Graduate Theses & Dissertations

Pages

Legacy Effects Associated with the World’s Largest Ongoing Liming and Forest Regeneration Program in Sudbury, Ontario, Canada
Soil and tree chemistry were measured across 15 limed sites that were established 14 to 37 years ago within the Sudbury barrens in Ontario, along with two unlimed pre-treatment condition reference sites and an unlimed remnant pine forest. Soil pH and base cation (calcium (Ca), magnesium (Mg), and potassium (K)) concentrations were elevated in surface organic [FH] horizons up to 37-years post limestone treatment. Limestone in the organic horizon was evident by higher Ca/Sr ratios (a good marker of dolomite) in younger sites. Base cation mass budgets were generally unable to account for the mass of added Ca and Mg. Sudbury is characterized by widespread metal contamination. Metal (copper (Cu), nickel (Ni), and lead (Pb)) concentrations were generally greatest within the FH horizon and unrelated to stand age. Copper and Ni concentrations in soil generally decreased with distance from the nearest smelter. Metal partitioning (Kd) in soil was most influenced by soil pH rather than organic matter suggesting that as liming effects fade over time metal availability may increase. Author Keywords: Afforestation, Degraded, Limestone, nutrient, Space-for-time, Sudbury
Sinc-Collocation Difference Methods for Solving the Gross-Pitaevskii Equation
The time-dependent Gross-Pitaevskii Equation, describing the movement of parti- cles in quantum mechanics, may not be solved analytically due to its inherent non- linearity. Hence numerical methods are of importance to approximate the solution. This study develops a discrete scheme in time and space to simulate the solution defined in a finite domain by using the Crank-Nicolson difference method and Sinc Collocation Methods (SCM), respectively. In theory and practice, the time discretiz- ing system decays errors in the second-order of accuracy, and SCMs are decaying errors exponentially. A new SCM with a unique boundary treatment is proposed and compared with the original SCM and other similar numerical techniques in time costs and numerical errors. As a result, the new SCM decays errors faster than the original one. Also, to attain the same accuracy, the new SCM interpolates fewer nodes than the original SCM, which saves computational costs. The new SCM is capable of approximating partial differential equations under different boundary con- ditions, which can be extensively applied in fitting theory. Author Keywords: Crank-Nicolson difference method, Gross-Pitaevskii Equation, Sinc-Collocation methods
Effects of hydrologic seasonality on dissolved organic matter composition, export, and biodegradability in two contrasting streams
Environmental and seasonal processes are important watershed drivers controlling the amount, composition, and fate of dissolved organic matter (DOM) in aquatic ecosystems. We used ten months of water samples and eight months of bioassay incubations from two contrasting catchments (agriculture and natural, forested) to assess the effects of seasonal variability on the composition, export, and biodegradability of DOM. As expected, the DOM composition and exports were more allochthonous-like and autochthonous-like in the forest and agriculture streams, respectively. However, we found no relationship between DOM composition and biodegradability in our study, suggesting that broad environmental factors play a large part in determining bioavailability of DOM. We found that both differences between the catchments and seasonal variability in hydrology and water temperature cause shifts in DOM composition that can affect exports and potentially affect its susceptibility to microbial activity. More research is needed to fully understand the impact of land use and temporal variability on bioavailability and delivery to downstream ecosystems. Author Keywords: Bioavailable dissolved organic carbon, Biodegradability, Dissolved organic matter, Export, Seasonality, Streams
Combinatorial Collisions in Database Matching
Databases containing information such as location points, web searches and fi- nancial transactions are becoming the new normal as technology advances. Conse- quentially, searches and cross-referencing in big data are becoming a common prob- lem as computing and statistical analysis increasingly allow for the contents of such databases to be analyzed and dredged for data. Searches through big data are fre- quently done without a hypothesis formulated before hand, and as these databases grow and become more complex, the room for error also increases. Regardless of how these searches are framed, the data they collect may lead to false convictions. DNA databases may be of particular interest, since DNA is often viewed as significant evi- dence, however, such evidence is sometimes not interpreted in a proper manner in the court room. In this thesis, we present and validate a framework for investigating var- ious collisions within databases using Monte Carlo Simulations, with examples from DNA. We also discuss how DNA evidence may be wrongly portrayed in the court room, and the explanation behind this. We then outline the problem which may occur when numerous types of databases are searched for suspects, and framework to address these problems. Author Keywords: big data analysis, collisions, database searches, DNA databases, monte carlo simulation
“The Darkest Tapestry”
This doctoral research project is a part of the quest for an inclusive telling of Canada’s national identity and will focus on the creation of a memorialization Keeping Place model to commemorate the Indian Residential School system in Canada. My dissertation is interdisciplinary and contributes to the fields of cultural history, memory and post-colonial studies. In response to the TRC recommendation that calls on all Canadians to “develop and implement a national heritage plan and strategy for commemorating residential school sites, the history and legacy of residential schools, and the contributions of Indigenous peoples to Canada’s history”, this project aims to contribute a unique analysis and discourse to the existing literature as it will focus on developing a process of commemoration of the IRS system by uniting the architectural/geographical location not only as a place/space of colonizing “perpetrator architecture” but also as a Keeping Place and “site of memory/lieu de memoire” or conscience. This project will also engage the concepts of “Indigenous Métissage” and “Cultural Interface” to aid in the creation of an educational commemoration and reconciliation Keeping Place model for all Canadians. Author Keywords: canada, indian residential schools, keeping place , memory, saskatchewan, sites of memory
