Graduate Theses & Dissertations

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Doing it Right
The cyanidation technique is currently a viable technique for gold recovery that can replace the present amalgamation technique in Guyana. To implement this technique effectively, laboratory scale experiments and at scale runs were conducted to determine the best particle size of the ore, cyanide concentration, and leaching time. In addition, the profitability of cyanidation was compared to the amalgamation technique so as to describe the economic value of cyanidation. Results indicated that up to 94% of gold can be recovered from the ore using an ore particle size of 150 (105 µm), meshes, a cyanide concentration of 0.05% and leaching for 24 h. An economic comparison of this technique with the amalgamation technique indicated that although initial costs are high for the cyanidation technique, profits as high as 83% can be achieved after initializing this method whereas profits would be capped at approximately 25% for the amalgamation technique. Keywords: gold recovery, cyanidation, mercury amalgamation, activated car Author Keywords: activated carbon, cyanidation, gold recovery, mercury amalgamation
ECTOPARASITIC INFLUENCES OF DIPTERA ON THE ACTIVITY AND BEHAVIOUR OF WOODLAND CARIBOU (RANGIFER TARANDUS) IN A MANAGED BOREAL FOREST LANDSCAPE IN NORTHERN ONTARIO
Caribou experience direct and indirect negative effects of harassment from biting flies, influencing behavior and activity on several spatial and temporal scales. I used systematic insect collection surveys during the summers of 2011 and 2012 to examine the spatial and temporal distributions of black flies (Simuliidae), mosquitoes (Culicidae), and deer flies and horse flies (Tabanidae) in a managed boreal forest in northern Ontario. Mosquitoes had a positive association with densely treed habitats, whereas black flies more often occurred in open areas, and tabanids had a strong presence in all habitat types. Habitats in proximity to large bodies of water had fewer biting flies than inland areas. Young stands supported higher abundances of tabanids despite vegetation community type. Next, I tested for seasonal effects of biting fly abundance on caribou activity by modelling the seasonal trend in abundance for each fly family for each year and compared this to an index of daily activity for 20 radio-collared female caribou in 2011 and 10 females in 2012. I modeled this index of caribou activity for each animal in each year and extracted the set of partial correlation coefficients from multiple regressions to test for effects of biting fly abundances on caribou activity. Caribou reduced their daily activity when tabanids were more numerous, and increased activity when mosquitoes were numerous. This divergent response may reflect a difference in the efficacy of moving to reduce harassment, owing to the stronger flight capabilities of tabanids. Author Keywords: Activity, Anthropogenic Disturbance, Behaviour, Insect harassment, Temporal distribution, Woodland Caribou
EVALUATION OF HAYFIELD MANAGEMENT STRATEGIES AND BOBOLINK TERRITORIAL HABITAT IN SOUTHERN ONTARIO
I implemented three hayfield management regimens in southern Ontario (a typical schedule at the farmer`s discretion, a delayed first harvest after July 14, and an early first harvest before June 1 with 65 days before second harvest), and evaluated the costs/benefits to farmers regarding hay quality and feasibility, and to Bobolinks (Dolichonyx oryzivorus) regarding reproductive activity and phenology. Typical management resulted in little to no Bobolink reproductive success, and early harvested sites were not (re)colonized. On delayed harvest sites Bobolinks experienced high reproductive success, but hay quality fell below ideal protein levels for most cattle before harvest. I also examined the habitat features Bobolinks use as the basis for establishing territories and associations between Bobolink territory size and habitat quality. I compared vegetation structure, patch size, and prey abundance between small and large territories. Small territories typically occurred on smaller fields with more preferred vegetation characteristics and greater prey abundance. Author Keywords: agro-ecosystem, Bobolink, Dolichonyx oryzivorus, grassland birds, hayfield management
EXPLORING THE EFFECTS OF WATERPOWER OPERATIONS ON RIVERINE ECOSYSTEMS ACROSS NORTHERN ONTARIO
