Graduate Theses & Dissertations


This thesis focuses on the design of a modelling framework consisting of loose-coupling of a sequence of spatial and process models and procedures necessary to predict future flood events for the years 2030 and 2050 in Tabasco Mexico. Temperature and precipitation data from the Hadley Centers Coupled Model (HadCM3), for those future years were downscaled using the Statistical Downscaling Model (SDSM4.2.9). These data were then used along with a variety of digital spatial data and models (current land use, soil characteristics, surface elevation and rivers) to parameterize the Soil Water Assessment Tool (SWAT) model and predict flows. Flow data were then input into the Hydrological Engineering Centers-River Analysis System (HEC-RAS) model. This model mapped the areas that are expected to be flooded based on the predicted flow values. Results from this modelling sequence generate images of flood extents, which are then ported to an online tool (ADAPT) for display. The results of this thesis indicate that with current prediction of climate change the city of Villahermosa, Tabasco, Mexico, and the surrounding area will experience a substantial amount of flooding. Therefore there is a need for adaptation planning to begin immediately. Author Keywords: Adaptation Planning, Climate Change, Extreme Weather Events, Flood Planning, Simulation Modelling
Acidification of lakes in northern Saskatchewan
The emission of acid precursors by large point sources in Western Canada (such as the Athabasca Oil Sands Region) has prompted studies into the possible impact to downwind aquatic and terrestrial ecosystems. Sensitivity of catchments to acidic deposition was estimated for the total lake population of northern Saskatchewan (n=89,947) using regression kriging. Under the Steady State Water Chemistry model, a range of 12-15% of the total catchment population was predicted to be in exceedance of critical loads under 2006 deposition levels and 6% of catchments were estimated to be very sensitive (pH below 6 and acid neutralizing capacity, alkalinity, calcium below 50 eqL-1). Temporal changes in soil and water chemistry estimated for 18 Alberta and Saskatchewan catchments using the Very Simple Dynamic and PROFILE models showed that changes in soil base saturation and lake acid neutralizing capacity between 1850 and 2100 were slight, declining 0.8% and 0.9% by 2012, respectively. Author Keywords: acidification, critical loads, exceedance, PROFILE, regression kriging, VSD
Aeolian Impact Ripples in Sand Beds of Varied Texture
A wind tunnel study was conducted to investigate aeolian impact ripples in sand beds of varied texture from coarsely skewed to bimodal. Experimental data is lacking for aeolian megaripples, particularly in considering the influence of wind speed on ripple morphometrics. Additionally, the modelling community requires experimental data for model validation and calibration. Eighteen combinations of wind speed and proportion of coarse mode particles by mass were analysed for both morphometrics and optical indices of spatial segregation. Wind tunnel conditions emulated those found at aeolian megaripple field sites, specifically a unimodal wind regime and particle transport mode segregation. Remote sensing style image classification was applied to investigate the spatial segregation of the two differently coloured size populations. Ripple morphometrics show strong dependency on wind speed. Conversely, morphometric indices are inversely correlated to the proportion of the distribution that was comprised of coarse mode particles. Spatial segregation is highly correlated to wind speed in a positive manner and negatively correlated to the proportion of the distribution that was comprised of coarse mode particles. Results reveal that the degree of spatial segregation within an impact ripple bedform can be higher than previously reported in the literature. Author Keywords: Aeolian, Impact Ripples, Megaripple, Self-organization, Wind Tunnel
An Evaluation of Wastewater Treatment by Ozonation for Reductions in Micropollutant Toxicity to Fish
Micropollutants are discharged into the aquatic environment with industrial and domestic wastewater and these compounds may cause toxic effects in aquatic organisms. In this study, the toxic effects to fish of micropollutants extracted from ozonated and nonozonated municipal wastewater effluent (MWWE) were measured in order to assess the effectiveness of ozonation in reducing toxicity. Juvenile rainbow trout (Oncorhynchus mykiss) injected with extracts prepared from ozonated MWWE had significantly reduced induction of plasma vitellogenin (VTG), significantly reduced hepatic total glutathione (tGSH) levels and an elevated oxidized-to-total glutathione (GSSG-to-tGSH) ratio. Exposure of Japanese medaka (Oryzias latipes) embryos to extracts prepared from both ozonated and non-ozonated MWWE resulted in elevated developmental toxicity in both treatment groups. These results indicate that wastewater treatment by ozonation reduces the estrogenicity of wastewater, but treatment may induce oxidative stress and embryonic developmental toxicity due to the production of toxic by-products. Author Keywords: Estrogenicity, Micropollutants, Oxidative stress, Ozonation, Toxic by-products, Wastewater
