No description available.

No description available.

Aquifers associated with the Oak Ridges Moraine (ORM) supply drinking water to more than 200,000 people. These aquifers are often overlain by relatively lower permeability till deposits (aquitards) often considered to provide protection to underlying aquifers. A transformer station is under construction by Hydro One (H1) on 11 hectares of H1 owned land on the ORM in the Municipality of Clarington, Ontario. The surficial geology is mapped as till. It is important to consider potential groundwater impacts of this transformer project. As part of the environmental assessment conducted by H1, groundwater information was collected from the property and from nearby homeowner wells. This thesis concerns the geology and groundwater conditions beneath the property utilizing both existing information and also study of a drill hole, commissioned by H1, continuously cored into bedrock at 127.76 m depth. There is a paucity of deep hydrogeological information over the eastern half of the ORM. This thesis reports on the hydrogeology of the local area, which is in a hydrologic setting common throughout much of the ORM, thereby providing valuable information to inform the regional context. The cored hole showed the presence of two deep regional sand aquifers, known as the Thorncliffe and Scarborough aquifers, overlying bedrock. The surficial till unit is interpreted to be over 75 m thick and includes a near-surface sand layer and two deeper, thin sandy layers within this very dense till. This study, conducted as a collaboration between the Universities of Guelph and McMaster, represents the first phase of a continuing study of the hydrogeology of the H1 property and adjacent area. The next phase includes installation of a depth-discrete, multilevel monitoring system (MLS) for water level measurement and groundwater sampling at 16 different depths. This thesis includes a design for this MLS to be installed beside the deep hole. / Thesis / Master of Science (MSc) / This thesis concerns the geology and groundwater conditions at the Hydro One transformer station under construction in the Municipality of Clarington, located near the southwestern periphery of the Oak Ridges Moraine (ORM). The ORM, throughout its full extent north of Lake Ontario, has aquifers supplying drinking water to more than 200,000 people, some near the transformer station. The thesis, which is the first phase of a longer term study, uses information obtained from a borehole that provided continuous core samples from near ground surface down through deposits formed by Pleistocene glaciers and into the shale bedrock at 127 m depth. This borehole and four monitoring wells installed by Hydro One nearby, provide the first deep groundwater information of its type available from this part of the ORM and indicate the presence of two deep regional sand aquifers and suggest the occurrence of two thin intermediate depth sand aquifers.

Tafoni have been confusingly defined in many ways: variations in size, rock type, and forming mechanisms. This study addresses tafoni in Quaternary eolian carbonates to help better define the term. Large tafoni were differentiated from other coastal caves in the Bahamas, specifically flank margin and sea caves, using morphometric analyses. The differentiation is important as all three cave types form in the same area, but flank margin and sea caves can be used as paleo-sea level indicators, while tafoni cannot. Small tafoni show a growth rate of 0.022 m3/yr; and may amalgmate to form larger tafoni, which grew at 0.65 m3/yr. Petrographic analysis helped identify tafoniorming mechanisms; results revealed no evaporites present, removing crystal wedging as a mechanism, while indicating wind erosion as the primary mechanism. This analysis found significantly greater cements within the Holocene rocks compared to previous studies, and SEM analysis revealed organic cements preserved by oil-based cutting.

No description available.

No description available.

<p> The Dundas Valley is a deep bedrock valley underlying the Hamilton-Wentworth region of southern Ontario that has been infilled with up to 180m of Quaternary sediment. These sediments contain a valuable record of past environmental change, as well as control groundwater and contaminant migration pathways throughout the region. Unfortunately, the nature, origin and spatial distribution of sedimentary units comprising the infill are poorly understood. This thesis demonstrates the use of 3-D modeling of subsurface geological data obtained from water well and borehole records, engineering and construction reports to delineate the form and geometry of the sedimentary infill of the Dundas Valley. ROCKWORKS 2002 is used to analyze and model over 2000 data points and create a variety of 3-D images used as an aid to the interpretation of the late Quaternary geological history of the study area. </p> <p> Sediments identified within the valley include fine-grained diamicts, clays, silty clays, sands, gravels and silty sands. These sediment types are grouped into five stratigraphic units that record changing environmental conditions during the late Quaternary. Unit 1 represents the eroded Paleozoic bedrock surface and is overlain by a patchy veneer of sandy gravel (Unit 2), probably deposited under fluvial or shallow lacustrine conditions. Fine-grained deposits of Unit 3 record glacially-influenced lacustrine deposition in the Dundas Valley, possibly during a subsequent episode of ice advance. Unit 4 consists of coarse-grained nearshore deposits associated with the development of post-glacial Lake Iroquois and uppermost silts and sands of Unit 5 record the development of protected lagoonal conditions at the western end of the Ontario basin. </p> <p> The 3-D images of the Dundas Valley infill are also used to identify and delineate the geometry of aquifers and aquitards and to help predict potential directions of groundwater flow and potential contaminant movement. </p> / Thesis / Master of Science (MSc)

