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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
91

Regional Modeling of the Glaciers of the North Cascades Mountains, Washington, USA

Gray, Christina Eileen 10 July 2019 (has links)
Glaciers in the North Cascades store winter snowfall as ice and release it in late summer as melt, providing an important regional source of water and hydroelectric energy. The future of glaciers in the North Cascades, Washington, were evaluated using a regional glaciation model driven by the Community Climate System Model 4 global climate model. The climate model was coupled with three Representative Concentration Pathways (RCPs), 2.6, 4.5, and 8.5. These RCPs provide a business-as-usual scenario (RCP 8.5), which assumes society makes little to no efforts to reduce greenhouse gas emissions, a best-case scenario (RCP 2.6) with strong attempts to mitigate greenhouse gas emissions, and a moderate scenario (RCP 4.5). Spun up from 850 C.E., modeled glacier area for 1970 was 96-102% of observed. By 2100 the predicted area relative to the total observed area in 1900 was 42% for RCP 2.6, 16% for RCP 45, and 5% for RCP 8.5. By 2100 only glaciers on high peaks, such as Mt. Baker and Glacier Peak, will remain (145.98 km2, RCP 2.6; 70.49 km2, RCP 4.5; 16.82 km2, RCP 8.5) and entirely gone by 2200 in any of the three climate scenarios.
92

Socioeconomic Status, Water, Sanitation, Hygiene, and Economic Cost of Childhood Diarrheal Diseases in Uganda

Nahalamba, Sarah Birungi 01 January 2019 (has links)
Worldwide, diarrhea is the second leading cause of death in children aged under 5, yet it is both preventable and treatable. Several studies have established the effects of exposure to inadequate water, sanitation, and hygiene (WASH) on diarrhea prevalence, but little was known on how the interactions of socioeconomic status and WASH influence the economic cost of treatment of diarrhea. This retrospective cross-sectional survey study was focused on assessing the correlation between socioeconomic status, WASH, and household cost of treatment of diarrhea among children aged under 5 in Uganda using the multiple exposure-multiple effect model. Secondary data from the 2015/16 Uganda National Panel Survey were used. At bivariate level of analysis, 5 of 6 independent variables (education level of mother, household expenditure, residence type, source of drinking water, and type of toilet facility) had statistically significant associations with household cost of treatment of diarrhea (p value < .05). The multivariate-hierarchical multiple linear regression indicated that only 3 of the 6 variables significantly predicated household cost of treatment of diarrhea. These were highest education level of mother (p = 0.001), source of drinking water (p = 0.022), and type of toilet facility (p = 0.012). At p value < .05, about 67% of the variation in the cost of treatment was explained by the independent variables. Households with a higher socioeconomic status incurred higher costs of treatment, although those with a lower status experienced the highest prevalence rates. Therefore, policy makers and practitioners could use these findings to employ multiple interventions to address the disease burden and cause behavior change.
93

Cooling Before Super-Eruption: No Role for Rejuvenation in the Cottonwood Wash Tuff Magma Body, Southern Great Basin Ignimbrite Province, Utah and Nevada