Assessing Brook Trout (Salvelinus fontinalis) Seasonal Occupancy in Haliburton County, ON Using Environmental DNA
Brook trout (Salvelinus fontinalis) are declining across Ontario in both numbers and distribution, prompting concern for their future. Here, conventional, emerging, and predictive tools were combined to document brook trout occupation across seasons using streams in Haliburton County, ON as model systems. By using the Ontario Ministry of Natural Resources and Forestry’s (OMNRFs) Aquatic Ecosystem Classification (AEC) system variables with environmental DNA (eDNA) sampling and backpack electrofishing, my research supports the development of species occupancy models (SOMs) and eDNA as tools to document brook trout occurrence. To do this, eDNA sampling was validated in Canadian Shield stream environments by comparison with single-pass backpack electrofishing before seasonally sampling two river systems across their main channel and tributaries to assess occupancy. Streams were classified as potential high, moderate, and low-quality brook trout habitats using indicator variables within the AEC and sampled seasonally with eDNA to quantify occupancy and relate it to habitat potential at the county scale. Results showed eDNA to be an effective tool for monitoring fish across Canadian Shield landscapes and that brook trout occupancy varied seasonally within and across watersheds, suggesting that habitat and fish management strategies need to consider seasonal movement and spatial connectivity. Using these tools will enable biologists to efficiently predict and document brook trout occurrences and habitat use across the landscape. Author Keywords: Aquatic Ecosystem Classification, brook trout, Canadian Shield, connectivity, environmental DNA, seasonal occupation
Assessing basin storage
Water storage is a fundamental component of drainage basins, controlling the synchronization between precipitation input and streamflow output. The ability of a drainage basin to store water and regulate streamflow may mediate sensitivity to climate and land cover change. There is currently no agreement on the best way to quantify basin storage. This study compares results of a combined hydrometric and isotopic approach for characterizing inter-basin differences in storage across the Oak Ridges Moraine (ORM) in southern Ontario. The ratio of the standard deviation of the stable isotope signature of streamflow relative to that of precipitation has been shown to be inversely proportional to mean water transit times, with smaller ratios indicating longer water transit times and implying greater storage. Stable isotope standard deviation ratios were inversely related to baseflow index values. Basins demonstrating longer transit times were associated with hydrological characteristics that promote infiltration and recharge of storage. Author Keywords: baseflow, basin storage, climate change, mean transit time, Oak Ridges Moraine, stable isotopes
Assessing limnological characteristics of subarctic Québec thaw ponds and mercury methylation and methylmercury demethylation within their sediments
Thawing permafrost due to increasingly warm temperatures in northern subarctic regions is releasing mercury. The consequent formation of thaw ponds in the peatland palsa valley of the Sasapimakwananisikw (SAS) river in Whapmagoostui-Kuujjuarapik, Québec may provide a pool for MMHg formation and a potential risk to aquatic and human life, if these ponds facilitate MMHg export through hydrological connections to nearby waterways. Hg methylation and MMHg demethylation activities were examined in thaw pond sediments using a Hg tracer isotope incubation experiment. Analysis by coupling gas chromatography cold-vapor atomic fluorescence spectrophotometry (GC-CVAFS) with inductively coupled mass spectrometry (ICP-MS) techniques showed that MMHg was produced at a higher rate and within the first 2 h of incubation for both summer and winter seasons. For thaw ponds SAS1A, SAS1B and SAS2A, MMHg was formed at 0.0048 % h-1, 0.0012 % h-1, and 0.0008 % h-1, respectively during winter and at 0.0001 % h-1, 0.0016 % h-1, and 0.0010 % h-1, respectively during summer. Detection of MMHg losses were not as expected likely due to limitations of the combined tracer spike and overestimation of the in situ ambient mercury levels. Physical and chemical properties vary within ponds, among ponds and between winter and summer. SAS1B’s location nearby an organic carbon rich palsa may be ideal to study DOC – Hg interactions. Variability in pond characteristics including depth, surface area, age, pH, temperature, colour, oxygen concentration, total dissolved and suspended solids, conductivity, carbon, mercury, ammonium, calcium, magnesium, sulfate, total phosphorous, potassium, and sodium between seasons indicate the challenge of predicting future environmental impacts of climate change related thaw pond creation in the north. Author Keywords: demethylation, mercury, methylation, methylmercury, SAS, thaw ponds
