A methodology of assessment is presented of the groundwater resources available in fracture zones, within the weathered mantle of gneiss, migmatite and granite. A model of weathering is developed, and values of porosity, hydraulic conductivity and electrical resistivity assigned to the different grades of weathering. A geophysical technique is developed, based upon a combination of electrical resistivity profiling and sounding, which allows a volume estimate of the various weathering grades to be made. A finite difference algorithm is used for this estimate which enables the apparent resistivity response of an inhomogeneous resistivity distribution to be calculated. An iterative approach is then adopted, adjusting the resistivity model until the calculated response agrees with the field data. An analysis of recharge in a savanna climate is developed based upon the Monteith equation for predicting evapotranspiration, and upon a model of unsaturated zone soil moisture movement. The recharge function developed is included in a one dimensional catchment water balance model. The results from this model are compared with observed runoff and groundwater hydrographs. The estimate of recharge is combined with the estimate of aquifer storage to produce an assessment of available groundwater. Optimal methods for the development of the resource are discussed. While developed in Northern Nigeria, the methodology of assessment is applicable to any similar geological and climatological environment.

Over the past decade, there has been an ever increasing interest in the relationship between weather and climate and how they are portrayed artistically. The representations of skies, atmosphere, weather, climate and climate change through a variety of artistic media have been considered thus far (Eliasson 2003; Olson et al 2004, Kunz et al 2005; Thornes 1999, 2008a, 2008b). Furthermore, there have been a number of studies that have contemplated the use of environmental art as a form of proxy data for past weather, air pollution and climate change (Lamb 1967; Neuberger 1970; Brimblecombe and Ogden 1977, Baker and Thornes 2006 and Zerefos et al 2007). Monet’s series paintings can be considered as another example of art representing aspects of the weather and climate, for example, when Monet painted his scenes of London, he would include the sun when it was visible or a representation of the sun when it was obscured, trying to illustrate the atmosphere, and thus the weather, in his paintings. However, Monet also reworked many of his canvases with the intention of reflecting how the atmosphere appeared on specific days from year to year, therefore it seems it could be concluded that Monet was consciously painting the climate of London as well as the weather. For this reason, the opportunity to deconstruct Monet’s representations of the skies in his London Series (1899-1905) could not have come at a better time.

Silver nanoparticles (AgNPs) are currently widely used and of special interest due to their anti-microbial properties. They have been used extensively in commercial applications and might be the most worrying of the manufactured nanoparticles because of their inherent toxicity. In this work, stable citrate and PEG stabilized AgNPs of three different core size (7, 10 and 20nm) were synthesized, the stability of citrate capped NPs was assessed in ecotoxicology media (used for OECD for Daphnia magna toxicity testing) and the stability of 20nm NPs in environmentally relevant conditions (like presence of humic substances, sunlight, different types of synthetic water, amongst other). The particles were fully characterized before and during the stability tests with a multimethod approach. The methods used were DLS, UV-vis, TEM, AFM, FI-FFF, HR-STEM, EELS, EDX. Not all methods were used for all the samples.

There is major concern that river temperature changes driven by a changing climate and associated hydrological changes will have profound impacts on freshwater ecosystems. To identify the rivers most sensitive to change and implement effective strategies to mitigate high thermal extremes, this thesis aims to improve understanding of the influences of hydrometeorology and riparian landuse on river temperature dynamics, controls and processes within a UK context. Four studies are presented within a multi-scale research design which aimed to improve understanding of: (1) spatial patterns and inter-annual variability in the shape and magnitude of annual river temperature regimes across England and Wales, and regime sensitivity to air temperature and river basin properties, (2) the effects of riparian vegetation on water temperature under a range of hydrometeorological conditions, (2) the processes by which cool water refugia are produced beneath semi-natural, deciduous forest canopies, and (4) how minimal riparian planting can be used to produce thermal refugia in reaches of differing aspect and hydraulic characteristics. The aims are achieved by combining observational, statistical and deterministic modelling techniques. The outcomes of the research contribute significant new knowledge and tools for evidence based management of river and stream temperature under present and future climates.

