Silicon (Si) isotopes have been extensively studied in low temperature environments but the science of Si isotopes in igneous material has been comparatively ignored. This is because the degree of isotopic fractionation at high temperatures is relatively small, making the accurate measurement of these variations extremely challenging. Using state-of-the-art analytical techniques and instrumentation, which deliver high levels of precision, the objective of this research is to rectify this omission. Specifically, this study aims to investigate whether there are systematic Si isotope variations within, and provide robust Si isotopic compositions for, the major silicate reservoirs on Earth. To this end, a broad range of mantle and crustal lithologies, sourced globally and from various tectonic regimes, have been analysed using high resolution MC-ICP-MS. Analyses indicate that the Si isotopic compositions of mantle-derived mafic and ultramafic material are extremely homogeneous. These data are used to calculate a Bulk Silicate Earth (BSE) average of δ³⁰Si = -0.29 ± 0.08 ‰ (2 s.d.). The degree of Si isotopic fractionation as a result of magmatic differentiation has also been assessed, and found to be small but resolvable between basalt and rhyolitic end-members. Finally, this research shows that, although igneous rocks and sediments derived from the continental crust can be relatively heterogeneous with respect to Si isotopes, bulk averages calculated for the upper, middle and lower continental crust are all very similar to that of BSE. Providing robust estimates for these reservoirs has greatly improved our knowledge of the behaviour of Si isotopes in silicate lithologies and provides a framework for further Si isotopic investigations of such material.

The Windward Islands are vulnerable to a number of natural hazards. This thesis examines the possibilities for Disaster Risk Reduction (DRR) in the Windward Islands. The Windward Islands offer a special case of “Island Vulnerability”. Island vulnerability is essentially defined as an increased probability in disaster events against what would be expected if vulnerability were to be measured against international levels of poverty, defined as Gross National Product per capita. There are three reasons for this namely the topography of islands, the site characteristics and the socio-economic setting. The topography is one where islands, largely of volcanic or coral origins, face multi-hazard experience particularly from flooding and storm surge. The site issue is that islands usually have a high ratio of coastline to land mass implying a relatively higher exposure to extreme events. The socio-economic conditions are peculiar to island including isolation, mono-agriculture and mono-industry essentially laid down by colonial experience, an absence of formal employment opportunities and weak capacity in local governance including the absence of NGOs. Though DRR has evolved over the last 20 years, some islands and communities remain more vulnerable than others. This research investigates the mainstreaming of DRR in the Windward Islands of Dominica, Grenada, Saint Lucia and St Vincent and the Grenadines. The key issue researched was whether DRR could be effectively implemented at the community level. To address this issue, the research investigates the vulnerability and capacity of communities to hazards in the Windward Islands and suggests ways to reduce risk and build community resilience. The factors affecting vulnerability and capacity to hazards in the Anglophone Windward Islands were identified as a means of determining how to reduce risks and build resilience to hazards in the Windward Islands. Efforts to enhance community development and build resilience are not effective as they fail to address fully community needs. This research concluded that some communities are more vulnerable than others and a major contributor to their vulnerability is poverty. None of the methods used in this research are unique to island vulnerability analysis as they have been applied elsewhere in DRR. What is unique is the scoping of the application of these methods to gain an overview of DRR possibilities. What emerges as a conclusion is the limited impact of top down interventions, especially those interventions that try to address poverty alleviation to lower risk. This is essentially because the poor themselves barricade their own coping mechanisms against external interventions, thus building a wall against external help. Building on local organisational capacity, including religious groups, can help address this problem. Research in this area is limited for the Anglophone Windward Islands and this thesis on vulnerability of household and communities will contribute to knowledge in this field.

The purpose of the present study was to determine the relative importance of aquatic and terrestrial beetles as possible vehicles in the passive overland dispersal of viable microorganisms.

The tidal-fresh James River experiences recurring blooms of toxin-producing cyanobacteria, including Microcystis aeruginosa. However, cyanobacteria cell densities in the James are relatively low. Our purpose was to identify key factors suppressing cyanobacteria growth in the face of eutrophication. A mesocosm experiment was designed to test the effects of light, mixing and grazing on cyanobacteria abundance, with nutrients held constant. We predicted that toxic cyanobacteria would be most abundant under stagnant conditions, with enhanced light, with no bivalve grazers present. Abundances of indicator gene copies and phytoplankton counts supported this hypothesis. However, chlorophyll-a, phycocyanin, and the toxin microcystin were all found to be most abundant under mixed conditions with ambient light. Statistically, light and mixing were important in controlling toxic cyanobacteria abundance, with little to no effect observed for bivalve grazers. Our findings suggest that toxin production may be regulated by factors independent from those driving algal growth and cyanobacteria abundance.