Assessing the Potential of Permaculture as an Adaptation Strategy Towards Climate Change in Central Ontario
This thesis uses three approaches to assess the potential of permaculture in Central Ontario. This was done using a vegetable field trial and modelling programs to determine the effectiveness of permaculture to decrease negative impacts of climate change based on projected climate values derived from regional circulation models. The first approach showed no statistical difference (P<0.05) of applying varied volumes and combinations of organic amendments on crop yields. The second approach indicated permaculture may be a sustainable production system with respect to soil erosion when compared to traditional agricultural practices. The third approach was inconclusive due to the lack of quantitative literature on permaculture management impacts on biomass yields, soil carbon or nutrient retention, which were missing from basic and scientific literature searches. The models used within this thesis include USLE, RUSLE2, AgriSuite, RothC and Holos. Author Keywords: Agriculture, Climate Change, Computer Modelling, Permaculture, Soil Erosion and Assessment
Augmented Reality Sandbox (Aeolian Box)
The AeolianBox is an educational and presentation tool extended in this thesis to represent the atmospheric boundary layer (ABL) flow over a deformable surface in the sandbox. It is a hybrid hardware cum mathematical model which helps users to visually, interactively and spatially fathom the natural laws governing ABL airflow. The AeolianBox uses a Kinect V1 camera and a short focal length projector to capture the Digital Elevation Model (DEM) of the topography within the sandbox. The captured DEM is used to generate a Computational Fluid Dynamics (CFD) model and project the ABL flow back onto the surface topography within the sandbox. AeolianBox is designed to be used in a classroom setting. This requires a low time cost for the ABL flow simulation to keep the students engaged in the classroom. Thus, the process of DEM capture and CFD modelling were investigated to lower the time cost while maintaining key features of the ABL flow structure. A mesh-time sensitivity analysis was also conducted to investigate the tradeoff between the number of cells inside the mesh and time cost for both meshing process and CFD modelling. This allows the user to make an informed decision regarding the level of detail desired in the ABL flow structure by changing the number of cells in the mesh. There are infinite possible surface topographies which can be created by molding sand inside the sandbox. Therefore, in addition to keeping the time cost low while maintaining key features of the ABL flow structure, the meshing process and CFD modelling are required to be robust to variety of different surface topographies. To achieve these research objectives, in this thesis, parametrization is done for meshing process and CFD modelling. The accuracy of the CFD model for ABL flow used in the AeolianBox was qualitatively validated with airflow profiles captured in the Trent Environmental Wind Tunnel (TEWT) at Trent University using the Laser Doppler Anemometer (LDA). Three simple geometries namely a hemisphere, cube and a ridge were selected since they are well studied in academia. The CFD model was scaled to the dimensions of the grid where the airflow was captured in TEWT. The boundary conditions were also kept the same as the model used in the AeolianBox. The ABL flow is simulated by using software like OpenFoam and Paraview to build and visualize a CFD model. The AeolianBox is interactive and capable of detecting hands using the Kinect camera which allows a user to interact and change the topography of the sandbox in real time. The AeolianBox’s software built for this thesis uses only opensource tools and is accessible to anyone with an existing hardware model of its predecessors. Author Keywords: Augmented Reality, Computational Fluid Dynamics, Kinect Projector Calibration, OpenFoam, Paraview
Biology and Management of Stratiotes Aloides in the Trent River, Ontario