In this study, we attempt to enhance current knowledge of ecological responses to riverine alterations from waterpower by using a bottom-up food up approach. A series of extensive and intensive study components were performed across northern Ontario, Canada, where biological (nutrients, dissolved organic matter (DOM) and periphyton) and physical (water level and thermal regimes) ecological indicators were examined in regards to alterations from dams and waterpower facilities. Overall, we found that the water levels and thermal regimes deviated from their reference condition at sites below the dams, whereas the biological indicators were more resilient to river alterations. Our results suggest that the characteristics of the watershed were influential in controlling the variability of nutrients and DOM resources in rivers within the boreal watersheds of northern Ontario, as well as the for the downstream recovery patterns of the physical indicators. The recovery of the periphyton communities downstream of the dams were also predicted to be cumulatively related to the physical alterations, nutrient availability and the possible displacement of invertebrate communities. Therefore, our bottom-up food web approach was not effective for better understanding how ecological responses from waterpower cascade through aquatic food webs, and instead multiple indicators should be used for examining the ecological responses in these particular river systems. Author Keywords: dissolved organic matter, ecological indicators, river alteration, waterpower facilities
Early Responses of Understory Vegetation to Above Canopy Nitrogen Additions in a Jack Pine Stand in Northern Alberta
Abstract Early Responses of Understory Vegetation After One Year of Above Canopy Nitrogen Additions in a Jack Pine Stand in Northern Alberta Nicole Melong Nitrogen (N) emissions are expected to increase in western Canada due to oil and gas extraction operations. An increase in N exposure could potentially impact the surrounding boreal forest, which has adapted and thrived under traditionally low N deposition. The majority of N addition studies on forest ecosystems apply N to the forest floor and often exclude the important interaction of the tree canopy. This research consisted of aerial NH4NO3 spray applications (5, 10, 15, 20, 25 kg N ha-1yr-1) by helicopter to a jack pine (Pinus banksiana Lamb.) stand in the Athabasca Oil Sands Region (AOSR) in northern Alberta, Canada. The main objective was to assess the impacts of elevated N after one year of treatment on the chemistry of understory vegetation, which included vascular plants, terricolous lichens, epiphytic lichens and a terricolous moss species. Changes in vegetation chemistry are expected to be early signs of stress and possible N saturation. Increased N availability is also thought to decrease plant secondary compound production because of a tradeoff that exists between growth and plant defense compounds when resources become available. Approximately 60% of applied N reached the ground vegetation in throughfall (TF) and stemflow (SF). Nitrate was the dominant form of N in TF in all treated plots and organic N (ON) was the dominant form of N in SF in all plots. The terricolous non-vascular species were the only understory vegetation that responded to the N treatments as N concentration increased with increased treatment. Foliar chemistry of the measured epiphytic lichens, vascular species, and jack pine was unaffected by the N treatments. Based on biomass measurements and N concentration increases, the non-vascular terricolous species appear to be assimilating the majority of TF N after one year. Vegetation from the high treatment plot (25 kg N ha-1yr-1) was compared to a jack pine forest receiving ambient high levels of N (21 kg N ha-1yr-1) due to its proximity to Syncrude mining activities. Nitrogen concentrations in plant tissues did not differ between the two sites; however, other elements and compounds differed significantly (Ca, Mg, Al, Fe). After one year of experimental N application, there were no environmental impacts consistent with the original N saturation hypothesis. Author Keywords: Athabasca Oil Sands Region, Canopy Interactions, Jack Pine, Nitrogen, Secondary Chemistry, Understory Vegetation
Effect of Attending a Virtual Oncology Camp on Childhood Cancer Patient's Pyshcosocial Functioning and Parental Stress - A Pilot Study
Objectives/purpose: The current study examined whether attending a 1-month virtual oncology camp (VOC) improved resilience and hope in childhood cancer patients and parental/caregiver stress. Methods:Childhood cancer patients/survivors and their parent/caregivers enrolled for VOC, participated in an online anonymous survey: before, after and 3-months after VOC. The survey included the Child and Youth Resilience Measure (CYRM) and the Snyder’s Children’s Hope Scale (CHS) for the childhood cancer patients/survivors and the Pediatric Inventory for Parents (PIP) for parent/caregivers. Results:CYRM scores increased from T1 to T2 (d=0.86). Compared to T1, at T2 CHS scores also increased (d=1.33). Both CHS and CYRM scores remained higher at T3 compared with T1 (d=1.34; d=0.86). There were no changes in PIP scores between any time points. Conclusion and significance: Our study demonstrated that participation in a VOC improved children’s resilience and hope but did not change parental stress. Highlighting the clinical significance of these VOCs and the impacts they have on childhood cancer patients/survivors. Author Keywords: cancer, children, hope, parental stress, resilience, virtual oncology camp
