This thesis examines both surface water and shallow groundwater connections in boreal watersheds at two study sites in the Athabasca Oil Sands Region using conventional hydrological techniques as well as stable water isotope techniques. Increased emissions due to oil sands development are expected to contribute significantly to acidifying airborne emissions. Specifically, nitrogen is forecasted to be deposited on the surrounding area within approximately 100 km of operations. The purpose of the research is to provide background information for predicting how individual terrain units such as fens, bogs, and uplands will respond to increased nitrogen loads, and to assess whether or not these units will act as sources or sinks of nitrogen under higher nitrogen deposition. Two study sites situated within 100 km of Fort McMurray, Alberta were instrumented with a total of 30 nested piezometers, 26 water table wells, 4 micro-meteorological stations, and two gauging stations (weirs) at outflow points. Monitoring occurred during the open water season of 2011 and 2012. This study estimates evaporation through a simplified energy balance, documents hydraulic conductivity of shallow aquifers, utilizes stable isotopes of water to assist in mapping seasonal flow patterns, and calculates a vertical water balance for the sites. Bogs and fens were hydrologically connected, as bogs fed fens laterally at shallow depths within the acrotelm during wet years. Upland terrain units were found to have more variable connections. In spring, upland runoff recharged the wetlands at both sites. At JPH groundwater flowed towards the fen, whereas in ML limited connections were observed between the uplands and the fen. Also, no connections were seen to indicate that the wetlands recharged the uplands. A conceptual model is developed that emphasizes the role of connectivity in the boreal landscape. The main implication for nitrogen cycling is that it is difficult to quantify one landscape as a source or sink for additional nitrogen as its role may vary depending on seasonality and temporal scales. Further work is needed to identify if nitrogen loadings will have adverse affects on geochemistry of water at the sites. / Graduate / 0366 / amyvallarino@gmail.com

Development of the Athabasca Oil Sands Region (AOSR) has increased atmospheric nitrogen emissions, a trend which is expected to increase in the future. The area surrounding development is comprised of Boreal upland forests and peatlands. Improved understanding of the hydrological connectivity between Boreal peatlands and uplands is needed to predict the fate and transport of atmospheric N deposited across the region. Two field sites: Jack Pine High (JPH, located 45 km north of Fort McMurray) and Mariana Lakes (ML, located 100 km south of Fort McMurray) were instrumented with piezometers nests and water table wells for this study (n= 108 sampling locations). The wells were placed along transects that cover target landscape units (bog, fen, upland). Wells were sampled for water isotopes and geochemical parameters during the summers of 2011-2014 to characterize the baseline geochemistry of groundwater in the different landscape units. Inorganic (nitrate, ammonium) and organic forms of nitrogen (dissolved organic nitrogen), major and minor ions and water isotope tracers (18O, 2H and 3H) were measured to identify the various forms of nitrogen in the different landscape units, as well as to assess connectivity and potential for nitrogen transport between the different units. At JPH surface and groundwater flow is from the uplands to the fen. There was little (<0.1-1.5 mg/L) nitrate, ammonium, or dissolved organic nitrate (DON) found throughout JPH. At ML nitrogen concentrations were higher (<0.1-30 mg/l) and concentrations of ammonium and DON increased at depths throughout ML. The distribution of 3H with depth within the peatland reveals limited connectivity between the peat and underlying mineral soils. Tritium sampling at ML indicates that at some locations the wetland residence time is greater than 50 years. Nitrogen movement out of peatlands may take longer due to conversions and storage. At ML nitrogen (NH4 and DON) is produced and stored at depth in the wetlands. At JPH higher nitrogen concentrations are found in the shallow groundwater of the fen. Increases in nitrogen inputs to JPH and ML are likely to be utilized by plants, but dramatic changes to the peatland may cause stored nitrogen to become mobile. / Graduate

