Graduate Theses & Dissertations


Passive sampling of indoor and outdoor atmospheric nitrogen dioxide in the greater Toronto area
The reliability and performance of four passive sampler membrane coatings specific to nitrogen dioxide (NO2) were evaluated through co-exposure at multiple Ontario Ministry of Environment and Climate Change (OMOECC) active monitoring stations. All four coatings performed relatively similar under a wide range of meteorological conditions, notably showing exposure-specific atmospheric uptake rates. Further, indoor and outdoor atmospheric concentrations of NO2 (a marker of traffic-related air pollution) were evaluated at multiple elementary schools in a high-density traffic region of Toronto, Ontario, using a Triethanolamine based passive sampler membrane coating. Samplers were also co-exposed at OMOECC active monitoring stations to facilitate calibration of exposure-specific atmospheric uptake rates. Indoor NO2 atmospheric concentrations were 40 to 50% lower than outdoor concentrations during the spring−summer and autumn−winter periods, respectively. In large cities such as Toronto (Population 2,700,000), the influence of a single major road on outdoor and indoor NO2 concentrations is predominantly masked by spatially-extensive high-density traffic. Author Keywords: active sampler, membrane coating type, nitrogen dioxide, passive sampler, Toronto, traffic density
Detecting anti-estrogens and anti-androgens in surface waters impacted by municipal wastewater discharges and agricultural runoff
This study focused on detecting 22 target anti-estrogenic and anti-androgenic compounds in surface waters influenced by both discharges of municipal wastewater and agricultural runoff in Canada and Argentina. Polar organic chemical integrative samplers (POCIS) were used to monitor the target compounds in surface waters. The removals of the target compounds in a municipal wastewater treatment plant (WWTP) in Canada were also evaluated. In both Canada and Argentina pesticides with potential anti-estrogenic and anti-androgenic activities were detected in the surface waters. The highest concentrations were found in Argentina (up to 1010 ng L-1) in areas impacted by heavy agricultural practices. Cyproterone acetate and bicalutamide were the only two anti-cancer drugs detected only at the Canadian study site, the Speed River, ON. In the Guelph WWTP, that discharges into the Speed River, these target compounds were not all efficiently removed (>70%) during treatment. Overall, this study provides insight to possible anti-estrogenic and anti-androgenic compounds that may be contributing to endocrine disrupting activities in surface waters. Author Keywords: Anti-androgens, Anti-estrogens, Cancer Therapy Drugs, Current use pesticides, Pharmaceuticals and Personal Care Products, Polar Organic Chemical Integrative Samplers
Geochemistry and Toxicity of a Large Slag Pile and its Drainage Complex in Sudbury, Ontario
This study was designed to determine the geochemistry and potential toxicity of water draining a large slag pile in Sudbury, Ontario, which runs through a pond complex prior to entering Alice Lake. Slag leaching experiments confirmed slag is a source of sulphate, heavy metals (including Fe, Al, Ni, Co, Cu, Zn, Pb, Cr, Mn) and base cations (Ca, K, Mg, Na). Concentrations of most metals draining through slag in column experiments were similar to metal concentrations measured at the base of the slag pile, although base cations, S and pH were much higher, possibly because of water inputs interacting with the surrounding basic glaciolacustrine landscape. The increase in pH rapidly precipitates metals leading to high accumulation in the surface sediments. Away from the base of the pile, an increase in vegetation cover leads to an increase in DOC and nutrients and transport of metals with strong binding affinities (Cu). Total metal concentration in water and sediment exceed provincial water quality guidelines, particularly near the slag pile, however WHAM7 modeling indicated that the free metal ion concentration in water is very low. Nevertheless, toxicity experiments showed that water with greater concentrations of solutes collected close to the slag pile negatively impacts D. magna suggesting that water draining the slag pile can adversely impact biota in nearby drainage areas. Author Keywords: geochemistry, heavy metals, leaching, non-ferrous slag, precipitation, toxicity
Executive Function as a Predictor of Emotional, Behavioural, and Social Competence Problems in Children with Epilepsy