Ross, Keryn Tobler 01 December 2015 (has links)
The model of rejuvenation of a near-solidus crystal mush to produce large volumes of crystal-rich magma is tested here by analyzing the mineralogical, chemical, modal, and physical characteristics of the 31.1 Ma super-eruptive (2000 km3) Cottonwood Wash Tuff. It is the oldest in a series of three so-called “monotonous intermediate” ignimbrites from the Indian Peak-Caliente volcanic field in southern Utah and Nevada. A crystal-rich (~50% Pl > Qz ≈ Hbl ≈ Bt > Mag ≈ Ilm > Cpx + Zrn + Ap+ Po) dacite (62 – 69 wt% SiO2), the Cottonwood Wash Tuff is similar in age, volume, mineralogy, crystallinity, and elemental composition to the 28.0 Ma, ~5000 km3 Fish Canyon Tuff (~45% Pl + Kfs + Qz + Hbl + Bt + Ttn + Mag + Ilm + Ap + Zrn + Po, 66 – 68 wt% SiO2), used as the basis of the rejuvenation model, which suggests that magma chambers remain in a near-solidus state until a late heating event melts the magma enough to allow eruption. The Cottonwood Wash magma chamber was compositionally varied, as shown by the composition of mineral and juvenile clast compositions. Most of the whole-rock compositional variations are likely due to the variation of mineral proportions induced by shear in the magma chamber. A volumetrically minor component with evolved mineral compositionss, is represented by “evolved” juvenile clasts. Mineral compositions and experimental phase relationships show the pre-eruption magma crystallized at 800°C, 2.3 kb under water-undersaturated but oxidized conditions (delta QFM = 2.1). The majority of plagioclase and amphibole grains exhibit small-scale oscillatory zonation; where systematic compositional zonation exists, normal and reverse zonation are equally present. Cathodoluminescence of quartz reveals typically normally zoned phenocrysts with late resorption, considered to be the result of eruptive decompression. Many of the characteristics used to identify the warming of a near-solidus mush for the Fish Canyon Tuff are not present in the Cottonwood Wash Tuff [i.e., reversely zoned hornblende or plagioclase, partially remelted mineral aggregates, evidence of fluid saturation, resorption textures not related to decompression, rapakivi mantles, and hybrid andesite inclusions]. The Cottonwood Wash Tuff magma system did not undergo rejuvenation from a near-solidus state. Instead, the magma was apparently cooling and crystallizing just prior to eruption.
94

An evaluation of an ion-exchange method for the removal of technetium-99 from groundwater

Elliott, Wanda Sue, January 2007 (has links) (PDF)
Thesis (M.S. in environmental Science)--Washington State University, December 2007. / Includes bibliographical references (p. 27).
95

Plankton and nutrient ecology of the Columbia River estuary

Haertel, Lois Steben 24 July 1969 (has links)
Monthly samples of nutrients, phytoplankton and zooplankton were taken in the Columbia River estuary over a period of 16 months in order to determine distribution with season and salinity, and interrelationships between plankton and nutrients. Nitrate and phosphate levels in the river water entering the estuary are high in the winter and show depletion during the summer. Silicate levels are high in the river water at all seasons. Nitrate and phosphate levels are high in the entering ocean water during summer offshore upwelling. The nutrient levels in the estuary generally show a linear relationship with salinity, resulting from the levels of nutrients in the entering river and ocean water. Superimposed upon this linear relationship is a tendency for the nutrients to be enriched in the bottom waters of the central part of the estuary. The estuary phytoplankton are primarily composed of freshwater forms, and probably represent a downstream extension of the river flora. Regression analysis of phytoplankton levels vs. light, nutrients, and river flow indicates that light probably limits phytoplankton abundance on most dates. The zooplankton of the estuary are composed of three groups, preferring fresh, oligohaline, and polyhaline waters respectively. Regression analysis indicates a strong correlation between abundance of the freshwater group and river temperature. The factors controlling the abundance of the oligohaline and polyhaline groups are less obvious. The oligohaline group, principally Eurytemora affinis, reaches the greatest population density (100,000/m³ or more). Regression analysis indicates a close correlation between Eurytemora abundance and phosphate levels. This indicates a strong potential for zooplankton regeneration of phosphate necessary for phytoplankton growth. / Graduation date: 1970
96

Ecology of woody riparian vegetation in tributaries of the Upper Grande Ronde River basin, Oregon

