A poluição dos corpos d\'água é de grande preocupação mundial, pois a maioria da população utiliza a água doce de reservatórios, represas ou rios como principal fonte de água potável. A presença no Brasil de florações de cianobactérias capazes de produzir anatoxina-a, revela a necessidade de métodos simples e rápidos que permitam sua detecção e monitoramento. Neste trabalho foram desenvolvidos, otimizados e validados dois métodos analíticos por GC/MS para identificação e quantificação de anatoxina-a em amostras de água e florações, respectivamente. A norcocaína foi usada como padrão interno em ambos os métodos. Os íons escolhidos para serem monitorados foram (íons quantificadores sublinhados): anatoxina-a: 191,164, 293 e norcocaína: 195, 136, 168. As curvas de calibração dos métodos mostraram-se lineares nas faixas de 2.5-200 ng.mL-1 e 13-250 ng.mg-1. Os limites de detecção obtidos foram 2 ng.mL-1 e 10 ng.mg-1. Os métodos demonstraram sensibilidade e especificidade adequada para seu uso no monitoramento ambiental da anatoxina-a. / The water pollution is a big concern around the world, since the most of cities use freshwater reservoirs, dams or rivers as the main drinking water suppliers. Cyanobacterial blooms capable to produce anatoxin-a are regularly present in Brazilian waters. Therefore, there is a necessity of simple and rapid analytical methods to monitor this cyanotoxin. In the present work, two analytical methods by GC/MS for identification and quantification of anatoxin-a in water and algae bloom samples were developed, optimized and validated. Norcocaine was used as internal standard in both methods. The ions chosen to be monitorated were (quantification ions underlined): anatoxin-a 191, 164, 293 and norcocaine: 195, 136, 168. Both method calibration curves showed linearity in the ranges of: 2.5-200 ng.mL-1 and 13-250 ng.mg-1. The obtained limit of detection were: 2 ng.mL-1 and 10 ng.mg-1. The methods showed sensitivity and specificity enough to be used routinely as a tool for anatoxin-a monitoring.

Les huiles essentielles extraites de plantes aromatiques, médicinales et à parfum, sont utilisées depuis des millénaires pour leurs propriétés médicinales ou olfactives. Pour des raisons de rentabilité, les distributeurs sont contraints à réduire leur coût au maximum et à commercialiser des huiles essentielles au plus bas prix. Certains ont recours à la fraude et proposent, des essences de qualité inférieure sous la dénomination produits naturels de haute qualité. Il existe des normes (AFNOR, pharmacopées) qui doivent être respectées. Mais leur seule application est souvent limitée. Cette étude a donc permis une nette amélioration du contrôle de la naturalité des huiles essentielles de citrus, et lavande. La connaissance des compositions moléculaires des volatiles et des polymethoxyflavones (citron), l'étude énantiomérique de molécules cibles telles que l'alpha-pinène, le sabinène (citrus), le linalol et l’acétate de linalyle (bergamote et lavande), les analyses isotopiques du carbone 13, deutérium, des linalol, acétate de linalyle (bergamote et lavande), citral, acétate de géranyle (citron) ainsi que les analyses isotopiques du deutérium et azote 15 du N-méthyle anthranilate de méthyle (mandarine) sont les analyses permettant la mise en évidence de nombreux types de fraudes. Pour une méthodologie efficace, les analyses en composante principale et discriminante ont été indispensables. Elles ont permis l’identification d’échantillons fraudés via l’étude des volatiles. Les analyses chirales et isotopiques permettent l'identification d'échantillon plus “ finement ” adultérés ou de mieux comprendre les processus de fraude / Essential oils extract from aromatics, medicinal and perfume plants, are used since ancient times for their medicinal or olfactory properties. They are quite expensive, and owing to the actual growing demand for getting high quality materials at lowest prices, fraudulent essential oils are frequently found on the market. In order to fight this problem, norms exist (AFNOR, pharmacopeas) which have to be respected. However those techniques are often limited. This work allowed great improves in the quality control of citrus and lavender essential oils. The knowledge of the chemical composition of volatiles and polymethoxy-flavones (lemon), of the chirale ratios of alpha-pinene, le sabinene (citrus), linalool et linalyl acetate (bergamot et lavender), isotope ratio analyses of carbon 13, deuterium, of linalool, linalyl acetate (bergamot et lavender), citral, geranyl acetate (lemon) as wall as isotope ratio analyses of deuterium of nitrogen 15 du Nmethyl anthranilate de methyl (mandarin) permitted the detection of various type of frauds. In order to have an efficient methodology, principal component and discriminant analyses have been proved indispensables. It allowed the identification of fraudulent samples via volatiles molecules study. Chirale analysis and isotope ratio highlight frauds on more “discrete” adulterated samples or a better understanding of adulteration’s process