M.Sc Thesis / Northern peatlands are able to persist on the landscape and continue to accumulate carbon in the long-term thanks to a suite of ecohydrological feedbacks that confer resilience to disturbance such as the drier and warmer conditions associated with climate change. One feedback of particular interest operates between peat pore-water residence time and chemistry, whereby changes in hydraulic structure with depth restrict turnover in deeper layers, allowing decay end-products to accumulate and thermodynamically suppress decomposition. In this way, the burial of peat facilitates its continued recalcitrance. While this feedback has been observed in more extensive northern peatlands, at least on the side of carbon dynamics and geochemistry, there has been no observational study of profiles of pore-water residence time nor has it been assessed in smaller peat-forming systems. The peat-filled bedrock depressions of the Canadian Shield offered a unique opportunity to study this feedback in systems where primary peat formation occurs under geological constraints on growth in the form of the largely impermeable bedrock. These systems play important hydrological, biogeochemical and ecological roles on the landscape. Understanding their resilience on the landscape may reveal key insights into their evolution and their response to disturbance, which is increasing in the eastern Georgian Bay region. These systems have previously exhibited a hydrological feedback between water table depth and specific yield that varies with depression size. To assess the hydraulic structure that constrains pore-water transport to support continued recalcitrance, profiles of hydrophysical properties and pore-water residence time in four deep (>0.4 m mean depth) and five intermediate (<0.4 m) depressions. Hydraulic structure varied by depression size and depth in the profile, with very low hydraulic conductivities measured in the catotelms of deep sites. The two classes of depressions exhibited distinct hydrology, in the form of dampened water table fluctuations and hydraulic gradients in the deeper sites. Stable isotope analysis of δ2H and δ18O was used to estimate relative pore-water residence times using the simplified inverse transit time proxy (ITTP) for samples collected from May-August 2017. These estimates were observed to have similar controls to hydraulic structure and a close relationship with depth-averaged conductivity on a whole-site basis. While it was hypothesized that the catotelms of deeper depressions would have less pore-water turnover than that of shallower depressions, the ITTP was only able to differentiate between catotelm-acrotelm and deep-intermediate individually. The relative residence time of pore-water in deep catotelms based on δ2H was longer than in intermediate catotelms, but not significantly. These results broadly supported previous pore-water residence time work despite the likely ubiquitous promotion of turnover in the wetter-than-average study period. Carbon accumulation was quantified from extracted peat cores and pore-water chemistry was assessed as dissolved organic matter (DOM) quality using fluorescence spectrometry of monthly pore-water samples. Fluorescence and absorption indices varied by the same depression characteristics as hydraulic structure of site size and depth, but only the humification index exhibited significant temporal variation. Characterization of pore-water DOM was somewhat unclear across the seven indices calculated, although the DOM of intermediate sites appeared to be less humified, more recently produced and autochthonous in nature compared to deep sites Carbon accumulation was predominantly driven by the waterlogged, relatively stable carbon stored deep in the catotelm. Total carbon accumulated in the profile, and even more so the amount stored in the catotelm, were strongly related to depression depth. The thickness and carbon storage of the acrotelm was insensitive to depression morphology, with some intermediate sites being considered all acrotelm based on their water table behaviour. Overall, deeper peat-filled depressions showed stronger signs of the pore-water residence time-chemistry feedback, suggesting the carbon stored in their deep peat layers is more resilient to decay, by way of less conductive deep peat, longer relative pore-water residence times and more humified, less biologically active DOM. In order to comprehensively assess this feedback, longer stable isotope records are essential to ensure robust residence time estimates through differing moisture conditions, and a greater variety of depression sizes may allow for elucidation of threshold depression sizes where hydrological behaviours diverge. This study, at least on a categorical basis, can be used to inform conservation strategies of the relative vulnerability of these important reptile habitats and carbon stores, as well as guide restoration efforts to construct sufficiently deep, resilient systems. / Thesis / Master of Science (MSc)

Delineating spatial patterns of precipitation isotopes (“isoscapes”) is important for studies including the hydrology of terrestrial systems, present and past interpretations of climate, and tracer-aided hydrological modelling, among others. However, the extent to which precipitation isoscapes can be predicted across Canada has not been fully articulated. This thesis combines isotopes in precipitation (δ18Oppt) observations from two regional and one global network to create long term and time series precipitation isoscapes for Canada and the northern United States. Multi-linear regressions of a small suite of geographic and climate variables generate the best performing long-term and seasonal models of δ18Oppt. These models are used to develop long term isoscapes for Canada, which capture the general spatial and seasonal trends in δ18Oppt, showing an improvement upon results from previous studies using global models. Building upon long-term δ18Oppt prediction, δ18Oppt observations alongside climatological and geographic predictors are used to create empirical time series prediction models. Five regionalization approaches are used to separate the study domain into isotope zones to explore the effect of spatial grouping on simulations. Generally, the models capture the timing and magnitude of intra-annual (seasonal) δ18Oppt cycles across the study domain while simulating moderate inter-annual variation; however often fail to capture the anomalies in observed δ18Oppt. Uncertainty in predictions is quantified spatially and temporally, and the Köppen-Geiger (Kpn) regionalization is selected as the preferred regionalization scheme for future applications due to adequate model performance and lack of border issues at regional boundaries. Finally, estimates of monthly δ18Oppt from Kpn models, long term annual averages, and daily REMOiso output are used to force an isotope-enabled hydrological model, isoWATFLOOD, in the Fort Simpson Basin, NWT, Canada. Results show streamflow simulations are not significantly impacted by choice of δ18Oppt input; however, oxygen-18 in streamflow and the internal apportionment of water (and model parameterizations) are impacted, particularly during large precipitation and snowmelt events. This work shows how isoWATFLOOD can be used in regions with limited δ18Oppt observations, and that the model can be of value in such regions. This study reinforces that a tracer-aided modelling approach works towards diagnosing issues surrounding model equifinality. / February 2017

