Environmental field analysis provides advantages that allow real-time decisions, interactive sampling and cost effective solutions to the problems faced at the time of investigation. Gas chromatography (GC), a widespread technique for the determination of organic pollutants in the environment, has also shown to be useful in environmental field analysis. Thermal desorption of solid environmental sample provides a technique for liberation of volatile analytes from the samples without the need for solvent extraction. Combining the thermal desorption technique with a field gas chromatograph (GC) thus provides the possibility of on-site determination of organic contaminants in soils. However, to better characterize trace level contaminants in complex sample matrices, laboratory analysis using analytical instrument with great separation and resolution power is required. Comprehensive two-dimensional gas chromatography (GC X GC) is such a powerful analytical tool that provides enhanced separation and resolution capacity for the task. The project presented here involves the development and validation of a field method for the analysis of total polychlorinated biphenyls (PCBs) in soils, and determination of individual PCB congeners in the same samples by further laboratory analysis. The field analytical system developed was a field portable GC interfaced with a thermal desorber. The identification of PCB congeners was realized by a GC X GC system with a time-of-flight mass spectrometer (TOF-MS) as a detector. The field method was developed by optimizing and characterizing the method using PCB standards, followed by the application of the developed method to environmental soil samples. Finally, analyses of PCB congeners in environmental soil samples were performed using the GC X GC system.

Environmental field analysis provides advantages that allow real-time decisions, interactive sampling and cost effective solutions to the problems faced at the time of investigation. Gas chromatography (GC), a widespread technique for the determination of organic pollutants in the environment, has also shown to be useful in environmental field analysis. Thermal desorption of solid environmental sample provides a technique for liberation of volatile analytes from the samples without the need for solvent extraction. Combining the thermal desorption technique with a field gas chromatograph (GC) thus provides the possibility of on-site determination of organic contaminants in soils. However, to better characterize trace level contaminants in complex sample matrices, laboratory analysis using analytical instrument with great separation and resolution power is required. Comprehensive two-dimensional gas chromatography (GC X GC) is such a powerful analytical tool that provides enhanced separation and resolution capacity for the task. The project presented here involves the development and validation of a field method for the analysis of total polychlorinated biphenyls (PCBs) in soils, and determination of individual PCB congeners in the same samples by further laboratory analysis. The field analytical system developed was a field portable GC interfaced with a thermal desorber. The identification of PCB congeners was realized by a GC X GC system with a time-of-flight mass spectrometer (TOF-MS) as a detector. The field method was developed by optimizing and characterizing the method using PCB standards, followed by the application of the developed method to environmental soil samples. Finally, analyses of PCB congeners in environmental soil samples were performed using the GC X GC system.

