Graduate Theses & Dissertations

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An Assessment of Spatial Trends in the Accumulation of Oil Sands Related Metals in the Clearwater River Valley and Temporal Trends in Six Northern Saskatchewan Lakes
The objective of this thesis was to assess current spatial trends and historic trends in the accumulation of trace metals related to the Athabasca Oil Sands Region (AOSR). The AOSR hosts some of the largest industrial developments in Canada, yet relatively little is known about the transport and fate of trace metal emissions from the region – particularly in the relatively remote areas to the east of the AOSR. Lichens are widely used as biomonitors and are employed in this thesis to assess the range of metals deposition within the Clearwater River and Athabasca River Valleys. Lake sediment cores can retain a historical record of the long-range transport and deposition of metals but can also respond to large regional metal emissions sources. This thesis used lake sediment cores to assess temporal trends in metals accumulation in six road accessible lakes in NW Saskatchewan that are likely to be used by local residents. Results show that metal concentrations (V, Co, Cu, Ni, Pb, Zn, Zr and Cd ) in lichen decline exponentially with distance from the AOSR and approach background levels within a few kilometers . Results from lake sediment cores show that there was no evidence that metal concentrations had increased due to industrial activities in the AOSR. Author Keywords: Air Emissions, Lakes, Lichens, Oil Sands, Saskatchewan, Trace Metals
Effects of flooding on nutrient budgets and ecosystem services
Increases in flooding due to anthropogenic influences such as climate change and reservoir creation will undoubtedly impact aquatic ecosystems, affecting physical, chemical, and biological processes. We used two approaches to study these impacts: a whole-ecosystem reservoir flooding experiment and a systematic literature review. In the whole-ecosystem experiment, we analyzed the impact of flooding on nutrient release from stored organic matter in an upland forest. We found that flooded organic matter produced N (nitrogen) and P (phosphorus), but that more N was released relative to P, increasing the N:P ratio over time. In the systematic literature review, we linked small (<10 year recurrence interval) and extreme (>100 year recurrence interval) floods to changes in 10 aquatic ecosystem services. Generally, extreme floods negatively impacted aquatic ecosystem service provisioning, while small floods contributed positively. Overall, we found that flood impacts vary depending on ecosystem properties (organic matter content) and flood characteristics (magnitude). Author Keywords: ecosystem services, flooding, nutrients, reservoirs, rivers
Estimating mineral surface area and acid sensitivity of forest soils in Kitimat, British Columbia
In 2012, the Rio Tinto aluminum smelter in Kitimat, British Columbia increased sulphur dioxide (SO2) emissions from 27 to 42 tonnes/day. An initial study was conducted to investigate the effect of the increased sulphur (S) deposition on forest soils. A key uncertainty of the initial study was mineral surface area estimations that were applied to critical load calculations. The current study investigates the effect of organic matter (OM) removal techniques on mineral surface area and the ability to predict mineral surface area using pedotransfer functions (PTFs). Mineral surface area was measured on bulk soil samples using BET gas-adsorption. Organic matter was removed from soil samples prior to surface area measurements using a sodium hypochlorite treatment (NaOCl), loss on ignition (LOI) and no treatment. Removal techniques were found to affect surface area measurements; decreasing in the order of LOI> untreated> NaOCl. Particle-size based PTFs developed from other regions were not significantly correlated with measured surface area. A regionally-specific particle-size based function had stronger predictive value of surface area measurements (adjusted R2=0.82). The PTF that best reflected surface area measurements of bulk soil for the Kitimat area used particle-size data as well as kaolinite, the most abundant clay mineral in the region. Surface area values estimated using the particle-size PTF were applied to the PROFILE model to calculate weathering rates. Weathering rates were then input to critical load calculations using steady-state mass balance. These estimates predicted that none of the 24 measured sites are receiving SO2 deposition in exceedance of their critical load. Author Keywords: acid deposition, critical loads, mineral surface area, mineral weathering, pedotransfer functions, PROFILE
Identification and Quantification of Organic Selenium Species Produced by Microbiological Activity in Freshwater Environments
