Dissertations / Theses on the topic 'Seam contamination'

Beim Siegeln von Verpackungen können nicht-qualitätsgerechte Siegelnähte dadurch entstehen, dass sich Teile des Packguts zwischen den zu fügenden Packmittelbahnen befinden. Im Gegensatz zum konventionellen Wärmekontaktsiegeln besteht beim Ultraschallsiegeln die Möglichkeit, für jeden einzelnen Siegelvorgang Prozessdaten zu erfassen. Aus dem Bereich des Ultraschallschweißens ist bekannt, dass sich anhand dieser Daten der Prozess überwachen und dessen Güte bewerten lässt. Die vorliegende Arbeit untersucht den Informationsgehalt dieser Prozessdaten hinsichtlich störungsbehafteter Siegelnähte und leistet damit einen Beitrag zur Verbesserung der Verpackungsqualität und damit im besten Fall auch zu weniger Lebensmittelverlusten. Es wird dazu zunächst eine Systematisierung von möglichen Störprinzipen beim Siegeln hinsichtlich ihrer physikalischen Wirkprinzipe vorgenommen. Darauf aufbauend konnte ein Versuchsstand und eine Methodik zur Untersuchung der Thematik entwickelt werden. Abschließend wurden ausgewählte Störprinzipe untersucht, wobei sich ein sehr starker Packstoff- und Einfluss der Prozessführung herausstellte. Es konnte ein prinzipieller Zusammenhang zwischen Auswirkung einer Störung auf die Nahtqualität und die Prozessdaten gezeigt werden, welcher sich jedoch auf Basis der erarbeiteten Ergebnisse nicht verallgemeinern lässt.

Sea water samples were collected from different sampling stations along the Lebanese coast in the summer of 1994. Chemical, biological and physical analysis were conducted to assess the recreational water quality in Lebanon.<br>Some 125 samples were then analyzed for the presence of Cadmium and Mercury by atomic absorption spectrophotometry. Cadmium content, holding a mean 0.77 $ mu$g/L, was generally low for most areas with only a few elevated readings in Tripoli (1.89 $ mu$g/L), Checca (1.83 $ mu$g/L), Kaslik (0.79 $ mu$g/L), Beirut (1.19 $ mu$g/L) and Ramlet Al-Bayda (1.77 $ mu$g/L). Mercury content, holding a mean value of 0.06 mg/Kg (wet weight), was below the accepted tolerance limit of 0.5 mg/Kg for all sampling sites.<br>Some 128 samples were then analyzed for fecal coliforms (Escherichia coli and Streptococcus feacalis). Approximately, 50% of the sampling stations showed satisfactory results (less than 100 colonies/100 ml). High counts of fecal coliforms, over 500 colonies/100 ml, collected at Dora, Ramlet Al-Bayda and Antelias, reveal poor sea water quality and a public health hazards to swimmers and fishermen.<br>Some 36 samples were collected and analyzed for dissolved oxygen (DO), pH, salinity and temperature. For all sites sampled, DO averaged 4.03 mg/L, pH averaged 7.97, salinity averaged 38.77 ppt and temperature averaged 27.9$ sp circ$C.<br>The degree of pollution was found to be related to population density, industrial and human activity, continental runoffs and hydrological and meteorological conditions.

Satellite borne radar scatterometers provide frequent estimates of near surface wind vectors over the Earth's oceans. However in the polar oceans, the presence of sea ice in or near the measurement footprint can adversely a ect scatterometer measurements resulting in inaccurate wind estimates. Currently, such ice contamination is mitigated by discarding measurements within 50 km of detected sea ice. This approach is imperfect and causes loss of coverage. This thesis presents a new algorithm which detects ice-contaminated measurements based on a metric called the Ice Contribution Ratio (ICR) which measures the spatial ice contribution for each measurement. The ICR calculation is made for each measurement using a spatial ice probability map which is determined using Bayesian probability theory. Determined by simulation, the ICR processing thresholds the ICR for each measurement depending on local wind, ice backscatter, and cross-track location. ICR processing retrieves winds at a distance of 22.5 km from the ice edge on average, while ensuring wind accuracy. Retrieved wind distributions using ICR processing more closely resembles uncontaminated wind distributions than winds retrieved using previous methods. The algorithm is applied to QuikSCAT in this thesis but could be applied to other scatterometers such as the Oceansat-2 scatterometer.

Seals are considered one of the important flow elements of a turbomachinery device. Traditional labyrinth seals have proven their performance functionality by reducing leakage rates. Significant improvements on labyrinth seal functionality were obtained through altering the design geometry of labyrinth seals to prevent contamination across a seal and maintaining small leakage flowrates. This results in a windback seal that has only one tooth which continuously winds around the shaft like a screw thread. These seals are used in gas compressors to isolate the gas face seal from bearing oil. A purge gas is passed through the seal into the bearing housing. The helical design allows the seal to clear itself of any oil contamination. Windback seal performance is controlled through changing the seal geometry. A 2D graphical design tool for calculating the total and cavity leakage flowrates for windback seals is introduced. The effectiveness of the Fluent CFD (Computational Fluid Dynamics) commercial code to accurately predict the leakage rate for windback seals was evaluated. The objective is to determine if CFD simulations can be used along with a few experimental tests to study windback seals of this design with air as the working fluid. Comparison of measurement and predictions for a windback seal using the κ-ε turbulence model with enhanced wall treatment functions show predictions and measurements comparing very well with a maximum difference of 5% for leakage rate. Similarly, the leakage rate of the tested smooth seal compares favorably with two dimensional CFD predictions, with a difference of 2%-11% and 8%-15% using laminar and κ-ε turbulent flow models, respectively. The variation of leakage with shaft speed and pressure ratio across the seals is accurately predicted by the CFD simulations. Increasing the rotor speed to 15000 rpm increases the measured leakage flowrate for the windback seal by 2% at high differential pressure and 4.5% at low differential pressure, and decreases it by 10 % for the smooth seal. The effects of seal clearance, tooth pitch, cavity depth and the tooth number of starts on leakage flowrate, velocity and pressure distributions were studied numerically for three differential pressures and four rotor speeds.

Sediments are the final repositories for most pollutants, which can accumulate and remain in the sedimentary matrix for long periods of time and may accumulate through the food web, affecting marine biota, aquatic-dependent wildlife, and ultimately human health. Thus, a wide-ranging work monitoring different groups of contaminants in sediments is a key tool for a comprehensive understanding of contaminants behavior and identification of the overall environmental quality and possible threatens to the whole marine ecosystem. POPs, among which PCBs and DDTs rank first, polycyclic aromatic hyrocarbons (PAHs), and selected groups contaminants of emerging concern (CECs) (fragrances, UV filters, endocrine disruptors) were the objective of this work. First, PCB congeners were analyzed in sediment cores and recent sediments along the north-south axis of the western Adriatic Sea. Chronological records of PCB concentrations and homologue patterns were assessed, supporting the reconstruction of PCBs fluxes and total inventories. Then, the spatial distribution and fate of selected legacy and emerging compounds were investigated in surface sediments sampled along the Adriatic mud-wedge and in deep-sea regions from the southern Adriatic basin, providing the first extensive dataset and also the evaluation of potential ecotoxicological risk of target emerging contaminants in sediments from the Adriatic Sea. Finally, the analyzes of selected legacy contaminants (PCBs, DDTs and PAHs) in sediment cores from coastal and deep-sea sediments from the Adriatic Sea supported the comparison between these two areas and further reinforces the hypothesis on the transfer of contaminants from contaminated areas in the northern Adriatic to the deep southern Adriatic basin. The present thesis is the summary of the work carried out in the last three year of the PhD program “Scienze ambientali: tutela e gestione delle risorse naturali” and contains three manuscripts (two under review and one in preparation), and the main conclusions regarding this PhD research project.

Flexible packaging is a growing successful market and the majority of flexible package applications are for the food industry. The demand for process optimization and reduced production costs, has led to an increase in flexible packaging. However, fast production lines can result in contamination in the seal area. For flexible food packaging, contamination is considered any food particle or substance trapped in the seal area. Current quality control processes can detect contamination in the seal area, but it is not determined if seal contamination effects seal quality. Oil-based and sodium based snack foods are two common categories that can be packaged on a horizontal flow film and seal (HFFS) flow-wrap machine. The study uses vegetable oil and a salt water solution to simulate the effect of liquid contamination along the T-point of flexible pouches made on an HFFS. The T-point refers to where the fin seal meets the end seal and requires the seal jaw to seal through four layers of film, which is the most difficult point to seal. The study tests a combination of different sealing temperatures and dwell time to determine the optimal sealing condition for a hermetic seal. A quality hermetic seal provides an enclosed seal with no leaks due to successful polymer chain entanglement between the two sealant layers. The different test categories of the study are non-contaminated (control), salt water solution for salt based foods, and vegetable oil for oil-based foods. Given the test parameters of the study, 140⁰C sealing temperature and 0.3 seconds dwell time are considered to be the optimal sealing condition for all three test categories. For Phase 1 of the study, salt water has a lower hermeticity pass rate compared to vegetable oil and non-contaminated seals. In addition, the effect of refrigerated storage temperature and ambient storage temperature did not show to be significant for any of the test categories. However, refrigerated conditions showed a higher hermeticity pass rate, but it was not statistically different. The findings for seal strength indicated no test category had higher or lower seal strength over the 14 day test period. Overall, the study shows there is no effect of liquid contaminant on hermeticity and seal strength for flexible film with LLDPE sealant layer.

CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO<br>Com a probabilidade de ocorrer derrames de óleo em águas marinhas e a carência de informação sobre o comportamento de metais neste evento, viu-se a necessidade de se intensificar estudos referentes aos complexos metálicos, para que se possa entender a competição entre os ligantes do petróleo e os ligantes da água do mar. Para isto é necessário determinar a estabilidade dos complexos formados no petróleo, compará-los com os correspondentes na água do mar. Neste trabalho foram estudados os sistemas binários de complexos de ácido hexanóico (ligante que representa os ácidos carboxílicos do petróleo) e 1-propanotiol (representante das mercaptans) com os íons metálicos de interesse para a indústria do petróleo - Ni(II), V(IV) e Fe(II) - por estarem presentes em maior quantidade. Embora presentes em menor quantidade, Cd(II) e Pb(II) foram estudados por serem metais tóxicos e controlados pelas organizações ambientais. O ácido hexanóico apresenta o oxigênio do grupamento carboxilato, como sítio de coordenação enquanto que o 1-propanotiol possui o enxofre do grupamento tiol. O estudo da complexação foi realizado em solução utilizando a titulação potenciométrica e a espectrofotometria de ultravioleta- visível, Foram calculadas as constantes de dissociação dos ligantes e de formação dos complexos ML, ML2, ML3, MLOH, ML(OH)2, ML(OH)3, ML2OH, ML2(OH)2, ML3OH. Os valores das constantes de estabilidade dos complexos poderiam ser divididos em dois grupos: o dos complexos binários com ácido hexanóico e os complexos binários do 1- propanotiol. Dos complexos formados com o ácido hexanóico, a espécie ML com o íon metálico Pb(II) foi que apresentou maior estabilidade. No sistema onde temse complexos com 1-propanotiol, a espécie ML do íon metálico Cd(II) foi o que apresentou maior estabilidade. Na distribuição de espécies com ligantes representantes do petróleo e ligantes da água do mar observou-se a formação de complexos em pH = 7 para os íon metálicos V(IV), Ni(II) e Fe(II) com o ácido hexanóico. Para o íon metálico Pb(II) o complexo formado foi com o 1- propanotiol. Já para o íon Cd(II) houve a formação de complexo com o cloreto. Para o íon Cd(II), neste pH houve formação de pouca proporção de complexos com 1-propanotiol e um percentual maior (60 por cento) de complexos com os íons cloreto e sulfato da água do mar. Entretanto, como a concentração de cádmio é em torno de ppb no óleo combustível, este valor tem pouca relevância em termos de poluição. Assim, se estes ligantes estudados, que são monodentados, ligam-se preferencialmente aos metais do que os ligantes da água, com certeza isto acontece com os ligantes polidentados do petróleo como por exemplo as porfirinas. Com a utilização da técnica de espectrofotometria de ultravioletavisível foi possível observar as bandas referentes a transferência de carga e banda d-d. Foi realizada também uma simulação de derrame de óleo combustível. Para isto analisou-se a concentração de metais foi medida em tempos variados. Os dados teóricos e da simulação confirmam que íons metálicos ficam retidos no óleo mesmo quando há derrame do óleo na água do mar.<br>In face of the probability of occurrences of oil spill in marine waters and the lack of information concerning the behavior of the metals in such events, it is necessary to intensify the studies of metal complexes in order to understand the competition between oil ligands and sea water ligands. For such, it is necessary to determine the stability of the complexes formed in oil and compare them with the correspondent ones in sea water. In the present work the binary systems of the complexes of hexanoic acid (a ligand that represents the carboxylic acids of the oil) and 1-propanethiol (which represents the mercaptans) with the metal ions of interest to the petroleum industry - Ni(II), V(IV) and Fe (II) - were studied because they are present in greater quantities. Despite being present in smaller quantities, Cd(II) and Pb(II) were also studied because they are toxic and controlled by environmental organizations. Hexanoic acid has an oxygen atom of the carboxylate group as donor atom, and 1-propanethiol has a sulfur atom of the thiol group. The complexation study was performed in solution using potentiometric titration and ultraviolet-visible spectrophotometry. The dissociation constants of the ligands and the formation constants of the complex species ML, ML2, ML3, MLOH, ML(OH)2, ML(OH)3, ML2OH, ML2 (OH)2 and ML3(OH) were calculated. The values of the stability constants can be divided in two groups: one with the binary complexes of hexanoic acid and the other with the binary complexes of 1-propanethiol. Among the complexes formed with hexanoic acid, the ML species with metal ion Pb(II) was the most stable. In the system of the complexes with 1-propanethiol, the ML species with Cd(II) was the most stable. In the species distribution as a function of pH including the representative ligands of oil and sea water, it could be observed that at pH =7 the most stable species for the metal ions V(IV), Ni(II) and Fe (II) were those with hexanoic acid. In relation to ion Pb(II) the complex formed was with 1- propanethiol. Cd(II), this pH occurred the formation of a small proportion of the complex with 1-propanethiol and a higher percentual (60 percent) of the complexes with the chloride and sulfate íons of sea water. Since the concentration of Cd(II) is in the range of ppb, this metal ion is less relevant when pollution is concerned. Thus, if the monodentate oil ligands studied in this work preferably bind metal ions rather than sea water ligands, than this certainly happens with the polydentate oil ligands such as porphyrins. Using the ultraviolet-visible spectrophotometry technique it was possible to observe the charge transfer bands and the d-d bands. A simulation of oil dispersion was also performed and the concentration of the metals was measured at various times. Both theoretical and simulation data showed that the metal ions are retained in the oil, even when the oil is spread in sea water.

Unlike municipal water supplies, provincial regulations do not require systematic testing of domestic well water, which may adversely impact local residents should contamination occur. Private wells are typically shallow relative to municipal wells, and thus, are particularly vulnerable to sources of surficial contamination if preferential recharge pathways such as natural fractures or faulty seals are present. In order to determine the relative importance of well seal integrity as a preferential pathway, a practical detection method was developed based on infiltrometry. This method successfully detected faulty well seals in a wide range of geological settings across Canada, including: Hobbema, Alberta; Lindsay, Ontario; and Chelsea, Québec. It was most successful in areas of minimal heterogeneity and where the surficial geology is composed of fine-grained sediments. The community of Chelsea (Québec) was also the primary study site to examine a range of factors affecting water quality including physical characteristics, faulty well seals, other anthropogenic activities and seasonality. Water samples were collected over a period of 14 months and analyzed for bacteria and major-ion chemistry. The results show that the consideration of physical features alone is not enough to predict vulnerability in the study area. Seasonal fluctuations in ionic concentrations (e.g. ionic strength, NO3-N and Cl-) and coliform bacteria are observed and result from disperse and rapid recharge events. Multivariate analysis techniques (e.g. principal components analysis and hierarchical cluster analysis) demonstrate that preferential recharge pathways and anthropogenic activities, such as domestic effluents affect the groundwater quality. The data and findings of this study were used to assist in the design of a probabilistic risk assessment model based on the Poisson distribution. This study demonstrates the complexity and the challenges related to bacterial contamination in drilled wells. In spite of these challenges, this analysis was useful as a baseline to assess the impact of anthropogenic activities, and may be used in future studies to assist municipalities in the evaluation and protection of groundwater supplies.

<p> Selenium (Se) is a trace element of great ecological importance whose environmental distribution is highly impacted by anthropogenic activity. In the 1980s, selenium was recognized as a major aquatic contaminant following widespread deformities and mortality among waterfowl hatchlings near the agricultural drainage evaporation ponds of the Kesterson Reservoir (CA, USA). Today, 400,000 km² in the Western United States are threatened by agricultural selenium contamination, as are parts of Canada, Egypt, Israel, and Mexico. From the soil aggregate to the watershed, from the soils of the Central Valley to the sediments of the Salton Sea, and from Environmental Science to Policy and Management, in this dissertation I explore agricultural selenium contamination across scales, ecosystems, and disciplines. I begin with a review of the science, policy, and management of irrigation-induced selenium contamination in California, the heart of worldwide research on the issue. I then delve into the physical and biogeochemical mechanisms that control selenium reduction and mobility within the structured surface soils that are the source of contamination, using an aggregate-scale combined experimental and reactive transport modeling approach. Finally, I present a diagenetic model for selenium incorporation into the sediment of the Salton Sea, which has been receiving seleniferous agricultural drainage over the last 100 years. </p><p> To extract lessons from the last 30 years of seleniferous drainage management and water quality regulation in California, I reviewed the history and current developments in science, policy, and management of irrigation-induced selenium contamination in California. Specifically, I evaluated improvements in the design of local attenuation methods and the development of programs for selenium load reductions at the regional scale. On the policy side, I assessed the site-specific water quality criteria under development for the San Francisco Bay-Delta in the context of previous regulation. This approach may be a landmark for future legislation on selenium in natural water bodies and I discussed challenges and opportunities in expanding it to other locations such as the Salton Sea. By combining proven management tools with the novel, site-specific policy approach, it may be possible to avoid future events of irrigation-induced selenium contamination. However, the majority of regional selenium load reductions in California were achieved by decreasing drainage volume rather than selenium concentrations. Thus, there appear to be opportunities for additional improvements through management practices that enhance selenium retention in source soils. </p><p> To quantify the likely implications of these experimental results for soils with different degrees of aggregation, I formulated a general mechanistic framework for aggregate scale heterogeneity in selenium reduction. Specifically, I constructed a dynamic 2D model of selenium fate in single idealized aggregates, in which reactions were implemented with double-Monod rate equations coupled to the transport of pyruvate, O₂, and Se-species (selenate, selenite, and elemental selenium). The spatial and temporal dynamics of the model were validated with the experimental data and predictive simulations were performed covering aggregate sizes between 1 and 2.5 cm diameters. Simulations predict that selenium retention scales with aggregate size. Depending on aeration conditions and the input concentrations of selenate and pyruvate, selenium retention was predicted to be 4-23 times higher in 2.5-cm-aggregates compared to 1-cm-aggregates. Under oxic conditions, aggregate size and pyruvate-concentrations were found to have a positive synergistic effect on selenium retention. Promoting soil aggregation on seleniferous agricultural soils may thus help decrease the impacts of selenium contaminated drainage on downstream aquatic ecosystems receiving it. </p><p> This work presents agricultural selenium contamination as a complex problem that crosses ecosystems, scales, and disciplines. From a management perspective, the tension between dispersed non-point sources and hotspots where elevated selenium concentrations and sensitive aquatic ecosystems converge is difficult to address. Differences in biogeochemical conditions and trophic transfer within food webs render traditional regulatory approaches ineffective and force regulators to engage with the science of site-specific selenium transfer between ecological compartments. At the same time, gaps still exist in our mechanistic understanding of selenium's environmental cycling and in our integration of scientific knowledge across different ecosystems and scales. Centimeter scale heterogeneity in the biogeochemical conditions within source soils may fundamentally control selenium emissions across large agricultural areas and thus determine the selenium loading of rivers, lakes, and estuaries. Within aquatic environments receiving seleniferous drainage, the first few centimeters of surface sediment may control selenium exposure for entire food webs. Improved understanding at this level holds the potential to simultaneously reduce selenium emissions and respond more effectively to pollution where it occurs. In order to preserve sensitive habitat while also meeting agricultural drainage needs in seleniferous regions we must bridge the gaps between ecosystems, scales, and disciplines.</p><p> (Abstract shortened by UMI.)</p>

De part l'importance et la diversité des pressions anthropiques en mer du Nord, les mammifères marins en tant que prédateurs supérieurs se trouvent de plus en plus exposés à ces activités (trafic maritime, activités industrielles et portuaires, surpêche, pollution chimique, etc.). Les campagnes d'observation SCANS et SCANS II mises en place en 1994 et 2005 pour estimer l'abondance des petits cétacés, ont mis en évidence un changement majeur dans la distribution du marsouin commun (Phocoena phocoena) en mer du Nord avec un déplacement du Nord vers le Sud. Ce changement peut être lié à une migration de ses proies préférentielles en mer du Nord et/ou à une afaptation de son régime alimentaire par rapport à la disponibilité des proies. Parallèlement, à ces modifications de distribution spatiale, un nombre croissant d'échouage de marsouin commun en Manche Orientale et sur les côtes belges a été observé depuis une dizaine d'années avec une augmentation conséquente ces deux dernières années. Pour étudier les causes responsables de ces échouages, un des objectifs de cette étude a été d'évaluer l'état de la contamination chimique des animaux échoués en relation avec l'état sanitaire des individus. L'analyse de deux familles de composés chimiques (éléments traces métalliques et polluants organiques persistants) sur des animaux échoués sur la période 2006-2013 révèlent des concentrations significativement plus élevées dans les organies des animaux présentant des pathologies que celles obtenues chez les animaux sains. Cette tendance a déjà été observée en Atlantique Nord pour le marsouin. Les comparaisaons des niveaux de concentration mesurées avec ceux d'études antérieures effectuées sur des marsouins échoués dans la même zone ou dans le Golfe de Gascogne suggèrent que l'augmentation du nombre de marsouins échoués n'est pas liée à une dégradation du milieu en terme de pollution chimique. Pour déterminer le régime alimentaire du marsouin commun, trois techniques complémentaires ont été utilisées : l'analyse des contenus stomacaux, des isotopes stables (carbone et azote) et des acides gras dans différents tissus. Pour ces deux dernières méthodes, les signatures obtenues pour le marsouin ont été comparées à celles de leurs proies potentielles. Les résultats ont mis en évidence la présences des gobies, merlans, lançons, sprats, trisopterus sp., harengs et sardines comme proies potentielles. Le déplacement des marsouins du nord jusqu'au sud de la mer du Nord a été attribué à la baisse de l'abondance du lançon dans le nord, ainsi qu'à la ré-invasion du sud de la mer du Nord par la sardine, probablement suite au changement climatique. Enfin, cette étude confirme la nécessité d'utiliser une approche multi-analyses qui intègre des informations complémentaires à différentes échelles de temps pour étudier le régime alimentaire de ces prédateurs supérieurs<br>The North Sea is heavely impacted by human activities such as overfishing and pollution. Due to their position as top predators in the ocean, marine mammals are becoming increasingly affected by anthropogenic activities. The large-scale surveys SCANS in 1994 and SCANS II in 2005 that were held in the North Sea to estimate the abundance of small cetaceans highlighted a major shift in the distribution of harbour porpoises (Phocoena phocoena) from the northern parts of the North Sea to its eastern parts. Alongside, over the past few decades harbour porpoises stranding has increased in the southern North Sea particularly along the French and Belgian coastal waters. Since the contaminant exposure presents, among others, a potential threat to harbour porpoises inhabiting the North Sea, the first objective of the present study was to assess the contamination status of this species in the southern North Sea. On the other hand, the distribution and abundance of marine mammals is expected to follow the distribution of their main prey species. Hence, the second objective of this study was to investigate whether the changes in the distribution of porpoises in the southern North Sea may be a result of the changes in prey availability. Moreover, the third objective was to evaluate the interest of combining three methods to investigate the diet of harbour porpoises : stomach contents, stable isotopes (carbon and nitrogen) and fatty acids analyses. First, the contamination status was evaluated through the determination of two components of chemical contaminants (metals and persistent organic pollutants) in tissues of harbour porpoises stranded along the southern North Sea between 2006 to 2013. Several chemical contaminants presented higher concentrations in diseased animals compared to healthy animals. In addition, some metallic contaminants showed bioaccumulation with age. Comparison with previous study suggests that the population status of harbor porpoises in term of chemical concentration has been stable from 1994 to 2013. This work suggested that the increase in the number of stranded individuals is not related to the decline in the quality of the environment. Secondly, the shift in the abundance of harbour porpoises was evaluated and interpreted in the light of prey species abundance. Three techniques were used in order to determine the diet of porpoises. Results highlighted the presence of gobies, whiting, sandeel, sprat, trisopterus sp., herring and sardine as potential preys. The shift of the abundance of porpoises form the northern parts of the North Sea to its southern parts was attributed to the sandeel abundance decline in the northern parts of the North Sea along with the re-invasion of the southern North Sea by the sardine species, probably in response to climate change. Finally, the value of a multi-approach dietary analysis was evaluated. Besides overcoming the limitations of each method, combining different techniques that integrate diet over days and weeks allowed gaining more complete understanding of harbour porpoise's diet

