<p>This thesis examines psychosocial effects in a population living near the Halton Regional Landfill site in Milton, Ontario. The data described and analyzed in this research were collected between 1990 and 1995 and capture key events in the landfill site's history--site approval, construction and operation. This longitudinal study, which examines indicators of stress, reappraisal and coping at three different points in time from the same individuals, is designed to document and examine the process whereby these people have experienced and come to live with the landfill facility over time. The theoretical basis for understanding this process of appraisal, reappraisal and coping is derived from environmental stress and coping theory generally, and from the framework proposed by Lazarus and Folkman (1984) specifically. Three research objectives are addressed: (1) to document changes in psychosocial effects in Milton area residents between 1990 and 1995; (2) to explore the processes of reappraisal and coping among Milton area residents; and, (3) to evaluate the appropriateness and usefulness of the Lazarus and Folkman (1984) framework in the context of a population living proximate to a solid waste facility. These objectives are addressed through three administrations of a telephone survey instrument comprised of a combination of pre-validated scales and open- and closed-ended items to a random stratified (by distance) sample of households immediately after the landfill site was approved (1990), shortly after the site was constructed and began operation (1992-3), and two years after operation had begun (1995). Due to attrition, the baseline cohort (n = 187) was reduced to 108 by time 3, although no significant bias was introduced. Data from all three surveys were obtained for a sub-group of 87 respondents. Five constructs derived from environmental stress and coping theory guide the examination of individual responses to the landfill over time: psychological distress, perceptions of the landfill site, concerns about the landfill site, actions and neighbourhood satisfaction. A series of hypotheses, which capture expectations about how Milton area residents have experienced the introduction of the landfill site into their community over time, were generated from the constructs and guide the analysis. Overall, the results portray a community that has changed from one actively opposing plans to locate a landfill site in its midst to one that has, for the most part, resigned itself to and accepted the presence of the new facility. (Abstract shortened by UMI.)</p> / Doctor of Philosophy (PhD)

Throughout the Holocene, a large sediment load coupled with river avulsions, tectonic activity and eustasy developed the complex stratigraphy of the Ganges-Brahmaputra-Meghna delta. Understanding this development is useful in predicting how the delta will respond to changes in the environmental setting such as climatic shifts and sea-level rise. The complex stratigraphy is also linked to high concentrations of naturally occurring arsenic in the shallow groundwater aquifers of Bangladesh through its controls on hydrogeology and aquifer biogeochemistry. This research investigates differences in the fluvio-deltaic deposits of the Ganges and Brahmaputra rivers, as well as differences in the tectonic setting across the lower delta plain. We investigate how these overarching controls influence stratigraphic architecture, the resulting aquifer systems, and ultimately arsenic distribution within the lower delta plain. A transect of 48 sediment cores spanning the lower delta plain of Bangladesh was drilled to a depth of 90m. Individual samples were analyzed for lithology, provenance and age to determine the stratigraphic architecture, the source of the sediments and the depositional history of the rivers. Delta stratigraphy was related to arsenic distribution by measuring groundwater arsenic near each borehole and combining this data with previously collected groundwater data. This study provides a better understanding of Holocene delta evolution and river behavior, as well as a more complete understanding of the geologic controls on arsenic and the characteristics of contaminant distribution in fluvial settings as they relate to stratigraphic features.

Riparian vegetation has been recognized as a controlling factor of stream channel morphology, but specific influences on bed topography and planform geometry are yet to be fully clarified. This project explores the influence of riparian vegetation on channel geometry in alluvial streams of different sizes. Field data suggest that the presence of hardwood vegetation modulates channel width, bed topography and planform geometry in low-order streams. In larger channels, rootwads have less influence on planform curvature, but create patchy variations in bed topography that amplify relief of curvature-dominated bedforms. Stream table experiments illustrate that greater values of relief and thalweg forcing are generated by larger riparian obstructions. Experiments regarding the downstream spacing of trees also reveal that specific spacing frequencies can amplify or disrupt bedform creation, suggesting that resonance between alternate-bar dynamics and forest density may generate increased bedform variation.

No description available.

It is important to understand what triggers silicic eruptions because of the implications for modern-day systems. Here, we use phase equilibria modeling to determine to what extent magmas within the crust are induced to erupt due to external triggers (e.g. earthquakes; new magma injection) and to what extent they naturally evolve to a point where eruption is inevitable. Modelling the effect of fluid exsolution on the increase in system volume demonstrates that rhyolitic magmas can reach internal triggering. We find that internal triggering is effective in magmas that are stored at 10 km or shallower, revealing a window of eruptibility within the Earthâs shallow crust. Optical mineralogy is a skillset typically introduced in a microscope lab supporting lessons in Earth materials in the classroom. Challenges arise because students do not know what to look for when looking down the microscope. Eight videos were developed with accompanying pre-lab questions and hosted online as part of semester-long, undergraduate Earth materials courses at Vanderbilt University and Illinois State University. Vanderbilt students self-report increased confidence and their testing grades in 2015, when videos were implemented, were comparable or improved compared to the 2014 offering with no videos used.