Despite being an essential nutrient at trace levels, selenium can be devastating to aquatic environments when present in excess. There is no apparent correlation between total aqueous selenium concentrations and observed toxic effects because bioaccumulation varies over several orders of magnitude depending on the chemical species of selenium and the biological species present in the lowest trophic level of the aquatic food chain. Despite being used in toxicity models due to its high bioavailability, free selenomethionine had not been found previously in the environment outside of a biological entity. Here, it is confirmed that selenomethionine is produced during the biological treatment of selenium-contaminated wastewater, and released in the effluent along with other discrete organic selenium species, including selenomethionine oxide. This identification followed the development of a rigorous preconcentration and cleanup procedure, allowing for the analysis of these organic selenium species in high-ionic strength matrices. A newly optimized anion-exchange chromatographic separation was coupled to inductively-coupled plasma mass spectrometry for the simultaneous quantification of these organic selenium species along with the more ubiquitous selenium oxyanions, selenite and selenate. This separation method was also coupled to electrospray tandem mass spectrometry for structural confirmation of selenomethionine and selenomethionine oxide. High resolution orbitrap mass spectrometry was used to identify another oxidation product of selenomethionine – a cyclic species which was tentatively identified, by coelution, in a selenium-contaminated river water sample. The production and release of selenomethionine, selenomethionine oxide, Se-(methyl) selenocysteine, and methyl selenic acid were observed for various laboratory algal cultures. Once the presence of free selenomethionine in a water system was confirmed, factors affecting its uptake into algal cultures were examined. The uptake of selenomethionine into Scenedesmus obliquus was noted to be significantly higher under low nitrate conditions, where it was incorporated into selenium-containing proteins more readily than at higher nitrate conditions where other metabolites were produced. With the increasing popularity of biological treatment systems for the remediation of selenium-contaminated waters, these observations, combined with existing knowledge, could be used to make predictions regarding the potential toxicity of selenium in various environmental scenarios. Author Keywords: bioremediation, electrospray mass spectrometry, inductively-coupled plasma mass spectrometry, selenium, selenoamino acids, selenomethionine
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
Molecular Composition of Dissolved Organic Matter Controls Metal Speciation and Microbial Uptake
Aquatic contaminant mobility and biological availability is strongly governed by the complexation of organic and inorganic ligands. Dissolved organic matter (DOM) is a complex, heterogeneous mixture of organic acids, amino acids, lipids, carbohydrates and polyphenols that vary in composition and can complex to dissolved metals thereby altering their fate in aquatic systems. The research conducted in this doctoral dissertation addresses 1) how DOM composition differs between phytoplankton taxa and 2) how DOM composition affects metal speciation and its subsequent microbial bioavailability in laboratory and field conditions. To accomplish this, a series of analytical methods were developed and applied to quantify thiols, sulphur containing DOM moieties, and the molecular composition of DOM. The works presented in this thesis represents one of the first comprehensive and multipronged analyses of the impact of phytoplankton metabolite exudates on microbial metal bioavailability. This dissertation demonstrated the analytical versatility of high-resolution mass spectrometry as a tool for compound specific information, as well as having the capabilities to obtain speciation information of organometallic complexes. The work presented in this PhD strengthens the understanding compositional differences of both autochthonous and allochthonous DOM and their effects on metal biogeochemistry. Author Keywords: Dissolved Organic Matter, Mercury, Metal Accumulation, Phytoplankton, Spring Melts, Thiol
Nitrogen Retention of Terricolous Lichens in a Jack Pine Forest in Northern Alberta
The Athabasca Oil Sands in Alberta, Canada is one of the largest point sources emitters of NOx in Canada and there are concerns that elevated nitrogen (N) deposition will lead to widespread eutrophication impacts, including altered species composition, similar to what has occurred in several parts of Europe. Atmospheric deposition rates as high as 25 kg N ha-1 yr-1 have been measured close to the industrial center. The role of the forest floor in regulating these potential eutrophication effects was investigated following a 5-year enrichment study in which N was applied as NH4NO3 above the canopy of a jack pine (Pinus banksiana Lamb) stand in northern Alberta close to Fort McMurray at dosages ranging from 5 – 25 kg N ha-1 yr-1 in addition to background deposition of 2 kg N ha-1 yr-1. Chemical analysis of lichen mats revealed that apical (upper) lichen tissue N concentration increased with treatment, as did the necrotic tissue. When expressed as a pool, the fibric-humic (FH) material held the largest quantity of N across all treatments due to its relatively large mass. Soil net N mineralization and net nitrification rates did not differ among N inputs after five years of application. A 15N tracer applied to the forest floor showed that N is initially absorbed by the apical lichen, FH material, and the foliage of the vascular plant Vaccinium myrtilloides in particular. After 2 years, the FH 15N pool size was elevated and all other measured pools were depleted, indicating a slow transfer of N to the FH material. Applied 15N was not detectable in mineral soil. The microbial functional gene ammonia monooxygenase (amoA) was undetectable using PCR screening of mineral soil microbial communities in all treatments, and broad fungal/bacterial qPCR assays revealed a weak treatment effect on fungal/bacterial ratios in mineral soil. This work suggests that terricolous lichen mats, which form the majority of ground cover in upland jack pine systems, have a large capacity to effectively retain elevated N deposition via the formation of stable humus. Author Keywords: Biogeochemistry, Boreal Ecology, Lichen, Nitrogen Enrichment, Oil Sands