The World Health Organization defines malnutrition as a variety of pathological conditions that arise as a result of deficiency of supply, transportation or use of nutrientes by the body s cells. Associated with energy and protein deficiency found in malnourished children there is a lack of vitamins and minerals. Currently, iron deficiency and vitamin A have been gaining importance as well as public health problem. Therefore, a balanced diet of macro and micronutrients such certainly decrease the rates of nutritional deficiencies. An alternative would be to include regional foods with nutritional value-added and low cost. One of these options would be the mussels (Mytella falcata) kind enough cultivated on the Brazilian coast and especially in Alagoas in the Estuarine Complex Mundaú-Manguaba (CEMM). On this basis it is proposed to examine the profile of micronutrients (vit. A, Fe and Zn) in mussels and their safety for consumption. For this, we evaluated the degree of contamination by heavy metals (As, Hg, Pb and Cd) from samples of fresh mussels, using the methodology of the AOAC, 2005, the hygienic and sanitary preparations of mussels, with and without milk coconut through microbiological parameters recommended by Ordinance 12/2001 of the Ministry of Health, according to AOAC methodology, 2005, APHA, 2004 and BAM / FDA, 2006 and the profile of micronutrients (vit. A, Fe and Zn) using methodology AOAC, 2005. The results indicated that the contamination levels for heavy metals were determined by the Division under the National Health Surveillance of Food (Decree 685/98) and the hygienic and sanitary preparations of mussels with and without coconut milk were considered satisfactory according to law. The concentrations of vit. A, Fe and Zn showed that the mussels, with and without coconut milk, have higher levels of iron than meat, besides being a good source of zinc, although their levels are lower than observed in the meat. Both preparations of mussels were not considered sources of vitamin A.<br>Coordenação de Aperfeiçoamento de Pessoal de Nível Superior<br>A Organização Mundial da Saúde define a desnutrição como uma pluralidade de condições patológicas que surgem em conseqüência de uma deficiência de aporte, transporte ou utilização de nutrientes pelas células do organismo. Associada a deficiência energética - protéica observada em crianças desnutridas verifica-se a carência de vitaminas e minerais. Atualmente a deficiência de ferro e de vitamina A vêm ganhando importância também como problema de saúde pública. Portanto, uma dieta balanceada em macro e nesses micronutrientes certamente diminuiria os índices de agravos nutricionais. Uma alternativa seria a inclusão de alimentos regionais com valor nutricional agregado e de baixo custo. Uma dessas opções seria o sururu (Mytella falcata) espécie bastante cultivada no litoral brasileiro e especialmente em Alagoas no Complexo Estuarino Mundaú-Manguaba (CEMM). Com base no exposto é que se propôs estudar o perfil de micronutrientes (vit. A, Fe e Zn) do sururu bem como sua inocuidade para consumo. Para tanto, foi avaliado o grau de contaminação por metais pesados (As, Hg, Pb e Cd) de amostras de sururu in natura, através da metodologia da AOAC, 2005, as condições higiênico-sanitárias das preparações de sururu, com e sem leite de coco, através de parâmetros microbiológicos recomendados pela Portaria 12/2001 do Ministério da Saúde, segundo metodologia AOAC, 2005, APHA, 2004 e BAM/FDA, 2006 e o perfil de micronutrientes (vit. A, Fe e Zn) através de metodologia da AOAC, 2005. Os resultados indicaram que os índices de contaminação para os metais pesados estavam abaixo do determinado pela Divisão Nacional de Vigilância Sanitária de Alimentos (Portaria 685/98) e as condições higiênico-sanitárias das preparações de sururu com e sem leite de coco também foram consideradas satisfatórias de acordo com a legislação em vigor. As concentrações de vit. A, Fe e Zn demonstraram que o sururu, com e sem leite de coco, apresentam teores de ferro superiores ao da carne bovina, além de ser uma boa fonte de Zn, apesar de seus teores serem menores que o observado na carne. Ambas as preparações de sururu não foram consideradas fontes de vitamina A.

O objetivo do presente trabalho foi avaliar a resistência à tração de botões ortodônticos fixados em esmalte bovino, utilizando-se três sistemas adesivos, com e sem contaminação com sangue humano. Foram selecionados noventa incisivos bovinos nos quais foram fixados botões de aço inoxidável com base de 3,5 mm de diâmetro, utilizando-se os sistemas adesivos Magic Bond (Vigodent) e resina TPH (Dentisply), Fill Magic Ortodôntico (Vigodente) e adesivo Transbond Plus Self Etching Primer (3M) e resina TPH. Para cada sistema adesivo 15 espécimes foram colados após contaminação da área com sangue humano e 15 sem contaminação (controle), resultando em seis grupos. Após colagem, os botões foram submetidos a ensaios de tração até deslocamento do mesmo e os resultados foram transformados para MPa. Os dados obtidos foram analisados estatisticamente (p 0,05) utilizando análise de variância a um critério (ANOVA) e teste de Tuckey. Para comparar os grupos contaminados com sangue com os controles utilizou-se Teste t de Student. A resistência à tração obtida (MPa), considerando-se os valores encontrados nos grupos estudados ocorreram na seguinte ordem: Adesivo Transbond Plus Self Etching Primer e resina TPH sem (2,66 1,41) e com contaminação (2,29 1,11); Adesivo Magic Bond e resina TPH sem (2,23 0,94) e com contaminação (1,68 0,78); e, Adesivo Fill Magic Ortodôntico sem (1,20 0,34) e com contaminação (0,51 0,37). Houve maior resistência à tração nos botões fixados sem contaminação e ocorreram diferenças estatisticamente significantes entre os diferentes sistemas adesivos utilizados.<br>The objective of this work was to evaluate the tensile strenght of orthodontic buttons settled in bovine enamel, using three systems adhesive, with and without contamination with human blood. Ninety bovine incisors had been selected in which stainless steel buttons had been fixed with base of the 3,5 mm of diameter, using themselves adhesive systems Magic Bond (Vigodent) and resin TPH (Dentisply), Fill Magic Ortoodôntico (Vigodente) and adhesive Transbond Plus Self Etching Primer (3M) and resin TPH. For each adhesive system 15 specimens had been glue after contamination of the area with human blood and 15 without contamination (control), resulting in six groups. After glue, the buttons had been submitted the assays tractive until displacement of the same and the results had been transformed for MPa. The gotten data had been analyzed for statistics (p 0,05) using analysis of variance to a criterion (ANOVA) and test of Tuckey. To compare the groups contaminated with blood with the controls Test t of Student was used. The tensile strenght gotten (MPa), considering the values found in the studied groups had occurred in the following order: Adhesive Transbond Plus Self Etching Primer and resin TPH without (2,66 1.41) and with contamination (2,29 1.11); Adhesive Magic Bond and resin TPH without (2,23 0,94) and with contamination (1,68 0,78); e, Adhesive Fill Magic Orthodôntico without (1,20 0,34) and with contamination (0.51 0,37). It had greater tensile strenght in the buttons settled without contamination and had occurred significant statistics differences between the different used adhesive systems.

Apis mellifera Linnaeus (1758) è un insetto eusociale conosciuto in tutto il mondo sia per la produzione di miele sia per il suo ruolo di impollinatore, uno dei servizi ecosistemici fondamentali per la biodiversità del pianeta. Durante la sua attività di foraggiamento, l’ape è esposta agli inquinanti ambientali tra cui il particolato atmosferico aerodisperso (PM). Il particolato atmosferico può depositarsi sul corpo dell’insetto e infine contaminare anche i prodotti apistici come polline e miele. Il PM può avere diverse dimensioni (es. PM10, PM2.5, PM0.1), composizione chimica, morfologia e fonti di emissione (naturale o antropica). Nel presente elaborato di tesi, tecniche di microscopia elettronica a scansione (SEM-EDX) sono state utilizzate per caratterizzare la contaminazione da PM di origine antropica del corpo dell’ape e dei suoi prodotti (Capitolo 2 e Capitolo 3) e analisi molecolari per studiare gli eventuali effetti sub-letali sul microbiota intestinale di api esposte ai PM per via orale (Capitolo 4).<br>Apis mellifera Linnaeus (1758) order Hymenoptera family Apidae, is a eusocial insect widely known for its role in pollination, a fundamental ecosystem service for plant biodiversity and ultimately for the planet. During flight and foraging activity, the honey bee can collect airborne particulate matter (PM) on their own body, especially on the forewings, and can also contaminate bee products as pollen and honey. Particulate matter can originate from natural or anthropic sources, and is characterised by size (e.g., PM10, PM2.5, PM0.1), chemical composition, and morphology. In this thesis, honey bee, pollen and honey were used as bioindicator of PM – from coarse to ultrafine – in industrial areas of the Po Valley, Italy (Chapter 2 and Chapter 3). The (sub-lethal) effects of Titanium dioxide – a widespread airborne PM1 pollutant – on the honey bee through oral exposure was then investigated (Chapter 4). The technique used to analyse the PM contaminating bees and bee products is the scanning electron microscopy (SEM) coupled with X-ray spectrometer (EDX). EDX spectra allowed us to obtain chemical information from specimens, while backscattered-electron (BSE) imaging and elemental mapping provided both compositional and topographic information of PM.