The study aimed to examine the association between different components of executive function (EF) and emotional, behavioural, and social competence problems (EBSP) in children with epilepsy. Although there is evidence of an association between EBSP and EF in typically developing children, little research has examined this relation in children with epilepsy. The sample comprised of 42 children with epilepsy, aged 6.0 to 18.1 years old. Results showed that EBSP were associated with EF in these children; however, different components of EF were related to different EBSP. Shifting was a significant predictor of emotional, behavioural, and social competence problems in children with epilepsy, whereas inhibition was a significant predictor of behavioural problems. This suggests that children with epilepsy, with different EF profiles may be at-risk for developing different types of problems. These results may aid researchers and clinicians with the development of new techniques to identify and treat children with EBSP. Author Keywords: behavioural problems, emotional problems, epilepsy, executive function, social competence
Assessing the Potential for Contamination of Lakes from Upwelling of Arsenic-Laden Groundwater Through Sediments
A bedrock fracture hosting arsenic (As) contaminated groundwater was suspected to be transported to Ramsey Lake, a drinking water resource for more than 50,000 residents of Sudbury, Ontario. A high resolution, spatial, water quality mapping technique using an underwater towed vehicle (UTV) was used to identify sources of upwelling groundwater into lake water and localize the upwelling As contaminated groundwater vent site. The top 7 cm of lake sediments (in-situ) at this vent site were observed to adsorb 93 % of the dissolved As, thus inhibiting lake water quality degradation from this contaminant source. Sediment samples from this location were used in laboratory experiments to assess the potential for this system to become a source of As contamination to Ramsey Lake water quality and elucidate As(III) fractionation, transformation and redistribution rates and processes during aging. Arsenic speciation is important because As(III) has been shown to be more toxic than As(V). To accomplish this a sequential extraction procedure (SEP) that maintains As(III) and As(V) speciation in (sub)oxic sediments and soils was validated for the operationally defined fractions: easily exchangeable, strongly sorbed, amorphous Fe oxide bound, crystalline Fe oxide bound, and the residual fraction for total As because the characteristics of the reagents required to extract the final fraction do not maintain As species. Batch reaction experiments using sediment spiked with As(III) or As(V) and aged for up to 32 d were sequentially extracted and analysed for As(III) and As(V). Consecutive reaction models illustrate As(III) is first adsorbed to the sediment then oxidized to As(V). Fractionation analyses show As(III) most rapidly adsorbs to the easily exchangeable fraction where it is oxidized and redistributes to the strongly sorbed and amorphous Fe oxide bound fractions. Oxidation of As(III) adsorbed to the amorphous and crystalline Fe oxide bound fractions is less efficient and possibly inhibited. Select samples amended with goethite provide evidence supporting Mn(II) oxidation is catalyzed by the goethite surface, thus increasing As(III) oxidation by Mn(III/IV) complexed with the strongly sorbed fraction. Although As immobilization through groundwater sediment interactions may be inhibited by increased ion activity, particularly phosphate or lake eutrophication, this threat in Ramsey Lake is likely low. Author Keywords: arsenic, fractionation, modelling, redistribution, speciation, water quality mapping
Carbon Exchange along a Natural Gradient of Deciduous Shrub Coverage in the Low-Arctic
Arctic terrestrial ecosystems have experienced substantial structural and compositional changes in response to warming climate in recent decades, especially the expansion of shrub species in Arctic tundra. Climatic and vegetation changes could feedback to the global climate by changing the carbon balance of Arctic tundra. The objective of this thesis was to investigate the influence of increased shrub coverage on carbon exchange processes between atmosphere and the Arctic tundra ecosystem. In this study a space-for-time substitution was used, referred to as a shrub expansion “chronosequence”, with three sites along a natural gradient of deciduous shrub coverage in the Canadian low Arctic. Leaf-level photosynthetic capacity (Amax) of dominating birch shrub Betula glandulosa (Michx.) was significantly higher (P<0.05) at