Lytjen, Danna J. 10 June 1998 (has links)
Two studies on Catherine Creek and Meadow Creek of the Upper Grande Ronde River basin, quantified several physical and biotic influences on woody riparian community composition and structure. The Catherine Creek study examined the association of woody riparian species with elevational and geomorphic gradients. The Meadow Creek study examined the influence of mammal herbivory on composition and abundance of woody riparian species. At Catherine Creek, twenty nine plots were established at 50 m intervals of elevation from near the stream origin at 2207 m in the Wallowa Mountains to the foothills of the Grande Ronde Valley at 988 m. Woody plant community composition was associated with the dominant environmental variable, elevation. Distribution of dominant riparian species was strongly associated with fluvial surfaces. Black cottonwood (Populus balsamifera) was associated with gravel and cobble bars proximal to the stream channel, and along with ponderosa pine (Pinus ponderosa) was also associated with elevated boulder bars. Alders (A. incana and A. viridis) and willows (Salix bebbiana, S. boothii, S. exigua, S. lucida, S. melanopsis, S. prolixa, and S. sitchensis) were associated with annual floodplains. At Meadow Creek, grazing by cattle was ended in 1991 on the entire study reach and three deer and elk exclosures were built within the reach adjacent to the creek. Inside deer/elk exclosures from 1991 to 1995, mean heights of tagged cottonwoods, willows, and alders increased by 86% to 180%. Outside exclosures, mean heights of cottonwoods and alders increased 109% and 99% respectively, but willows showed little change in height. Both inside and outside of exclosures mean crown volume of cottonwoods increased over 1000% and mean crown volume of alders increased over 600%. Willow volume inside exclosures increased 376% in root sprouting (clonal) species and 528% in crown sprouting (non-clonal) species, while outside of exclosures volume increased 79% and 144% respectively. On both sides of exclosure fences, beaver herbivory had a significant effect on cottonwood height growth in 1994 and 1995, and on height and crown volume growth of willows in 1995. Over 50% of stem density increase on transects was attributable to expansion within two large clones of Salix melanopsis inside exclosures. Excluding these two clones, overall woody plant density increased by 72% from 3.7 plants per 100 m�� of transect in 1991 to 6.3 plants per 100 m�� of transect in 1995. / Graduation date: 1999
97

Origin of the Tucannon phase in Lower Snake River prehistory

Lucas, Steven W. 29 September 1994 (has links)
Approximately 5,500 years ago a discreet period of wetter and cooler environmental conditions prevailed across the southern Columbia Plateau. This period was marked by the first prominent episodes of erosion to occur along the lower Snake River following the height of the Altithermal and eruption of Mt. Mazama during the mid post-glacial. In addition to the reactivation of small stream courses choked with debris and sediment, large stream channels began downcutting and scouring older terrace faces incorporated with large accumulations of Mazama ash. The resulting degradation of aquatic habitats forced concurrent changes within human economies adapted to the local riverine-environments. These adjustments reported for the Tucannon phase time period along the lower Snake River are notable and demonstrate the degree to which Cascade phase culture was unsuccessful in coping with environmental instability at the end of the Altithermal time period. This successionary event has demonstratively become the most significant post-glacial, qualitative change to occur in the lifeways of lower Snake River people prior to Euro-American influence. / Graduation date: 1995
98

Remote sensing of forest biomass dynamics using Landsat-derived disturbance and recovery history and lidar data

