Magma-poor rifted margins (MPRMs) are characterised by extreme crustal attenuation that increases ocean ward, serpentinised mantle, detachment fault systems and low volumes of syn-rift magmatism. An apparent “extension discrepancy” exists at MPRMs, whereby the amount of stretching accommodated by seismically observable faults is far less than that required to thin the entire crust to the extent observed on wide-angle seismic and gravity models. Unrecognised polyphase faulting can accommodate the required extension. High degrees of stretching require polyphase faulting (PPF), so that the extension discrepancy may simply be a failure to recognise multiple generations of faulting at MPRMs. The polyphase faulting hypothesis is tested through the consideration of the structural geometries likely to result, generation of synthetic seismic images from those geometries and comparison of synthetic images with reflection seismic data from the hyper-extended Porcupine Basin. From this comparison, I have identified at least two cross-cutting fault generations on the margins of the Porcupine Basin. The models demonstrate PPF can accommodate extremely high strain but is practically un-interpretable when β ≥ c.2.5, remaining hidden on hyper-extended crust. Crustal embrittlement is achievable over two fault generations (minimum) leading to hyper-extension and mantle serpentinisation, with the remaining extension likely accommodated by serpentinite detachment systems.

The linkages between the stream and its riparian zone have been well studied in many diverse systems on short (generally annual) timescales. No research has yet considered this in the context of longer (multi-decadal to centennial) timescales at which landscape and successional processes operate. Glacier Bay National Park and Preserve, in southeast Alaska, has a well-documented history of glacial retreat, which allows for the study of ecosystem development using a space-for-time chronosequence approach. This research was unique in analysing terrestrial invertebrates on floodplains of different ages in Glacier Bay, and was the first to utilise two complementary methods of dietary analysis to study the movement of resources between terrestrial and aquatic habitats at sites of different ages. A combination of gut contents dietary analysis and stable isotope analysis was used to determine the food sources of aquatic and terrestrial consumers. Physical habitat complexity, rather than substrate age alone, was an important factor in structuring reciprocal subsidies. This has clear implications for river managers seeking to restore streams to their natural state, particularly where juvenile salmonids are present, as well as underlining the importance of considering a stream in the wider context of its riparian zone.

pH is a fundamental parameter controlling physicochemical processes in environmental systems. Cloud droplet pH controls the dissolution of important micronutrients (iron, phosphorus) which in turn affects the biological carbon pump and ultimately global climate. Using bulk cloud/fog water pH measurements to represent the whole pH spectrum can potentially lead to large errors in climate models. Optochemical sensors (optodes and nanosensors) have been developed for numerous analytes and applications. Optodes for pH however, are typically limited to biomedical applications due to their small pH sensing range (2 – 4 pH units). In this work, pH sensing optodes were developed ultimately combined into a single pH sensing optode with an extended range of pH 1-11. The optode material properties were re-designed to allow for the collection, storage and analysis of individual droplets on the sensor surface. Core-shell pH nanosensors were also developed and used to map the pH distribution within the model organism Daphnia magna, the pH along the gut was found to range from pH 5.8 – 7.2. Finally, a device (electrostatic precipitator) for collecting individual cloud/fog droplets was designed and constructed. The electrostatic precipitator was used in conjunction with the optodes to deposit and measure pH in standard (artificial) cloud/fog droplets under laboratory conditions.

Although the urban heat island (UHI) is well studied, the dynamic nature (i.e. with wind) receives little attention. The concept, urban heat advection (UHA), can warm air temperatures in surrounding rural areas. This may lead to a misinterpretation of local climate and bias in long-term climate records. Using observational analysis and numerical modelling this thesis investigates these limitations by spatially quantifying UHA. A methodology to separate UHA from the background air temperature was applied to a high-density urban observation network in the city of Birmingham, UK demonstrating mean downwind UHA of 0.4oC and up to 1.2oC at individual stations (wind speeds 2 – 3 m s-1). This UHA methodology was adapted to show that even small urban areas (~1 km2) can produce a mean UHA of 0.6oC. TheWeather Research & Forecasting numerical model was used to refine the UHA methodology (accounting for regional heat advection) and conduct semiidealised simulations. Here, a square city with 16 km size produced UHA of 2.4oC at the city edge, with 0.5oC warming extending 9 km downwind. A relationship was found between city size and UHA intensity, enabling statistical scaling. This demonstrated an approach to estimate UHA without the need for computationally expensive simulations.

The collapse of host sediments at the crests of salt anticlines is associated with the devel- opment of hydrocarbon traps in salt overburden rocks, and stratigraphic traps in palaeo- valleys incising salt wall crests. The capacity and integrity of these traps are controlled by complex spatial variations in the geometry of collapse structures, and are difficult to char- acterise using traditional sub-surface datasets. An in-depth understanding of the structural styles that control salt wall collapse, particularly at the ‘sub-seismic’ scale, is essential so that meaningful interpretations of potential prospects can be made based on sub-surface data. The exceptional exposure and preservation of a number of collapsed salt anticlines and re- lated structures within the Paradox Basin, Utah and Colorado, U.S.A., provide an ideal op- portunity to study the geometry and development of salt-related collapse structures. This study combines three-dimensional seismic data from the U.K. Central North Sea with de- tailed structural mapping of exposed structural analogues from the Paradox Basin. The results are used to identify and characterise the range of structural geometries that result from salt anticline collapse, and to elucidate controls on their development. Collapse geometries range from ductile down-warping of the overburden, creating axial synforms, to brittle deformation, creating graben and half-graben structures. Where col- lapse is brittle, half-grabens form the principle structural element of salt anticline collapse structures. Graben-like structures are generated through subsidence of the hanging-wall an- ticlines associated with half grabens, or within areas of interaction between kinematically- linked, oppositely-dipping half-grabens. Accommodation structures between oppositely- dipping half-grabens are associated with structural lows, and contribute to compartmental-isation of potential reservoirs within the overburden. The summary models presented here can be used to guide seismic interpretation within complex, salt-controlled basins, and to identify the potential risks associated with structural traps formed by salt anticline collapse.

