~ 3 μmol N kg−1 higher (p < 0.001) during the upwelling season compared to the non-upwelling period. These results suggest that N-loss in the Cariaco Basin may vary seasonally in response to changes in the flux of sinking particulate organic matter. We attribute the increase in N2xs concentrations, or N-loss, observed during upwelling to: (1) higher availability of fixed nitrogen derived from suspended and sinking particles at the oxic–anoxic interface and/or (2) enhanced ventilation at the oxic–anoxic interface during upwelling.

Spatial And Temporal Patterns In Ungulate-Ecosystem Interactions, Bryan D. Murray

Dissertations, Master's Theses and Master's Reports - Open

Ungulates are important components of a variety of ecosystems worldwide. This dissertation integrates aspects of ungulate and forest ecology to increase our understanding of how they work together in ways that are of interest to natural resource managers, educators, and those who are simply curious about nature. Although animal ecology and ecosystem ecology are often studied separately, one of the general goals of this dissertation is to examine how they interact across spatial and temporal scales. Forest ecosystems are heterogeneous across a range of scales. Spatial and temporal habitat use patterns of forest ungulates tend to be congregated in patches …

Using Stable Isotope Analysis Of Zooplankton To Document Trophic And Biogeochemical Changes In The San Francisco Estuary, Steven C. Westbrook, Julien Moderan

STAR Program Research Presentations

Zooplankton represent a vital link between phytoplankton and fish, like the endangered Delta Smelt. Human interferences (nitrates from waste water, flow alteration, invasive species introduction…) have altered the structure of the San Francisco Estuary (SFE) ecosystem. We use stable isotope analysis to improve our knowledge of the planktonic food web in the SFE and gain insights into its evolution over the past decades. We use the ratios of certain isotopes (Nitrogen, Carbon, Sulfur, etc.) in different species of zooplankton to tell us what it is feeding on as well as the trophic level it feeds in. My research focused on …

Nitrogen Removal From Natural Gas Using Solid Boron: A First-Principles Computational Study, Qiao Sun, Meng Wang, Zhen Li, Ping Li, Weihua Wang, Xiaojun Tan, Aijun Du

Australian Institute for Innovative Materials - Papers

Selective separation of nitrogen (N2) from methane (CH4) is highly significant in natural gas purification, and it is very challenging to achieve this because of their nearly identical size (the molecular diameters of N2 and CH4 are 3.64 Å and 3.80 Å, respectively). Here we theoretically study the adsorption of N2 and CH4 on B12 cluster and solid boron surfaces a-B12 and c-B28. Our results show that these electron-deficiency boron materials have higher selectivity in adsorbing and capturing N2 than CH4, which provides very useful information for experimentally exploiting boron materials for natural gas purification.

Short-Term Denitrification In The Metalimnion Of A Eutrophic Reservoir, Aki Kogo, Erin M. Grantz, Thad Scott

Discovery, The Student Journal of Dale Bumpers College of Agricultural, Food and Life Sciences

Denitrification in metalimnetic water was examined under different conditions to determine how addition of nitrate (NO3 -) and particulate carbon (PC), aeration, and concentrations of nitrate affect denitrification. In the first experiment, water samples from a metalimnion were treated with different combinations of NO3 - and PC. Changes in excess N2 -N concentration for 10 days were measured using membrane inlet mass spectrometry (MIMS). The second experiment used the same treatments as the first experiment after aeration of water. Besides excess N2 -N concentrations, O2 concentrations were measured for 16 days. The third experiment examined how different initial concentrations of …

A Multi-Scale Investigation Of Nutrient Dynamics In The Lake Pontchartrain Estuary And Basin, Eric Daniel Roy

LSU Doctoral Dissertations

Humans are responsible for global-scale alteration of nitrogen (N) and phosphorus (P) biogeochemical cycles to support food production. Increases in N and P inputs into soils and waste-streams has resulted in excessive nutrient loading to surface waters, including the Mississippi River, leading to eutrophication. Here I investigated N and P dynamics occurring in the Lake Pontchartrain Estuary and Basin. I measured two biogeochemical processes using intact sediment core incubations and quantified their importance in the context of nutrient-rich Mississippi River flood diversions through the Bonnet Carré Spillway. I show that diffusion of nitrate-N into sediments accounts for a substantial magnitude …

Decade-Scale Nutrient Enrichment Effects On Wetland Plant Community Structure, Function, And Stability, Sean A. Graham

LSU Doctoral Dissertations

Human activities have increased the supply of nitrogen (N) and phosphorus (P) to coastal waters worldwide, threatening coastal wetlands with excess nutrient loading and subsequent eutrophication. In this dissertation, I present results from two decade-scale fertilization experiments in a Sagittaria lancifolia dominated oligohaline marsh that examined the species-, community-, and ecosystem-level effects of nutrient enrichment. My objectives were to determine (1) which nutrient limits primary production, (2) how increased supply of the limiting nutrient affects plant community structure and function, both above- and belowground, and (3) whether nutrient over-enrichment compromises ecosystem stability. Overall, significant changes in plant growth occurred with …