<p>Nitrate is one of the most common groundwater contaminants, with levels commonly exceeding established drinking water limits. In areas of high agricultural or industrial nitrate use, nitrate contaminated groundwater poses a potential health risk. In situ denitrification is the microbially mediated reduction of nitrate to innocuous nitrogen gas compounds and is the principal process for nitrate removal in contaminated aquifers. This process is becoming increasingly recognized for its ability to reduce or eliminate nitrate concentrations in groundwater with minimal site disturbance and cost. Predicting the extent to which denitrification occurs in aquifers as well as the rate, therefore, has become the focus of numerous mathematical models. However, the predictive capabilities of numerical models are constrained because knowledge of the biological processes implicated in denitrification is limited.</p> <p>This report examines the microbial processes involved in <i>in situ</i> denitrification, and then applies this knowledge to assess the capability of a two-dimensional numerical model, NBI02D. NBI02D is a variation of a code, SEAM2D, developed by Widdowson (1988,1992).</p> <p>Model development and model application are presented. The model development overview provides insight to the mathematical methods used to simulate the microbial processes. The model application compares model predictions with data received from a USGS research site on Cape Cod, Massachusetts. Data are derived from a natural gradient experiment in which formate was injected into a carbon-limited aquifer in order to stimulate and accelerate denitrification. NBI02D simulations for the Cape Cod site are developed for model verification and model applicability.</p> / Master of Science

Atmospheric deposition of reactive nitrogen (N) from anthropogenic sources to forested systems may have acute and long-term deleterious impacts on tree species and water quality. Understanding how nitrate (NO3-) moves through the soil system and if it has the potential to be retarded from vertical or lateral leaching allows for a better understanding of the processes important for NO3- movement and export from forested watersheds. We examined four watersheds at Coweeta Hydrologic Laboratory (CHL) and determined that soil NO3- sorption is a mechanism for abiotic NO3- retention. NO3- sorption was best described with an S-shaped, sigmoidal model for B horizons that suggests that NO3- sorption to soil colloidal surfaces has a higher affinity for soil solution at low equilibrium concentrations. Parameter a, the sorption maximum, was most strongly correlated to ammonium oxalate extractable Al (Alo) and Mn (Mno), suggesting that amorphous Al and Mn oxides may be the primary source of positively charged sorption sites. Parameter b, the width of the sigmoid curve slope, was best predicted by %C in the soil; suggesting that C compounds may bind to and reduce the availability of positively charged exchange sites for NO3- sorption. Previously harvested watersheds exhibited larger variability in parameter values Xo, the inflection point of the curve, and b. High elevation watersheds had higher median values for Alo, Mno and the ration of oxalate to dithionite extractable Fe (Feo/Fed), suggesting that the soils at higher elevations are at earlier stages of pedogenic development and have more poorly crystalline Fe and Al oxides. The greatest potential for sorption maybe at an intermediate soil depth between where there is a significant decrease in biologically cycled C, phosphate and sulfate yet there is enough mineral weathering to provide the mineralogical structures that can support positively charged surfaces. / Master of Science

Molybdenum compounds present a series of baffling chemical puzzles. By no means are all of these yet even clearly defined and many may never be. This complexity results from the ability of molybdenum to form six different oxidation states, which can possess three different coordination numbers. Furthermore, molybdenum compounds readily disproportionate to yield mixed valence compounds; and finally, molybdate ions readily aggregate in solution to form a variety of polyions by polymerization-condensation reactions which are controlled by pH and the concentration of the system. Molybdenum' s complexity can best be summed up in the words of the late Edgar Smith who described molybdenum to his classes as “ambidextrous, bi-sexual and polygamous.”

Indiana University-Purdue University Indianapolis (IUPUI) / Background: Pulmonary Hypertension (PH) is a devastating disease characterized by pulmonary arterial remodeling, right ventricular dysfunction and ultimately right heart failure. Increased emphasis has been given to skeletal muscle dysfunction in PH, and to its implication in the severe exercise intolerance that is a hallmark of the condition. In this dissertation, skeletal muscle blood flow was measured via the microsphere technique at rest and during exercise (Aim 1), with an acute dose of dietary nitrate via beetroot juice (BRJ) gavage used to determine if supplementation could improve muscle blood flow and alter energetics (Aim 2). VO2max, voluntary running and grip strength tests were used to determine the effect of disease on performance, and to test for an ergogenic effect of BRJ vs. placebo (PL) in healthy and PH rats (Aim 3). Methods: A prospective, randomized, counterbalanced, placebo-controlled trial was used to examine the aforementioned aims across four groups; PH rats (induced with monocrotaline, MCT, 60mg/kg, s.q., 4 weeks) supplemented with BRJ (MCT BRJ, n=9); PH rats supplemented with placebo (MCT PL, n=9); healthy control rats (vehicle, s.q.) supplemented with BRJ (CON BRJ, n=8); healthy control rats supplemented with placebo (CON PL, n=9). Results: Monocrotaline induced a severe PH phenotype evidenced by increased RV wall thickness, RV hypertrophy, RVSP and reduced cardiac output and stroke volume compared to controls (p=<0.001). MCT rats demonstrated lower muscle blood flow at rest, and more prominently during exercise compared to controls (p=0.007-0.047), regardless of supplementation. MCT rats displayed a greater reliance on anaerobic metabolism, demonstrated by increased blood lactate accumulation (p=<0.001), and this was significantly related to reduced blood flow during exercise (r=-0.5879, p=0.001). BRJ supplementation resulted in increased plasma nitrate and nitrite compared to PL (p=<0.001), but at the skeletal muscle level, only nitrate was increased after BRJ. BRJ did not have a significant effect on blood flow, with no improvement during exercise shown vs. PL. Similarly, BRJ did not significantly improve exercise function in MCT or CON rats. Conclusion: MCT rats demonstrated a reduction in muscle blood flow, with BRJ supplementation not resulting in improved flow or exercise performance.