Effect of Carbon Source and Phytohormones on the in vitro Growth of Euglena Gracilis
Microalgae are a promising source of valuable compounds relevant to biofuels, biomaterials, nutraceuticals as well as animal and human nutriment. Unfortunately, low cell density and slow growth result in reduced economic feasibility. Heterotrophic cell culturing using an organic carbon source in lieu of light has proven to be an effective alternative to photobioreactors; however, further improvement may be possible with the addition of growth promoting phytohormones. In this thesis, growth and endogenous hormone profiles in heterotrophic cultures of Euglena gracilis were evaluated using glucose and ethanol as carbon sources. Cytokinin (CK) and abscisic acid (ABA) were quantified by HPLC-ESI-MS/MS and compared to culture growth dynamics. Exogenous phytohormones treatments were also conducted to determine if they may mitigate nutrient reduction and improve growth. Phytohormones CK and ABA were purified and analyzed at seven points along the growth curve in small scale (250 mL flasks, 100 mL working volume) cultures. Among the key findings was that ethanol cultures undergoing exponential growth, primarily synthesize freebase cytokinins (FBCKs) and methylthiol-cytokinins (MeSCKs), while not producing detectable levels of ABA. In exogenous studies, dry biomass was positively influenced with the addition of exogenous ABA; however, the most notable result revealed the ability of transZ to alleviate nutrient reduction. These findings suggest a communication network in algal culture using FBCKs and MeSCKs, as well as the potential for exogenous hormone supplementation to increase growth rates and overall biomass productivity. Author Keywords: abscisic acid, cytokinin, Euglena gracilis, heterotrophy, phytohormones
Effect of SP600125 JNK Inhibitor on Cadmium-Treated Mouse Embryo Forelimb Bud Cells In Vitro
This study investigated the role of the JNK signaling pathway in cadmium-treated mouse embryo forelimb bud cells in vitro. Primary cultures of forelimb bud cells harvested at day 11 of gestation were pre-treated with JNK inhibitor SP600125, and incubated with or without CdCl2 for 15, 30, 60, 120 minutes and 24, 48 hours or 5 days. Endpoints of toxicity were measured through cell differentiation by Alcian Blue Assay and phosphorylation of JNK proteins by Western blot. The results demonstrated that, in the cell differentiation assay, inhibiting JNK activation by 20 μM SP600125 causes an enhanced toxic effect in limb cells and inhibits cell differentiation, whereas 2 μM decreases differentiated nodule numbers under both cadmium stress and normal conditions. In conclusion, the JNK pathway has an essential role in the differentiation processes of limb bud cells in normal growth conditions. Author Keywords: Cadmium, Cell Signaling, JNK, Limbs, Mouse Embryo, Teratology
Effect of Water Surface Simulated Rain Drop Impacts on Water to Air Chemical Transfers of Perfluorinated Carboxylic Acids (PFCAs)
Perfluorinated carboxylic acids (PFCAs) are anthropogenic environmentally ubiquitous surfactants that tend to concentrate on water surfaces. This investigation looked at the effect of simulated rain on the atmospheric concentration of a suite of PFCAs (C2 - C12) above the bulk water system. Increased air concentrations of all PFCAs were detected during simulated rain events. Long chain PFCAs (>C8) were found to be much more concentrated in the air above the bulk water system than their short chain counter parts (
Effect of the neonicotinoid imidacloprid on embryogenesis and anuran survivorship in frog virus 3 infected tadpoles