A new phase equilibria âmagma-meterâ determines a number of magmatic storage and crystallization conditions, including pressure, oxygen fugacity (fO2), state of fluid saturation, and maximum temperature for glass-bearing rocks containing the assemblage plagioclase+orthopyroxene+clinopyroxene (plag+opx+cpx). This newly developed magma-meter can better constrain crystallization conditions of shallow, glass-bearing andesites to dacites. The magma-meter utilizes rhyolite-MELTS to determine crystallization conditions utilizing the glass compositions coexisting with the plag+opx+cpx assemblage in natural samples. The magma-meter retrieves crystallization conditions for experiments from the literature. We applied the magma-meter to the plag+opx+cpx-bearing systems: Mt. Ruapehu, in the southern Taupo Volcanic Zone, New Zealand, and the Palmas unit of the Paraná volcanic province, Brazil. The samples from Mt. Ruapehu and Paraná were tested from ~5 MPa to ~400 MPa and from super-liquidus to ~90% crystalline (~1200 ºC to ~700 ºC). Mt. Ruapehu is an active, structurally well-understood volcano; it serves as a methodological testing ground for the magma-meter. Results show a distribution of crystallization pressures for different eruptions, with modes of ~110 MPa and 130 MPa, consistent with field interpretations of different eruptive styles based on juvenile clast textures and previous knowledge of the magma plumbing system. The distribution indicates that the magma batches were stored over a range of pressures. Mt. Ruapehu magmas are water saturated, with fO2 of ÎQFM ~+1. Paraná includes extinct, super-eruption deposits, with preliminary results suggesting shallow (~90 MPa) storage conditions.

Methane (CH&#8324) in the atmosphere accounts for 18% of the climate warming attributed to greenhouse gases. The majority of CH&#8324 emitted is due to natural mechanisms (biogenic CH&#8324), but even the smaller contribution of anthropogenically sourced CH&#8324 (thermogenic CH&#8324) will have a deleterious effect on global temperatures. A portion of this human-derived methane stems from the rapid growth in high volume hydraulic fracturing (HVHF) technologies used to procure natural gas from the subsurface. In order to address growing concerns, we measured the flux and carbon isotope composition of CH&#8324 emitted from the soil into the atmosphere in eastern Tennessee (Morgan Co.). These measurements were made with cavity ring down spectroscopy (CRDS); CRDS permitted the collection of in situ and rapid (1 Hz) measurements of CH&#8324 emissions. We designed our study by making identical sets of measurements at three HVHF wells and four geologically similar corresponding comparison sites, where HVHF activity was absent. The primary objective was to better understand the strength of the connection between HVHF activity and the increasing concentration greenhouse gases in the atmosphere. Through measurements made during two different field sessions (10 Oct 2015 and 29 Feb-01 Mar 2016), we found elevated background concentrations (> 2.0 ppm) of CH&#8324. Through measurements made during two different field sessions (10 Oct 2015 and 29 Feb-01 Mar 2016), we found elevated background concentrations (> 2.0 ppm) of CH&#8324 at the test sites relative to the comparison sites. Furthermore, our data, though not significantly different, showed positive CH&#8324 fluxes (from soil into the atmosphere) at the test sites, whereas CH&#8324 fluxes were generally negative at comparison sites. These results suggest excess CH&#8324 in the soil that may be connected to leakage contributed by HVHF activity. Evidence from stable carbon isotope analysis of the emitted CH&#8324 supports the conclusion of the presence of thermogenic gas at two of the three wells measured. at the test sites relative to the comparison sites. Furthermore, our data, though not significantly different, showed positive CH&#8324 fluxes (from soil into the atmosphere) at the test sites, whereas CHâ´ fluxes were generally negative at comparison sites. These results suggest excess CH&#8324 in the soil that may be connected to leakage contributed by HVHF activity. Evidence from stable carbon isotope analysis of the emitted CH&#8324 supports the conclusion of the presence of thermogenic gas at two of the three wells measured.