La présente étude traite de la contamination par les hydrocarbures, des sédiments superficiels de différentes stations réparties sur deux sites : la baie de Skikda (située en Méditerranée) et l'oued Saf-Saf (dans sa partie aval) qui se jette dans cette baie. Cette contamination a été étudiée des points de vue répartition géographique, origine et nature des hydrocarbures extraits. Les teneurs en hydrocarbures trouvées sont légèrement plus élevées dans le site oued Saf-Saf (278 mg.kg-1sed. sec), que dans le site mer (200 mg.kg-1sed. sec).Comparativement à d'autres études effectuées en mer Méditerranée, nos résultats témoignent d'un niveau moyen de contamination. L'identification des principales origines des hydrocarbures présents dans les sédiments des deux sites, a été effectuée en utilisant plusieurs indices relatifs aux hydrocarbures saturés et aux hydrocarbures aromatiques polycycliques.Les valeurs de ces indices ont permis de mettre en évidence plusieurs origines pour les hydrocarbures aussi bien dans le site oued Saf-Saf, que dans le de la baie de Skikda (origines biogènes naturelles terrestre et/ou marine, origines pyrolytiques naturelle ou pétrolière et origines pétrolières). Une étude statistique a fait l'objet d'une seconde partie de ce travail, à l'aide d'une série d'analyses et de tests univariés (ANOVA, Tukey et Dunnett appliqués aux périodes, puis aux stations pour chacune des 5 caractéristiques étudiées), bivariés (étude des corrélations) et multivariés (MANOVA, ACP et analyse hiérarchique). Ces tests ont été appliqués aux données des deux sites d'études et ont permis de confirmer les résultats obtenus dans la première partie du travail<br>The present study treats with the contamination by hydrocarbons, with superficial sediments of various stations repartee on two sites : the bay of Skikda (situated in the Mediterranean Sea) and the Saf-Saf oued (in its part downstream) with flows into this bay.This contamiation was studied by point of view geographical distribution, origin and nature of hydrocarbons extracts. The contents in found hydrocarbons are slightly more raised in the Saf-Saf oued (278 mg.kg-1sed. dry), that in the site sea (200 mg.kg-1 sed. dry). Compared with other studies made in the Mediterranean Sea, our results testify of an average level of contamination. The identification of the main origins of hydrocarbons presents in sediments of both sites, was made by using several indications relative to hydrocarbons saturated and in aromatic polycyclic hydrocarbons. The values of these indications allowd to highlight several origins for hydrocarbons as well in the Saf-Saf oued, as in Skikda bay (originate biogenic natural terristerial and/or marine, originate natural or oil pyrolytic and oil origins). A statistical study made the object of a second part of this work, by means of series of analysisesand of one-various tests (ANOVA, Tukey and Dunnett applied to periods, then to the stations for each of 5 characteristics), two-various (study of the correlations) and several-various (MANOVA, ACP and hierarchical analysis). These tests were applied to the data of both sites of studies and allowed to confirm the results obtained in the first part of the work

A baía de Sepetiba, localizada a 60 km na direção Oeste da região metropolitana do Rio de Janeiro, vem sendo submetida, nas últimas décadas, a um considerável desenvolvimento populacional e industrial, contando hoje com aproximadamente 400 indústrias (em sua maioria metalúrgicas) instaladas nas bacias de drenagem da baía, as quais lançam seus resíduos diretamente na baía ou nos corpos d'água da região. Além disso, o Porto de Sepetiba trouxe muitos investimentos industriais para a área. Toda esta expansão industrial e urbana resultou em uma série de impactos ambientais, devido ao lançamento de efluentes domésticos e industriais, os quais são ricos em metais pesados e outras substâncias potencialmente tóxicas. O objetivo deste trabalho foi avaliar a contaminação e mobilidade dos metais Cd, Cu, Ni, Pb e Zn, em sedimentos da baía de Sepetiba. Foram determinados os Sulfetos Voláteis em Ácido (AVS) e os Metais Extraídos Simultaneamente (SEM) em 65 amostras de sedimentos, coletadas de modo a cobrir toda a área da baía. Os resultados obtidos na extração ácida mostraram que os metais Cd, Cu, Pb e Zn apresentaram as mais altas concentrações extraíveis na região NE (principalmente na saídas dos rios Guandu e Canal de São Francisco), enquanto que as mais altas concentrações de Ni foram observadas na porção Oeste da baía. A comparação dos valores dos SEM com os valores guias de qualidade de sedimento (VGQS) canadenses (TEL e PEL) indicou que os metais Cd e Zn apresentaram teores nos quais é freqüente a ocorrência de efeitos negativos à biota (valores acima do PEL); já os metais Cu e Pb e Ni apresentaram concentrações que indicam uma baixa probabilidade de ocorrência de efeitos adversos aos organismos aquáticos de Sepetiba. Por outro lado, a razão S[SEM]/[AVS], ficou abaixo de 1 na porção NE, sugerindo que, apesar das altas concentrações dos metais na região, estes estão retidos no sedimento, na forma de sulfetos. Foram também determinadas as concentrações totais dos metais nos sedimentos, e observou-se que o padrão de distribuição das concentrações totais seguiu o mesmo padrão observado para os SEM, com as mais altas concentrações na porção NE da baía, classificando a área como nivel 2, com relação ao Zn, e como nível 1, com relação aos metais Cd, Cu, Pb e Ni, de acordo com a Resolução CONAMA 344/04. Apresenta-se um modelo geoestatístico, o modelo de atenuação das concentrações, que tem como proposta estimar a mobilidade de um elemento nos sedimentos. O modelo proposto mostrou os mais altos valores de atenuação para Zn, Cd, Cu e Pb na região NE, indicando que a mobilidade destes metais na região é baixa, o que está de acordo com as conclusões obtidas com o modelo S[SEM]/[AVS], indicando boas possibilidades de aplicação do modelo em estudos de contaminação de sistemas estuarinos por metais.<br>Sepetiba bay, located about 60 km west of the metropolitan region of Rio de Janeiro city, has undergone notable development in the last decades, with the establishment of about 400 industrial plants in its basin, basically metallurgical, which release its industrial waste either straight into the bay or through local rivers. The Sepetiba harbor also brought up a lot of industrial investment in that area. This urban and industrial expansion caused several environmental impacts, mainly due to the presence of heavy metals and other potentially toxic substances present in the effluents discharged into the bay. This work aimed to assess heavy metal (Cd, Cu, Ni, Pb e Zn) contamination and mobility in sediments from Sepetiba bay. The acid-volatile sulfides (AVS) and the concentration of simultaneously extracted metals (S[SEM) were determined in 65 sediment samples from Sepetiba bay, representing the whole area. The results obtained showed that Cd, Cu, Pb and Zn presented higher concentrations in the northeastern area (mainly in the mouth of Guandu and Canal de São Francisco rivers), while the highest concentration of Ni were observed in the western region of the bay. The comparison between SEM concentrations with the Canadian Sediment Quality Guidelines (TEL and PEL) indicated that Cd and Zn presented values which may hazard to aquatic organisms (concentration levels above PEL); the elements Cu, Pb and Ni presented concentration levels below PEL, suggesting low probability of toxicological effects to the aquatic organisms. On the other hand, the ratio S[SEM]/[AVS] was below 1 in the northeastern region, indicating that, in spite of the high concentration of the analyzed metals in this area, they are trapped in the sediment, as sulfides. The total metal concentrations in the sediments were also determined and the same distribution pattern obtained for the SEM were observed, with high concentrations in the northeastern region of the bay, classifying the area as level 2, for Zn, and as level 1, for Cd, Cu, Pb and Ni, according to the CONAMA 344/04 act. A geostatiscal approach is presented, the attenuation of concentrations model, which aims to estimate metal mobility in sediments. The proposed model showed the highest attenuation values for Zn, Cd, Cu and Pb in the northeastern region, indicating that the mobility of these metals is low in this region, suggesting low availability, which is in good agreement with the results obtained by the S[SEM]/[AVS] model. These results indicate good possibilities of applying this model in metal contamination studies in estuarine ecosystems.

Elevated levels of trace elements in the environment are of great concern because of their persistence, and their high potential to harm living organisms. The exposure of aquatic biota to trace elements can lead to bioaccumulation, and toxicity can result. Furthermore, the transfer of these elements through food chains can result in exposure to human consumers. Sea-fill or coastal fill sites are among the major anthropogenic sources of trace elements to the surrounding marine environment. For example, in the Maldives, Thilafushi Island is a sea-fill site consisting of assorted municipal solid waste, with multiple potential sources of trace elements. However, there is limited data on environmental trace element levels in the Maldives, and although seafood is harvested from close to this site, there is no existing data regarding trace element levels in Maldivian diets. Following the Christchurch earthquakes of 2011,

CAPES<br>O monitoramento em tempo real da água do mar em ambientes críticos, como na entrada de portos e de canais de navegação, é necessário para evitar grandes contaminações do meio ambiente marinho, principalmente em regiões costeiras. A contaminação mais recorrente é por derramamento de hidrocarbonetos. Um indicativo de contaminação por óleo, em tempo real, viabiliza a atuação imediata dos setores responsáveis. Tal medida pode evitar que as impurezas se espalhem por uma área maior, o que torna o processo de limpeza e descontaminação mais rápido e eficaz. Este estudo visa detectar alterações no comportamento físico da água do mar quando existir contaminação por hidrocarbonetos. O parâmetro físico a ser estudado é a variação na curva de transmitância da água do mar, com específicos comprimentos de onda, quando existir contaminação na amostra. A variação da absorção da onda eletromagnética detectada pelo foto sensor pode indicar que a amostra de água esteja contaminada por hidrocarbonetos. O equipamento base para a tomada de dados das curvas de transmitância é o espectrofotômetro, que tem como característica a capacidade de realizar uma varredura em uma faixa de comprimento de onda eletromagnética compreendida entre 190 nm a 1100 nm. A avaliação dos resultados é feita utilizando uma placa de aquisição do espectro de um LED de 400 nm. Dois métodos foram realizados utilizando a mesma fonte de radiação, o primeiro com incidência horizontal da luz na amostra de água (próximo à superfície) e o segundo com incidência vertical, submetendo a radiação à absorção causada pela coluna de água e contaminante (gasolina e querosene). Os resultados obtidos neste trabalho apresentam uma queda bem significativa da transmitância em função do aumento da concentração de poluente (hidrocarbonetos) na água, nas faixas mais pertinentes de cada substância, com suas diferentes estruturas moleculares. O ponto do espectro de maior sensibilidade para este hidrocarboneto na medição da transmitância está em 360 nm. Utilizando a lei de Lambert-Beer, foi calculada a correlação exponencial dos pontos obtidos com um determinado comprimento de onda, em 360 nm esta correlação é superior a 99%. O método utilizado e os resultados levantados possibilitam o desenvolvimento e aplicação de um sensor óptico para sensoriamento da água do mar baseado na variação da absorção da luz em função do aumento da concentração de contaminantes (hidrocarbonetos), e a utilização da lei de Lambert-Beer para estimar a concentração deste produto na água.<br>The real time monitoring of seawater in critical environments such as ports entrances and navigation channels is needed in order to avoid major contaminations of the marine environment especially in coastal regions. The most recurrent contamination is hydrocarbon spills. A real time contamination indicator enables immediate action from the responsible sectors. Such measurement might prevent impurities from spreading into a greater area, resulting in faster and more effective cleaning and decontamination process. This study aims to detect changes in the physical behavior of the sea water when hydrocarbon contamination exists. The physical parameter under study is the variation in the transmittance curve of seawater, with specific wavelengths, when there is contamination in the sample. The absorption variation of the electromagnetic wave detected by the photo sensor can indicate that the water sample is contaminated by hydrocarbons. The base equipment for collecting data from the transmittance curves is the spectrophotometer, which is able to perform a scan on an electromagnetic wavelength range between 190 nm to 1100 nm. Two methods were performed using the same radiation source, the first one with horizontal light incidence into the water sample (near-surface) and the second one with vertical incidence, subjecting radiation to absorption caused by the water column and contaminant (gasoline and kerosene). The results obtained in this study show a significant decrease of transmittance in function of the increase in concentration of pollutant (hydrocarbon) in the water, in the more relevant ranges of each substance, with their different molecular structures. The hydrocarbon used in the evaluation of both methods validation was gasoline. The spectrum point of greater sensitivity in measuring the hydrocarbon transmittance is in 360 nm. Using the Lambert-Beer law it was calculated exponential correlation of points obtained with a specific wavelength, in 360 nm this correlation is greater than 99%. The method and results raised enabled the development and application of an optical sensor for sensing seawater according to the variation of light absorption in function of the increasing contaminants concentration (hydrocarbons), and using the Lambert-Beer law to estimating the concentration of product in water.