No description available.

The objectives of this study were: 1) To evaluate short-term composting of hardwood bark with combinations of poultry litter and ammonium nitrate and 2) To determine the suitability of composted material for ornamental plant media. In a 3-month accelerated composting study, hardwood bark was amended with (20% & 40%) poultry litter, (1% & 2%) ammonium nitrate, or unamended. Composting was run in fifteen 35- gallon containers and samples were collected at day 0, 45, and 90 for pH, moisture content, carbon-to-nitrogen ratio, compost maturity, toxicity, and green house evaluations. The amendment containing 40% poultry litter showed significantly higher weight reduction than others at days 45 and 90. Also, this treatment showed significantly higher mass weight in transplanted zinnia and gardenia than other treatments and was comparable to commercial media. Overall, results indicated that the amendment of hardwood bark with poultry litter could produce comparable product to currently used commercial container media.

Installation of low-grade weirs in agricultural drainage ditches is being evaluated as an innovative, and cost effective, management practice that decreases nutrient concentrations and loads by increasing water volume and hydraulic residence time of the ditch. Results revealed that weirs significantly increased (P = 0.029) hydraulic residence time (HRT) and ditch water volumes, leading to considerable reductions in outflow water volumes (61%). Furthermore, ditches with weirs achieved greater (P = 0.09) cumulative outflow load reductions (96%) and greater (P = 0.029) concentration reductions during the biogeochemical reduction phase of the experiment. Similarly, field research from Terrace Ditch in Yazoo County, MS yielded significant percentage concentration reductions for baseflow (53%), stormflow (63%), and load (65%). Results from the experimental approach and field scale research offer promising insight into the future of low-grade weir’s establishment as an additional best management practice in agricultural landscapes.

<p> The experiments described in this thesis were performed to investigate the: 1. Role of nitrate in the growth of maize seedling and 2. Role of amino acids in the assimilation of nitrate by the growing embryo.</p> <p> Nitrate stimulated the germination of Zea mays L. seeds by 10 to 15 percent. Further growth of the embryo axis, up to 6 days, however, was not affected by nitrate. During the early growth of the seedling, endosperm nitrogen was able to support the requirements of the embryo for 6 to 8 days. After a lag of 2 days, the protein content of the embryo increased linearly up to 6 days at a rate of 597 μ g a day. Some increase was observed between 6 and 8 days also. After 8 days, the protein level of embryo plateaued. Addition of 10 mM nitrate caused an increase in the protein and total nitrogen of the embryo only after 6 days. The endosperm mutant of maize, opaque-2, also responded to the nitrate in the same way.</p> <p> The protein content of the primary leaves increased linearly between 5 and 7 days. After 7 days, there is no increase in the leaf protein. Nitrate increased the protein level of primary leaves by 25 percent after 7 days. It protected against the further loss of protein in mature leaf. These results suggest that the primary role of nitrate in the growth of maize seedlings is to prevent protein loss.</p> <p> Out of 8 amino acids tested individually, only lysine and to a lesser extent arginine, inhibited the induction of nitrate reductase in the maize root tips. Different ammonium salts had no effect on the induction of nitrate reductase. The initial rate of induction in opaque-2 mutant (high lysine) was lower than the wild type, W64A (low lysine). From a comparison of the rate of induction of nitrate reductase between young and mature leaf, it was suggested that the amino acid supply from the endosperm may inhibit the induction of nitrate reductase. In the young maize seedling, this effect of amino acids may be more effective in vivo and in this way the assimilation of exogenous nitrate could be restricted, when the endosperm amino acids are supporting the growth of the embryo.</p> / Thesis / Master of Science (MSc)

An investigation of the sodium aluminate-sodium nitrate system was conducted. The effect of sodium nitrate on the solubility of aluminum is important to the retrieval of waste from the tanks at the Hanford nuclear facility located in the state of Washington. Experiments were performed on the NaAlO2 - NaNO3 - H2O system at 25?aC and 50?aC. The results obtained from these experiments were then compared to predictions from the Environmental Simulation Program (ESP, OLI Systems, Inc.) and available literature data. The presence of sodium nitrate increased the solubility of sodium aluminate in water. Sodium nitrate exhibited a greater effect on the solubility of sodium aluminate at higher temperature. Error analysis of the experimental data was performed and indicated that the experimental molalities were accurate to within an average of +3%. The measured data will be used to improve existing databases for ESP.

No description available.