Lambic beer is one of the oldest beer styles still being brewed in the western world today and the only beer that is still brewed through spontaneous fermentation. Lambic beers are only produced within a 500 km radius of Brussels because of the natural microflora found within the air in that region. Little is known about the chemical composition of lambic beers. The objective of this research were (1) to compare SPME and SAFE for the isolation of flavor and aroma compounds,  (2) determine the volatile composition and acids of commercially available lambic gueuze using SPME/GC-MS and HPLC, and (3) determine the major aroma compounds of aging lambic beer using GC-O.  Comparing the two extraction methods, both SPME and SAFE were able to identify a similar number of chemical compounds, however SAFE identified a greater number of acid compounds. A total of 50 compounds were identified within nine commercial brands of lambic beer. HPLC was used in the identification and quantification of acetic and lactic acids. The concentration of acetic acid in the commercial products ranged from 723 mg/L â " 1624 mg/L and lactic acid ranged from 995 â " 2557 mg/L. GC-O was used in the analysis of aged (3-28 months) lambic beer samples. As the samples increased in age, the number of aroma compounds detected by the panelists also increased. Panelists were detected nine aroma compounds in the 3 month old sample, while 17 compounds were detected in the 28 month old sample. The research conduct increased the number of volatile and semi-volatile compounds identified in lambic beer from 27 to 50. / Ph. D.

The fractionation between different stable isotopic species of the elements carbon and oxygen provides a powerful tool for investigation of various physical, chemical and biological processes in nature. Complex systoms involving the interaction of several such processes can be studied by combining isotope ratio measurements with other suitable data. The oceans constitute one of the most important of these systems; the distribution of carbon and oxygen in the sea is governed by a balance amongst physical, chemical and biological forces so that information on the isotopic abundances can be profitably used in oceanographic description. In this work, experimental techniques for determination of 6180 of seawater, and extraction and measurement of total dissolved inorganic carbon (EC02) from seawater and its 613C -assay are described. The assumptions involved in these methods are investigated and the associated errors discussed, in particular with regard to the mass spectrometry. The storage of oceanographic water samples between collection and analysis may allow biological activity to alter the dissolved oxygen/ carbon system. Inconsistencies in previously published work are pointed out and experiments are detailed which illustrate that temporal rCO2 and ý13C variations mirror the changes known to occur in the bacterial population of seawater stored without the addition of poison. Different types of storage vessel are investigated for preserving sample integrity and it is concluded that the importance of immediate poisoning and proper storage has been seriously underestimated in much previous work. Vater samples have been collected from areas of the Pacific and Antarctic Oceans, and analysed for 5180 of the water, >C02 and its 613C and, in some cases, pH and dissolved oxygen. The 6180 results have been taken in conjunction with conventional, hydrographic data to provide descriptions of the physical oceanography of the regions; water mass structure, and mixing has been elucidated and discussed. In the light of this, the ECO2,613C, pH and dissolved. oxygen measurements have been used to investigate the chemical and biological regimes. Comparison of the results of several different investigators in the Pacific has suggested that systematic errors may exist between directly and indirectly determined. ECO2 values. The regional oceanography deduced from this research has been in general accord with commonly accepted views derived from other studies.

Data assimilation is the act of merging observed data into a mathematical model. This act enables scientists from a wide range of disciplines to make predictions. For example, predictions of ocean circulations are needed to provide hurricane disaster maps. Alternatively, using ocean current predictions to adequately manage oil spills has significant practical applications. Predictions are uncertain and this uncertainty is encoded into a posterior probability distribution. This thesis aims to explore two overarching aspects of data assimilation, both of which address the influence of the mathematical model on the posterior distribution. The first aspect we study is model error. Error is always present in mathematical models. Therefore, characterising posterior flow information as function of model error is paramount in understanding the practical implications of predictions. In a model describing advective transport, we make observations of the underlying flow at fixed locations. We characterise the mean of the posterior distribution as a function of the error in the advection velocity parameter. When the error is zero, the model is perfect and we reconstruct the true underlying flow. Partial recovery of the true underlying flow occurs when the error is rational, the denominator of which dictates the number of Fourier modes present in the reconstruction. An irrational error leads to retrieval only of the spatial mean of the flow. The second aspect we study is the control of ocean drifters. Commonplace in oceanography is the collection of ocean drifter positions. Ocean drifters are devices that sit on the surface of the ocean and move with the flow, transmitting their position via GPS to stations on land. Using drifter data, it is possible to obtain a posterior on the underlying flow. This problem, however, is highly underdetermined. Through controlling an ocean drifter, we attempt to improve our knowledge of the underlying flow. We do this by instructing the drifter to explore parts of the flow currently uncharted, thereby obtaining fresh observations. The efficacy of a control is determined by its e↵ect on the variance of the posterior distribution. A smaller variance is interpreted as a better understanding of the flow. We show a systematic reduction in variance can be achieved by utilising controls that allow the drifter to navigate new or ‘interesting’ flow structures, a good example of which are eddies.