Les biomatériaux à usage orthopédique posent le problème de leur devenir dans l'organisme. Lorsqu'ils sont métalliques, ils posent le problème du relargage de métaux dans les tissus voisins. L'alliage de titane Ti6AI4V est utilisé pour ses bonnes propriétés mécaniques et pour sa résistance à la corrosion. L'usage d'un revêtement permet d'améliorer encore ses performances. J'ai étudié deux revêtements en verre référencés BVA et BVH. La caractérisation in vivo et in vitro a été menée grâce à plusieurs techniques complémentaires d'analyse : microscopies électroniques et méthodes nucléaires (PIXE. . . ). Le verre BVA s'est révélé être bioactif. Il se transforme en un gel de silicium avec incorporation de protéines et d'oligo-éléments (Zn et Sr), et ce, dès 3 mois après implantation. Ce gel disparaît peu à peu et est remplacé par un os néoformé. Cet os a été analysé comme mature après un an d'implantation ; il assure une meilleure ostéointégration de l'implant. Quant au verre BVH, il est bioinerte. Sa composition est constante au cours du temps. Cependant, la formation d'une interface de 2 µm d'épaisseur, induite par le processus de dépôt du revêtement, fragilise les liaisons inter-granulaires. Cela se traduit par la fragmentation du revêtement et la migration de grains de verre à travers le réseau lacunaire de l'os environnant. Les deux verres sont une barrière efficace contre la corrosion de l'alliage, tant qu'ils restent en place. J'ai proposé les bases d'une nouvelle méthodologie d'analyse : la combinaison de la cartographie PIXE et de l'histopathologie. Le principal intérêt est de corréler une éventuelle réponse tissulaire à la présence de certains éléments atomiques. J'ai introduit pour la première fois la théorie de la percolation pour essayer de modéliser la résorption de biomatériaux poreux tel que le corail et les hydroxyapatites. Les premières simulations sont très prometteuses et rendent bien compte de plusieurs résultats expérimentaux observés

Pas de résumé en français<br>Plasmonic circuitry is considered as a promising solution-effectivetechnology for miniaturizing and integrating the next generation ofoptical nano-devices. The realization of a practical plasmonic circuitry strongly depends on the complete understanding of the propagation properties of two key elements: surface plasmons and electrons. The critical part constituting the plasmonic circuitry is a waveguide which can sustain the two information-carriers simultaneously. Therefore, we present in this thesis the investigations on the propagation of surface plasmons and the co-propagation of surface plasmons and electrons in single crystalline metal nanowires. This thesis is therefore divided into two parts. In the first part, we investigate surface plasmons propagating in individual thick penta-twinned crystalline silver nanowires using dual-plane leakage radiation microscopy. The effective index and the losses of the mode are determined by measuring the wave vector content of the light emitted in the substrate. Surface plasmon mode is determined by numerical simulations and an analogy is drawn with molecular orbitals compound with similar symmetry. Leaky and bound modes selected by polarization inhomogeneity are demonstrated. We further investigate the effect of wire geometry (length, diameter) on the effective index and propagation losses. On the basis of the results obtained during the first part, we further investigate the effect of an electron flow on surface plasmon properties. We investigate to what extend surface plasmons and current-carrying electrons interfere in such a shared circuitry. By synchronously recording surface plasmons and electrical output characteristics of single crystalline silver and gold nanowires, we determine the limiting factors hindering the co-propagation of electrical current and surface plasmons in these nanoscale circuits. Analysis of wave vector distributions in Fourier images indicates that the effect of current flow on surface plasmons propagation is reflected by the morphological change during the electromigration process. We further investigate the possible crosstalk between co-propagating electrons and surface plasmons by applying alternating current bias

Plasmonic circuitry is considered as a promising solution-effectivetechnology for miniaturizing and integrating the next generation ofoptical nano-devices. The realization of a practical plasmonic circuitry strongly depends on the complete understanding of the propagation properties of two key elements: surface plasmons and electrons. The critical part constituting the plasmonic circuitry is a waveguide which can sustain the two information-carriers simultaneously. Therefore, we present in this thesis the investigations on the propagation of surface plasmons and the co-propagation of surface plasmons and electrons in single crystalline metal nanowires. This thesis is therefore divided into two parts. In the first part, we investigate surface plasmons propagating in individual thick penta-twinned crystalline silver nanowires using dual-plane leakage radiation microscopy. The effective index and the losses of the mode are determined by measuring the wave vector content of the light emitted in the substrate. Surface plasmon mode is determined by numerical simulations and an analogy is drawn with molecular orbitals compound with similar symmetry. Leaky and bound modes selected by polarization inhomogeneity are demonstrated. We further investigate the effect of wire geometry (length, diameter) on the effective index and propagation losses. On the basis of the results obtained during the first part, we further investigate the effect of an electron flow on surface plasmon properties. We investigate to what extend surface plasmons and current-carrying electrons interfere in such a shared circuitry. By synchronously recording surface plasmons and electrical output characteristics of single crystalline silver and gold nanowires, we determine the limiting factors hindering the co-propagation of electrical current and surface plasmons in these nanoscale circuits. Analysis of wave vector distributions in Fourier images indicates that the effect of current flow on surface plasmons propagation is reflected by the morphological change during the electromigration process. We further investigate the possible crosstalk between co-propagating electrons and surface plasmons by applying alternating current bias

O estuário de Santos abriga o maior porto da América Latina e um dos maiores complexos industriais do Brasil. Na década de 1970 foi considerado um dos maiores exemplos de degradação ambiental em ambientes costeiros, e apesar da melhora na qualidade ambiental observada nos últimos anos algumas áreas deste estuário apresentam sedimentos ainda altamente contaminados com compostos tóxicos e genotóxicos, especialmente os Hidrocarbonetos Policíclicos Aromáticos (HPA). Operações de dragagem para manutenção das atividades portuárias são necessárias e consequentemente durante este processo pode ocorrer a ressuspensão de contaminantes presentes nesses sedimentos, tornando-os disponíveis novamente na coluna d\'água. Desta forma é interessante ter uma estratégia eficiente e aplicável no monitoramento da qualidade dessas águas. O Blue rayon (BR) é um adsorvente seletivo para compostos policíclicos com três ou mais anéis fundidos em sua molécula e tem sido utilizado com sucesso no monitoramento de HPA e atividade mutagênica em ambientes aquáticos. Este trabalho teve como objetivo padronizar o uso da técnica de Blue rayon in situ ancorado, onde as fibras são fixas a uma distância padronizada dos sedimentos, associada ao teste de Salmonella/microssoma em microssuspensão a ser aplicada no monitoramento das águas desse estuário. Foram selecionados três pontos de amostragem com diferentes características e sedimentos com variados níveis de contaminação. As duas campanhas iniciais foram realizadas com o objetivo de avaliar a eficiência do BR e de escolher a linhagem de Salmonella mais sensível aos compostos mutagênicos possivelmente presentes nos extratos obtidos bem como verificar a presença de HPA. As cinco campanhas posteriores foram realizadas para verificar o comportamento e a eficiência da estratégia previamente definida no monitoramento das águas desse estuário utilizando experimentos de dose resposta. Os resultados obtidos nas duas primeiras campanhas mostraram que as águas do ponto 1, que contém os sedimentos mais contaminados e recebe os efluentes da COSIPA, apresentam maior contaminação por HPA e atividade genotóxica mais elevada que o ponto 2. Também foi possível determinar que a linhagem de Salmonella YG1041 foi a mais sensível para detectar atividade mutagênica tanto no ponto 1 quanto no ponto 2. Nas cinco campanhas subsequentes as maiores potências mutagênicas foram também observadas no ponto 1 com valores máximos de 5.100 e 36.000 revertentes/g de BR para a linhagem YG1041 na ausência e na presença de ativação metabólica (S9) respectivamente. Nos pontos 2 e 3 as potências observadas foram similares entre si, com valores em torno de 1.000 revertentes/g de BR. Com base nos resultados obtidos nas duas etapas deste trabalho pode-se concluir que a o Blue rayon utilizado in situ a uma distância padronizada dos sedimento associado ao teste de Salmonella/microssoma em microssuspensão com a linhagem YG1041 na presença e na ausência de ativação metabólica (S9) é uma ferramenta que pode ser aplicada no monitoramento da qualidade do estuário de Santos.<br>Santos estuary is the major Latin American harbor and one of the largest industrial complex of Brazil. In the 1970s, it was considered one of the major examples of coastal degradation. Due to enforcement actions the quality of the environment has improved in the last years in relation to the chemical parameters and toxicity but unfortunately the sediment is still contaminated with toxic and genotoxic compounds especially Polycyclic Aromatic Hydrocarbons (PAHs). For the maintenance of the port activities sediment dredging is needed and during this process contaminants resuspension can occur, leading to the contamination of the water column. Therefore it is interesting to have an efficient strategy that can be used for the water quality monitoring of this area. The Blue rayon is a selective adsorbent to polycyclic compounds containing three or more fused rings and has been successfully used in the monitoring of PAHs and mutagenic activity in aquatic environments. The objective of this work was to evaluate a modified blue rayon hanging technique, denominated in this work \"Blue rayon anchored technique\", where the fibers are placed at a fixed distance from the sediment, associated with the Salmonella/microsome microsuspension assay in order to monitor the water quality of Santos estuary. Three sites with different sources and sediment contamination levels were selected in this study. Two initial samplings were performed in order to evaluate the efficiency of the BR modified technique and find the most sensitive strain of Salmonella typhimurium to the mutagens possibly present in the those waters as well as verify the presence of PAHs. Five subsequent samplings were performed to verify the performance and efficiency of the defined strategy in the estuary water quality monitoring using dose response experiments. In the two initial samplings, the water from the site containing the most contaminated sediment and under influence of COSIPA (site 1) presented higher mutagenic activity and higher levels of PAHs. It was also possible to verify the highest sensitivity of the YG1041 strain in the detection of the mutagenic activity in both sites analyzed. In the subsequent five samplings, higher mutagenic potencies were again observed for site 1, reaching 5,100 and 36,000 revertants per gram of BR for the YG1 041 strain in the absence and presence of S9 respectively. Sites 2 and: presented similar potencies, around 1000 revertants per gram of BR. Based on the obtained results we can conclude that the Blue rayon anchored technique associated with the Salmonella/microsome microsuspension assay with the YG1041 strain in the presence and absence of S9 is an suitable tool to monito Santos estuarine waters.

