Browsing Faculty of Graduate Studies (Electronic Theses and Practica) by Subject "137Cs"
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- ItemOpen AccessHistorical loading and current sorption capacity of phosphorus in the sediments of Delta Marsh(2020-03-31) Hope, Christopher Kevin; Stout, Jake (Biological Sciences) Akinremi, Wole (Soil Science); Goldsborough, Gordon (Biological Sciences) Badiou, Pascal (Biological Sciences)Delta Marsh is a freshwater inland coastal wetland located along the southern basin of Lake Manitoba, Canada. Spanning over 19,000 hectares, Delta Marsh is a eutrophic wetland complex that was formerly a world-renowned destination for waterfowl hunting. Over the past half century, the marsh has been in a state of decline due to invasive plant and animal species, stabilized water levels, and eutrophication due to increased nutrient loading from surrounding development. This prompted a coalition of organizations, including Ducks Unlimited Canada, to begin the “Delta Marsh: Restoring the Tradition” project in 2008 aimed at revitalizing the ecological processes and human traditions of the marsh. The objectives of this study were to investigate the marsh sediments to determine their historic rates of phosphorus accumulation and the current ability to bind phosphorus. I determined how nutrient levels have changed in the marsh over time as well as the ability for surface sediments to act as a sink or a source of phosphorus to the marsh. This was accomplished by collecting two sets of core samples; ten 50-cm cores dated using 210Pb and 137Cs and twenty-two 5-cm cores utilized for phosphorus sorption experiments. All core samples were analyzed for sediment physiochemical parameters including phosphorus concentrations, metal cations, and organic matter. For the most part, surficial sediments acted as a phosphorus sink with some inter-season variability. Furthermore, I found that phosphorus in the sediments, and by proxy the marsh waters, have been both increasing and becoming more labile over the past century (particularly since 1960), potentially indicating increasing eutrophic conditions in the marsh. These results varied across the marsh, with the largest nutrient increases occurring in the west side of the marsh, and higher phosphorus concentrations in the emergent and wet meadow vegetation zones relative to the open-water. Overall, these results indicate that although the marsh sediments are acting as a sink for phosphorus, the marsh is an increasingly eutrophic system, with a particular risk for algal blooms on the west side.
- ItemOpen AccessThe sediment and particulate organic carbon cycle of Lake Melville, Labrador: a fjard estuary undergoing hydrologic and climatic change(2015) Kamula, Christina Michelle; Macdonald, Robie (Environment and Geography) Lobb, David (Soil Sciences); Kuzyk, Zou Zou (Geological Sciences) Stern, Gary (Environment and Geography)To evaluate potential impacts of anthropogenic and climatic changes on Lake Melville, a large fjard estuary that receives runoff from the Churchill River in central Labrador, modern sedimentological processes, sources, and distribution of sediment and particulate organic carbon (POC) were investigated in recently deposited sediment (i.e., last 100-150 yrs.). This investigation showed that the Churchill River is the dominate source of sediment and terrestrial POC to the Lake Melville system which could double in the first two years following the proposed hydroelectric development on the Lower Churchill River. The sources, sinks, and losses of particulates and development of sediment and terrestrial and marine POC budgets established in this study can be used to assess changes to the system from future hydroelectric development or climatic changes.
- ItemOpen AccessSoil erosion and fluxes of sediment within landscapes of the Canadian Prairies(2023-08-23) Zarrinabadi, Ehsan; Koiter, Alexander (Soil Science); Lawley, Yvonne (Plant Science); Badiou, Pascal (Soil Science); Si, Bing (Universty of Saskatchewan); Lobb, DavidMaintaining the future sustainability of agriculture and ensuring soil security is of primary concern across Canada. Understanding the state of soil erosion and determining the vulnerable areas are essential measures in combatting future soil erosion and avoiding soil degradation. Therefore, the general goal of this thesis was to quantify soil erosion rates and develop an improved understanding of erosion processes within the Canadian Prairies. To fulfill the aim of the research project, typical agricultural and native prairie landscapes of the region were studied within three watersheds including the Red River Valley and the Broughton’s Creek watershed in Manitoba, and the Bigstone Creek watershed in Alberta. Initially, passive uni-directional wind erosion sediment samplers were employed to assess wind-eroded soil movement in agricultural lands of the Red River Valley. Cesium-137 (137Cs) measurements were conducted to quantify total soil loss and deposition rates within the wetland landscapes in the Broughton’s Creek and Bigstone Creek watersheds. In addition, soil and sediment properties were characterized to understand tillage-, water- and wind-induced sediment transport dynamics and distinguish between eroded and depositional zones. Landform classification maps of the studied wetland catchments were also created to assist developing sediment budgets of soil loss and accumulation, and quantify sediment flux rates from agricultural fields to wetland environments. Furthermore, soil erosion models were used to characterize spatial patterns of soil loss by tillage, water, and wind erosion and assess relative contribution of these processes towards total soil erosion. This study found that: i) Measured soil loss and sedimentation caused by wind erosion are very small in the Red River Valley. Moreover, abrasion of crops by wind-transported sediment was not observed in this study; ii) Using the measurements of 137Cs, average annual soil losses in cultivated fields were estimated at about 1.2 kg m-2 yr-1 and 0.9 kg m-2 yr-1 in Manitoba and Alberta, respectively, with approximately 70% of cultivated field being classified as eroded zone in both provinces; and iii) On the knoll of hummocky landscapes, tillage erosion dominates the pattern of total soil erosion and the effects of water erosion and wind erosion are minor.