Graduate Theses & Dissertations

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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
Organic Matter and Total Mercury in Acid-Sensitive Lakes in Ireland
The following study measured dissolved organic carbon (DOC) and total mercury (THg) concentrations in acid sensitive lakes in the Republic of Ireland. Sixty-eight upland lakes and 48 lowland lakes were sampled for DOC; the upland lakes were additionally sampled for THg. Spatial variability of DOC was explained by regional precipitation and soil organic matter. A subset of lakes was tested for long-term trends and in contrast to reports of rising DOC in European surface waters, changes in DOC were minor. Spatial variability in THg was explained by DOC and organic matter aromaticity. Long-term THg concentrations increased, likely caused by inputs of terrestrial THg. A subset of lakes was sampled for sediment and soil and the results suggested soils drove THg variation in lake water and sediment. Lake water and sediment THg was low and consistent with background regions, while soil THg was relatively high due to high organic content. Author Keywords: Dissolved Organic Carbon, Lakes, Organic Matter, Soil, Total Mercury, Water
Effects of Agricultural Land Use Change on Nitrogen and Phosphorus in North Shore Lake Ontario Tributaries
Row crop agriculture and associated land use practices including tile drainage and conservation tillage have been cited as a probable cause of re-emerging eutrophication in the lower Great Lakes. In this thesis, I sought to quantify and evaluate the effect of agricultural land cover and land use changes on total phosphorus (TP) and nitrate-nitrogen (NO3-N) concentrations and export in north shore Lake Ontario tributaries. This included (a) a long-term data analyses at 12 large watersheds (47 to 278 km²) using historical land cover and water quality data (1971-2010), and (b) a space-for-time study examining 12 small sub-catchments (< 8 km²) with majority (> 50%) row crop, pasture, or forest cover. Concentrations of TP were greatest in urbanized watersheds and declined particularly during the first decades of the study period, while NO3-N concentrations were greatest and steadily increased in agricultural catchments with increasing row crop cover. The space-for-time approach revealed that TP concentrations were similar across agricultural land uses and that export was most dependent on runoff. Meanwhile, NO3-N concentrations and export were greatest in row crop catchments and were positively related to row crop area. These results suggest that increases in row crop cover and associated agricultural practices including increased nutrient amendments and tile drainage may be responsible for increased NO3-N concentrations and export in northern Lake Ontario tributaries. Author Keywords: agriculture, Lake Ontario, nitrogen, phosphorus, streams, Water quality
Ecosystem Response to Above Canopy Nitrogen Addition in a Jack Pine (Pinus banksiana) Forest in the Athabasca Bituminous Sands Region of Northeastern Alberta, Canada
In this study we seek to better understand the potential effects of short-term (5-year) N fertilization on jack pine forest biogeochemistry, vascular plant community composition and to project a temporal endpoint of nitrogen leaching below the major rooting zone. Aqueous ammonium nitrate (NH4NO3) was applied above the forest canopy across five treatment plots (20 x 80 m) four times annually. The experimental deposition gradient followed those known for localized areas around the major open pit operations at 0, 5, 10, 15, 20 and 25 kg N ha-1 yr-1 over a five-year period (2011 – 2015). Nitrate recovery in throughfall was significantly higher than NH4+ (p < 0.05), indicating canopy NH4+ immobilization. There was a strong treatment effect (p < 0.05) of N on the epiphytic lichen thalli concentrations of Hypogymnia physodes and Evernia mesomorpha after five years. The canopy appeared to approach saturation at the highest deposition load (25 kg N ha-1 yr-1) during the fifth year of N additions as most N added above the canopy was accounted for in throughfall and stemflow. The non-vascular (lichen and moss) vegetation pool above the forest floor was the largest receptor of N as cryptogam foliar and thalli N concentrations showed a significant treatment effect (p < 0.05). Nitrogen in decomposing litter (25 kg N ha-1 yr-1) remained immobilized after five years, while treatments ≤ 20 kg N ha-1 yr-1 started to mobilize. Understory vascular plant cover expansion was muted when deposition was ≥ 10 kg N ha-1 yr-1. Finally, modeling suggests the forest may not leach N below the rooting zone until around 50 years after chronic addition begin (25 kg N ha-1 yr-1). The modeling results are consistent with empirical data from a high exposure (~20 - 25 kg N ha-1 yr-1) jack pine site approximately 12 km west of the experimental site that has not yet experienced N leaching. Author Keywords: Biogeochemistry, Canopy, Deposition, Jack Pine, Nitrogen, Understory
Phosphorus delivery in the Rainy-River Lake of the Woods Watershed