Despite the importance of ice streaming to the evaluation of West Antarctic Ice Sheet (WAIS) stability, we know little about mid-to long term changes in grounding line migration, ice streaming and ice accumulation in the upper Institute Ice Stream (IIS) catchment. In this thesis ground penetrating radar (GPR) and airborne radio-echo sounding (RES) methods have been employed to investigate the subglacial topography, internal stratigraphy and Holocene flow regime of the upper IIS catchment, in and around Horseshoe Valley. High resolution step-andcollect mode GPR was employed to assess the continuity of a Blue Ice Area (BIA) horizontal ice core climate record at Patriot Hills, where analysis has revealed two unconformities in the otherwise conformable 30,000 year climate sequence. By combining these data with airborne RES returns and pre-existing ice sheet models it is suggested that these unconformities represent periods of erosion, occurring as the former ice surface was scoured by katabatic winds in front of Liberty and Mable Hills. Snow_Blow simulations suggest that katabatic winds have scoured the leeward slopes of these mountain ranges for over 10,000 years. This temporal stability can account for the large volume of BI moraine deposits in Horseshoe Valley, where compressive BI flows promote glacial erosion and near-surface debris entrainment through freeze-on processes at the ice/bed interface and compressive thrust faulting. By investigating thicker ice flows in the upper IIS catchment and the Evans Ice Stream, this thesis has also analysed debris entrainment mechanisms at depth, where clasts are incorporated into the ice flow by englacial stratigraphic folding and shearing at the glacial thermal boundary, governed by spatial and temporal changes in ice flow, ice temperature and sediment availability. Mid-to long term changes in ice flow in the wider IIS catchment have been investigated from airborne RES transects, revealing internal layer buckling, and therefore former enhanced ice-sheet flow in three distinct tributaries of the IIS. Buckled ice layers throughout the slow flowing ice in the Independence Trough and the fast-flowing ice in the Ellsworth Trough suggest that enhanced ice flow through these topographically confined regions was the source of ice streaming and iceflow reconfiguration during the mid-to-late Holocene. Although buckled layers also exist within the slow-flowing ice of Horseshoe Valley, a thicker sequence of surface-conformable layers in the upper ice column suggests slowdown more than 4000 years ago, indicating that enhanced flow switch off here cannot be attributed to late-Holocene ice flow reorganisation. The dynamic nature of ice flow in the IIS and its tributaries suggests that ice stream switching and mass change may have been regular during the Holocene, and that these changes may characterise the decline of the WAIS in this area. These results have important implications for our understanding of ice-sheet dynamics and the response of the ice sheet to climate change and provides explanations for fluctuations in debris entrainment and transportation processes in Antarctica.

Population growth, increasing affluence, and greater access to medicines have led to an increase in active pharmaceutical ingredients (APIs) entering sewerage networks. Wastewater in lower and lower middle-income countries use that use wastewater for irrigation may use untreated or poorly treated wastewater resulting in the potential for greater concentrations of APIs to enter soils in this way. Wastewater re-used for irrigation is currently not included in environmental risk assessments for APIs in soils. The addition of wastewater to soils changes the organic content and can increase the pH of soils, which will have an impact on the fate of any ionisable APIs introduced during the irrigation process. As the input of APIs to soil from wastewater irrigation is not currently included in the risk assessments, this is an area that requires increased attention. A study was undertaken using a modified sorption-desorption batch equilibrium method (OECD 106) to simulate the addition of synthetic wastewater (SWW) to soils compared to a normal OECD 106 study. The APIs studied were ofloxacin, propranolol, naproxen and nevirapine, and represent a range of API physico-chemical properties. These experiments showed that the changes to soil properties (pH and dissolved organic carbon (DOC)) caused by irrigation with SWW can change the fate of APIs in soils. The ionisation state of the API at the altered pH was more important for the positively charged propranolol than it was for the negatively charged naproxen and neutral nevirapine. The Kd and Log Koc increased during the sorption experiment in some cases with SWW. This has implications on the current terrestrial risk assessment where the trigger value for a more detailed soil risk assessment in at Log Koc >4. If the experiment is only performed in 10 mM CaCl2 as is currently required this may lead to unknown risks of APIs in wastewater irrigated soils not being taken into account. Three soil sterilisation or microbial enzyme suppression methods were investigated to identify how successful they were and if there was any impact on the soil physical chemical structure. Gamma irradiation, autoclaving and the addition of 0.2 g L-1 sodium azide were studied. None of the methods successfully sterilised the soils and some changes in soils were identified post-treatment. Autoclaving destroyed the soil structure, turning it into a fine powder and significantly increasing DOC. Sodium azide changed the pH of the loam soil but not the sandy loam soil. Literature suggested that gamma irradiation was the most likely to sterilise the soils with the least amount of disturbance to its physico-chemical properties but increases in DOC were identified in the current study. The changes to soils after sterilisation varied depending on the individual soil properties, indicating that soils should be studied on a case-by-case basis. Irrigation with wastewater provides continuous inputs of chemicals into soils throughout the growing season so it is vital that more work is done to understand the ultimate fate of pollutants in soil as a result. Wastewater has the potential to change the fate of chemicals in soils meaning that current risk assessments may not thoroughly assess all risks involved.