La mer Méditerranée (MS) est une mer semi-fermée divisée en deux bassins: le bassin occidental et le bassin oriental. Les deux sites méditerranéens étudiés dans cette thèse sont au nord-ouest de MS et sud-est de France pour la rade de Toulon et à l'est de MS, Liban pour la baie de St-Georges. Les deux sites sont soumis à une forte densité de population le long de la côte et, sont exposés à de nombreuses activités anthropiques (telles que le tourisme, les transports maritimes, l’aquaculture, les rejets d’eaux usées et des activités industrielles) contaminant l’environnement (colonne d’eau, sédiments, biote, etc.) avec différents contaminants tels que les éléments traces métalliques et métalloïdes (ETMM). Chaque site est caractérisé par la présence d'un fleuve urbanisé: le Las (France) et le fleuve Beyrouth (Liban). Les sédiments sont considérés comme une source secondaire de contamination en raison des processus biogéochimiques influençant la mobilité des ETMM dans les sédiments. Dans ce contexte, les objectifs de cette thèse sont (1) d’étudier la contamination des ETMM le long des rivières et dans les deux baies; (2) d'élucider l'influence de la diagenèse précoce sur la mobilité des ETMM; et (3) de caractériser la matière organique sédimentaire dans les deux sites. Pour ces raisons, des sédiments superficiels, des carottes sédimentaires, des eaux superficielles et interstitielles ont été collectés le long des deux rivières et dans les deux sites durant la période 2016-2018. Les échantillons de sédiments et d'eaux ont été analysés pour déterminer leurs principaux paramètres physiques, nutriments, carbone organique (dissous et particulaire) et les éléments majeurs/traces. Les résultats ont montré que les processus de la diagenèse précoce contrôlent fortement la mobilité de la ETMM dans les sédiments. De plus, les résultats ont confirmé que la rade de Toulon est fortement contaminée suite à la deuxième guerre mondiale mais aussi aux activités contemporaines, et que les apports du Las ne contribuent et n’affectent pas de manière significative les sédiments de la baie de Toulon. Quant à la baie de St-Georges, il a été constaté qu’elle est impactée par plusieurs activités (effluents industriels rejetés sans traitement, ruissellement de la zone agricole) transportées par le fleuve Beyrouth et/ou par des apports directs (décharge côtière)<br>Mediterranean Sea (MS) is a semi-enclosed sea divided into two basins: the Occidental and the Oriental basins. The two studied Mediterranean sites in this thesis are located respectively at N-W of MS and S-E of France for Toulon Bay and at E of MS, Lebanon for St-Georges Bay. They both host high population density especially along the coast and therefore exposed to numerous anthropogenic activities (e.g. tourism, marine transport, aquaculture, wastewater discharge, and industrial activities) contaminating the surrounding environment (water column, sediment, biota …) with different contaminants such as trace metals (TM). In addition, each site is characterized by the presence of an urbanized river: le Las (France) and Beirut River (Lebanon). Sediments are considered as a secondary source of contamination due to biogeochemical processes influencing TM mobility in the sediments. In this context, the objectives of this thesis are (1) to investigate TM contamination along the rivers and in bays; (2) to elucidate the influence of early diagenesis on TM mobility; and (3) to characterize organic matter at both sites. For all the above, superficial sediments, sediment cores, superficial waters and pore waters were collected along the two rivers and at both sites during the period 2016-2018. Sediments and waters samples were analyzed for main physical parameters, nutrients, organic carbon (dissolved and particulate) and major/ trace elements. Results showed that early diagenesis processes strongly control TM mobility in the sediments. In addition, the results confirmed that Toulon bay is strongly contaminated due to the 2nd World War and the present bay activities. The Las River inputs do not contribute and affect significantly the sediments of Toulon Bay. As for St-Georges Bay, we found that it has been impacted by several activities (industrial effluents discharged without treatment, runoff from agricultural zone) transported by Beirut River and/or by direct inputs (coastal landfill)

Que l’on soit un simple promeneur ou un fin observateur, l’eau est présente partout. Pourtant, l’atout qu’elle représente pour les activités anthropiques cache souvent sa réalité environnementale, celle de son cycle. Ce constat se reflète dans l’appréhension juridique de l’eau laquelle est conçue comme un bien ou une chose. Cette qualification l’assigne donc à un statut juridique dont les manifestations révèlent la fonction utilitariste de la ressource. Or, l’émergence des problématiques environnementales confronte le statut juridique de l’eau à sa réalité physique. Ainsi, le droit et les exigences environnementales s’influencent réciproquement pour générer des règles protectrices de l’eau et des représentations juridiques du cycle hydrologique qui engendrent des évolutions du statut. Dès lors, ce dernier s’émancipe des catégories juridiques traditionnelles issues du droit des biens et s’habille d’une finalité protectrice dont les règles et les concepts, qui s’attachent à la fonction écologique de l’eau et à la réalité environnementale du cycle hydrologique, lui façonnent une autre condition juridique<br>Along a simple stroll or through fine observations, you will always find water, wherever you go. However, the asset this resource represents for anthropogenic activities often hides its environmental reality, the one of its cycle. This is reflected in the legal definition of water which conceives it as property. This latter qualification assigns it to a judicial status which reveals the utilitarian function of the resource. Yet, the emergence of the environmental issues confronts water’s legal status to its tangible reality. Thus, the conflict between the law and water’s environmental demands makes way for protective regulations. Along with the hydrologic cycle’s legal representation, they both influence the evolution of water’s status. Consequently, the latter goes beyond property law traditional legal categories and arms itself with a protective purpose. Its rules and concepts are tied to the ecological function of water and to the environmental reality of the hydrologic cycle which shape yet another judicial condition for the water

Beim Siegeln von Verpackungen können nicht-qualitätsgerechte Siegelnähte dadurch entstehen, dass sich Teile des Packguts zwischen den zu fügenden Packmittelbahnen befinden. Im Gegensatz zum konventionellen Wärmekontaktsiegeln besteht beim Ultraschallsiegeln die Möglichkeit, für jeden einzelnen Siegelvorgang Prozessdaten zu erfassen. Aus dem Bereich des Ultraschallschweißens ist bekannt, dass sich anhand dieser Daten der Prozess überwachen und dessen Güte bewerten lässt. Die vorliegende Arbeit untersucht den Informationsgehalt dieser Prozessdaten hinsichtlich störungsbehafteter Siegelnähte und leistet damit einen Beitrag zur Verbesserung der Verpackungsqualität und damit im besten Fall auch zu weniger Lebensmittelverlusten. Es wird dazu zunächst eine Systematisierung von möglichen Störprinzipen beim Siegeln hinsichtlich ihrer physikalischen Wirkprinzipe vorgenommen. Darauf aufbauend konnte ein Versuchsstand und eine Methodik zur Untersuchung der Thematik entwickelt werden. Abschließend wurden ausgewählte Störprinzipe untersucht, wobei sich ein sehr starker Packstoff- und Einfluss der Prozessführung herausstellte. Es konnte ein prinzipieller Zusammenhang zwischen Auswirkung einer Störung auf die Nahtqualität und die Prozessdaten gezeigt werden, welcher sich jedoch auf Basis der erarbeiteten Ergebnisse nicht verallgemeinern lässt.

Windback seals work similarly to labyrinth seals except for the effect of helical groove. These seals are essentially a tooth on stator or tooth on rotor labyrinth seal where the grooves are a continuous helical cut like a thread. Windback seals are used in centrifugal gas compressor to keep oil out of the gas face seal area. These face seals cannot be contaminated by oil. A purge gas is applied to the seal to help force the oil back into the bearing area. The windback seal should be designed to prevent any oil contamination into the supply plenum and to reduce purge gas leakage. The CFD simulations have been performed with the effect of clearance, tooth width, cavity shape, shaft rotation, eccentricity, and tooth location on the seal leakage performance and the flow field inside the seal. The leakage flow rate increases with increasing the pressure differential, rotor speed, radial clearance, cavity size, and shaft diameter and with decreasing the tooth width. The eccentricity has a minimal effect for the windback seal. From oil simulations, the windback seal with 25% rotor eccentricity has some of the journal bearing action and drives back flow into the gas plenum. However the windback seal can be used to force the oil back into the bearing side before starting the compressor by applying a purge gas flow since the positive axial velocity inside the cavity is larger than the negative axial velocity. m A Rw cav & / ? is constant for varying shaft rotation since the leakage flow rate for the windback seal increases linearly as the the rotor speed increases. The leakage flow rate for the windback seal increases as the groove size increases due to the pumping action of the windback seal. A windback seal design based upon the numerical simulations that minimize gas leakage and help prevent gas face seal oil contamination was optimized. The windback seal has two leakage flow paths. Since the leakage flow rate under teeth of windback seals is the same as for a similar geometry labyrinth seal, the flow under the teeth can be predicted by two-dimensional labyrinth seal analysis. An empirical model for the leakage rate through the cavity has been developed which fits the data with a standard deviation of 0.12.

碩士<br>國立彰化師範大學<br>光電科技研究所<br>100<br>This thesis investigates the pollution of the sealant materials on the liquid crystal (LC) materials in the One Drop Fill process. The obtained results reveal that the pollution of the LC materials is mainly attributed to the acrylic and epoxy composites in the sealant materials. Increasing the acryl concentration effectively decreases the pollution of the LCs, and also increases polymerization ratio of the sealant materials. Furthermore,the concentration of the acrylic composite does not influence the adsorption capability, durability and stability of sealant materials. When the acrylic concentration exceeds 40 wt%, the pollution of the LCs from the sealant materials meets the criterion for mass production of the LC displays.

碩士<br>國立臺灣海洋大學<br>海洋環境資訊系<br>105<br>The present study reviewed the published papers (1998-2017) investigated the trace metal (Al, Cd, Cu, Fe, Pb, Mn, Ni, Zn and Hg) concentrations in the East China Sea (ECS) to assess the contamination status of the ECS. Most of the interpretation in this study focused on the trace metals in sediment. On the other hand, the interpretation of trace metals in seawater was few because the published data were much less than those of in sediment. The published data showed that the trace metal concentrations in surface sediments of the ECS were as follows: Al, < LD-10 %; Cd, 0.019-0.127 µg/g; Cu, 1.9-41.5 µg/g; Fe, 0.17-4.92 %; Pb, 6.2-44.8 µg/g; Mn, 152-1783 µg/g; Ni, 8.17-108 µg/g; Zn, 18-134 µg/g and Hg, <0.5-62.3 ng/g. The spatial distribution of trace metals generally exhibited higher concentration in the inner shelf, especially in the estuarine mouth of the Changjiang Estuary. The trace metal concentrations decreased with seaward. However, the concentration variations between the middle and the outer shelves were not significant. With the exception of Ni, the published data of trace metal concentrations in sediment of the ECS were generally lower than the values of the A level of the China EPA and the adverse biological effect range-low (ERL) of the NOAA, USA. In contrast, there were 122 Ni data among 135 data exceeded the ERL value (20.9 µg/g) and 22 data exceeded the ERM value (51.6 µg/g). This result suggests that the ECS was contaminated by Ni element, and the contamination by the other elements was not significant. The published data showed that the trace metal concentrations in seawater of the ECS were as follows：Al，0.2-35.1 µg/l；Cd，0.04-0.33 nM；Cu，0.87-11.09 nM；Fe，4.06-320.18 nM；Pb，0.003-2.22 nM；Mn，1.13-25.89 nM；Ni，0.92-16.28 nM；and Zn，1.83-25.78nM. The dissolved concentrations of Cd, Cu, Pb and Zn found in the ECS were much lower than seawater standard values of EPA, USA and the European Union, suggesting that trace metal concentrations in seawater are rather difficult to exceed the seawater standard values.