Depuis plusieurs siècles les racines de vétiver sont utilisées en Inde du sud afin de prévenir l'érosion du sol. Par la suite, la production de l’huile essentielle des racines de vétiver a permis d’alimenter l’industrie de la parfumerie. De nos jours, cette matière première sert principalement à la confection de parfums masculins, où elle apporte des notes boisées, terreuses, de pamplemousse et de rose. En dépit de son utilisation abondante, la nature des molécules responsables de son odeur est encore un sujet de controverses. Dans un premier temps, l’étude des constituants volatils a été entreprise, et certaines incohérences de la littérature ont été mises en évidence. Par la suite, l'analyse par GC × GC d'huiles de vétiver d'origines différentes a permis de mieux comprendre la variabilité de cette matière première. Elle a également facilité l’identification de substances odorantes d'impact, réalisée par GC-O sur l’huile essentielle et l’acétate de vétiveryle. La synthèse de plusieurs dérivés zizaane a également été développée pour confirmer certains des résultats de la caractérisation des odorants. Nous avons également développé une nouvelle procédure pour la synthèse à grande échelle de dérivés nor-zizaane à puissante odeur de vétiver. Lors de cette étude, nous avons développé une nouvelle réaction de décarbonylation utilisant le peroxyde d'hydrogène en milieu alcalin. Cette réaction a pu être appliquée sur différents aldéhydes aliphatiques, les meilleurs résultats étant obtenus avec des substrats α-disubstitués. Une bonne sélectivité a également pu être observée sur les aldehydes linéaires, qui conduisent généralement à l’acide dans de telles conditions. / Vetiver have been used from centuries in South India to prevent soil erosion and later on, the essential oil produced by distillation of this raw material has begun to been largely employed in perfume composition. This essential oil is now abundantly used in the confection of men perfumes for its pleasant fragrance of wood, earth, grapefruit and rose. However, paradoxically, the nature of its impact odorants still remains controversial. At first, we have realized the review of the volatile constituents identified in this material, and some discrepancies of the literature have been highlighted. Then, the analysis by GC × GC of vetiver oils from different origins has permitted to better understand the composition of these materials. Subsequently, the characterization of the impact odorants of Haitian vetiver essential oil and vetiveryl acetate has been performed by GC-O. To confirm some of the results of this investigation, several zizaane derivatives have been synthesized, and in the course of this study, we developed a new reaction of decarbonylation of aliphatic aldehydes using alkaline hydrogen peroxide. A new procedure for the large scale preparation of highly potent nor-zizaane odorants could then be developed. Moreover, when exploring the scope and limitations of this reaction, it appeared to be applicable on various aliphatic aldehydes. The best results were obtained with α-disubstituted substrates, and a surprisingly good selectivity of this reaction was noticed on linear aldehydes.

This study investigates d13C and d18O variations in the shells of modern brachiopods that represent all extant groups of calcite-precipitating brachiopods, and were collected live from 8 locations. Protocols and methods of sample preparation are presented that can produce good estimations of annual mean temperatures of ambient seawaters from some brachiopod groups. SEM examinations determined the ultrastructural characteristics of each species prior to isotope analyses. d13C and d18O analyses of shell carbonate were carried out with samples representing different morphological features and ultrastructural shell layers of both ventral and dorsal valves. Generally, d18O values from the fibrous secondary or prismatic tertiary shell layers of the articulated Terebratulida and Rhynchonellida species were in oxygen isotopic equilibrium with ambient seawater. Isotopic temperatures extrapolated from these values are close to measured annual mean seawater temperatures. d18O values were relatively unaffected by shell specialisation. The only exception was Antarctic species Liothyrella uva, which did not have a complete tertiary shell layer typical of this genus and had d18O values of the innermost layer strongly correlated with d13C and mostly not in oxygen isotopic equilibrium with ambient seawater. With the exception of the rhynchonellid Notosaria nigricans, the outer primary layer material was depleted in d13C and d18C and highly variable. Inclusion of this material even as part of a whole shell sample could lead to misinterpretation of seawater temperature, therefore only fossil secondary layer material should be used. The anomalous articulated thecideidine brachiopod Thecidellina barretti is composed of mainly primary shell material and was not in oxygen isotope equilibrium.

Numerical simulations of buoyant, gravity-driven coastal plumes are summarized and compared to the inviscid geostrophic theory of Thomas & Linden (2007) and to laboratory studies for plumes owing along a vertical-wall coastline (those of Thomas & Linden (2007) and additional experiments performed at Warwick University). In addition, results of two new laboratory studies with different scales for plumes owing along a more realistic inclined-wall coastline are presented and compared to an extended theoretical model from the geostrophic theory of Thomas & Linden (2007). The theoretical and experimental results for plumes flowing along inclined-wall coastlines are compared to the inclined-wall experimental studies of Avicola & Huq (2002), Whitehead & Chapman (1986) and Lentz & Helfrich (2002), to the inclined-wall scaling theory of Lentz & Helfrich (2002), and to oceanic observations. The lengths, widths and velocities of the buoyant gravity currents are studied. Agreement between the laboratory and numerical experiments, and the geostrophic theories for both vertical-wall and inclined-wall studies is found to depend mainly on one non-dimensional parameter which characterizes the strength of horizontal viscous forces (the horizontal Ekman number). The best agreement between the experiments and the geostrophic theories is found for plumes with low viscous forces. At large values of the horizontal Ekman number, laboratory and numerical experiments depart more significantly from theory (e.g., in the plume propagation velocity). At very low values of the horizontal Ekman number (obtained in the large-scale inclined-wall experimental study only), departures between experiments and theory are observed as well. Agreement between experiments and theory is also found to depend on the steepness of the plumes isopycnal interface for the vertical-wall study, and on the ratio between the isopycnal and coastline slopes for the inclined-wall study.

