Graduate Theses & Dissertations

Absorbance and Fluorescence Characteristics of Dissolved Organic Matter in North Atlantic, Pacific and Arctic Oceans
This thesis was designed to quantify absorbance and fluorescence characteristics of dissolved organic matter (DOM) in North Atlantic, Pacific and Arctic Oceans. DOM was described in water masses of distinct sources and formation pathways as well as in regions where environmental forcings such as deep water upwelling, enhanced biological activity and receipt of freshwater discharge were prevalent. Influence of sea ice on DOM in Beaufort Sea mixed layer (0 to 30 m) seawater was investigated based on sea ice extent as well as freshwater fractions of meteoric (fmw) and sea ice melt water (fsim) calculated from oxygen isotope ratio (δ18O). The effect of DOM exposure to simulated solar radiation was also assessed to determine the resilience of fluorescent fractions of DOM to photodegradation. This research aims to further our ability to trace DOM in marine environments and better understand its transformation pathways and predict its fate as part of the oceanic carbon cycle in a changing climate. Author Keywords: Absorbance, Arctic Ocean, Dissolved organic matter, Fluorescence, Parallel Factor Analysis, Sea Ice
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 (
Spatial and Temporal Variation in Peatland Geochemistry in Sudbury, Ontario, Canada
The damage to Sudbury's landscape from over a century of smelter and logging activity has been severe and impacts well documented. However, despite their abundance in the region, wetlands have received little attention. Recent studies have identified that nutrient limitation is as much a problem as metal toxicity and highlighted not only the importance of wetlands but also the need for more detailed studies examining the role of wetlands in the recovery of lakes. The objective of this work is to characterize the spatial and temporal variability in the geochemistry of 18 wetlands (poor fens) surrounding Sudbury, Ontario. Peat and water chemistry in the wetlands exhibited large spatial and temporal variability. Copper and Ni concentrations in surface peat decreased with distance from the largest smelter in the area, but water chemistry was also strongly influenced by natural factors such as climate, groundwater and peat carbon content. Redox processes contribute greatly to temporal variation in pore-water chemistry: the August and October campaigns were characterized by higher SO4, lower pH and higher concentrations of metals such as Ni, Cu and Mn compared with the May campaign. Other factors contributing to the temporal variability in pore water chemistry include DOC production, senescence and water source. Despite the large variability, soil-solution partitioning can be explained by pH alone for some metals. Modeling is significantly improved with the addition of other variables representing dissolved organic matter quality and quantity, sulphate concentration and hydrology. Author Keywords: metal contamination, metal mobility, organic matter quality, peatland geochemistry
Relationships between Dissolved Organic Matter and Vanadium Speciation in the Churchill River, MB and the Mackenzie River Basin, NWT using diffusive gradients in thin films (DGT)
This study examines the influence of dissolved organic matter (DOM) on dissolved vanadium (V) speciation in the Churchill River and Great Slave Lake using diffusive gradients in thin film (DGT). Vanadium is commonly found in natural environments such as rivers, lakes and oceans. It regulates normal cell growth, but in excessive amounts, it can have toxic effects on human and aquatic organisms. The use of in situ, time integrated DGT devices allows to better (1) monitor the most bioavailable fraction of V, the DGT-labile V, in Arctic Rivers and (2) assess the influence of DOM on dissolved V speciation. Higher DGT-labile V was found in the the central regions of the Mackenzie River (MR), with an average of 7.7 ± 2.3 nM, likely due to sediment leaching and permafrost thawing. The Churchill River and Great Slave Lake (GSL) showed lower DGT-labile V levels (2.2 ± 1.6 nM and 3.6 ± 2.7 nM, respectively), compared to central regions in MR. The CR DGT-labile V concentrations was positively correlated to protein-like DOM concentration and abundance (r = 0.3, p < 0.05). The data collected from this study will help in developing new strategies regarding environmental health and impact assessments of environmentally hazardous waste that consist of potentially high levels of toxic vanadium species. Developments in the use of DGT devices as a sampling method will also aid in future studies involved in analyzing environmental health and specifically dissolved V species in natural waters. Author Keywords: diffusive gradients in thin-films, dissolved organic matter, fluorescence, mass spectrometry, UV-Vis, vanadium
In situ measurements of trace metal species in the Athabasca and Mackenzie Rivers using diffusive gradient in thin films (DGT) devices
This study assesses the bioavailable metal (Cu, Ni, Zn, Pb) species in the Athabasca-Mackenzie watersheds using diffusive gradient in thin films (DGT) devices. Metal toxicity is not only based on the concentration of metal in natural waters, but also on the nature of metal species. Four main forms in aquatic systems are: free ion, inorganic species, DOM bound (humic) species and metal colloidal species. The free ion and inorganic species and very small humic species are known as DGT-labile species and, are considered to be more bioavailable to micro-organisms due to the size and thus may be toxic to microorganisms. In this study, DGT devices were applied to (1) monitor the DGT-labile metal species in the lower Athabasca River and the Mackenzie River watershed and (2) assess the DGT-labile metal concentrations on temporal and spatial scales. In the lower Athabasca River, comparison between the DGT results and the Windermere Humic Acid Model (WHAM) calculation indicated good agreements for all metals when the precipitated iron(III) hydroxide was assumed as an active binding surface. No significant variations in labile species were found over 2003-2012 (RAMP database) despite the development of oil sands. In the Mackenzie River, no significant difference in DGT-labile metal concentrations and DOC concentrations was found in yearly basis 2012-2014. Only DOC was lower in August (6.98 and 3.85 ppm, respectively; p< 0.05) due to dilution from heavy rain events. Spatially, DGT-labile Cu and Ni in the downstream Mackenzie River were higher than upstream (1.79 and 0.58 ppb for Cu, 1.68 and 0.77 ppb for Ni, 4.06 and 6.91 ppm for DOC; p < 0.05). Overall the in situ measurements of metals constitute a benchmark for future studies in water quality and be helpful in environmental management in Alberta and the Northwest Territories in Canada. Author Keywords: Athabasca River, DGT, Mackenzie River, Speciation, Trace Metal, WHAM