This thesis examines the migration strategy, diet and foraging ecology of the smallest Atlantic seabird, the European Storm Petrel Hydrobates pelagicus.Evidence was found for sex-specific migration behaviour, opportunistic feeding, temporal variation in diet, and the strategy regulation of energy reserves in response to varying environmental conditions, as a buffer against starvation during migration. Molecular sexing from feather and faecal samples revealed an unexpectedly strong female bias in the sex ratio of Storm Petrels attracted to tape-lures of conspecific calls, during their northwards migration past the coast of SW Portugal. The thesis describes the development and application of molecular techniques, in combination with stable isotope analysis, to study Storm Petrel diet by the detection of prey DNA from faecal samples. The major category of prey detected was fish (chiefly European Sardines Sardina pilchardus). Other components of the diet were other pelagic and demersal fish species, Cephalopoda (primarily cuttlefish Sepia spp.), Amphipoda, Isopoda and a range of terrestrial invertebrates. Large between-year fluctuations in the level of body reserves carried by these birds were observed over the 21-year study period (1990-2010). The pattern of body mass variation followed a smooth oscillation, which was not an artefact of differences among years in the distribution of capture effort, body size or sex ratio changes. Local sea surface temperature (SST), net primary production (NPP) and European Sardine biomass were key factors associated with between-year changes in Storm Petrol body reserves. These associations suggest that Storm Petrels strategically regulate their body reserves to buffer against starvation in years of low food abundance.

This thesis examines the forcing and behaviour of oceanographic physical features, relevant to recruitment in fish populations, in the Gulf of Guinea Large Marine Ecosystem, on seasonal and interannual time scales. Remotely sensed sea-surface temperature (SST) data covering the period 1981–1991 was used to identify and describe a number of oceanographic features, including the Senegalese Upwelling influence, the Ghana and Côte d’Ivoire coastal upwelling, river run-off, fronts and the previously unrecorded observation of shelf-break cooling along the coast of Liberia and Sierra Leone during the boreal winter. Interannual variability in SST was observed on an approximate three year scale and an extended warm phase was noted between 1987 and 1991. Principal components analysis (PCA) was used to further investigate the variance structure of these SST data and this technique was shown to be able to accurately define boundaries of the Gulf of Guinea system and its constituent subsystems. River discharge data from throughout the Gulf of Guinea was also investigated using PCA, confirming the hydroclimatic regions identified by Mahé and Olivry (1999). The boundaries between these regions correspond closely to those identified between subsystems in the SST data, suggesting a degree of coupling between oceanographic and meteorological variability in the Gulf of Guinea. To further investigate this coupling, local climate data and global/basin scale indices were compared qualitatively and statistically with remotely sensed and in situ SST data and indices of interannual variability in oceanographic features. A new basin scale index was proposed as a measure of zonal atmospheric variability in the subtropical North Atlantic (SNAZI) and this was shown to be the dominant mode of climate variability forcing SST in the Gulf of Guinea. The implications of these results for fisheries recruitment dynamics are discussed.