Changes in mean sea (MSL) level recorded relative to tide gauge benchmarks (TGBM) are corrupted by vertical land movements. Accurate estimates of changes in absolute sea level, require these MSL records to be corrected for ground level changes at tide gauge sites. For more than a decade, the Global Positioning System (GPS) has been used to determine positions of TGBMs and to monitor their position changes, i.e. station velocities, over time in the International Terrestrial Reference System (ITRS). This was initially carried out by episodic GPS campaigns and later on by continuous GPS (CGPS) or a combination of both. Highly accurate realizations of the ITRS, satellite orbits and models for the mitigation of systematic effects currently enable the determination of station positions using GPS at the centimetre or even millimetre level. It is however argued that accurate long--term estimates of changes in the vertical component at the 1mm/yr level cannot be achieved, making intercomparisons between GPS estimates and other techniques necessary. Daily processing and analysis of continuous GPS networks requires automated procedures. The modifications and improvements to the existing procedures at the IESSG are described. The newly developed tools include the monitoring and quality control of daily archived GPS observations and of processing results. A special focus is on the coordinate time series analysis and methodologies used to obtain the best possible estimates of vertical station velocities and associated uncertainties. The coordinate time series of 21 CGPS stations in the UK and France are analysed. Eight of these stations are co-located with tide gauges. The effects of two processing strategies and two realizations of the ITRS on the coordinate time series are investigated. Filtered coordinate time series are obtained by application of a regional filtering technique. Station velocity estimates are obtained by fitting a model including a linear and annual term, and offsets to the unfiltered and filtered coordinate time series. Realistic uncertainties for these velocities are obtained from the application of two empirical methods which account for coloured noise in the coordinate time series. Results from these are compared to the Maximum Likelihood Estimation (MLE), which allows for more rigorous and accurate, simultaneous estimation of the model parameters and their uncertainties. Strategies for coordinate time series analysis on a daily or monthly, and annual or bi-annual basis are defined. At two CGPS stations the dual-CGPS station concept is tested and compared to the single baseline analysis and the application of an adaptive filter. An empirical method to obtain coordinate time series specific filter parameters is described. This investigation shows that reliable relative vertical station velocity estimates can be obtained after much shorter observation spans than absolute vertical station velocity estimates. The availability of dual-CGPS station pairs allows a simplified processing strategy and a multitude of coordinate time series analysis methods, all contributing to a better understanding of the variations in the positions of CGPS stations. Vertical station velocity estimates for the unfiltered and filtered coordinate time series and different analysis strategies are compared for 17 of the CGPS stations and show disagreements of up to 2mm/yr. At the eight CGPS stations co-located with or close to tide gauges alternative estimates of vertical land/crustal movements from absolute gravimetry, geological information and glacial isostatic adjustment models are compared to the GPS estimates, and it is suggested that the latter are systematically offset. An alignment procedure is demonstrated, correcting the vertical station velocity estimates of all 17 CGPS stations for this offset. The correlation of the geology-aligned vertical station velocity estimates and the MSL records from eight tide gauges suggests changes in absolute sea level of approximately +1mm/yr around the UK.