the site where shrubs were more abundant and taller than at the other sites. For all sites, mean Amax in 2014 was significantly lower than in 2013, in part potentially due to differences in precipitation distribution. Bulk soil respiration (RS) rate was significantly higher (P<0.05) at the site with more shrubs compared with the other sites. The differences in RS across sites appeared to be driven by differences in soil physiochemical properties, such as soil nitrogen and soil bulk density rather than soil microclimate factors (e.g. soil temperature, moisture). The three sites were either annual CO2 sources (NEP<0) to the atmosphere or CO2 neutral, with strongest annual CO2 sources (-44.1±7.0 g C m-2) at the site with most shrubs. Overall this study suggests that shrubs tundra carbon balance will change with shrub expansion and that shrub ecosystems in the Arctic currently act as annual carbon sources or neutral to the atmospheric CO2 and further shrub expansion might strengthen the CO2 emissions, causing a positive feedback to the warming climate. Author Keywords: arctic tundra, carbon exchange, climate change, photosynthetic capacity, shrub expansion, soil respiration
Comparison of the Optical Properties of Stratiotes aloids and the Local Plant Community
As part of a mandate to control the spread of Stratiotes aloides (WS; water soldier) in the Trent Severn Waterway, the Ministry of Natural Resources (MNR) created a management plan to eradicate WS. However, one of the biggest challenges in eradicating WS or any invasive aquatic plant is the ability to estimate the extent of its spread and detect new populations. While current detection methods can provide acceptable detection, these methods often require extensive time and effort. The purpose of this thesis was to assess the use optical properties of WS and WS exudates for detection, in order to improve on current detection methods. The optical properties of WS were sampled at three different sites during three different seasons (spring, summer, and fall) by a) randomly sampling tissue from WS and the local plant community at each site, and recording the reflectance properties in a laboratory setting b) collecting dissolved organic matter (DOM) samples from plant incubations and river water in the field. Significant differences in the reflectance properties of WS were observed among samples from different sites and different sampling times; however, changes in fluorescence properties were only seasonal. Despite spatial differences in WS reflectance; WS was detectable using both hyperspectral and multispectral reflectance. When hyperspectral reflectance was used, significant differences between WS and the local plant community were found in June using two bands (i.e. bands 525 and 535, R 2 = 0.46 and 0.48, respectively). Whereas multispectral reflectance was significant different in October using the coastal and blue band. While WS produced a unique signal using both reflectance types, multispectral reflectance had a greater potential for detection. Its greater potential for detection was due to the reduced noise produced by background optical properties in October in comparison to June. DOM derived from WS was also characterized and compared with whole-river DOM samples in order to find unique markers for WS exudates in river samples. While similarities in DOM concentrations of WS exudates to Trent River water limited the ability to detect WS using compositional data, the ratio of C4/C5 components were compared in order to find components that were proportionally similar. Based on the results of this study multispectral and fluorescence techniques are better suited for the detection of a unique WS signature. The results derived from this work are intended to have practical applications in plant management and monitoring, DOM tracing, as well as remote sensing. Author Keywords: Dissolved organic matter, Hyperspectral reflectance, Invasive species management, Multispectral reflectance, PARAFAC, Stratiotes aloides
Comparing Biological Responses to Contaminants in Darters (Etheostoma spp.) Collected from Rural and Urban Regions of the Grand River Watershed, Ontario