The present-day seabed in the eastern English Channel is an erosional landscape dissected by a complicated network of palaeovalleys. The largest of these palaeovalleys has been interpreted as the product of catastrophic flooding though the Straits of Dover during the Mid Quaternary. Whilst the eastern English Channel is a valuable source of aggregates, little attention has been paid to the sedimentary record preserved on the continental shelf in terms of its ability to document landscape change throughout the Quaternary. This thesis aims to establish the first stratigraphic model of deposits preserved on the continental shelf in the eastern English Channel and chronometrically constrain the timing of deposition using Optical Stimulated Luminescence (OSL) dating. The model will be used as a framework to reconstruct landscape change and address questions regarding the preservation potential of sediments, and the imprint sedimentary processes have on the landscape, in continental shelf settings over glacial-interglacial cycles. The stratigraphic model was constructed through the integration of high resolution mutlibeam bathymetry, shallow sub-surface 2D seismic profiles, lithological information from vibrocores, and chronometric data obtained through OSL. A variety of drowned landscapes including terrestrial (fluvial and colluvial), coastal and shallow marine, were identified. These landscapes document palaeoenvironmental change on the continental shelf from MIS 6 to MIS 1. The fluvial landscape in the English Channel is dominated by multiple phases of lateral and vertical erosion, primarily in response to changes in sea level, but also as a result of reorganisation of drainage basins and variable discharges due to fluctuating ice margins. Exposure of the continental shelf during cold periods is documented in the form of remnant periglacial deposits and extensive palaeosols. The most volumetrically significant sediments preserved on the continental shelf were deposited in shallow marine and coastal settings. These sediments are typically restricted to palaeovalleys where accommodation created during relative sea-level rise enabled deposition. Elsewhere, sediments are preserved as relict coastal landforms, in particular, as part of an exceptionally rare drowned barrier complex at Hastings Bank. Over multiple sea-level cycles, sediments are recycled by fluvial and marine processes, with the most recent phase of deposition having the greatest preservation potential. Erosional processes have the greatest persistence in the landscape record. However, they create a composite record and distinguishing between different events without a correlative sediment package is problematic. The results presented in this thesis highlight the timing and nature of ‘normal’ sedimentary regimes in a continental shelf setting over multiple glacial-interglacial cycles. Further, they reveal evidence for erosion and deposition by fluvial processes in the Northern Palaeovalley during the last glacial period, thus contradicting an existing hypothesis that states the palaeovalley formed through catastrophic flooding.

Nanomaterials (NMs) can be defined as having at least one external dimension between 1-100nm. Due to their small size, NMs have a large surface area giving them characteristics that differ from bulk material. NMs are incorporated into numerous applications making environmental exposure to NMs likely. Increased reliance on plastic results in accumulation of nano-plastics in fresh waters. Polystyrene (PS) acts as a representative of both nano-plastic and NMs. The deposition of gold (Au) NMs is also likely due to their use in medical applications so that both PS and Au have a potential to interact with environmental organisms. Daphnia manga (D. magna) is an ideal candidate in fresh water toxicity testing. Toxicity, uptake and retention of NMs by organisms is dependent on several factors such as NM charge, shape, chemical composition and the absorption of natural biomolecules binding to the surface of the NM creating an eco-corona, altering stability of the NMs thereby changing their toxicity. This work investigates the toxicity of PS and Au NMs and explores the effects of charge, shape, presence of a corona and the impact of realistic modes of presentation of NMs to D. magna and how these factors impact toxicity, uptake, retention and depuration.

L’ovoproduit est une matrice biologique complexe, constituée de protéines, lipoprotéines, lipides et de nombreux micronutriments (vitamines, minéraux, etc.). Cependant, une fois cassé et homogénéisé l'ovoproduit entier liquide perd une bonne part de ses propriétés de conservation, devenant ainsi pour certaines bactéries un excellent milieu de croissance. Ce développement bactérien non maîtrisé provoque en plus des risques sanitaires, des altérations biochimiques modifiant fortement les qualités organoleptiques de l’ovoproduit. On se propose dans cette thèse d’étudier les mécanismes biochimiques impliqués par des approches de métabolomique combinées (profilage métabolique par GC-MS et prise d’empreinte métabolique par GC-MS et RMN). Cette approche permettra de décrire et de comprendre de façon intégrée certains mécanismes jusqu’alors peu ou pas caractérisés et d'identifier in fine des marqueurs précoces de ces altérations microbiologiques. / Egg products are complexes biological matrix constituted of proteins, lipoproteins, lipids and many micronutrient (vitamins, mineral, etc…). However, once broken and mixed, the liquid egg product looses a great deal of its keeping properties, thus becoming an excellent growth media for many bacteria. This uncontrolled bacterial development induces, beside the involved health risks, biochemical alterations which modify the product’s organoleptic qualities. This manuscript aims to study the involved biochemical mechanisms using combined metabolomics approaches (Metabolic profiling by GC-MS and metabolic fingerprinting by GC-MS and NMR). This approach will allow the description and understanding of certain mechanisms which characterization was previously absent or limited. It will also allow the identification of early prediction biomarkers of these biological alterations.