Nutrient Metabolism of an Aquatic Invertebrate and its Importance to Ecology
Aquatic consumers frequently face nutritional limitation, caused in part, by imbalances between the nutrients supplied by primary producers and the metabolic demands of the consumers. These nutritional imbalances alter many ecological processes including consumer life-history traits, population dynamics, and food web properties. Given the important ecological role of organismal nutrition, there is a need to have precise and specific indicators of nutritional stress in animals. Despite this need, current methods used to study nutrition are unable to distinguish between different types of nutritional limitation. Here I studied nutritional metabolism in the freshwater zooplankter, Daphnia. A greater understanding of nutritional metabolism would allow for the development of dietary bio-indicators that could improve the study of the nutritional ecology of animal consumers. Specifically, I addressed the question: What affects the biochemical composition of a generalist aquatic consumer? My overall hypothesis was that the quantity and quality of the diet affects the biochemical composition in a nutrient specific manner. To test this hypothesis, I examined various response variables involved in nutrient metabolism such as alkaline phosphatase activity, whole metabolome, and free amino acid composition. For each response variable, I grew Daphnia under various nutritional stressors and determined if responses are nutrient specific or are a general stress response. I found the current method of measuring alkaline phosphatase was not a phosphorus specific indicator, as activity increased in all nutrient stressed treatments. Analyzing the whole metabolome resulted in nutritional stressors being separated in multivariate space, with many identified metabolites being significantly different from nutrient rich Daphnia. Upon further examination the daphnids free amino acids profiles are caused by differences between the supply of amino acids from the algae and the demand within the Daphnia. These differences in supply and demand resulted in the ability to classify the nutritional status of Daphnia with the use of discriminant analysis, a classification multivariate model. In addition to a deeper understanding and advanced knowledge of the physiological changes caused by nutrient limitation, this research has provided strong evidence for the application of nutritional biomarkers/profiles to identified the nutritional status of Daphnia. Author Keywords: Bio-indictor, Ecological stoichiometry, Metabolism, Nutritional limitation, Nutritional status
Patterns of Vegetation Succession on Nickel-Copper Mine Tailings near Sudbury, Ontario
Natural establishment of vegetation on mine tailings is generally limited. Understanding the processes leading to vegetation germination and the survival mechanisms that vegetation species employ in these harsh environments is critical to future remediation efforts. As metalliferous mine tailings are generally nutrient-poor, high in harmful metals, and acidic, vegetation species require distinct mechanisms to germinate and survive in such harsh environments. In this study, edaphic and biotic factors linked to vegetation establishment and diversity were studied at two nickel-copper (Ni-Cu) tailings sites near Sudbury, Ontario. One site had experienced minimal treatment, and the second site was split into partial (hand-distribution of lime) and full (lime, fertilizer, seeding) treatment areas. Tailings were generally acidic, low in organic matter and “available” nutrients, and high in metals such as Al, Cu, Fe, and Ni, but these physical and chemical properties were extremely spatially variable. At both sites, vegetation was distributed in sparse patches, with the greatest diversity in treated areas. There was no clear link between metals and vegetation establishment/diversity at the sites. The primary limiting nutrients on the tailings were phosphorous (P) and potassium (K), and while there were areas of increased soil fertility at the sites, they were not clearly associated with increased vegetation diversity. Both traditional ecological succession and nucleation succession patterns were observed on the site, and the chief species associated with nucleation were primary colonizing trees such as B. papyrifera and P. tremuloides. The relationship between B. papyrifera nutrient retranslocation and tailings restoration was assessed and while B. papyrifera at the sites were deficient in P and K, the trees efficiently retranslocated both P and K during senescence. This research can provide insight into possibilities for future revegetation of similar tailings, enabling industry to make educated decisions when choosing where and how to revegetate, mimicking natural succession patterns. Author Keywords: Acid-mine drainage, Betula papyrifera, ecosystem health, metals, Sudbury, tailings
Predictive Digital Mapping of Soils in Kitimat, British Columbia