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
Chemical characterization of dissolved organic matter in relation with hydrography in the Arctic Ocean
In this thesis, water mass distribution of dissolved organic matter (DOM) characteristics (i.e. molecular weight, fluorescent components, thiols and humic substances concentration) was observed in the Arctic Ocean. For the first time, DOM molecular weight (MW) in Beaufort Sea was assessed using asymmetrical flow field-flow fractionation, as well as the first monitoring of thiols and humic substances (HS) using cathodic stripping voltammetry (CSV) in the Arctic Ocean. Based on fluorescence property, DOM characterization was carried out using parallel factor analysis – excitation-emission matrices. Pacific winter waters in the Canada Basin showed higher MW DOM associated with higher fluorescence intensity. High HS was associated with the Arctic outflow waters in top 300 m of the Canadian Arctic Archipelago. Interestingly, maximum thiol concentration was associated with the subsurface chlorophyll-a maximum at most sites, but not universal along the study area. Comparable distributions of CSV-based HS and humic-like fluorescent components suggest similar sources/ processes in the Arctic Ocean. The findings in this thesis suggested DOM characteristics could be used as fingerprints in tracing water masses in the Arctic Ocean. Author Keywords: Asymmetrical flow field-flow fractionation, Cathodic stripping voltammetry, DOM, Metal-binding ligands, Molecular weight, PARAFAC-EEMs
Hydrochemistry and critical loads of acidity for lakes and ponds in the Canadian Arctic
Threats such as climate change and increased anthropogenic activity such as shipping, are expected to negatively affect the Arctic. Lack of data on Arctic systems restricts our current understanding of these sensitive systems and limits our ability to predict future impacts. Lakes and ponds are a major feature of the Arctic landscape and are recognized as ‘sentinels of change’, as they integrate processes at a landscape scale. A total of 1300 aquatic sites were assessed for common chemical and physical characteristics. Geology type was found to be the greatest driver of water chemistry for Arctic lakes and ponds. Acid-sensitivity was assessed using the Steady State Water Chemistry model and a subset of 1138 sites from across the Canadian Arctic. A large portion of sites (40.0%, n = 455) were classified as highly sensitive to acidic deposition, which resulted in a median value of 35.8 meq·m―2·yr―1 for the Canadian Arctic. Under modelled sulphur deposition scenarios for the year 2010, exceedances associated with shipping is 12.5% (n = 142) and 12.0% (n = 136) for without shipping, suggesting that impacts of shipping are relatively small. Author Keywords: Acidic deposition, Arctic lakes, Critical loads, Shipping emissions, Steady-State Water Chemistry Model, Water chemistry
Fingerprinting of dissolved organic matter and copper ligands in the Canadian Arctic and North Pacific Ocean
Dissolved organic matter (DOM) in oceans provides nutrients and ultraviolet radiation protection to microbes. Some DOM compounds can chelate with metals, including copper, controlling their transport and bioavailability in marine systems. As copper functions as both a nutrient and toxicant, studies into the chemical structures of Cu-ligands is important, however currently limited. In this thesis, the chemical composition of total and Cu-binding DOM is investigated using Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) in the Canadian Arctic and North Pacific. Chapter 2 reveals chemical differences in DOM composition between the southern and northern Canada Basin, revealing the influence of terrestrial and biological sources. Chapter 3 shows the uniqueness of Cu-binding ligands found in the Canadian Arctic and North Pacific Ocean. Studying the composition of DOM gives insight into the chemical diversity of marine DOM, helping to predict the effects of a changing climate on marine ecosystems. Author Keywords: biological, dissolved organic matter, fluorescence, immobilized metal-ion affinity chromatography, mass spectrometry, terrestrial
Effects of Recycled Media on Culture Growth and Hormone Profiles in Heterotrophic Euglena gracilis
The rapid expansion of the worldwide population has caused an urgent need for the development of new, more environment-conscious, food sources. In this context, algae, such as Euglena, are of interest thanks to their capacity to naturally produce essential nutrients such as proteins and oils commonly found in animals and plant sources. While these processes are currently being investigated, underlying measures affecting growth of Euglena gracilis like hormonal influences and growth stress like nutrient deprivation are poorly understood. From this vantage point, this thesis seeks to understand the role of phytohormones cytokinin (CKs) and abscisic acid (ABA) in complex mechanisms underlying heterotrophic growth of Euglena gracilis under recycled, organic media conditions with no supplementation. Hormone profiles were quantified by HPLC-ESI-MS/MS and compared to culture growth dynamics of pH, weight accumulation, glucose content, cell count and morphology. It was expected that ABA acted as an inhibitory hormone and this was confirmed by its higher levels when CKs where low and vice versa. Contrastingly, it was expected that CKs stimulated growth, in which this was shown not to be the case. Interestingly, it was revealed that both hormone groups increase with increasing recycling. Other key findings include: E. gracilis synthesizes CKs via the tRNA-degradation pathway and is cZ and iP dominated, recycling E. gracilis medium is viable for growth, however, the percentage (25% or less) is crucial to cell viability and markedly no ABA was detected in E. gracilis pellet fractions from recycled media. Therefore, this data revealed that recycled media has a striking influence on physiological aspects of growth and illustrated unique changes in hormone profiles of which could be manipulated to help the food industry. Author Keywords: cytokinin, endogenous hormones, Euglena gracilis, heterotrophic, large scale microalgae cultivation, recycled medium

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