Lake of the Woods (LOW) is a large international waterbody which suffers from frequent and widespread algae blooms. Previous studies have highlighted the importance of the lake's largest tributary, the Rainy River (RR) and its significance in total phosphorus (TP) delivery to the LOW. Unfortunately, little is known about TP contributions from the RR and its tributaries within the Canadian portion of the watershed. This thesis examines patterns and sources of TP from four tributaries on the Canadian side of the lower RR region, two of which are predominantly natural, and two that are predominantly agricultural. Relationships between water quality parameters, land use and geologic characteristics were observed over a complete hydrologic year (Oct 1, 2018 - Sept 31, 2019), and through an intensive sampling campaign using a nested watershed approach during the spring high flow and summer low flow periods. Results revealed that TP and total suspended sediment (TSS) concentrations (>100 µg/L and >20 mg/L respectively), and loads (>20 kg/km2 and >3500 kg/km2, respectively), were greater at agricultural sites compared with natural sites (<65 µg/L TP and <15 mg/L TSS concentration, and <20 kg/km2 TP and <4000 kg/km2 TSS export). Total P, TSS, Fe, and Al were significantly positively correlated (R2= 0.26-0.59; p<0.05) and intensive sampling revealed that these relationships were strongest during the spring and at the agricultural sites (R2= 0.73-0.98; p<0.05). In contrast, the summer intensive sampling revealed that TP and redox sensitive Fe were significantly correlated (R2= 0.72; p<0.005), whereas redox insensitive Al and TSS were not, suggesting TP may be sourced via redox processes in the summer due to favourable hydrologic conditions. This was observed not only at sites with high wetland influence, but also at sites with more agricultural presence suggesting that redox sourced TP may also originate from mineral stream bed sediment during low flow periods. This research suggested two primary TP sources in the lower RR region: erosion in the spring, and redox processes (internal release) in the summer. It is recommended that intensive monitoring continue in Canada, and further research be conducted to fully understand the significance of internal P release in the tributaries. Author Keywords: erosion, land use, nutrients, particulates, redox, water quality
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:
Hydroclimatic and spatial controls on stream nutrient export from forested catchments
Winter nutrient export from forested catchments is extremely variable from year-to-year and across the landscape of south-central Ontario. Understanding the controls on this variability is critical, as what happens during the winter sets up the timing and nature of the spring snowmelt, the major period of export for water and nutrients from seasonally snow-covered forests. Furthermore, winter processes are especially vulnerable to changes in climate, particularly to shifts in precipitation from snow to rain as air temperatures rise. The objective of this thesis was to assess climatic and topographic controls on variability in stream nutrient export from a series of forested catchments in south-central Ontario. The impacts of climate on the timing and magnitude of winter stream nutrient export, with particular focus on the impact of winter rain-on-snow (ROS) events was investigated through a) analysis of long-term hydrological, chemical and meteorological records and b) high frequency chemical and isotopic measurements of stream and snow samples over two winters. The relationship between topography and variability in stream chemistry among catchments was investigated through a) a series of field and laboratory incubations to measure rates and discern controls on nitrogen mineralization and nitrification and b) analysis of high resolution spatial data to assess relationships between topographic metrics and seasonal stream chemistry. Warmer winters with more ROS events were shown to shift the bulk of nitrate (NO3-N) export earlier in the winter at the expense of spring export; this pattern was not observed in other nutrients [i.e. dissolved organic carbon (DOC), total phosphorus (TP), sulphate (SO4), calcium (Ca)]. Hydrograph separation revealed the majority of ROS flow came from baseflow, but the NO3-N concentrations in rainfall and melting snow were so high that the majority of NO3-N export was due to these two sources. Other nutrient concentrations did not show such a great separation between sources, and thus event export of these nutrients was not as great. Proportionally, catchments with varying topography responded similarly to ROS events, but the absolute magnitude of export varied substantially, due to differences in baseflow NO3-N concentrations. Field and laboratory incubations revealed differences in rates of net NO3-N production between wetland soils and upland soils, suggesting that topographic differences amongst catchments may be responsible for differences in baseflow NO3-N. Spatial analysis of digital elevation models revealed strong relationships between wetland coverage and DOC and dissolved organic nitrogen (DON) concentrations in all seasons, but relationships between topography and NO3-N were often improved by considering only the area within 50 or 100m of the stream channel. This suggests nutrient cycling processes occurring near the stream channel may exert a stronger control over NO3-N stream outflow chemistry. Overall, topography and climate exert strong controls over spatial and temporal variability in stream chemistry at forested catchments; it is important to consider the interaction of these two factors when predicting the effects of future changes in climate or deposition. Author Keywords: biogeochemistry, forest, nitrate, south-central Ontario, stream chemistry, winter
regional comparison of the structure and function of benthic macroinvertebrate communities within Precambrian Shield and St. Lawrence lowland lakes in south-central Ontario