A method of synthesizing and controlling the size of germanium nanocrystals is developed. A tri-layer metal-insulator-semiconductor (MIS) memory device structure comprising of a thin (~5nm) silicon dioxide (SiO₂) layer grown using rapid thermal oxidation (RTO), followed by a layer of Ge+SiO₂ of varying thickness (3 - 6 nm) deposited using a radio frequency (rf) co-sputtering technique, and a capping SiO₂ layer (50nm) deposited using rf sputtering is investigated. It was verified that the size of germanium (Ge) nanocrystals in the vertical z-direction in the trilayer memory device was controlled by varying the thickness of the middle (cosputtered Ge+SiO₂) layer. From analyses using transmission electron microscopy and capacitance-voltage measurements, we deduced that both electrons and holes are most likely stored within the nanocrystals in the middle layer of the trilayer structure rather than at the interfaces of the nanocrystals with the oxide matrix. / Singapore-MIT Alliance (SMA)

The effect of germanium (Ge) concentration and the rapid thermal oxide (RTO) layer thickness on the nanocrystal formation and charge storage/retention capability of a trilayer metal-insulator-semiconductor device was studied. We found that the RTO and the capping oxide layers were not totally effective in confining the Ge nanocrystals in the middle layer when a pure Ge middle layer was used for the formation of nanocrystals. From the transmission electron microscopy and secondary ion mass spectroscopy results, a significant diffusion of Ge atoms through the RTO and into the silicon (Si) substrate was observed when the RTO layer thickness was reduced to 2.5 nm. This resulted in no (or very few) nanocrystals formed in the system. For devices with a Ge+SiO₂ co-sputtered middle layer (i.e., lower Ge concentration), a higher charge storage capability was obtained than with devices with a thinner RTO layer, and the charge retention time was found to be less than in devices with a thicker RTO layer. / Singapore-MIT Alliance (SMA)

Thesis (Ph. D.)--University of Oregon, 2006. / Typescript. Includes vita and abstract. Includes bibliographical references (leaves 209-218). Also available for download via the World Wide Web; free to University of Oregon users.

This Masters research took place in the Kat River Valley in the Eastern Cape, South Africa. The Kat River Valley is a semi-rural catchment that covers an area of approximately 1700km2 and is characterized by a complicated history of dispossession and resettlement. Farming is the main activity that is practiced in the area. This includes the farming of citrus at a commercial scale, rangeland stock farming and small-scale vegetable farming. The economy of the catchment is enhanced mostly by commercial citrus farming, which consumes by far the largest amount of water in the river through irrigation. Water allocation is a burning issue among water users in the catchment and needs to be negotiated taking into consideration social, economic and environment impacts. The aim of this study is to describe, discuss and evaluate the Companion Modelling (ComMod) approach, which used a simulation model and a role-playing game related to the model in order to facilitate and develop negotiating skills as well as build capacity in decision-making amongst local stakeholders for water resource management in the Kat River Valley. The ComMod approach, developed by a group of Companion Modellers, is a community-based science approach that emerged in the 1990s. The ComMod approach is used in order to facilitate collective learning, negotiation and institutional innovation in dealing with resource management complexities faced by rural communities. Through ComMod, the model (KatAWARE) and its related role-playing game was developed by having the contact with local stakeholders. The information to feed the model and the role-playing game came from informal interviews, surveys, geographic information systems (GIS), workshops and focus groups. The use of workshops in the implementation of ComMod was a success. Results show that (1) new knowledge was acquired, which allowed stakeholders to have a broad understanding of a catchment system. (2) Awareness was created about complex systems and enabled stakeholders to see an individual action into to the broader system. (3) Strong interrelationships were fostered amongst different water users, which allowed stakeholders to share their view points. The ComMod process was however associated with a number of limitations, many of which resulted from the constraints that were imposed by the socio-economic background of the study area. Nevertheless, the outcome of the study shows that the ComMod process was useful in helping the Kat River Water Users Association (KRWUA) stakeholders develop negotiating skills regarding water allocation strategies for the development of the Catchment Management Plan.

No description available.

Abstract The primary objective for this study is to determine the variations of germanium (Ge) to silicon (Si) ratios in diatom shells from down core sediments off the southwestern coast of the Africa. Because Ge behaves like Si in the ocean and the major source of these two elements is rivers, Ge/Si ratios of the diatom are thus expected to record the intensity of weathering on continents. Two sediment cores (Site 1081 and 1084) were collected during the ODP Leg 175 in August, October 1997 and were analyzed for intervals between 3.1 and 1.9 Ma. Generally, the (Ge/Si)diatom ratios in this study show the similar trend with those reported from the Antarctic Ocean. The decline of Ge/Si ratios after 2.5 Ma is caused by the high opal mass accumulation rate, indicating the increasing rivers input of silica to the ocean. Relatively high Ge/Si ratios of diatom shells during warm periods shown by the depleted benthic foraminiferal £_18O values from the North and Equatorial Atlantic, suggesting a scenario of intensified chemical weathering on continent. Cold periods signified by £_18O-enriched values are associated with lower Ge/Si ratios. Very likely the reduced Ge/Si values reflect the prevailing weathering on continents was less chemical-dissolving due to the dry weather in cold stages.