In surface hydrology, much attention is paid to the effects of changing water fluxes, however there is less of a focus on the effects of changing energy fluxes. These energy fluxes are an important driver of many hydrological processes such as evapotranspiration and snow sublimation/ablation. The hypothesis that varying energy fluxes are important to the hydrological features of a catchment is tested by an experiment that involves calculating mean transit times for a number of catchments that drain different aspects of a large dome located in the Valles Caldera, New Mexico, called Redondo Peak. These catchments have different orientations and therefore receive different amounts of solar radiation. There is a general correlation between mean transit times, as determined by lumped-parameter convolution, and aspect, suggesting that in the Valles Caldera, transit times might be affected by a variety of features that are influenced by exposure to solar radiation, such as slope steepness, vegetation patterns, and soil depth. To put these transit times into context, I also used a distributed physically-based model to simulate a number of factors simultaneously to determine how hydrological features are influenced by aspect. This modeling excercise has illuminated the aspect-dependence of hydrological features such as the timing and intensity of snowmelt and soil moisture patterns, and it has quantified differences in energy and water fluxes on different aspects. These factors affect both water storage and water fluxes, and are therefore tied to transit times.

BRITO, Adriano Leal de. Oxigênio-18 e deutério traçadores do sistema de aqüíferos na Bacia Sedimentar do Araripe. 2012. 96 f. Dissertação (Mestrado em Física) - Programa de Pós-Graduação em Física, Departamento de Física, Centro de Ciências, Universidade Federal do Ceará, Fortaleza, 2012. / Submitted by Edvander Pires (edvanderpires@gmail.com) on 2015-10-21T21:30:43Z No. of bitstreams: 1 2012_dis_albrito.pdf: 1763548 bytes, checksum: 4fe45ca63d81b9f56baf5d804acb37a4 (MD5) / Approved for entry into archive by Edvander Pires(edvanderpires@gmail.com) on 2015-10-22T21:31:50Z (GMT) No. of bitstreams: 1 2012_dis_albrito.pdf: 1763548 bytes, checksum: 4fe45ca63d81b9f56baf5d804acb37a4 (MD5) / Made available in DSpace on 2015-10-22T21:31:50Z (GMT). No. of bitstreams: 1 2012_dis_albrito.pdf: 1763548 bytes, checksum: 4fe45ca63d81b9f56baf5d804acb37a4 (MD5) Previous issue date: 2012 / The natural tracers deuterium and oxygen-18 were used to identify the dynamic characteristics of the groundwater reserves in the Araripe Sedimentary Basin, through the analysis of water samples collected in 40 wells in January, April, July and October 2011. The sampling points are located in 08 municipalities and electrical conductivity measurements, which expresses water salinity, were also performed. The results show spatial and temporal variation of the parameters analyzed, but the average values of δ18O in samples from 33 wells is -3.22 ± 0.05 (‰) which is the average rainfall in the region today. Samples of the remaining seven wells showed higher fluctuations and four had values below -3.2 ‰. The meteoric lines that express measures of deuterium versus oxygen-18, constructed with values of each sample show a mean slope of 7.87 ± 0.60 ‰ about the value of the World Meteoric Line. The excess of deuterium in the sample period increased from 7.26 to 9.38 ‰ reflecting internal processes in the aquifer. Samples with values of δ18O in meteoric waters below the current mix of show paleowater already identified with modern recharge water, the samples with these values are not distinguishable by their electrical conductivities that are current in the range of samples characterizing the importance of isotopic tracers / Os traçadores naturais oxigênio-18 e deutério foram utilizados para identificar características dinâmicas das reservas hídricas subterrâneas na Bacia Sedimentar do Araripe, através da análise de amostras de água coletadas em 40 poços nos meses de janeiro, abril, julho e outubro de 2011. Os pontos de amostragem localizam-se em 08 municípios e medidas de condutividade elétrica, que expressa salinidade das águas, também foram realizadas. Os resultados mostram variação espacial e temporal dos parâmetros analisados, mas a média dos valores de δ18O em amostras de 33 poços é de -3,22 ± 0,05 (‰) que é o valor médio das chuvas atuais na região. As amostras dos sete poços restantes apresentaram maiores flutuações e quatro deles apresentaram valores abaixo de -3,2‰. As retas meteóricas, que expressam medidas de deutério versus oxigênio-18, construídas com valores de cada coleta mostram coeficiente angular com média de 7,87 ± 0,60 ‰ cerca do valor da Reta Meteórica Mundial. O excesso de deutério cresceu no período de amostragem de 7,26 a 9,38 ‰ refletindo processos internos no aquífero. As amostras com valores de δ18O em abaixo do das águas meteóricas atuais mostram mistura de paleoáguas já identificadas com águas de recargas modernas; as amostras com estes valores não são distinguíveis pelas suas condutividades elétricas que estão na faixa das amostras atuai caracterizando a importância dos traçadores isotópicos.

Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgico / Os traÃadores naturais oxigÃnio-18 e deutÃrio foram utilizados para identificar caracterÃsticas dinÃmicas das reservas hÃdricas subterrÃneas na Bacia Sedimentar do Araripe, atravÃs da anÃlise de amostras de Ãgua coletadas em 40 poÃos nos meses de janeiro, abril, julho e outubro de 2011. Os pontos de amostragem localizam-se em 08 municÃpios e medidas de condutividade elÃtrica, que expressa salinidade das Ãguas, tambÃm foram realizadas. Os resultados mostram variaÃÃo espacial e temporal dos parÃmetros analisados, mas a mÃdia dos valores de &#948;18O em amostras de 33 poÃos à de -3,22  0,05 (â) que à o valor mÃdio das chuvas atuais na regiÃo. As amostras dos sete poÃos restantes apresentaram maiores flutuaÃÃes e quatro deles apresentaram valores abaixo de -3,2â. As retas meteÃricas, que expressam medidas de deutÃrio versus oxigÃnio-18, construÃdas com valores de cada coleta mostram coeficiente angular com mÃdia de 7,87  0,60 â cerca do valor da Reta MeteÃrica Mundial. O excesso de deutÃrio cresceu no perÃodo de amostragem de 7,26 a 9,38 â refletindo processos internos no aquÃfero. As amostras com valores de &#948;18O em abaixo do das Ãguas meteÃricas atuais mostram mistura de paleoÃguas jà identificadas com Ãguas de recargas modernas; as amostras com estes valores nÃo sÃo distinguÃveis pelas suas condutividades elÃtricas que estÃo na faixa das amostras atuai caracterizando a importÃncia dos traÃadores isotÃpicos. / The natural tracers deuterium and oxygen-18 were used to identify the dynamic characteristics of the groundwater reserves in the Araripe Sedimentary Basin, through the analysis of water samples collected in 40 wells in January, April, July and October 2011. The sampling points are located in 08 municipalities and electrical conductivity measurements, which expresses water salinity, were also performed. The results show spatial and temporal variation of the parameters analyzed, but the average values of &#948;18O in samples from 33 wells is -3.22  0.05 (â) which is the average rainfall in the region today. Samples of the remaining seven wells showed higher fluctuations and four had values below -3.2 â. The meteoric lines that express measures of deuterium versus oxygen-18, constructed with values of each sample show a mean slope of 7.87  0.60 â about the value of the World Meteoric Line. The excess of deuterium in the sample period increased from 7.26 to 9.38 â reflecting internal processes in the aquifer. Samples with values of &#948;18O in meteoric waters below the current mix of show paleowater already identified with modern recharge water, the samples with these values are not distinguishable by their electrical conductivities that are current in the range of samples characterizing the importance of isotopic tracers.

Water isotope tracers and multi-proxy paleolimnological approaches are used to characterize the present and past hydrology of the Slave River Delta (SRD), NWT. This research addresses crucial gaps in knowledge about the role of major hydrological processes on the water balances of northern freshwater lakes, and responds to concerns expressed by local land users about declining flood frequency in the delta following upstream river regulation. Contemporary hydrological studies were conducted using multiple lakewater sampling campaigns from a suite of 41 delta lakes situated in three previously recognized biogeographical zones - outer delta, mid-delta and apex – that were initially sampled in fall 2002, and again immediately following the spring melt, during summer, and in the fall of 2003-2005. Paleolimnological studies aimed at reconstructing flood frequency in the Slave River focus on a sediment core obtained from a flood-susceptible lake in the active delta. Together, contemporary and past studies of SRD hydrology provide a detailed picture of environmental change and variability in an important northern freshwater ecosystem.