Engineered nanoparticles are defined as having a dimension that is between one and one hundred nanometres. With toxicology studies reporting various degrees of toxicity the need to investigate nanoparticle fate and behaviour is vital. Monodispersed engineered nanoparticles were synthesised in-house to produce suitable materials to examine such processes. Iron oxide nanoparticles (5 nm) and citrate coated silver nanoparticles (20 nm) were subjected to different conditions of pH, ionic strength and different types of commercially available natural organic matter. Changes in particle size and aggregation were examined using a multi-method approach. Results showed that the natural organic matter was able to absorb onto nanoparticle surfaces and improve their stability when subjected to changes in pH and ionic strength, where they would normally aggregate. The presence of higher concentrations of NOM in some cases promoted aggregation due to bridging. This work also concluded that silver nanoparticles could be produced in the presence of NOM without additional stabilisers and that they themselves were stable. This work has demonstrated that engineered nanoparticles could remain stable within a range of environmental conditions, and thus raise future pollution concerns.

By deploying Fibre-Optic Distributed Temperature Sensing, this thesis aims to improve understanding of the influences of drought-induced low flows, surface water warmings, shifts between up- and downwelling flows, and hydroclimatological controls on surface water and streambed temperature dynamics. First, the potential drought impacts on surface water and streambed temperature patterns of lowland streams are quantified. Second, high-resolution streambed sediments temperature distributions following altered groundwater-surface water exchange under distinct increased surface water temperatures are analysed. Third, the hyporheic refuge hypothesis is tested at high spatio-temporal resolution under different groundwater-surface water exchange and warming scenarios. Fourth, high-resolution seasonal variability in streambed sediments temperature distributions of a forested stream reach is quantified. The main outcomes are: 1) surface water and streambed temperature patterns in co-evolved vegetated artificial lowland streams varied with water level; 2) the direction of groundwater-surface water exchange impacted on the transfer of thermal stress into gravel streambeds under different warming scenarios; 3) alterations of the direction of groundwater-surface water exchange influenced the potential of the hyporheic zone of gravel streambeds to provide a refuge under warming; 4) seasonal variations of streambed temperatures in a forested stream reach are primarily driven by hydroclimatological conditions.

Perturbation of natural environments through anthropogenic nitrogen (N) inputs and climate change significantly alter soil systems. Few pristine environments remain in which to study natural controls on the development of soil N cycling over time and thus increase our understanding of the natural development of such mechanisms. This study took place in Glacier Bay National Park and Preserve (GBNP), southeast Alaska. This area presented a unique opportunity to study microbial cycling in near pristine soil systems. Six river catchments were selected for study across a chronosequence of 200 years of primary succession. Within each watershed soil nutrient content and microbial processes where evaluated to determine a time frame for development. Samples were collected from riparian and wider catchment areas in order to investigate the effects of dominant vegetation types and slope steepness. These data were coupled with percent vegetation type generated by analysis of satellite imagery allowing the scaling up of soil variables. A key finding of this research was that vegetation type is the primary influence on nitrogen cycling processes and soil characteristics. With increasing age potential microbial activity increased in particular nitrification, which linked with the low soil NO\(_3\)- indicated a large heterotrophic microbial community in older soils.

An area of Lewisian Gneiss some 150 sq km in extent is described, Coll in some detail, Tiree only partially. A history of deformation of at least seven phases is envisaged for the complex, although other indistinguishable phases occurred at an earlier stage in the history of the complex. Quartzo-felspathic gneisses, metasediments, basic, intermediate and ultramafic rocks, and early concordant Granites show the varying effects of three metamorphic episodes. The earliest was at granulite facies and succeeded by amphibolite facies and greenschist facies metamorphism. Some tectonic phases may be correlated with metamorphic events. Certain Geochemical evidence points to a pre-granulite facies lower grade metamorphism. Many of the macroscopic features of the complex have been caused primarily by deformation. The types of structure in each phase were probably controlled by prevailing conditions, especially the presence or absence of hydrous fluids. Much evidence points to a chemical evolution of the complex perhaps analogous to a crustal layering of the metamorphic facies in basement rocks, and having a bearing on the processes active early in the history of this portion of the continental crust.

Estimating manufactured nanoparticle mobility using fast, simple methods could form a useful part of a risk assessment tool. The aim of this work was to investigate whether zeta potential could be used for this purpose. Using a new surface zeta potential measurement technique, the surface zeta potential of a 50m sandstone sequence was found to vary little with lithofacies when chemical conditions were kept constant. A surface area modified linear mixing model was able to describe the sandstone zeta potential, suggesting that clay minerals are the dominant control on bulk properties. The sandstone and silica nanoparticle zeta potentials were sensitive to the chemical composition and pH of the surrounding fluid, which was influenced by ion exchange and carbonate dissolution. The zeta potential of the sandstone and nanoparticles can be used to qualitatively describe the relative mobility under different chemical conditions. Calculations using DLVO and colloid filtration theory (CFT) can reproduce the equilibrium concentration (C’/C\(_0\)) values observed experimentally, however the significant tailing in the breakthrough curve is not described by this traditional particle transport model. Further work is required to determine whether DLVO and CFT can be used as part of a mobility screening tool, as this initial study suggests.