Soil is an essential natural resource that supports provisioning services such as agriculture, silviculture, and mining. However, there is limited knowledge on forest soil properties across Canada. Digital soil mapping may be used to fill these data gaps, as it can predict soil properties in areas with limited observations. The focus of this study was to develop predictive maps of select soil physicochemical properties for the Kitimat Valley, British Columbia, and apply these maps to assess the potential impacts of sulphur dioxide emissions from an aluminum smelter, on soil properties in the Valley. Exchangeable [Ex.] magnesium, organic matter, pH, coarse fragment, Ex. potassium, bulk density, Ex. calcium, Ex. acidity, and Ex. sodium were all mapped with acceptable confidence. Time to depletion of base cation pools showed that ~240 km2 of the study area had a depletion time of 50 years or less. However, sources of base cations such as atmospheric deposition and mineral weathering were not considered. Author Keywords: acidification, buffering capacity, Digital soil mapping, predictive mapping, regression kriging, soil properties
Purification and Identification of Selenium-containing C-phycocyanin from Spirulina
Selenium is an essential trace nutrient to many organisms, yet in high concentrations it is toxic. Organic selenium is more bioavailable to aquatic biota than inorganic selenium, but is usually found in much lower concentrations. Algae are known to biotransform inorganic selenium into several organo-selenium compounds, but it is unknown whether any of these bioaccumulate in the food chain. In this study, selenium was incorporated into the methionine residues of an algal photosynthetic protein, c-phycocyanin from Spirulina spp. The extent of selenium incorporation was quantified by inductively coupled plasma-mass spectrometry (ICP-MS), and the protein was identified using electrospray mass spectrometry (ES-MS). C-phycocyanin was isolated and purified from Spirulina with a final recovery of 20-30 % of the total c-phycocyanin present. Selenomethionine replaced 92.8% ± 1.22 of the methionine residues in c-phycocyanin when grown in 2.5 ppm sodium selenite. ES-MS was used to obtain protein spectra, and pure c-phycocyanin was identified. Data of full scans provided estimated masses of both protein subunits--α-chain measured at 18,036 Da; β-chain measured at 19,250 Da--close to the theoretical masses. Protein fragmentation by collision-induced dissociation and electron capture dissociation provided approximately 52 % amino acid sequence match with c-phycocyanin from Spirulina platensis. This study demonstrates the incorporation of selenium into an algal protein, and the identification of c-phycocyanin using electrospray ionization-mass spectrometry. Author Keywords:
Size and fluorescence properties of allochthonous dissolved organic matter
Dissolved organic matter (DOM) is a mixture of molecules with dynamic structure and composition that are ubiquitous in aquatic systems. DOM has several important functions in both natural and engineered systems, such as supporting microorganisms, governing the toxicity of metals and other pollutants, and controlling the fate of dissolved carbon. The structure and composition of DOM determine its reactivity, and hence its effectiveness in these ecosystem functions. While the structure, composition, and reactivity of riverine and marine DOM have been previously investigated, those of allochthonous DOM collected prior to exposure to microbes and sunlight have received scant attention. The following dissertation constitutes the first in-depth study of the structure, composition, and reactivity of allochthonous DOM at its point of origin (i.e. leaf leachates, LLDOM), as detected by measuring its size and optical properties. Concomitantly, novel chemometric methods were developed to interpret size-resolved data obtained using asymmetrical flow field-flow fractionation, including spectral deconvolution and the application of machine learning algorithms such as self-organizing maps to fluorescence data using a dataset of more than 1000 fluorescence excitation-emission matrices. The size and fluorescence properties of LLDOM are highly distinct. Indeed, LLDOM was correctly classified as one of 13 species/sources with 92.5% accuracy based on its fluorescence composition, and LLDOM was distinguished from riverine DOM sampled from eight different rivers with 98.3% accuracy. Additionally, both fluorescence and size properties were effective conservative tracers of DOC contribution in pH-controlled mixtures of leaf leachates and riverine DOM over two weeks. However, the structure of LLDOM responded differently to pH changes for leaves/needles from different tree species, and for older needles. Structural changes were non-reversible. Copper-binding strength (log K) differed for the different fluorescent components of DOM in a single allochthonous source by more than an order of magnitude (4.73 compared to 6.11). Biotransformation preferentially removed protein/polyphenol-like fluorescence and altered copper-binding parameters: log K increased from 4.7 to 5.5 for one fluorescent component measured by fluorescence quenching, but decreased from 7.2 to 5.8 for the overall DOM, as measured using voltammetry. The complexing capacity of DOM increased in response to biotransformation for both fluorescent and total DOM. The relationship between fluorescence and size properties was consistent for fresh allochthonous DOM, but differed in aged material. Since the size and fluorescence properties of LLDOM are strikingly different from those of riverine DOM, deeper investigation into transformative pathways and mixing processes is required to elucidate the contribution of riparian plant species to DOM signatures in rivers. Author Keywords: Analytical chemistry, Chemometrics, Dissolved organic matter (DOM), Field-flow fractionation, Fluorescence spectroscopy, Parallel factor analysis (PARAFAC)

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Graduate student theses produced at Trent University. You may also browse theses and dissertations by year, program, or author.

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