Exposure of pre-metamorphic amphibians to neonicotinoid insecticides may be contributing to the global decline in amphibian populations. In this study, anuran embryos and tadpoles of the African clawed frog (Xenopus laevis) and the North American leopard frog (Lithobates pipiens) were used to determine the effects of embryonic exposure to neonicotinoids. In addition, Xenopus was used to determine if prolonged exposure to neonicotinoids influenced tadpole sensitivity to frog virus 3 (FV3). Exposure of anuran embryos to concentrations of the neonicotinoid insecticide, imidacloprid, ranging from 1 -20 ppm induced a concentration dependent increase in malformations of the retina in Xenopus embryos. However, similar responses were not observed with embryos of leopard frogs. Exposure of Xenopus tadpoles to 500 ppb concentration of imidacloprid followed by challenge with FV3 showed that pesticide exposure unexpectedly decreased the rates of mortality, although total mortalities by the end of the experiment were not significantly different from controls. This unexpected observation may be attributed to a reduced inflammatory response induced by exposure to imidacloprid. Despite the low acute toxicity of neonicotinoid insecticides to vertebrates, these studies indicate that exposure to this class of insecticides causes sublethal effects in anuran species during early life stages. Author Keywords: embryogenesis, Lithobates pipiens, neonicotinoid, ranavirus, tadpole, Xenopus laevis
Effects of Agricultural Land Use Change on Nitrogen and Phosphorus in North Shore Lake Ontario Tributaries
Row crop agriculture and associated land use practices including tile drainage and conservation tillage have been cited as a probable cause of re-emerging eutrophication in the lower Great Lakes. In this thesis, I sought to quantify and evaluate the effect of agricultural land cover and land use changes on total phosphorus (TP) and nitrate-nitrogen (NO3-N) concentrations and export in north shore Lake Ontario tributaries. This included (a) a long-term data analyses at 12 large watersheds (47 to 278 km²) using historical land cover and water quality data (1971-2010), and (b) a space-for-time study examining 12 small sub-catchments (< 8 km²) with majority (> 50%) row crop, pasture, or forest cover. Concentrations of TP were greatest in urbanized watersheds and declined particularly during the first decades of the study period, while NO3-N concentrations were greatest and steadily increased in agricultural catchments with increasing row crop cover. The space-for-time approach revealed that TP concentrations were similar across agricultural land uses and that export was most dependent on runoff. Meanwhile, NO3-N concentrations and export were greatest in row crop catchments and were positively related to row crop area. These results suggest that increases in row crop cover and associated agricultural practices including increased nutrient amendments and tile drainage may be responsible for increased NO3-N concentrations and export in northern Lake Ontario tributaries. Author Keywords: agriculture, Lake Ontario, nitrogen, phosphorus, streams, Water quality
Effects of Geographic Factors on the Wild Harvest of Large Mammals across North America
While the harvest of mammals is monitored in each jurisdiction across Canada and the USA, there has been no analysis of this wild harvest at a continental scale across North America. The recreational wild harvest of large mammals varies geographically across North America, and I hypothesized that this variation is influenced by both anthropogenic and other environmental factors on the landscape. I tested this hypothesis using annual harvest tallies collected by Conservation Visions Inc. for mammals for each state, provincial, and territorial jurisdiction in Canada and the USA. I built multiple additive models of the harvest, in one harvest year, 2015 – 2016, to test for landscape gradients that explain the variation in harvest levels for seven large mammal species: white-tailed deer (Odocoileus virginianus), black bear (Ursus americanus), bighorn sheep (Ovis canadensis), elk (Cervus canadensis), mule deer (Odocoileus hemionus), pronghorn (Antilocapra americana), and moose (Alces alces). I built these models from a suite of nine putative predictor variables that comprised landcover, human footprint, and evapotranspiration. For all large mammal species except for pronghorn, anthropogenic influence had a positive effect on the wild harvest density, consistent with the idea that the proximity of human populations and roads are important for fostering wild harvest activity by providing hunters access to hunting areas. The harvest of white-tailed deer, elk, and pronghorn were negatively affected by vegetation structure, urbanization, and primary productivity, respectively. Understanding the recreational wild harvest at a broad-spatial scale provides a unique perspective of the North American model of wildlife conservation and spurs future comparative analyses of the wild harvest across spatial scales. Author Keywords: Anthropogenic Influence, Hunting, Large Mammals, Primary Productivity, Vegetation Structure, Wild Harvest

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