published_or_final_version / Physics / Doctoral / Doctor of Philosophy

<p>This study is concerned with speciation and fractionation of the rare earth elements (REE) and calcium (Ca) in aqueous solutions. The aim is to investigate the chemical states and physical sizes in which these elements can be present. The REE (including neodymium) and Ca have contrasting geochemical behavior in aqueous solutions. Ca is a major dissolved element, while the REE are trace components and highly reactive with aquatic particles.</p><p>The major interests of the five papers included in this thesis are the following:</p><p>· Papers I and V deal with the behavior of neodymium (Nd) and its isotopes in the Kalix River and some marine waters.</p><p>· The diffusive gradients in thin-films (DGT) method is developed for measuring Ca and Mg in Paper II.</p><p>· Paper III presents a speciation and fractionation study of Ca in the Kalix and Amazonian rivers.</p><p>· The rare earth elements and their carrier phases are investigated in the Kalix river in Paper IV.</p><p>For most elements a detailed study of speciation and fractionation can not be performed using only one method. This is due to the overall heterogeneity of the material, considering both size and chemical composition, which is present in aquatic solutions. During this project the aquatic geochemistry of the REE and Ca has been studied using mainly three methods; cross-flow filtration (CFF), field-flow fractionation (FFF) and diffusive gradients in thin-films (DGT). Field work has to a large part been conducted in the Kalix River, in northern Sweden, which is one of the last pristine river systems in Europe. Some field work has also been conducted in the Baltic Sea and the Arctic Ocean. Results from Amazonian rivers are also presented.</p><p>These are the main conclusions from this work:</p><p>The DGT technique works equally well for measuring Ca and Mg in natural waters as previously reported for trace metal.</p><p>A significant colloidal phase for Ca could be detected in the Kalix River and in different Amazonian rivers. This was concluded independently using both CFF and FFF.</p><p>Variations in REE signatures in the Kalix River suggests two different pathways for the REE during weathering and release form soil profiles and transport in the river.</p><p>No significant variation in Nd-isotopic composition could be detected in the Kalix River although concentrations varied by a factor of ~10. This suggests that there is one major source for Nd in the river although different pathways for the REE may exist.</p><p>A study of Nd in the Kalix River, the Baltic Sea and the Arctic Ocean showed that the isotopic compositions in the diffusible fractions were similar to water samples. However, the relative amount of diffusible Nd increased with salinity, probably reflecting the lower concentration of colloidal and particulate material in marine waters.</p>

It is well known that the atmosphere of the earth emits a glow throughout the night. The major contribution to this nightglow was first observed in 1901 and was later shown to be due to the transition: O(<SUP>1</SUP>S) → O(^1D) +<i>hv</i>. After many years of controversy, the accepted method for the production of the O(^1S) at a height around 100 km is the Barth mechanism: O(<SUP>3P) + O(<SUP>3P) + M →O <SUP>ast<SUB>2 + M </SUB></SUP>O<SUP>ast<SUB>2 + O(<SUP>3P) →O<SUB>2 + O(<SUP>1S)</SUB></SUP> Where O^ast_2 represents an excited species of oxygen. The precursor can be any of four possible states: O_2(<i>A</i>^3 Σ+_u), O_2(<i>c</i>^1Σ-_u), O_2(<i>A'</i>^3Δu) and O_2(^5πg). All of these states have been proposed as the O(^1S) precursor at one time or another, but none conclusively. For a long time it has been realised that atmospheric measurements of O(^1S), its possible precursors and other relevant species, needs to be taken simultaneously. However up to now this has not been achieved in the laboratory. In the work described here, O(^1S) and the three precursors O_2(<i>A</i>^3Σ+_u), O_2(<i>A'</i>^3Δu) and O_2(<i>c</i>^1Σ-_u) were observed in a laboratory fast flow system. A new method is described whereby upon the addition of a quencher to the system each species can be tested to see if it could be acting as the Barth precursor to O(^1S). Three different quenchers were added in turn; CO_2, SF_6 and O_2. The results gained lead to the conclusion that O_2(<i>c</i>^1Σ-_u), O_2(<i>A'</i>^3Δu) and O_2(<i>A</i>^3Σ+_u)(vleq4) cannot be acting as a O(^1S) precursor, and that O_2(<i>A</i>^3Σ+_u)(vgeq5) is able to do so. The absolute concentrations of O_2(A^3Σ+_u), O(^1S) and O(^3P) were measured and the results compared with the values of these quantities found at a height of 97 km in the earths atmosphere. This comparison shows that O_2(<i>A</i>^3Σ+_u)(vgeq5) can account for all the O(^1S) production at that height at night. The thesis concludes with a discussion of the application of the same method to the determination of the precursors for some of the excited species of O_2.