Increased nitrogen deposition has been shown to promote the dominance of invasive species, and nitrogen deposition rates have steadily increased in most of the Western United States in recent years due to population increases. The purpose of this study was to determine if increased rates of nitrogen deposition are contributing to the success of Hedera helix in the Pacific Northwest. Plots were established in Lesser Park in Portland, Oregon and received monthly treatments of ammonium nitrate for one year. Growth, measured as change in percent cover, was compared between treated and untreated plots for both H. helix and native species. Additionally, a greenhouse experiment was employed wherein H. helix was grown in shared pots with two native species, Fragaria vesca and Polystichum munitum, and three treatment levels were compared; none, low, and high nitrogen. Relative growth rate was compared between treatments for each species after twelve weeks of treatment. Results from the greenhouse experiment were highly variable and no general conclusions could be drawn about the effects of increased nitrogen deposition on competition between H. helix and native species. In the field, treatment did not have a significant effect on growth but species did have a significant effect, as H. helix had a greater increase in percent cover than native species regardless of treatment. However, a marginally significant interaction was found between species and treatment. Native species cover actually increased in plots that received nitrogen addition and decreased in control plots, while H. helix had a slightly higher increase in cover in control plots. Though the growth of H. helix was significantly higher than the growth of native species in control plots, nitrogen addition caused the growth rates to converge towards more similar means in treated plots. Results indicate that increased nitrogen deposition may actually have a positive effect on the growth of native species by reducing the invasive potential of H. helix.

Ce travail de thèse porte sur la synthèse de nouveaux composés chiraux à partir de l’isosorbide et de l’isomannide en vue de leurs applications en catalyse asymétrique. Dans une première partie, de nouvelles monophosphines ont été synthétisées et appliquées en tant que ligands dans la réaction d'hydrogénation asymétrique d’oléfines. Des excès énantiomériques jusqu’à 96% ont été observés. Elles ont également été employées en tant que catalyseurs organiques dans les réactions de cyclisation [3 +2]. De bonnes activités catalytiques et des excès énantiomériques modestes sont obtenus. Dans une deuxième partie, une série de composés azotés chiraux a été synthétisée en 3 à 4 étapes avec de bons rendements globaux. Ils ont été testés en tant que ligands dans la réaction de réduction de cétones aromatiques par transfert d’hydrogène. Des excès énantiomériques jusqu’à 73% ont été obtenus. La réaction d’addition de phénylacétylène sur d’imines a également été étudiée. Les complexes formés se sont montrés actifs mais pas très énantiosélectifs. Ces composés azotés ont également été utilisés en tant que catalyseurs organiques dans la réaction d’addition de Michael de cétones aromatiques sur le nitrostyrène. Toutefois, ils n’ont permis de conduire qu’à de faibles énantiosélectivités. Dans une dernière partie, des composés de type thiourée ont été synthétisés en 5 étapes. Ces thiourées ont été appliquées en catalyse organique dans la réaction d’alkylation de type Friedel-Crafts entre différents substrats indoliques et nitrooléfines, et dans la réaction d’addition conjuguée des hydroxylamines sur des pyrazoles pour la synthèse de dérivés β-aminoacides. Ces catalyseurs se sont révélés actifs mais peu énantiosélectifs. / The Thesis deals with the synthesis of new chiral compounds derived from isosorbide and isomannide and their applications to asymmetric catalysis. The first part of this work consisted in perfecting the chemical and enantioselective hydrogenation conditions of olefins using chiral monophosphines as ligands (up to 96% ee). These phosphines were also used as organocatalysts for [3+2] cyclisation reactions showing good catalytic activity and moderate enantioselectivity. The second part turned to the synthesis of a series of chiral nitrogen compounds which were evaluated in the asymmetric transfer hydrogenation of aromatic ketones giving good enantioselectivity (up to 73% ee). The complexes formed with amine ligands were also applied to the addition reaction of phenylacetylene to imines. Good catalytic activity but low enantioselectivity were observed. These nitrogen compounds were also used as organocatalysts in the Michael addition reaction of aromatic ketones to the nitrostyrene. Again, low enantiomeric excess was obtained. The last part of this work consisted in preparing new chiral thiourea compounds which were applied as organocatalysts to the Friedel-Crafts alkylation reaction of different indoles with nitroolefines, and to the conjugate addition reaction of hydroxylamines to pyrazoles derivatives for the synthesis of β-amino acids. In two cases, these catalysts have proved active but not enantioselective.