Monitoring and fate of selected tire-derived organic contaminants
Road runoff is a vector for the transport of potentially toxic chemicals into receiving waters. In this study, selected tire-derived chemicals were monitored in surface waters of rivers adjacent to two high traffic highways in the Greater Toronto Area in Ontario, Canada. Composite samples were collected from the Don River and Highland Creek in the GTA during 5 hydrological events that occurred in the period between early October 2019 and late March 2020, as well as an event in August 2020. Grab samples were collected from these rivers during a period of low flow in August 2020, as well as during a storm event in July of 2020. Analysis was performed using ultra-high pressure liquid chromatography with high resolution mass spectrometric detection (UHPLC-HRMS). Hexamethoxymethylmelamine (HMMM), a cross-linker of tire material, was detected at elevated concentrations (> 1 µg/L) during rain events in the fall and winter of 2019-20 and during a period of rapid snow melt in early March of 2020. These samples were also analyzed for the tire additive, 6PPD, and its oxidation by-product, 6PPD-quinone, as well as 1,3-diphenylguanidine (DPG). In many samples collected from the Don River and Highland Creek during storm events, the estimated concentrations of 6PPD-quinone exceeded the reported LC50 of 0.8 µg/L for Coho salmon exposed to this compound. Temporal samples collected at 3-hour intervals throughout rain event the October 2020 showed that there was a delay of several hours after the start of the event before these compounds reached their peak concentrations. In addition, 26 candidate transformation products and precursor compounds of HMMM were monitored; 15 of these compounds were detected in surface waters in the GTA. The maximum total concentration of this class of methoxymethylmelamine compounds in surface water samples was estimated to be 18 µg/L. There is limited knowledge about the properties of HMMM, its precursor contaminants, and its transformation compounds, as well as their fate in the environment. COSMO-RS solvation theory was used to estimate the physico-chemical properties of HMMM and its derivatives. Using the estimated values for these properties (e.g., solubility, vapour pressure, log Kow) as inputs to the Equilibrium Criterion (EQC) fugacity-based multimedia model, the compounds were predicted to readily partition into aqueous media, with mobility in water increasing with the extent of loss of methoxymethyl groups from HMMM. Overall, this study contributes to the growing literature indicating that potentially toxic tire-wear compounds are transported via road runoff into urban surface waters. In addition, this study provides insight into the environmental behaviour of HMMM and its transformation products. Author Keywords: 6PPD-quinone, COSMOtherm, Fugacity, Hexamethoxymethylmelamine, Road runoff, Tire wear
Influence of geodemographic factors on electricity consumption and forecasting models
The residential sector is a major consumer of electricity, and its demand will rise by 65 percent by the end of 2050. The electricity consumption of a household is determined by various factors, e.g. house size, socio-economic status of the family, size of the family, etc. Previous studies have only identified a limited number of socio-economic and dwelling factors. In this thesis, we study the significance of 826 geodemographic factors on electricity consumption for 4917 homes in the City of London. Geodemographic factors cover a wide array of categories e.g. social, economic, dwelling, family structure, health, education, finance, occupation, and transport. Using Spearman correlation, we have identified 354 factors that are strongly correlated with electricity consumption. We also examine the impact of using geodemographic factors in designing forecasting models. In particular, we develop an encoder-decoder LSTM model which shows improved accuracy with geodemographic factors. We believe that our study will help energy companies design better energy management strategies. Author Keywords: Electricity forecasting, Encoder-decoder model, Geodemographic factors, Socio-economic factors
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
Composition and Transformation of Dissolved Organic Matter in Hudson Bay, Canada
The Hudson Bay region is a sensitive environment, where anthropogenic (e.g., dams, diversions, and/or reservoirs) impacts have increased in recent decades, potentially influencing the functioning of the ecosystem. Dissolved organic matter (DOM) entering Hudson Bay comes from both terrestrial (allochthonous) and aquatic (autochthonous) sources. The chemical composition of DOM is important, as it controls carbon biogeochemistry, nutrient cycling, and heat exchange. In rivers, estuaries, and oceans, photochemical processes and microbial degradation play a significant role in the chemical composition of DOM. Yet, our knowledge is scarce into how photochemical and microbial processes effect DOM composition specifically in Arctic aquatic systems making it difficult to predict how the carbon cycle will respond to a changing environment. This Ph.D. thesis addresses: (1) the composition of photochemically altered autochthonous and allochthonous DOM; (2) the photochemical transformations of DOM in surface waters of Hudson Bay; and (3) the microbial transformations of DOM in Hudson Bay surface waters. Using multiple analytical techniques, this work demonstrated that photochemical and microbial effects were different for light absorbing DOM compounds and ionisable DOM analyzed by Fourier transform-ion cyclotron-resonance-mass spectrometry (FT-ICR-MS). Based on FT-ICR-MS analysis, microbial processes had a greater impact on the molecular composition of allochthonous DOM originating from riverine sources and estuary whereas photochemical processes were the dominant mechanism for degradation of autochthonous DOM in Hudson Bay. Photochemical processes significantly decreased colored dissolved organic matter (CDOM) and fluorescence dissolved organic matter (FDOM) loss whereas microbial degradation was minimal in Hudson Bay river, estuary, and coastal waters. The results of this thesis highlight the importance of photochemical and microbial alteration of DOM in Arctic regions, two processes that are expected to be enhanced under climate change conditions. Author Keywords: Carbon cycle, Field flow fractionation, Microbial transformation, Optical properties, Photochemical degradation