The problem of cross-shore beach face evolution in the swash zone is examined within the framework of the shallow water theory. A system comprising the shallow water and Exner equations is solved numerically using both uncoupled and fully coupled approaches. The uncoupled model assumes that changes in bed height have a negligible effect on the flow over a swash event, whereas the fully coupled model updates the hydrodynamic variables and beach profile simultaneously. In order to obtain accurate results over a single swash event several new numerical solvers based on the method of characteristics (MaC) and the MacCormack (1969) explicit finite-difference scheme are detailed. Particular attention is given to the treatment of discontinuities. A procedure for the explicit treatment of discontinuities, derived from techniques employed in gas dynamical problems, is developed and applied. Certain rather novel shock capturing approaches are also investigated. The shoreline boundary is discussed and a new robust algorithm for the treatment of this boundary on both fixed and mobile beds is presented. The resulting numerical models are used to simulate a variety of different swash events on an initially plane sloping mobile beach. Predictions of beach face evolution are made using the fully coupled approach and are compared with predictions made using an uncoupled analytical beach evolution model based on that of Pritchard and Hogg (2005). The fully coupled model leads to some interesting observations, in particular the possibility of local onshore sediment transport and the occurrence of a seaward facing sediment bore in the backwash. A characteristics based analysis is performed and reveals important differences in the flow structure of coupled and uncoupled swash events. The maximum wave run-up is also considered and it is shown that for the fully coupled system the run-up is significantly less than that predicted by the Shen and Meyer (1963) theory and motion of the leading edge can no longer be determined using simple ballistics concepts. Additionally, for verification purposes, new quasi-analytical solutions are constructed for the mobile bed dam-break problem using two distinct sediment transport formulae.

Since the early Cenozoic, the Earth’s climate has been gradually cooling. Large ice sheets have expanded on several occasions in the past 5000 kyr (50 Ma), with the last major expansion being the onset of major ice sheets in the Northern Hemisphere between 3600 and 2500 ka. This period was characterised by a prolonged increase in ice volume, modulated by orbital forcing. At the same time, major tectonic changes were taking place, with the closure of the Central American Seaway most significant. This thesis aims to address the issue of what caused the onset of major Northern Hemisphere glaciation through an in depth study of samples from North Atlantic ODP Site 982 (57° 31’ N, 15° 51’ W; 1145 m water depth). Multi-species benthic foraminifera composite trace metal records (Mg/Ca, B/Ca, Li/Ca, Cd/Ca) were produced, and the composite Mg/Ca record was used to develop a new regional temperature calibration for the Pliocene. Paleoceanographic records of bottom water temperature and saturation state were produced, as well as bottom water flow speed records using the Sortable Silt (SS) proxy. Bottom water temperature (BWT) records showed an abrupt, ~2°C cooling at 2800-2700 ka, consistent with other previously published records. These data are combined with previously published benthic stable isotope (δ18Ob) records to reconstruct seawater oxygen isotope reconstructions (δ18Osw) across the period of study, and this is found to predominately reflect changes in global ice volume. A major and prolonged increase in ice volume (3500-3000 ka) is identified, equivalent to up to ~55m sea level decrease. The response of the North Atlantic region to this ice sheet growth was tested using previously published sea surface temperature (SST) and δ18Ob records from ODP Site 982, in addition to the new record from this study. The ice volume was found to have influenced the response of SST, δ18Ob, and SS to orbital forcing from changing insolation. Prior to the ice sheet growth, bottom water flow speed varied proportionally with sea surface temperatures, with increased deep water formation during periods of high seasonality. The growing ice sheets responded more slowly to insolation changes, and the presence of this ice sheet increased deep water formation by further cooling saline surface waters. This resulted in feedback loops that intensified deep water flow, leading to a significant increase in North Atlantic Deep water penetration to the southern ocean. A major decrease in δ18Osw at 2800-2700 ka was interpreted as either a loss of Antarctic ice mass, or a reorganization of North Atlantic water masses. Comparison of ice volume records with orbital spectra and reconstructions of the closure of the Central American Seaway suggest the immediate cause of Northern Hemisphere glaciation was a period of orbital conditions favourable to ice sheet growth. Another underlying cause was a series of tectonic shifts, including the closure of the Central American Seaway from 4200 ka, which changed heat and moisture transport patterns to the high latitudes.