From the Proceedings of the 1971 Meetings of the Arizona Section - American Water Resources Assn. and the Hydrology Section - Arizona Academy of Science - April 22-23, 1971, Tempe, Arizona / The nitrogen balance of a watershed near the city of New Prague, Minnesota was evaluated as part of an overall study on lake and stream eutrophication. Although the n-balance of a humid Midwest watershed cannot be expected to be identical to that of an arid watershed, the processes are the same and differences should be mainly quantitive. Sources of input and causes of depletion are reviewed for 4 points in the nitrogen cycle: the atmospheric zone, the soil-atmosphere interface, the plant-root and soil-water zone and the surface water zone. In the New Prague watershed, commercial fertilizer and bulk precipitation were the major sources of input, contributing, respectively, 53% and 34.4% of the total input of 2.34 million lb/yr. Crop yield and soil or groundwater storage contributed 52.1% and 20.4% of non-enrichment depletions. The closeness of the values of crop yield and commercial fertilizer application was an unfortunate coincidence and is certainly not an indication that the entire fertilizer supply was taken up cry crops. In an arid environment, free from fertilized agriculture, bulk precipitation probably provides the major source of nitrogen compounds.

From the Proceedings of the 1974 Meetings of the Arizona Section - American Water Resources Assn. and the Hydrology Section - Arizona Academy of Science - April 19-20, 1974, Flagstaff, Arizona / This study attempts to determine the water quality changes in stock tanks and what factors are instrumental in the changes, and to assess the effects of the changes. Algal growth was the most prominent change taking place in the tanks with time. Little change in the water chemistry was noted until just before the tanks dried up. As algae died, ions tied up by the algae were released to the water, causing an increase in concentration of many of the nutrients. In order to determine the impact of various factors on algal growth, the data from eight stock tanks were analyzed by stepwise linear regression. Although 20 variables were used in the complete analysis, six variables were associated with 56.3 percent of the variance: time (since first sampling), total n, potassium, pH, inflow (recharge to the tanks), and hco3 concentration. Time and total n explained 51.3 percent of the variance, and potassium increased the variance to 52.8 percent. The pH reversed the relative positions of time and total n, with total n becoming dominant. The last two factors, inflow and hco3 were negative (resulting in a decrease in algal population) and increased the coefficient of variance to 56.3 percent.

Freshwater ecosystems are subject to a wide variety of stressors, which can have complex interactions and result in ecological surprises. Non-native fish introductions have drastically reduced the number of naturally fishless lakes and have resulted in cascading food web repercussions in aquatic and terrestrial habitats. Additional anthropogenic influences that result from increases in global airborne emissions also threaten wildlife habitat. Atmospheric nitrogen deposition has been recognized as an anthropogenic contributor to acidification and eutrophication of wilderness ecosystems. Planktonic communities have shown declines in response to predation and shifts in composition as a result of nutrient inputs and acidification, both of which are potential fates of nitrogen deposition. This study identified the response of zooplankton communities from two lakes (fish present vs. absent) in Mount Rainier National Park to manipulations simulating an episodic disturbance event in mesocosms. The experiment used a 2 x 2 factorial design with acid and nitrogen treatments. Treatments resulted in significantly elevated nitrogen and decreased pH conditions from control mesocosms over 42 days, indicating that the treatment effects were achieved. Results indicate that zooplankton communities from lakes with different food web structure respond differently to the singular effects of acid and nitrogen addition. Surprisingly, the interaction of the two stressors was related to increases in community metrics (e.g., abundance, biomass, body size, richness, and Shannon-Weiner diversity) for both lake types. This work can aid management decisions as agencies look to restore more aquatic montane habitats to their historic fishless states, and assess their abilities to recover and afford resistance to atmospheric pollution.