Pflugmacher, Dirk 23 November 2011 (has links)
Improved monitoring of forest biomass is needed to quantify natural and anthropogenic effects on the terrestrial carbon cycle. Landsat's temporal and spatial coverage, fine spatial grain, and long history of earth observations provide a unique opportunity for measuring biophysical properties of vegetation across large areas and long time scales. However, like other multi-spectral data, the relationship between single-date reflectance and forest biomass weakens under certain canopy conditions. Because the structure and composition of a forest stand at any point in time is linked to the stand's disturbance history, one potential means of enhancing Landsat's spectral relationships with biomass is by including information on vegetation trends prior to the date for which estimates are desired. The purpose of this research was to develop and assess a method that links field data, airborne lidar, and Landsat-derived disturbance and recovery history for mapping of forest biomass and biomass change. Our study area is located in eastern Oregon (US), an area dominated by mixed conifer and single species forests. In Chapter 2, we test and demonstrate the utility of Landsat-derived disturbance and recovery metrics to predict current forest structure (live and dead biomass, basal area, and stand height) for 51 field plots, and compare the results with estimates from airborne lidar and single-date Landsat imagery. To characterize the complex nature of long-term (insect, growth) and short-term (fire, harvest) vegetation changes found in this area, we use annual Landsat time series between 1972 and 2010. This required integrating Landsat data from MSS (1972-1992) and TM/ETM+ (1982-present) sensors. In Chapter 2, we describe a method to bridge spectral differences between Landsat sensors, and therefore extent Landsat time-series analyses back to 1972. In Chapter 3, we extend and automate our approach and develop maps of current (2009) and historic (1993-2009) live forest biomass. We use lidar data for model training and evaluate the results with forest inventory data. We further conduct a sensitivity analysis to determine the effects of forest structure, time-series length, terrain and sampling design on model predictions. Our research showed that including disturbance and recovery trends in empirical models significantly improved predictions of forest biomass, and that the approach can be applied across a larger landscape and across time for estimating biomass change. / Graduation date: 2012 / Access restricted to the OSU Community at author's request from Nov. 29, 2011 - Nov. 29, 2012
99

Sedimentology and stratigraphy of the Granite Wash: Contact Rapids and Keg River Sandstone (Red Earth area)

Balshaw, Kevin Ewart 11 1900 (has links)
The Granite Wash is comprised of diachronous, Cambrian to Devonian sandstone deposits, which include the Devonian Contact Rapids and Keg River sandstones of which this study will focus. Prolific oil production from the Granite Wash has fueled exploration since the 1950s and as a result substantial core and wireline data is available. Mapping of the Precambrian subcrop suggests that palaeo-highs, known as inselbergs, strongly influenced sedimentation transport, volume, rate, and ultimately preservation after marine transgression. Several distinct surfaces identified from wireline data and cores indicate an overall marine transgression throughout Keg River time. The facies observed represent continental, shallow marine and sabkha environments and a climatic shift from arid to semi-arid to arid. This detailed sedimentological and stratigraphic study provided the depositional framework that allowed for palaeogeographic maps to be constructed.
100

Perceptions of Water, Sanitation and Hygiene Interventions in Select Communities in Central America. Recommendations to Explore the Issue of Sustainability

Gleaton, Arlyn Nathalia 20 December 2012 (has links)
Background: Estimations from the Joint Monitoring program for Water Supply and Sanitation (JMP, 2012) reveal that “less than five percent of water and sanitation interventions are revisited once they have been completed and less than one percent are monitored over the long term”. Since 2000, the Centers for Disease Control and Prevention(CDC) has been working with the American Red Cross (ARC) to evaluate the long-term sustainability of post-disaster water, sanitation and hygiene interventions (WASH) provided in Guatemala, Honduras, Nicaragua and El Salvador. Sustainability assessments were conducted in 2006, 2009 and most recently in 2012. In the 2012 evaluation, a qualitative approached was included to extent the results obtained from quantitative surveys through an exploration of individual perceptions and current practices. Methodology: Key-informant interviews were conducted with the heads of household in 15 communities purposively selected. All interviews were recorded, transcribed, coded and analyzed using the computer assisted qualitative data analysis software MAXQDA10 Results: Interviewees discussed issues related to the quality, safety and adequacy of the water and sanitation infrastructure and hygiene education sessions received. Issues of corruption in the water committees and delayed repair of damaged infrastructure resulting in erratic service were frequently reported. In addition, lack of financial support, community engagement, and equity were identified by heads of household as major limitations to sustain and improve WASH interventions. Conclusions: This exploration provides valuable information to further examine the factors driving people’s adoption of hygienic practices and maintenance of water and sanitation facilities in the Central American region.

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