Why fish when you could farm? A stable isotope analysis of changing diet and ritual killing in the Virú Valley, Peru
Stable carbon and nitrogen isotope analyses were performed on individuals from the Virú Valley, Peru to better understand the people and society in this region of early-state development. This analysis also sheds light on the lives of individuals from a ritual killing event at Huaca Santa Clara. Bone collagen stable isotope analysis revealed that all individuals had diets predominantly based on terrestrial resources, while incremental hair segments, skin, tendon, and nails revealed that marine resources made small, non-seasonal contributions to the diet. The prioritization of farming over fishing in the Virú Valley may be indicative of the economic specialization of agricultural and marine subsistence practices by distinct communities and the tendency of state-level societies to monopolize agricultural resources. The isotopic compositions of the individuals from the Huaca Santa Clara ritual killing event showed no evidence of a controlled diet before their death and identified a likely migrant to Virú. Author Keywords: Diet, Early Intermediate Period, Early-State Development, North Coast Peru, Ritual Killing Event, Stable Isotope Analysis
Comparison of Nature Activities
Research shows spending time in nature can result in many positive effects, including improving mood, connection to nature, and environmental concern. Certain activities may increase these positive effects of nature exposure. Citizen science (non-scientists collecting data to contribute to science) and environmental education (receiving information about the environment) are two potential ways to boost the positive effects of nature exposure. But little research has been done comparing citizen science with environmental education. To address this gap in knowledge, undergraduate participants were randomly assigned to spend five minutes outside daily, for two weeks, either simply observing nature, looking for birds, or looking for and recording bird sightings. Over time, all groups experienced improvements in mood, connection to nature, and environmental concern. However, connection to nature increased the most in people who simply observed nature. Unexpectedly, simply spending time in nature was the most effective intervention. Limitations and future directions are discussed. Author Keywords: Citizen Science, Emotional Well-Being, Environmental Concern, Environmental Education, Nature Exposure, Nature Relatedness
Untitled (dissertation 4.2)
Untitled (dissertation 4.2) offers a performative take on the political implications of digital archives. I argue that technological developments and their increasing ubiquity has not resulted in more reliable archives; it has facilitated the exacerbation of what Jacques Derrida calls mal d’archive—or archive fever—which refers to the institutionally supported passion to preserve that is perpetually threatened by the inevitably of loss. A performative perspective, specifically derived from the work of contemporary performance theorists and artists, affords a contemporary archival practice that not only accepts, but is informed by mal d’archive because it shifts the focus from what is preserved to how it has become and continues to be preservable through archival acts. This is important in our contemporary moment because the ubiquity of digital technologies has exacerbated the symptoms of mal d’archive: a rapid increase in both the formal and informal production of preservable content, and consequently, as Derrida reminds us, archival violence. Untitled (dissertation 4.2) also includes a performative engagement with mal d’archive through two interludes. The first interlude features what I am calling “glitch-utterances,” which refers to the visual representations of technological mishaps. The documents in the second interlude—an iteration of the exhibition catalogue that resulted from my 2020 artist residency at the Art Gallery of Peterborough—engage with the productive function of the archive because they performatively constitute the exhibition as having happened regardless of whether or not it actually occurred, which, significantly, it did not. I conclude Untitled (dissertation 4.2) with a look at the ecological impact of digital archives—perhaps an “ecological fever.” It is not my intention to offer a solution for this “ecological fever,” nor address its full impact. My aim is to conclude this dissertation with a supplement of sorts: a look at the ecological impact of digital archives because I feel it is irresponsible not to given their increasing ubiquity. With this in mind, the glitch-utterances featured in both interludes can perform an important role in calling attention to the technological materialities and computational processes that are rendered invisible by Big Tech companies via metaphors—the ethereal Cloud metaphor, for example. These glitch-utterances point to the very material substrates that support the virtual, and can thus act as an important reminder of the ecological consequences of digital archives, which, like archival practices, are tied to institutional agendas. Author Keywords: Archive , Curation , Digital Archive, Documentation, Multimedia performance, Performativity

Pages

Search Our Digital Collections

Query

Filter Results

Date

1973 - 2033
(decades)
Specify date range: Show
Format: 2023/09/24