Benthic macroinvertebrtes (BMI) are functionally important in aquatic ecosystems; as such, knowledge of their community structure and function is critical for understanding these systems. BMI were sampled from ten lakes in each of two regions of south-central Ontario to investigate which chemical and physical variables could be shaping their community structure and function. Ten Precambrian Shield lakes in the Muskoka-Haliburton region, and ten St Lawrence lowland lakes in the Kawartha lakes region were sampled. These lakes are geologically and chemically distinct, creating natural chemical and physical gradients within and between both regions. Community function was assessed using stable isotope analysis to elucidate carbon transfer dynamics (δ13C) and food web interactions (δ15N). It was predicted that the BMI from Shield lakes would have a δ13C signature indicative of allochthonous carbon subsidies, whereas the lowland lake BMI signatures would reflect autochthonous production. Additionally, it was predicted that the food web length (measured in δ15N units) would be different in Shield and lowland lakes. Both of these predictions were supported; however, the data indicate that δ13C signatures are more likely influenced by catchment geology (represented by bicarbonate concentration) than the extent of allochthony. The best predictor of food web length was found to be region. To assess BMI community structure, taxonomic richness, %EPT (% Ephemeroptera, Plecoptera, Trichoptera; a water quality index), and distribution of functional feeding groups were examined. Based on chemistry it was expected that the Shield lakes would be more speciose, and of greater water quality (relatively lower nutrient levels). These predictions were rejected; since there were no significant regional differences in taxonomic richness or biologically inferred water quality (%EPT). However, sediment size was found to best explain the variability in both metrics, with greater richness and %EPT found at sites with medium and small substrates than those with large substrates. Significant regional differences were found in the distribution of functional feeding groups. Most notably, there were significantly greater proportions of scrapers and shredders in the lowland and Shield lakes, respectively. Based on the feeding mechanisms of these invertebrates it can be inferred that allochthonous subsidies are likely of greater importance to Shield lake BMI communities than those of the lowland lakes; supporting the carbon transfer prediction. These findings provide insight about the structure and function of BMI communities from two dominant lake types in Ontario, and could be useful when determining how future chemical and physical changes will impact these communities. Author Keywords: benthic macroinvertebrates, community function, community structure, Precambrian Shield, stable isotopes, St. Lawrence lowlands
Early Responses of Understory Vegetation to Above Canopy Nitrogen Additions in a Jack Pine Stand in Northern Alberta
Abstract Early Responses of Understory Vegetation After One Year of Above Canopy Nitrogen Additions in a Jack Pine Stand in Northern Alberta Nicole Melong Nitrogen (N) emissions are expected to increase in western Canada due to oil and gas extraction operations. An increase in N exposure could potentially impact the surrounding boreal forest, which has adapted and thrived under traditionally low N deposition. The majority of N addition studies on forest ecosystems apply N to the forest floor and often exclude the important interaction of the tree canopy. This research consisted of aerial NH4NO3 spray applications (5, 10, 15, 20, 25 kg N ha-1yr-1) by helicopter to a jack pine (Pinus banksiana Lamb.) stand in the Athabasca Oil Sands Region (AOSR) in northern Alberta, Canada. The main objective was to assess the impacts of elevated N after one year of treatment on the chemistry of understory vegetation, which included vascular plants, terricolous lichens, epiphytic lichens and a terricolous moss species. Changes in vegetation chemistry are expected to be early signs of stress and possible N saturation. Increased N availability is also thought to decrease plant secondary compound production because of a tradeoff that exists between growth and plant defense compounds when resources become available. Approximately 60% of applied N reached the ground vegetation in throughfall (TF) and stemflow (SF). Nitrate was the dominant form of N in TF in all treated plots and organic N (ON) was the dominant form of N in SF in all plots. The terricolous non-vascular species were the only understory vegetation that responded to the N treatments as N concentration increased with increased treatment. Foliar chemistry of the measured epiphytic lichens, vascular species, and jack pine was unaffected by the N treatments. Based on biomass measurements and N concentration increases, the non-vascular terricolous species appear to be assimilating the majority of TF N after one year. Vegetation from the high treatment plot (25 kg N ha-1yr-1) was compared to a jack pine forest receiving ambient high levels of N (21 kg N ha-1yr-1) due to its proximity to Syncrude mining activities. Nitrogen concentrations in plant tissues did not differ between the two sites; however, other elements and compounds differed significantly (Ca, Mg, Al, Fe). After one year of experimental N application, there were no environmental impacts consistent with the original N saturation hypothesis. Author Keywords: Athabasca Oil Sands Region, Canopy Interactions, Jack Pine, Nitrogen, Secondary Chemistry, Understory Vegetation
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
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

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