B.B. Mamba

M.Sc. / Water that is free from toxic organic pollutants is essential to human health and the environment at large. Organic contaminants may affect the endocrine system of animals and humans, even when present in very low concentrations (i.e. levels ppb). Current technologies fail to remove these organic compounds efficiently from water at ppb levels. So, the development of new technologies that are capable of removing and degrading organic pollutants from water is crucial. Hence, recently in our laboratories cyclodextrin (CD) polymers have demonstrated that they are capable of removing organic pollutants from water at ppb levels. The research has also demonstrated that both functionalized and unfunctionalized CD polymers can remove organic species to as low as parts per billion (ppb) from water. In this project, Si and Ti based compounds which have been reported to degrade organic compounds through photocatalysis in an aqueous media were incorporated. Firstly, attempts were made to attach the silicon (Si) and titanium (Ti) pendent chains onto the CD moiety to form silicon-based cyclodextrin (Si-CD) and titanium based cyclodextrin (Ti-CD) precursors. The Si-CD precursor was synthesized by attaching the 3-(triethoxysilyl)propyl isocyanate onto the native b-CD moiety. The synthesis of the Si-CD precursor was successful and high yields (80%) of the product were obtained. A hydrolysis of this Si-CD precursor in an inert atmosphere led to the formation of silanol. This was followed by curing the silanol in air, after adding TiO2 nanoparticles, and the Ti-CD precursor was formed. The polymerization of Si-CD with suitable bifunctional linkers was a success and water-insoluble polymers were produced. An attempt to polymerize the Ti-CD precursor failed, because the precursor was decomposed. The Si-CD polymers were tested for their capabilities to encapsulate and destroy organic pollutants from water. 1H NMR, FT-IR and EDX spectroscopic techniques were used to prove the formation of the Si-CD and Ti-CD precursors and their corresponding polymers. The Si-CD polymers showed capabilities of being able to remove organic pollutants (33-55%) from water. Unfortunately, the removal is slightly less efficient than the corresponding native CD polymers. However, their efficiency in removing organic pollutants improved when exposed to light. Moreover, the polymers formed display good thermal stabilities, since they decompose at about 300- 400°C. This is observed from the thermograms obtain ed from DSC and TGA. Their morphological studies showed that most of the Si-CD polymers formed were crystalline. This was observed from the SEM images obtained. Based on the information provided by the FT-IR spectroscopy, the synthesis of the Ti-CD precursor was success. However, the challenge was the fact that it decomposed after a while. Hence, it was difficult polymerize it into a water insoluble polymer. The explanation of this phenomenon is not yet established.

No description available.

"[L]a pollution de l'air [fait] peser une menace importante sur le plan sanitaire partout dans le monde." L'OMS estime ainsi que, pour l'année 2012 (OMS, 2014), plus de 3,7 millions de décès prématurés dans le monde seraient imputables à la seule pollution de l'air, dont près de 70% surviendraient en ville. Pourtant la connaissance du dépôt sec, particulièrement en milieu urbain, reste très parcellaire. L'object de ce travail de thèse vise à améliorer la compréhension des mécanismes de dépôts atmosphériques en milieu urbain. Historiquement, les dépôts atmosphériques ont été étudiés et modélisés sur des couverts végétaux, plan d'eau ou surface nue, et ce afin d'évaluer, notamment, l'impact sur les écosystèmes des dépôts acides, ou encore de l'eutrophisation. Or, le milieu urbain est caractérisé par une géométrie complexe, et des surfaces variées. Par conséquent, ces modèles de dépôts atmosphériques peuvent ne pas convenir pour simuler les flux de dépôts dans les zones urbaines.Le modèle développé dans cette thèse est un modèle à longueur de mélange. Ces travaux se sont attelés à prendre en compte les principaux processus qui prennent place au sein de la canopée urbaine en modifiant la longueur de mélange et en la rendant dépendante des caractéristiques morphologiques de la ville. Aussi, le profil des vitesses de vent moyen est directement impactée par ce changement de longueur de mélange. Par conséquent, ce nouveau modèle offre la possibilitéde calculer les dépôts secs en milieu urbain en fonction de quelques paramètres représentant les principales caractéristiques de la canopée urbaine (hauteur moyenne des bâtiments, largeur moyenne des rues, densité du bâti) / Pas de résumés

