Cyanobacterial and algal blooms can negatively affect water quality particularly when producing toxins that affect human health and wildlife. While reports of blooms are on the rise globally, their underlying causes remain unclear. The goal of this thesis was to determine temporal changes in cyanobacterial abundance and composition through sediment cores in relation to (1) altered land-use leading to cultural eutrophication and (2) warmer air temperatures that have been recorded in the past few decades. This involved evaluating the use of DNA extracted from lake sediments to quantify cyanobacterial abundance and composition. Lake sediments preserved under appropriate storage conditions showed the potential to yield high quality DNA for downstream molecular applications. Cyanobacteria, quantified using the 16S rRNA gene, were found to have increased over the last three decades in comparison to historical averages (since the 1850s) both inside and outside a protected area in western Quebec, Canada, in concert with recent regional warming. Copy numbers of 16S rRNA genes specific to cyanobacteria largely correlated to temporal trends in cyanobacterial pigments. Larger percent increases were seen in cyanobacterial genes in recent times compared to changes in the eubacterial glutamine synthetase (glnA) gene. The mcyD gene was quantified as a proxy for microcystin production through sediment cores from two lakes of western Canada. Copy numbers of both mcyD and Microcystis 16S rRNA correlated with chemical analyses of microcystin through time in cores. Cyanobacteria in the more eutrophic of these lakes shifted toward less diverse assemblages and more toxigenic taxa in recent years. Lastly, temporal and spatial changes in cyanobacterial diversity were analyzed through pyrosequencing of cyanobacterial 16S rRNA along a latitudinal transect representative of northern Canada. Significant shifts towards less diverse assemblages were found, composed of potentially toxigenic strains, suggestive of climate warming in northern latitudes. These results support recent reports of increased abundance and geographic expansion of cyanobacteria and point to increases in cyanotoxins in some cases. Using DNA archived in sediments to determine the historical state of cyanobacterial abundance and diversity could help inform lake management policies.

Almost all sediment transport equations incorporate the Shields parameter, which is a ratio of the total boundary shear stress as a driving force and the particle weight as a resisting force. Shields (1936) equated particle resistance to entrainment with particle weight, which is proportional to particle diameter, or bed texture. The present work analyses the particle resistance term in the Shields parameter. As the bed material adjusts to a given flow condition, bed stability increases. The arrangement of particles into more stable configurations is here termed geometric structure, and includes the formation of pebble clusters, and imbrication. After an initial surface coarsening, here termed textural structure, particle resistance to movement is a function primarily of geometric structure. The Shields number for entrainment is thus a measure of particle resistance due to both types of bed structure rather than the conventional notion of particle resistance due to particle weight. The response of a mobile bed surface composed of < 8 mm diameter gravels to flowing water was explored in a 6 meter by 0.5 meter flume using four different slopes and various water depths. Corrected bed shear stresses varied between 0.05 and 2.79 Pa. Step increases in discharge with a constant slope caused the bed surface to develop a structure which was more stable at the end of a run than at the beginning. Under these conditions, the Shields number for incipient motion was found to vary between 0.001 and 0.066. This variability can be explained by the degree of geometric structure present. Previous studies, including Shields' work (1936), have implicitly included the effects of geometric structure on incipient motion. Surface coarsening develops with very low flows, but subsequent coarsening in higher flows is minor, with less than 5% increase in median diameter following a 50% increase in bed shear stress. Calculations of Manning's n based on depth, slope, and velocity measurements show an increase in flow resistance as structure develops. The development of a coarse surface layer appears to be limited by flow characteristics near the bed which are in turn modified by the development of structure. Measurements of the area occupied by the largest stones show that they do not cover more than 14% of the surface during maximum coarsening. Froude scaling of the flume data indicates that the time necessary for development of maximum strength is on the order of a month for natural rivers under steady flow conditions. This suggests that gravel river beds are rarely in equilibrium with natural flow conditions. / Arts, Faculty of / Geography, Department of / Graduate

The phenomenon of the debris torrent is explored by examining the mechanisms of initiation, particularly those of rainfall and deforestation. The types of precipitation likely to contribute to instability are identified and data collection is reviewed. Debris torrents have characteristics unlike that of ordinary stream flow, and are capable of transporting massive quantities and sizes of material. Models to explain this transport capability are compared and contrasted. A theoretical analysis of the flow regime is carried out which is argued to be consistent with the observed turbulent nature of a debris torrent. This analysis is extended to the calculation of superelevation in bends and shows that current attempts to estimate velocities from super-elevation data may be very conservative. Further application of the turbulent stress analysis is used to estimate the angle of spread of the debris torrent in the deposition zone, and this analysis may be useful in zoning the downstream area to safeguard construction. / Applied Science, Faculty of / Civil Engineering, Department of / Graduate