The aim of the work presented in this thesis was to understand processes of bioaccumulation and biomagnification of mercury (Hg) in a Southern Ocean (SO) food web, and to evaluate the effect of organism size and habitat in Hg accumulation during the last decade. To do this, tissues of various species occupying different trophic levels were analysed in samples collected over various sampling years (2006/07 and 2016/17) from areas with distinctive environmental characteristics. Different accumulation patterns were found: Antarctic krill juveniles had higher Hg concentrations than adults; in squid, Hg concentration increased with individual size in one species (Alluroteuthis antarcticus), decreased in another (Galiteuthis glacialis), and in another still, there was no obvious relationship (Bathyteuthis abyssicola); for myctophid fish there was a consistent increase of Hg concentration with fish size, with the exception of Electrona antarctica females. Proportions of organic Hg also varied between trophic groups, from relatively low (15-37%) in krill to virtual 100% in all myctophid tissues. Regarding Hg tissue allocation, squid muscle was the tissue that had highest Hg, followed by digestive gland and gills. Myctophids’ Hg concentrations were higher in the liver and heart than in muscle or gills. Geographic differences in Hg concentration in krill were found, with individuals from the South Orkney having Hg levels 5 to 7 times higher than South Georgia: this geographic variation was not found in myctophids. As expected, when evaluating Hg along the food web, POM spell out had the lowest Hg levels, followed in increasing concentration by zooplankton, squid, myctophid, notothenid fish and seabirds. Predators exhibited variability in Hg levels which corresponding to the trophic level of their diets, with lower 􀁇15N levels corresponding to lower Hg concentrations. The mid food web groups (squid and myctophids) showed a decreasing trend in Hg level over the last decade, but that difference was not reflected in top predators, for which Hg levels were higher in 2016/17 than in 2007/08. This difference between years may be due to a decrease in the abundance of krill that year, which would have necessitated a change by krill predators to myctophids, a higher Hg body burden prey. This thesis revealed details of Hg contamination in SO biota, emphasizing the role of atmospheric transportation in global mercury contamination. Present-day regional warming may lead to increasing Hg availability in the SO as glacial melt is releasing contaminants previously trapped following atmospheric precipitation. Climate change, pollution and growing fishing pressure are together placing increased pressure on SO marine ecosystems and the living resources they contain.<br>O objetivo desta tese foi compreender os processos de bioacumulação e biomagnificação do mercúrio (Hg) na cadeia alimentar do Oceano Antártico (OA) e avaliar o efeito do tamanho e habitat do organismo na acumulação de Hg, durante a última década. Tecidos de várias espécies de diferentes níveis tróficos foram analisados em amostras recolhidas de vários anos de amostragem (2006/07 - 2016/17) de áreas com características distintas. Diferentes padrões de acumulação foram encontrados: os juvenis do krill antártico apresentaram maiores concentrações de Hg que os adultos; nas lulas, a concentração de Hg aumentou com o tamanho individual em algumas espécies (Alluroteuthis antarcticus), diminuiu em outras (Galiteuthis glacialis) e em outras não houve relação óbvia (Bathyteuthis abyssicola). Nos mictofídeos, houve um aumento da concentração de Hg com o tamanho dos peixes, com exceção das fêmeas de Electrona antarctica. As proporções de Hg orgânico variaram entre os grupos, de relativamente baixas (15-37%) em krill a virtual 100% em todos os tecidos de mictofídeos. Quanto ao Hg em tecidos, o músculo das lulas foi o tecido que apresentou maior Hg, seguido pela glândula digestiva e brânquias. Hg nos mictofídeos foi mais elevado no fígado e no coração do que nos músculos ou brânquias. Há diferenças geográficas na concentração de Hg no krill, indivíduos da Órcades do Sul têm níveis de Hg 5 a 7 vezes superiores aos da Geórgia do Sul. Esta variação geográfica não foi encontrada nos mictofídeos. Como esperado, ao avaliar o Hg ao longo da cadeia alimentar, POM apresentou os níveis mais baixos de Hg, seguidos de uma concentração crescente no zooplâncton, lulas, mictofídeos, peixes nototenídeos e aves marinhas. Os predadores exibiram variabilidade nos níveis de Hg que correspondiam ao nível trófico das suas dietas, com níveis mais baixos de 􀁇15N correspondendo a concentrações mais baixas de Hg. Os grupos do meio da cadeia alimentar (lulas e mictofídeos) mostraram uma tendência decrescente no nível de Hg na última década, mas esse decréscimo não se refletiu nos principais predadores, para os quais os níveis de Hg foram mais altos em 2016/17 do que em 2007/08. Essa diferença entre os anos pode ser devida a uma diminuição na abundância de krill naquele ano, o que exigiria uma mudança na dieta dos predadores de krill para mictofídeos, que têm níveis de Hg maiores. Esta tese revelou detalhes da contaminação por Hg na biota do OA enfatizando o papel do transporte atmosférico na contaminação global de mercúrio. O aquecimento regional atual pode levar ao aumento da disponibilidade de Hg no AO. Os glaciares a derreter, libertam contaminantes que foram retidos após a precipitação atmosférica. As mudanças climáticas, a poluição e a crescente pressão da pesca estão a exercer uma pressão crescente sobre os ecossistemas marinhos de OA e os recursos vivos que eles contêm.<br>Programa Doutoral em Ciência, Tecnologia e Gestão do Mar

A ilha de São Tomé é uma importante área de nidificação e alimentação para quatro das sete espécies de tartarugas marinhas existentes no mundo. As tartarugas marinhas são classificadas como espécies ameaçadas (lista vermelha da IUCN) e sabe-se que as tartarugas marinhas estão sujeitas a muitas outras ameaças, nomeadamente a poluição oceânica. São poucos os estudos que têm sido desenvolvidos para avaliar como estas espécies interagem com o meio ambiente e como a poluição as afeta. O objetivo principal deste estudo foi avaliar as concentrações de metais acumulados na espécie Chelonia mydas e os impactos que estes contaminantes terão sobre as respostas de stress e inferir sobre o seu estado de saúde. De modo a alcançar estes objetivos, uma técnica menos invasiva foi efetuada, sendo recolhido sangue de fêmeas nidificantes, durante a desova, em locais de desova bem documentados em São Tomé. Amostras de sangue foram retiradas do seio cervical dorsal e uma porção foi armazenada em tubos contendo EDTA a -20ºC até a análise das concentrações de metais, e outra parte foi armazenada em RNAlater a -20 ° C até extração de RNA e análise de expressão genética usando PCR quantitativo em tempo real (qPCR). Também foram preparados esfregaços com o sangue das tartarugas e os danos no ADN foram avaliados através da observação de micronúcleos ao microscópio. Os resultados demostraram correlações significativas entre a expressão de alguns genes e os níveis de metais contaminantes, apontando alguns genes candidatos para serem usados como biomarcadores de interesse. Este estudo representa o primeiro esforço de abordar os níveis de poluentes e os danos biológicos de tais contaminantes nesta espécie de tartaruga que desova em São Tomé, contribuindo com informação relevante para ser usada em programas de biomonitorização para a conservação desta espécies ameaçadas.

Cd levels were measured in three different body compartments of the echinoid Stomopneustes variolaris after exposure to concentrations of 5 ug 1l, 20 ug 1l and 50 ug 1l Cd for a period of two weeks. The body compartments investigated included the intestine, gonads and skeleton. The gonads did not exhibit dose-dependent bioaccumulation. The levels of cadmium in the intestine and skeleton were significantly different between the treatments, suggesting that dose dependent bioaccumulation had occurred in these compartments (except in the skeleton where higher levels -were recorded for those exposed to 20 ug 1l than those exposed to 50 ug 1l) The levels recorded in the intestine were higher than those recorded in the gonads and skeleton at the higher Cd exposures of 20 and 50 ug 1i. The levels accumulated in the gonads and skeleton were not significantly different from each other. A separate group, exposed to 20 ug 1`1Cd over a period of two weeks, was placed in uncontaminated seawater to determine if the echinoids were capable of bioremediation. Bioremediation was found to lower the Cd levels in the gonads, but not in the intestine and skeleton. Cadmium levels for the three body compartments were also recorded from specimens collected from the field, indicating the presence of this element in the environment. In addition to using atomic absorption spectroscopy (AAS), energy dispersive X-ray analysis (EDX) was used as a comparative technique to detect the presence of Cd in the skeleton of the urchin. Cadmium was detected in the skeleton with AAS, but not with EDX. S. variolaris proved to be a capable biomonitor of Cd contamination.<br>Thesis (M.Sc.Eng.)-University of Durban-Westville, 2002.

Dissertação de Mestrado em Ecologia apresentada à Faculdade de Ciências e Tecnologia<br>As pescas são uma das maiores atividades do Oceano Austral. Pescado sob medidas precaucionária, o Bacalhau da Antártida Dissostichus mawsoni é uma das principais espécies alvo desta atividade na Antártida. No entanto, pouco se sabe acerca da variabilidade sua dieta, ecologia alimentar e trófica, três pilares na gestão de recursos marinhos, em diferentes zonas do Oceano Austral. A contaminação de mercúrio (Hg), um elemento tóxico ao humano, no músculo do peixe deve ser controlada regularmente para garantir uma comercialização segura. Apesar disso, desde o inicio da pesca do D. mawsoni, apenas por três vezes a contaminação foi analisada, apesar do conhecido aumento da concentração de Hg em águas oceânicas. Para preencher estas lacunas, o objetivo desta tese é estudar a dieta, ecologia alimentar e trófica e a contaminação de Hg do D. mawsoni nos mares de Ross, Amundsen e Dumont D’Urville, três principais zonas de pescas desta espécie, durante a época de pesca 2016/17. Os cefalópodes dos três mares, que são pouco conhecidos, foram também estudados em detalhe. A ontogenia e contaminação de Hg das duas espécies de cefalópodes mais frequentes na dieta do D. mawsoni (Psychroteuthis glacialis e Kondakovia longimana) nos mares de Amundsen e Dumont D’Urville foi também analisada. A dieta do D. mawsoni foi estudada usando os conteúdos estomacais de peixes capturados em quatro SSRUs na zona de convenção CCAMLR pertencentes ao Mar de Ross (subárea 88.1), Mar de Amundsen (88.2) e Mar de Dumont D’Urville (58.4.1). Este trabalho confirmou que o D. mawsoni se alimenta principalmente de peixes e cefalópodes, tendo também, em menor número, outros taxa (ex. crustáceos, cnidários) na sua dieta. A sua dieta varia entre áreas de pesca em termos de número de espécies presente e a importância de cada uma nas diferentes áreas. Todavia, quatro espécies (Macrourus sp., Antimora rostrata, P. glacialis and K. longimana) estão presentes em todas as áreas amostradas, e em números elevados, mostrando que são presas principais do D. mawsoni. A presença de presas pelágicas e bentónicas, bem como pequenas pedras nos estômagos, confirmam que esta espécie alimenta-se na zona bentopelágica.A ecologia alimentar e trófica, através da análise de isótopos estáveis de δ13C e δ15N, e a contaminação de Hg em D. mawsoni foi analisada utilizando músculo de peixe capturado em três SSRUs do Mar de Amundsen (88.2F (peixes mais pequenos) e 88.2H) e do Mar de Dumont D’Urville (58.4.1G), localizados num monte marinho (88.2H) e no talude (88.2F e 58.4.1G). Valores de δ13C mostram que o D. mawsoni tem a mesma estratégia alimentar, mas diferentes zonas de alimentação, sugerindo que os peixes maiores encontrados no talude migraram até às zonas mais costeiras para se reproduzirem. Valores de δ15N mostram que esta espécie tem um nível trófico semelhante independente da área e do tamanho do peixe, sugerindo que, apesar de presas diferentes, o seu papel na rede-trófica é semelhante. Em relação à contaminação de Hg foram encontradas diferenças entre áreas e tamanho de peixe. Peixes mais pequenos apresentam menor concentração de Hg, confirmando a acumulação de Hg ao longo da vida do peixe. Também foram encontradas diferenças entre áreas de captura, com os peixes do monte marinho (88.2H) a apresentarem os maiores valores (média de ~0.7ppm), tendo pela primeira vez, valores superiores ao permitido para comercialização.Os cefalópodes dos três mares foram estudados devido à necessidade de investigação destes organismos, usando os bicos encontrados na dieta do D. mawsoni. A espécie mais abundante nos mares de Amundsen e Dumont D’Urville foi a P. glacialis, sendo que no Mar de Ross todas as espécies apresentaram abundâncias semelhantes. A diversidade entre mares não é similar, com algumas espécies a habitar apenas um dos mares. A distribuição, ecologia trófica e contaminação de Hg de P. glacialis e K. longimana em juvenil e adulta, foi estudada através da análise de isótopos estáveis e determinação de T-Hg em duas secções do bico superior. A P. glacialis habita exclusivamente a região Antárctica e a K. longimana está presente na região Antárctica e Subantárctica, movendo-se livremente através da Frente Polar. Ambas as espécies apresentaram um aumento de nível trófico entre fases da vida, com a P. glacialis a apresentar maior nível trófico que a K. longimana em ambas as fases da vida. Relativamente ao Hg, ambas as espécies apresentaram maior contaminação em adultos, com a P. glacialis do Mar de Amundsen a apresentar os maiores valores de Hg entre as espécies estudadas (~0.017 pppm).Neste trabalho, também é sugerido algumas alterações na gestão das pescas do Oceano Austral, mais especificamente uma revisão dos limites de captura de bycatch e a necessidade de uma análise anual dos níveis de Hg. Além do mais, é sugerido uma revisão ao limite máximo de Hg permitido para D. mawsoni como feito para outros predadores de topo.<br>Fisheries are major activities in the Southern Ocean. Fished under exploratory catches and precautionary measures, Antarctic toothfish Dissostichus mawsoni is one of the principal targets of this activity in Antarctica. However, little is known about the variability of its diet, feeding and trophic ecology, three major topics in the management of marine living resources, in different regions of the Southern Ocean. Mercury (Hg) contamination in the fish muscle must be regularly controlled to secure a safety commercialization, because of the high poisoning effect of this element to humans. Yet, since the beginning of D. mawsoni exploration, only for three times this contamination was assessed, despite the known increase Hg concentration in oceanic waters. To fulfil these gaps, the main objective of this thesis is to study the diet, feeding and trophic ecology and Hg contamination of D. mawsoni in the Ross, Amundsen and Dumont D’Urville Seas, three major fishing grounds of this species, during the 2016/2017 fishing season. In addition, the cephalopod component found in the diet of D. mawsoni was studied in detail in the three seas. Moreover, ontogenic shifts and Hg contamination of the two-main squid prey species (Psychroteuthis glacialis and Kondakovia longimana) in Amundsen and Dumont D’Urville Seas was also studied.The diet of D. mawsoni was studied using stomach contents from fish captured in four CCAMLR SSRUs within the Ross Sea (subarea 88.1), Amundsen Sea (88.2) and Dumont D’Urville Sea (58.4.1). I confirmed that D. mawsoni fed primarily in fish and cephalopods, having also many other taxa (e.g. crustaceans, cnidarians) in its diet, however in small number. Its diet varied between the different fishing areas in terms of the species present and the importance of every species in each area. Nevertheless, four species (Macrourus sp., Antimora rostrata, P. glacialis and K. longimana) were present in all the sampling areas, and in high numbers, suggesting that are main prey species for D. mawsoni. The presence of pelagic and benthic species, as small stones in the stomachs, confirmed D. mawsoni as a benthopelagic feeder.The feeding and trophic ecology, through a stable isotopic analysis of δ13C and δ15N, and Hg contamination of D. mawsoni were analysed using muscle collected from fish captured in three SSRUs from the Amundsen Sea (88.2F (with smaller fish) and 88.2H) and Dumont D’Urville Sea (58.4.1G), located in seamount (88.2H) and slope (88.2 F and 58.4.1G) regions. δ13C values showed that D. mawsoni presents the same feeding strategy, but different foraging areas, suggesting that bigger fish found in the slope can be spawning fish that migrated to coastal areas. δ15N values showed that D. mawsoni have similar trophic level independently of the area and fish size, suggesting that, despite having different species in the stomach, their role in the trophic-web is similar. In relation to the Hg contamination, the results contrast with those from isotopic analysis, with differences between fish size and fishing areas. Smaller D. mawsoni presented lower concentrations of Hg confirming the bioaccumulation throughout the fish life. Moreover, differences were found between the fishing areas, with fish from seamount (88.2H) having the highest values of the study (average of ~0.7ppm), presenting also for the first time, since the beginning of fisheries, an average above the limit for commercialization.Cephalopods in the three seas were studied, due to the need of research in this poorly known organisms, using the beaks found in the diet of D. mawsoni. P. glacialis was the most abundant species in the Amundsen and Dumont D’Urville Seas, whereas in the Ross sea all the species were equally abundant. Further, diversity is not similar between the three seas, with some species inhabiting exclusively one of the seas. Distribution, trophic-ecology and Hg contamination of P. glacialis and K. longimana, when juvenile and adult, was studied using stable isotopic analysis and T-Hg determination in two sections of the upper beak. P. glacialis showed to be entirely Antarctic, with K. longimana inhabiting the Antarctic and Subantarctic region, moving freely through the Antarctic Polar Front. Both species showed an increase of trophic level between both life-stages, with P. glacialis presenting higher trophic level than K. longimana in both life-periods. Relative to Hg, both species had higher contamination as adults, with P. glacialis in the Amundsen Sea presenting the highest Hg concentration among these species (~ 0.017 ppm).In this thesis, it is also suggested some changes in terms of Antarctic fisheries management, in particular a bycatch capture limits revision and the necessity of an annual assessment of Hg fish contamination. Furthermore, Hg limits for D. mawsoni should be revised, as made for other top-predators’ species.<br>Outro - O José Queirós foi apoiado financeiramente pela FCT/MCTES através de fundos nacionais (PIDDAC) e do Programa Polar Português. O trabalho cientifico foi apoiado pela British Antarctic Survey, Government of South Georgia, Government of South Sandwich Islands e por vários programas científicos, i.e. CEPH, SCAR AnT-ERA, SCAR EGBAMM, PROPOLAR and ICED.