Organically modified montmorillonite has been extensively used as nanofiller in studies of polymer layered silicate nanocomposites, promising materials for today's automotive industry because the nano-materials reduce the overall weight of vehicle. However, industrial applications have not followed suit primarily due to cost/performance issues. Supercritical carbon dioxide is promising as an aid in the production of a fully exfoliated polymer layered silicate nanocomposite but has not been fundamentally studied in this regard at present. As the first stage in studies of using supercritical carbon dioxide for aiding the production of thermoplastic elastomer nanocomposites, this thesis investigates the influence of this unique supercritical fluid on the microstructure and surface chemistry of five organically modified clays. Four alkyl-based quaternary ammonium surfactants with different number and length of chains attached and one aromatic quaternary ammonium surfactant were chosen to vary the degree of C02-philicity exhibited by the organoclay. In a high pressure batch vessel, the different organoclays were suspended in the supercritical solvent at temperatures of 50°C and 200°C and pressures of 7.6 MPa and 9.7 MPa for a fixed time and then removed after depressurization at 0.2 MPa/s or 4.8 MPa/s. The structures of these treated clays were characterized by XRD, TEM, DSC, TGA, FT -IR, and SEM, and their chemical properties were analyzed by various methods including atomic absorption spectroscopy, and contact angle measurement. The potential role of water to favor the interaction between scC02 and an organoclay was also investigated. Solute-solvent interactions plasticized the organic modifier while suspended in the supercritical fluid, which resulted in greater chain mobility and further cation exchange. The results indicate that surfactants exhibiting a paraffin-type conformation within the galleries of the clay were most likely to experience significant basal expansion, provided the tilt angle was not already close to being perpendicular to the silicate surface. For those organoclays demonstrating basal expansion, it was noted that the resulting particle size was increased due to enhanced porosity. Water proved useful in clay expansion in certain cases and primarily while operating conditions allowed the co-solvent to remain adsorbed to the clay surface. / Thesis / Master of Applied Science (MASc)

This thesis is missing page 57, this page is not in any of the other copies. -Digitization Centre / Scientists believe that the global climate is undergoing significant changes due to anthropogenic increases of carbon dioxide (CO2) and other Greenhouse gases. The relationship between climate and vegetation is not fully understood. Knowledge of the response of vegetation to past climate change aids in the understanding of potential vegetation responses to climatic changes due to the Greenhouse effect. The objectives of this thesis were to determine if vegetation in the lower Lena River Region has changed in the past, what were the factors which caused the changes and over what time scales did the changes occur. To address the objectives, the pollen, stomate and sediment stratigraphy of a core from a medium size lake, located in north-central Siberia, were analysed. Radiocarbon dating indicates that the record spans the last 12310 yr BP, and possibly the last 15000 yr BP. The early part of the fossil record was characterised by short rapid changes in the vegetation. The initial shrub tundra was quickly replaced by herb tundra with sparse vegetation cover. This was followed by a reversion to shrub tundra conditions at ~12000 yr BP. A clear Younger Dryas signal is found in this record between 11000 and 10000 yr BP, characterised by a shift from shrub tundra to herb tundra dominated by taxa with arctic affinities. The warming at the close of the Younger Dryas signalled the first appreciable climatic amelioration at this site. Following 10000 yr BP, Alnus became abundant in the pollen record and likely on the landscape. The dominance of Alnus was short lived however. At ~8500 yr BP arboreal vegetation, dominated by Larix dahurica, became abundant in the pollen and stomate record. The expansion of forests was the result of changes in the orbital parameters of the earth as predicted by Milankovitch cycles. Arboreal vegetation persisted in this region until-3500 yr BP when the modem shrub tundra vegetation was established. The use of a new technique, stomate analysis, proved extremely useful. Stomates accurately recorded the expansion and retreat of treeline across this region. This study clearly indicates the usefulness of this technique, especially for investigating fluctuations of treeline. / Thesis / Master of Science (MS)

Quaternary ammonium compounds (QACs) are antimicrobial disinfectants commonly used in commercial and household settings. While these compounds have been used for decades, reproductive toxicity has not been thoroughly evaluated. Extensive use of QACs results in ubiquitous human exposure to potentially toxic compounds. Reproductive toxicity of two common QACs, alkyl dimethyl benzyl ammonium chloride (ADBAC) and didecyl dimethyl ammonium chloride (DDAC), was investigated to determine gender-specific toxicity with an emphasis on male reproductive function. Breeding pairs of mice exposed for six months to ADBAC+DDAC exhibited decreases in fertility and fecundity, with fewer pregnancies and decreased numbers of pups over a six month period. Females proceeded through significantly fewer estrus cycles, and both ovulation and implantation rates were reduced. Males exhibited declines in both sperm concentration and motility. Male reproductive toxicity was further assessed in a series of in-vitro and in-vivo experiments. ADBAC+DDAC were cytotoxic to testicular Sertoli cells in culture at concentrations greater than or equal to 0.0005%. Changes in blood-testis-barrier integrity (BTB) were observed at 0.01% ADBAC+DDAC using a two-compartment culture system that measures transepithelial electrical resistance (TER). Sertoli cell cytotoxicity correlated with decreased TER at ADBAC+DDAC concentrations above 0.001%. In-vitro fertilization capacity of epididymal sperm was reduced in males given a 10-day rest period following ADBAC+DDAC exposure. Multigenerational changes in sperm parameters and in mRNA expression of enzymes involved with epigenetic modifications were evaluated across three generations. Sperm concentration and motility were reduced in F0 males exposed directly to ADBAC+DDAC. In F1 males, sperm concentration was increased and motility decreased, while there was no change in the F2 progeny. Genes involved in epigenetic modifications were altered in the exposed F0, with upregulation of two histone acetyltransferases (Hat1 and Kat2b) and downregulation of one lysine-specific demethylase (Kdm6b). F1 and F2 generations were not different from controls except for downregulation of the methyltransferase Dnmt1 in F1 progeny. The reproductive toxicity of ADBAC+DDAC identified in these studies, particularly to the male, compels further investigation into the potential effects that these compounds may have on human reproduction. / Ph. D.