Fifty-three earthflows in south-central British Columbia were identified from an air photograph search and from a review of previous geologic reports. Many have parallel 'en echelon1 lateral deposits indicative of several movement phases during the postglacial period, and some have been active during the present century up to the time of the study. The purpose of this study was to date phases of earthflow activity during the postglacial period and relate them to climatic fluctuations. Earthflows in the study area are concentrated in serpentinised peridotite, basalt, sediments (mainly volcaniclastics), and other volcanics. Earthflows take place preferentially down dip in sediments and many are associated with fault lines. All earthflow materials, except those derived from serpentinised peridotite, weather to montmorillonite-rich material, and each yields a characteristic grain-size distribution. Earthflow gradient in the study area depends upon material type, indicating that earthflow texture and mineralogy govern shearing resistance and hence partially determine characteristic slope angles. Earthflow movement during the past 60 years was investigated using air photograph chronosequences dating back to 1928. Reactivations of six flows were identified in the period 1950 to 1960, and an analysis of precipitation records from four stations around the study area showed that the level of winter precipitation increased around 1950. It was concluded that the observed reactivation was a response to rising groundwater levels during a period of increased winter precipitation. Earthflow movement and climatic fluctuations over the last 200 years were investigated in an analysis of tree-ring width records at four sites. Moist phases were recorded in the periods 1800-1830, 1870-1920 and from 1945 to the present. Compression wood formation at three sites corresponded with moist phases, so it was concluded that, over the last two centuries, earthflow movement was probably coincident with phases of higher precipitation. A postglacial climatic chronology was inferred from published pollen analyses and from Neoglacial ice fluctuations, both within and outside the study area. New palynological data were collected from Red Mountain, a high elevation site in the west of the study area. These showed a two-phase cooling period following the close of the Hypsithermal. The first cooling period took place around 6-7,000 BP, and the second around 3,000 BP. Earthflow movement during the postglacial period was analysed using radiocarbon dates, tephrochronology, stratigraphy, carbonate accumulation, and earthflow morphology. Data from twenty-one sites showed that movement was concentrated mainly after 7,000 BP, and at several sites the stratigraphic position of the Bridge River tephra dated movement around 2,400 BP. It was concluded that, at this longer timescale, movement at many sites could be attributed to post-Hypsithermal climatic deterioration. / Arts, Faculty of / Geography, Department of / Graduate

Metal concentrations in sediment and two species of freshwater fish (lake trout [Salvelinus namaycush], and grayling [Thymallus arcticus) were examined in four Arctic lakes in Alaska. Concentrations of several metals were naturally high in the sediment relative to uncontaminated lakes in other Arctic regions and more temperate locations. For example, concentrations of Hg and Ni were 175 ng/g and 250 ng/g dry weight, respectively, in Feniak Lake surface sediment. If any anthropogenic enrichment has occurred, it is not distinguishable from background variability based on surface sediment to down core comparisons. With the exception of Hg, the site rank order of metal concentrations (Cu, Cd, Ni, Pb, and Zn) in sediment and freshwater fish tissue among lakes is not consistent. This suggests that a number of physical, chemical, and physiological parameters mediate metal bioavailability and uptake in these systems. Maximum concentrations of most metals in fish from this study are equal to or higher than those collected from remote Arctic lakes and rivers in Canada, Finland, and Russia. Muscle Hg concentrations in excess of 1 μg/g wet weight were observed in lake trout from Fenink Lake, which has no identified Hg source other than naturally Hg enriched sediments. Fish diet seems to influence some heavy metal burdens, as evidenced by the higher concentrations of some metals in lake trout compared to grayling, and differences among lakes for lake trout. Cadmium, Cu, and Zn burdens were higher in lakes where snails were consumed by trout compared to lakes without snails.

The Port of Gulfport along with others on the Mississippi Gulf Coast experience large amounts of sediment deposition within their harbors and channels. The primary tool for sediment removal is dredging, which can be expensive and create downtimes in port operations. Research will study deposited material to determine its sources and suggest solutions for reduction of sediment deposition using structures, technologies and/or practices. Instruments used for such studies will be clam-shell dredges, Niskin tubes, and automatic samplers to test bed sediment gradation, suspended point sediments and tidal variations in suspended sediments, respectively. Additionally, fluid mud data will be retrieved from the U.S. Army Corps of Engineers ERDC. This combination of data will assist in the development of solutions for reducing sediment deposition within the port. Furthermore, research will be performed to compare the estimated throughput without dredging to throughput with dredging. This estimation will be shown in a simulated model.

No description available.

<p>A gravel pit west of Galt exposed about 6m of shallow braided outwash gravels which overlie deposits of unknown origin with eroded topography. The outwash shows two cycles of coarse sediment deposition with a relatively quiet period between. The lower cycle fines upwards from coarse gravel, through cross-bedded pebbly sand, to silty ripple-drift. The upper cycle erodes the silty sand and coarsens upwards from pebbly sand cross-beds to cobble gravel of longitudinal bars. These bars can be shown by their internal sandy horizons and stoss side sandy deposits to have grown by deposition at their upstream end. </p><p>The two major depositional cycles are related to north-westward flowing meltwater from the glacier as it stood at the Paris and Galt moraines respectively with the quiet period representing the time of retreat between the moraines. Subsequent melting to the north initiated an ice-contact spillway which ended the outwash deposition west or Galt. </p> / Thesis / Bachelor of Science (BSc)

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Abstract Not Provided / Thesis / Bachelor of Science (BSc)