Urban and agricultural activities may introduce chemical stressors, including contaminants of emerging concern (CECs) and current use pesticides (CUPs) into riverine systems. The objective of this study was to determine if fish collected from sites in a river show biomarkers of exposure to these classes of contaminants, and if the biomarker patterns vary in fish collected from urbanized and agricultural sites. The watershed selected for this study was the Grand River in southern Ontario, which transitions from areas dominated by agricultural land use in the north to highly urbanized locations in the southern part of the watershed. Rainbow darters (Etheostoma caerluem) and fantail darters (Etheostoma flabellare) were collected from the Grand River in June, 2014 for biomarker analysis from two urbanized sites and three agricultural sites (n=20 per site). Over the same period of time, Polar Organic Chemical Integrative Samplers (POCIS) were deployed for 2 weeks at each site to monitor for the presence of CUPs and CECs. The amounts of the target compounds accumulated on POCIS, determined using LC-MS/MS were used to estimate the time weighted average concentrations of the contaminants at each site. Data on the liver somatic index for darters indicate site-specific differences in this condition factor (p<0.05). Significant differences in the concentrations of thiobarbituric acid reactive substances (TBARS) in gill tissue (p<0.05) indicate differences in oxidative stress in fish collected from the various sites. Measured concentrations of ethoxyresorufin-O-deethylase (EROD) in liver tissue were significantly different between sites (p<0.05), indicating differences in CYP1A metabolic activity. Finally, acetylcholinesterase (AChE) activity in brain tissue was significantly different between fish from rural and urban sites (p<0.05). The analysis of these biomarkers indicates that fish may be experiencing different levels of biological stress related to different land uses. These data may be useful in developing mitigation strategies to reduce impacts on fish and other aquatic organisms in the watershed. Author Keywords: AChE, Biomarker, Darter, EROD, POCIS, TBARS
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
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
Regional Assessment of Soil Calcium Weathering Rates and the Factors that Influence Lake Calcium in the Muskoka River Catchment, Central Ontario
(MRC) in central Ontario was carried out to determine the range and spatial distribution of soil Ca weathering rates, and investigate the relationships between lake Ca and soil and catchment attributes. The MRC is acid-sensitive, and has a long history of impacts from industrial emission sources in Ontario and the United States. Small headwater catchments were sampled for soil and landscape attributes (e.g. elevation, slope, catchment area) at 84 sites. Soil Ca weathering rates, estimated with the PROFILE model, were low throughout the region (average: 188 eq/(ha·yr)) compared to global averages, and lower than Ca deposition (average: 292 eq/(ha·yr)). Multiple linear regression models of lake Ca (n= 306) were dominated by landscape variables such as elevation, which suggests that on a regional scale, landscape variables are better predictors of lake Ca than catchment soil variables. Author Keywords: Calcium, Lakes, Regional assessment, Regression, Soils, Weathering
Factors affecting road mortality of reptiles and amphibians on the Bruce Peninsula
Road mortality is one of the leading causes of global population declines in reptiles and amphibians. Stemming losses from reptile and amphibian road mortality is a conservation priority and mitigation is a key recovery measure. I developed a model of road mortalities relative to non-­‐mortalities, based on predictors varying across space (road surface type, traffic volume, speed limit, distance to wetland) and time (weather conditions, traffic volume). Herpetofauna road mortalities were recorded during daily bicycle and vehicle surveys to investigate the impact of roads on reptiles and amphibians within the Bruce Peninsula, Ontario in 2012 and 2013. A total of 2541 observations of herpetofauna on roads were recorded, 79% of which were dead. The major factor influencing turtle road mortality was proximity to the nearest wetland and dates early in the season (spring). For the Massasauga, high daily temperatures and low daily precipitation were associated with road mortality. The major factors driving colubrid snake mortality were also high daily temperature, low daily precipitation, as well as low speeds and paved roads. Frog and toad mortality was driven by proximity to wetland and late summer dates. These models will increase our understanding of factors affecting road losses of herpetofauna and serve as a basis for planned, experimental mitigation within the Bruce Peninsula. Author Keywords: amphibians, hotspot, mitigation, reptiles, road ecology, road mortality


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Format: 2023/06/06