This thesis presents a series of numerical modelling studies into hydrodynamic transport and larval dispersal. The initial investigation seeks to evaluate retention timescales in Liverpool Bay. The flushing time and residence time are equal to 136 days and 103 days respectively, however small concentrations of seawater are retained over several years due to vigorous tidal mixing. The age distribution is shown to be highly variable and dependent upon tracer input duration, however salinity can be used to estimate the mean age, which is not directly observable in practice. Chapters 3, 4 and 5 all focus upon the dispersal of meroplanktonic larvae and aim to determine how larval behaviour affects their transport. Vertical migration is a significant influence upon larval dispersal within each case study, although the effect of this behaviour is conditional upon local hydrodynamic conditions. For example diel vertical migration promotes dispersal in the western Irish Sea, however the identical swimming pattern facilitates local retention in the eastern Irish Sea. The ecological implications of these findings are discussed. This thesis concludes with an investigation into the impact of large CO2 leakages on the marine carbonate system at potential carbon sequestration sites in the North Sea. Perturbations to seawater pH are found to vary according to the rate, duration and location of CO2 input. The northern North Sea is particularly vulnerable to large perturbations ( > 1 pH units) during the summer months, as the strong seasonal thermocline suppresses CO2 outgasing.

Exposures of the lower Waterford Formation, Karoo Basin, South Africa provide rare three-dimensional control to an exhumed low-gradient basin margin, which permits increased understanding of sub-seismic scale process-regime and lateral variability. The study section overlies a 500-m-thick channelized submarine slope succession and is subdivided into eight mappable parasequences clinothems. The central 40 km 2D reference profile parallel to depositional dip (i.e. west-to-east) enables characterization of the shelf-to-slope transition for two successive clinothems and the establishment of robust criteria for identifying the shelf edge at outcrop. The two clinothems exhibit differing process responses to the gradient increase at the shelf edge rollover. The fluvial-dominated, mouth-bar clinothem of WfC 3 exhibits a 5 km dip-parallel zone of extensional growth faulting at the shelf edge with limited delivery of sediment beyond the shelf edge rollover. In contrast, WfC 4 is a wave and storm dominated shoreface-clinothem that supplied a thick upper slope turbidite succession via closely spaced gullies at the shelf edge and a large upper slope channel. This suggests that the delivery of sediment to deep-water settings is governed by parameters other than the presence and proximity of a fluvial point source, which is heavily advocated in current models for shelf construction. It would be common practice to attribute variability between successive clinothems on a single 2D dip profile to lateral variability across the basin margin. However, two additional, sub-parallel dip profiles across depositional strike to the north and south of the reference profile indicate significant 3D variability in the nature of the clinothems. A greater supply of sediment to the upper slope in the north of the region, in the absence of a clear fluvial driver, suggests that the deltaic/shoreface system was able to transit quickly to the shelf edge and establish itself in that position for an extended period. Increasing parasequence thickness toward the north indicates greater accommodation in this area throughout the lower Waterford succession. It is therefore likely that differential subsidence across the margin controlled the position of the shelf edge and maintained a narrower shelf in the north, which would have had significant influence on sediment routing paths, diverting them to the north. Abundant shelf-confined soft sediment deformation in successive clinothems along all three dip margin profiles is attributed to instability on the frontal slopes of inner shelf deltas, due to high rates of sediment supply. The basinward splitting and abrupt thinning of deformed packages beyond the inferred shelf edge rollover shows that the presence of soft-sediment deformation alone is not an adequate criterion with which to define the shelf edge rollover. The significant thickness of shelf deposits without subaerial exposure indicates that the margin was subject to a relatively high subsidence rate but that the rate of sediment supply was sufficient to drive the system to the shelf edge and deliver sand to the slope without the development of incised valleys. Therefore, the lower Waterford Formation is considered a high accommodation / high supply system. This study provides a high-resolution outcrop-based dataset with three-dimensional constraints. It enables greater understanding of the controls on basin margin construction, and the sub-seismic scale processes that control the spatial and temporal variability of sediment delivery to the slope and basin floor.