Scales of the stoneroller, Campostoma anomalum (Rafinesque), common shiner, Notropus cornutus (Mitchill), and the bluntnose minnow, Pimephales notatus (Rafinesque) were analyzed by means of atomic absorption spectrophotometry to determine levels of cadmium, calcium, copper, iron, lead, manganese, nickel and zinc. Metal concentrations were determined seasonally and relationship established between scale metal content and environmental water metal levels. Calcium, iron manganese and zinc were found in all samples analyzed. Cadmium, copper, lead and nickel were not observed in measurable quantities. Metal concentrations varied interspecifically, but most showed little fluctuation in response to increased metal content of the water. Elemental composition of the scales was found to have been selective in that zinc and manganese were more readily taken up, even when present in considerably lower concentrations in the water. The metal content of scales was found to be related to behavioral characteristics of the species and the size of the fish.

This study examined the diet composition of ninety-nine Sacramento pikeminnow (150-410 mm [5.9-16 in] fork length [FL]) collected from the upper and lower main stem of Chorro Creek, Morro Bay Watershed, California in 2006. The goal of this study was to characterize the spatial and seasonal variability in the diet of Sacramento pikeminnow within Chorro Creek and to determine what proportion of the diet is represented by rainbow trout (Oncorhynchus mykiss) and their anadromous form (steelhead). Prey was identified in 88% of the samples collected in the early season and 84% of the samples collected in the late season. Fish and/or scales were identified in 12% of the samples collected. Sacramento pikeminnow consumed a wide variety of prey; the diversity of individual diets was higher in the lower main stem than the upper. Overall, diet diversity increased with Sacramento pikeminnow length. In both the early and late season, crayfish formed the largest part of the diet of large Sacramento pikeminnow (>250 mm [9.8 in]). There was a slight increase in the proportion of fish in the diet during the late season, and tendency for cannibalism which was primarily observed in the upper main stem of Chorro Creek. In summary, the overall results of this study support the conclusion that Sacramento pikeminnow are not significant predators of O. mykiss in natural stream conditions. However, conclusions about the ability of Sacramento pikeminnow in Chorro Creek to reduce O. mykiss populations will require further information on the prey selection of Sacramento pikeminnow when juvenile O. mykiss and adult pikeminnow are abundant.

Natural lake-watershed ecosystems in Oregon compose a diverse and valuable assemblage of land and water resources. With an increasing demand on lakes for recreation, water supplies, and aesthetic values and an increase in available data on Oregon lake systems, there is a need for applicable and timely scientific water management information about lake conditions statewide. This thesis is an attempt to summarize some of the data collected on natural Oregon lake-watershed ecosystems. The purpose of the thesis is to identify the most typical natural systems out of an initial data base of twenty-four variables, measured over ninety-eight lake-watershed ecosystems. The selected variables are reduced to five common factors using principal components factor analysis. K-means cluster analysis is used to create similar groups of lake systems. These groups are compared to ecoregions in Oregon and a typical, representative lake ecosystem is identified for each group. Results show that several lake systems of the state are unique.

Signaling and sensing with rotating magnet sources have both Terrestrial and Extraterrestrial applications. The dual spinning magnet unit presented in this paper is a simple, lightweight solution to help understand soil densities and locate water and ice pockets, for example, on Mars. Traditional magnetic telemetry systems that use energy-inefficient large induction coils and antennas as sources and receivers are not practical for extraterrestrial and remote field sensing applications. The recent proliferation of strong rare-earth permanent magnets and high-sensitivity magnetometers enables alternative magnetic telemetry system concepts with significantly more compact formats and lower energy consumption. There are also terrestrial applications, for example, subterranean objects such as underground infrastructure and unexploded ordnances (UXO) that are often unmapped and difficult to find on Earth. Current ground penetrating radar units are expensive, large, and heavy. The research presented explores the viability and possibility to develop a unit that will induce an oscillating magnetic field with controllable shape to reliably locate buried ferromagnetic and non-ferromagnetic objects while remaining lightweight and cost effective. A Dual Rotating Magnet (DRM) design is presented. Experiments and numerical simulations assess the system for terrestrial and extraterrestrial detection of: 1) differences in soil densities, 2) water and ice pockets at shallow depths in the subsurface, and 3) subterranean ferromagnetic and non-ferromagnetic objects of interest.