In recent years, there has been growing concern about the effect of environmental pollutants on the immune system. In the current study, we investigated the toxicity induced by certain environmental pollutants on the immune systems of fish, amphibians, and mice. Fish in the laboratory were tested for susceptibility to immunosuppression by treatment with 1,3-Bis (chloroethyl)-1-nitrosourea (BCNU). Immunotoxicity of the tilapian immune system was detectable using mitogen-induced proliferation assay and cell-mediated toxicity assay. Fish from various streams of the Roanoke River were tested for immunotoxicity and parasitic infection. Fish from the more polluted North Fork of the Roanoke River exhibited a stronger mitogenic response when compared to fish from the South Fork of the Roanoke River. The effect of perinatal exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), commonly referred to as dioxin, a highly toxic environmental pollutant, was tested in C57BL/6 mice. TCDD was administered on gestational day 14 and pup thymocytes were studied for apoptosis on postnatal days 2, 4, 7, 14, and 21. Perinatal exposure to TCDD decreased thymic cellularity and induced apoptosis in the thymocytes of the pups. Amphibians from polluted areas of Bermuda were similarly tested for immunotoxicity and compared with amphibians from less polluted areas. The lymphocyte responsiveness of toads from the more polluted Bermuda Biological Station of Research (BBSR) to mitogens such as lipopolysaccarhide (LPS) was significantly less than in toads from less polluted areas of Bermuda. Histological studies revealed differences in the liver and spleen tissues of the two groups. Melanomacrophage centers were prevalent in the livers of amphibians from the more polluted BBSR when compared to the less polluted Zoo site. These data taken together encompass a broad study on the effect of environmental pollutants across species. In each study, immunotoxicity is the end result of contact with contamination, whether occurring in the environment or induced in the laboratory. These data suggest that the immune system may serve as a biomarker for pollutants present in the environment. / Master of Science

No description available.

No description available.

To assess the impacts of non-point source pollution on Ontarios wetlands I examined the landuse in the watershed, the water and sediment quality, and the aquatic vegetation in 22 wetlands. I characterized the primary contaminants that enter marshes in Ontario and relate their concentrations to the relative amounts and types of land use in their watershed. I measured levels of nutrients, suspended particulates and trace organics in water and sediment. Species richness and structural diversity of the vegetative community was used as an indicator of wetland health. I included a comparison of two techniques, immunoassays and gas-chromatography (GC) to measure trace organics (PAHs and metolachlor; Chapter 1). Comparison of results from both techniques indicated that immunoassays overestimated analyte concentration by approximately a third. I utilized the immunoassay results, along with selected water quality variables, to characterize contaminants entering these wetlands (Chapter 2). Watersheds containing greater than 95% agriculture contributed the highest suspended particulate, compared with those dominated by urban or forested land. Using multivariate statistics I identified important water and sediment variables that structured these wetlands to be: total phosphorus (TP), ammonia nitrogen (TAN), suspended solids (TSS), specific conductance (COND), sediment phosphorus CTPsed) and inorganic material (lnorgsed) in the sediment. Of these TP, COND and Inorgsed were negatively related to the submergent plant community, while TPsed was positively related. There was no relationship between water quality and the floating or emergent plants but the structural diversity of the plant community was negatively affected by poor water quality. The negative impact of developed land in the watershed on the health of the aquatic plant communities underscores the need to maintain natural areas to trap nutrients and sediments in runoff. / Thesis / Master of Science (MS)

No description available.

Sixteen small scale Subsurface vegetated beds (SVB) were installed down slope of the residence at the Whitethorne Planation (WP) site. Treatments included three detention times (2.6, 3.9, and 5.9 days), two recirculation ratios (0 and 0.5), and two plant species [woolgrass (<i>Scirpus cyperinus</i>) and cattail (<i>Typha latifolia</i>)]. Twelve larger scale SVBs were constructed at the Powell River Project (PRP) site, Wise County, VA. Treatment consisted of three detention times (4, 8, 12 days) with the same plant species (cattail and woolgrass). At the WP site, pollutant removal incresed with detention time for 5-day biochemical oxygen demand (BOD₅), total Kjeldahl nitrogen (TKN), ammonium (NH₄-N), phosphates (PO₄³⁻-P), redox potential (Eh), and total dissolved solids (IDS). The pollutant removal rates, based on 23 data sets, were: BOD₅ (54-70%); NH₄⁺-N (30-61%); TKN (33-52%); PO₄³⁻-P (7-28%); fecal coliforms (FC) (>99%) and coliphages (>95%). Recirculation appeared to have no apparent benefit. There were no differences in P, S and secondary and trace metals concentrations in the SVBs planted to cattail and woolgrass. Plants could remove 2 -10% of the total N applied and 13-57% of the total P applied to the SVBs if harvested once a year during the growing season. At the PRP site, differences were observed among the detention times for BOD₅, TKN, NH₄-N, PO₄-P, TDS, pH, EC and Eh. The pollutant removal percentages were: FC (>99%); BOD₅ (30-75%); NH₄-N (27-88%); TKN (27-81%); PO₄³⁻-P (24-46%); and TDS (12-73%). Samples collected from shallow wastewater column exhibited a higher level of treatment. There were no differences in FC, BOD₅, TKN and NH₄⁺-N concentrations between s VB s planted to cattail and woolgrass, and there were no differences in tissue N content between cattail and woolgrass at both sites. The average NH₃ volatilization rate was 236 mg N/m²/day, and accounted for 7-37% of total N applied to the SVBs. Average measured denitrification rates ranged from 3.87 to 6.69 mg N₂O /m²/ h, and accounted for 2-17% of total N applied. / Ph. D.