Lake-rich thermokarst landscapes, such as Old Crow Flats (OCF) in northern Yukon, Canada have been identified as amongst the most vulnerable to climate change. This has raised concerns of the Vuntut Gwitchin First Nation (VGFN) and Parks Canada (Vuntut National Park) about the ecological integrity of this significant wetland. The influence of climate change on the hydroecological conditions of thermokarst lakes are complex and vary across the landscape, thus long-term hydroecological monitoring is essential to adequately assess the ecological integrity of the aquatic ecosystem and how it is changing over time. In a genuine interdisciplinary and collaborative approach, this thesis establishes an integrated approach using isotope hydrology, aquatic ecology, and paleolimnology to develop a robust long-term aquatic monitoring program that has already been adopted by Parks Canada. In collaboration with Parks Canada, 14 of 58 lakes that were previously studied during the International Polar Year from 2007-09 were selected to represent monitoring lakes. Lakes were sampled in early June and late August/early September 2010-11. Water samples for analysis of hydrogen and oxygen isotope composition and chemistry (i.e., ions and nutrients) were collected to track hydrological and limnological conditions. Artificial substrates were deployed in June and accrued algae were collected at the end of the ice-free season to assess community composition and abundance. Sediment coring was conducted in a culturally-significant lake (Zelma Lake – OCF06) to reconstruct long-term baseline hydroecological conditions over the past three centuries. Radiometric dating techniques (137Cs, 210Pb) were used to develop a sediment core chronology. Baseline hydroecological conditions were reconstructed through analyses of loss-on-ignition, bulk organic carbon and nitrogen elemental and isotope compositions, and pigments. Meteorological data and a multi-year evaporation pan experiment were used to develop a robust isotope framework, which provides the basis for interpreting five years (2007-11) of lake water isotope measurements and deriving knowledge of hydrological conditions for the monitoring lakes. Using this framework and the coupled-isotope tracer method, isotopic compositions of input water (δI) and evaporation-to-inflow (E/I) ratios were calculated and provide key hydrological information for each sampling interval. δ¬I values distinguish snowmelt- and rainfall-sourced lakes, with δP representing a threshold between the two isotopic-based hydrologic regimes. A Mann-Kendall test showed that three lakes (OCF11, 26, and 49) displayed significant increasing trends in δI values indicating a potential transition from snowmelt-sourced to rainfall-sourced isotope-based hydrologic-regimes. E/I ratios >0.5 signifies lakes that are evaporation-dominated with positive water balances and E/I ratios >1 indicates lakes that are evaporation-dominated with negative water balances. Six lakes in OCF (OCF06, 19, 37, 46, 49, and 58) surpass the 0.5 threshold and three of these lakes (OCF06, 19, and 46) crossed the significant evaporation threshold (E/I > 1) during dry climatic conditions. Multi-proxy paleolimnology analysis conducted on Zelma Lake reveals different hydroecological transitions during the past ~330 years that include: phase 1 (~1678-1900) characterized by stable hydroecological conditions; thermokarst expansion (~1900-1943) marked by decreases in productivity; phase 2 (~1943-2007) distinguished by increasing productivity; and a post drainage phase following rapid drainage in 2007 characterized by further increases in productivity. The stratigraphy of Zelma Lake shows that hydroecological conditions in dynamic landscapes such as OCF are complex and require multi-proxy paleolimnological analysis. In particular, organic matter, δ13Corg, and pigment concentrations are important parameters to consider when interpreting past hydroecological conditions, thermokarst expansion, and lake drainage events.

Water isotope tracers and multi-proxy paleolimnological approaches are used to characterize the present and past hydrology of the Slave River Delta (SRD), NWT. This research addresses crucial gaps in knowledge about the role of major hydrological processes on the water balances of northern freshwater lakes, and responds to concerns expressed by local land users about declining flood frequency in the delta following upstream river regulation. Contemporary hydrological studies were conducted using multiple lakewater sampling campaigns from a suite of 41 delta lakes situated in three previously recognized biogeographical zones - outer delta, mid-delta and apex – that were initially sampled in fall 2002, and again immediately following the spring melt, during summer, and in the fall of 2003-2005. Paleolimnological studies aimed at reconstructing flood frequency in the Slave River focus on a sediment core obtained from a flood-susceptible lake in the active delta. Together, contemporary and past studies of SRD hydrology provide a detailed picture of environmental change and variability in an important northern freshwater ecosystem.