Invasive aquatic plants can create negative ecological, economic and social impacts when they displace local vegetation, interfere with shipping and navigation and inhibit water-based recreational activities. In 2008, the first North American occurrence of the invasive plant Stratiotes aloides (Water soldier) was identified in the Trent River, Ontario. This research measured offset photosynthesis and turion germination to determine the light compensation point (5.2-5.4m) and maximum depth of colonization (4-6m) for S. aloides propagules using in situ incubations and controlled growth experiments. The effects of spring and fall chemical (Diquat) and physical (hand raking) treatments on S. aloides biomass, local macrophyte recovery and community dynamics in the Trent River were also measured. The target of a 75% minimum reduction in S. aloides biomass was not attained using any of the treatment methods and no perceivable recovery of the local plant community was observed. Significant S. aloides regrowth was recorded for both treatment methods regardless of application timing. Author Keywords: herbicide, invasive species, macrophyte, photosynthesis, propagule
Bioremoval of copper and nickel on living and non-living Eugelna gracilis
This study assesses the ability of a unicellular protist, Euglena gracilis, to remove Cu and Ni from solution in mono- and bi-metallic systems. Living Euglena cells and non-living Euglena biomass were examined for their capacity to sorb metal ions. Adsorption isotherms were used in batch systems to describe the kinetic and equilibrium characteristics of metal removal. In living systems results indicate that the sorption reaction occurs quickly (<30 min) in both Cu (II) and Ni (II) mono-metallic systems and adsorption follows a pseudo-second order kinetics model for both metals. Sorption capacity and intensity was greater for Cu than Ni (p < 0.05) and were described by the Freundlich model. In bi-metallic systems sorption of both metals appears equivalent. In non-living systems sorption occurred quickly (10-30 min) and both Cu and Ni equilibrium uptake increased with a concurrent increase of initial metal concentrations. The pseudo-first-order model was applied to the kinetic data and the Langmuir and Freundlich models effectively described single-metal systems. The biosorption capacity of Cu (II) and) was 3x times greater than that of Ni (II). Sorption of one metal in the presence of relatively high concentrations of the other metal was supressed. Generally, it was found that living Euglena remove Cu and Ni more efficiently than non-living Euglena biomass in both mono- and bi-metallic systems. It is anticipated that this work should contribute to the identification of baseline uptake parameters and capacities for Cu and Ni by Euglena as well as to the increasing amount of research investigating sustainable bioremediation. Author Keywords: accumulation, biosorption, Cu, Euglena gracilis, kinetics, Ni
Biosynthesis and impact of cytokinins on growth of the oyster mushroom, Pleurotus ostreatus
The oyster mushroom, Pleurotus ostreatus, is one of the most widely cultivated edible basidiomycetes. It has gained increased attention for its economic, environmental, and medicinal properties. While a lot is known about cytokinins (CKs) and their actions at the molecular and cellular levels in plants, much less is known about the function of CKs in other kingdoms. Cytokinins, which have been detected in several fungal species, play a role in pathogenic attack against plants or during plant growth promotion by plant beneficial microbes; however, the role of CKs in fungal physiology, separate from plant associations remains largely unknown. This thesis focuses on the occurrence of fungal-derived CKs in P. ostreatus when grown in vitro as submerged or aerial mycelium. Cytokinin profiling by UHPLC-HRMS/MS revealed that P. ostreatus produces CKs and that the tRNA degradation pathway is the main source of these molecules. CK dynamics within fungal growth supported previous evidence, which suggested that tRNA degradation products have a role in the physiological development of fungi for which CKs act as fungal growth regulators. A second component of the thesis demonstrated that P. ostreatus responds to exogenous applications of aromatic and isoprenoid CKs and their effects were dependent on the dose and CK type. N6-Benzyladenine (BAP), Kinetin (KIN), N6-isopentenyladenine (iP), and trans-zeatin (tZ) bioassays revealed hormone-type responses (hormesis: biphasic response). At low doses, mycelium growth could be stimulated, whereas, at high doses only inhibitory effects were observed. This stimulation/inhibition was observed whether the measured response was an increase/decrease of aerial mycelium colony diameter, biomass accumulation or a change in mycelium morphology as compared to the controls. Results indicated there is potential to alter mycelium growth and development of P. ostreatus; thus, CKs may play the role of a “mycohormone” and may be specifically helpful for medicinal fungi by increasing growth and efficiency to produce many biologically active substances with valuable medical and environmental applications. Author Keywords: cytokinins, fungal-derived CKs, hormesis, mycelium, mycohormone, Pleurotus ostreatus


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