Dissertação de mestrado, Aquacultura e Pescas, Faculdade de Ciências e Tecnologia, Uniersidade do Algarve, 2015<br>Global world population is expected to reach approximately 9 billion by 2050, and the world food-producing sector must secure food for the growing population through increased production and reduced waste. Due to this, aquaculture can represent a solution to the substitution and increase of fish protein available to the populations. However, a higher development of aquaculture is constrained by different causes, being one of the most important diseases. In Southern Europe, especially in the Mediterranean area, amyloodiniosis represents a major bottleneck for semi-intensive aquaculture production in Southern Europe affecting the majority of fish farms, in different types of rearing tanks and systems, and causing extremely high mortalities. Amyloodinium ocellatum is the most common and important dinoflagellate parasitizing fish, and is one of the few fish parasites that can infest almost all fish, crustacean and bivalves that live within its ecological range are susceptible to infestation. In recent years there has been developed a large amount of largescale approaches in biology that promise to revolutionize systems-level understanding of cellular and organism functions. Amongst them, proteomics is getting an increasing interest, because information of DNA sequence, mRNAs and transcriptional activity provides only a static snapshot of the various ways in which a cell might use its proteins, whereas the life of the cell is a dynamic process. So in this work we have analysed the proteome and relate it with osmoregulatory and stress indicators of gilthead sea bream (Sparus aurata) plasma, in order to enlighten the different physiological responses when exposed to an A. ocellatum outbreak. After the proteomic DIGE, condition index (CI), hepatosomatic index (HSI) and spleen somatic index (SSI), and all the stress (cortisol), metabolic (glucose and lactate) and osmotic (pH, osmolarity) analysis, we have obtained statistical differences in the cortisol and lactate levels, and identified several proteins associated with immune response, acute phase response, inflammation, lipid transport, homeostasis, osmoregulation, wound healing, neoplasia, oxidative stress, and iron transport. Overall, this preliminary study revealed that amyloodiniosis can upregulate or downregulate proteins with known functions and provoke stress and metabolic responses in gilthead sea bream.<br>É esperado que a população mundial atinja 9 biliões de pessoas em 2050, sendo necessário que o sector alimentar assegure comida para esta população em crescimento, através de um aumento de produção e de uma redução de desperdícios alimentares. A aquacultura apresenta-se como uma área que pode representar uma solução para o aumento de pescado disponível para as populações. No entanto, um maior desenvolvimento desta indústria está limitada por diferentes causas, sendo uma das mais importantes as doenças que afetam as espécies cultivadas. No sul da Europa, uma das doenças que se apresenta como limitativa para o desenvolvimento da aquicultura é a amilodiniose. Esta doença afeta grande parte das pisciculturas (com diferentes sistemas de produção), provocando mortalidades muito elevadas. Esta doença é causada pelo parasita dinoflagelado Amyloodinium ocellatum, que é um dos poucos parasitas capazes de infetar todos os peixes, crustáceos e bivalves no seu alcance ecológico. Têm-se vindo a desenvolver desde há alguns anos uma série de abordagens de larga escala em biologia, que prometem revolucionar o nosso conhecimento a nível do funcionamento celular e do organismo. Entre as mais promissoras encontra-se a proteómica, porque providencia infirmações sobre os processos dinâmicos da vida de uma célula ou órgão, ao contrário de outras técnicas como a sequenciação de ADN, ARN mensageiro ou da transcriptómica. Dados estes factos, decidimos analisar o proteoma do plasma de dourada (Sparus aurata), assim como diversos indicadores metabólicos, osmorregulatórios e de stress, em resposta a um surto de A. ocellatum. Após a análise proteómica por intermédio de géis DIGE, com posterior sequenciação dos spots selecionados por LC-MS/MS, análise do índice de condição (IC), do índice hepatossomático (HSI), índice somático do baço (SSI) e de todas as análises de stress (cortisol), metabólicas (glucose, lactato) e de índices osmorregulatórios (pH, osmolaridade), obtivemos diferenças nos níveis de cortisol e lactato, assim como a identificações de diversas proteínas com funções a nível da resposta imunitária, de resposta de fase aguda, de resposta inflamatória, a nível de homeostasia e osmorregulação, de stress oxidativo, de cicatrização e neoplasia, e de transporte lipídico e de iões de ferro. Podemos assim verificar que este estudo revelou que o parasita A. ocellatum pode provocar uma super ou sub expressão de proteínas com funções conhecidas, assim como respostas metabólicas e de stress em dourada.<br>COST Action FA1002 - Farm Animal Proteomics<br>BONAQUA (0433_BONAQUA_5_E)

Dissertação de Mestrado em Geociências apresentada à Faculdade de Ciências e Tecnologia<br>O objetivo desta dissertação foi avaliar a modificação nas propriedades físico-químicas e na composição química dos solos pelos efeitos da urbanização e avaliar os riscos para a saúde humana em solos urbanos de cidades angolanas (Benguela, Lubango e Humpata) em rápida expansão, com diferentes condições climáticas e substratos geológicos. Os solos urbanos de Benguela e Lubango apresentaram valores de pH e condutividade elétrica mais elevados do que os solos naturais. Nos solos urbanos de Benguela, a média do carbono orgânico foi superior à dos solos naturais e dos solos agrícolas. O cálculo dos fatores de enriquecimento demonstrou que alguns solos de Benguela estavam extremamente enriquecidos em Cd e Pb, os solos de Lubango encontram-se moderadamente enriquecidos em Pb e alguns solos de Humpata possuem enriquecimento significativo em Cd e Pb. Para os solos urbanos, apenas a região de Benguela exibiu índice de carga de poluição superior a 1, o que indicou contaminação dos solos em Cd, Cu, Mn, Mo, Pb, Sb, Sn e Zn. Para os metais Cd, Cu, Pb e Zn nos solos urbanos de Benguela, o índice de risco foi inferior a 1 representando um risco não-cancerígeno insignificante. O risco cancerígeno através de ingestão para o Pb ultrapassou o limite máximo aceitável estabelecido pela USEPA para crianças, mas o Pb é apenas considerado potencialmente cancerígeno. O solo urbano de Benguela encontrava-se poluído em Cd, Cu, Pb e Zn. Estes metais foram adicionados aos solos por atividades antrópicas e os seus teores são controlados pelo tipo de solo e pelo pH. Apesar dos processos de urbanização serem semelhantes nas 3 cidades, os solos urbanos de Benguela apresentaram maior poluição em Cd, Cu, Pb, Sb, Sn e Zn. Tal deve-se às características geográficas, climáticas e geológicas da região de Benguela, que condicionam o tipo de solo.<br>The objective of this dissertation was to evaluate the changes in physical-chemical properties and chemical composition of soils due to the effects of urbanization and to evaluate the risks to human health in urban soils of the Angolan cities (Benguela, Lubango and Humpata) in rapid expansion, with different climatic conditions and geological substrates. The urban soils of Benguela and Lubango have higher values of pH and electrical conductivity than natural soils. In urban Benguela soils, the average of organic carbon was higher than that of natural soils and agricultural soils. The calculation of the enrichment factors showed that some soils of Benguela were extremely enriched in Cd and Pb, the soils of Lubango are moderately enriched in Pb and some soils of Humpata have significant enrichment in Cd and Pb. For the urban soils, only the Benguela region showed a pollution load index higher than 1, indicating soil contamination in Cd, Cu, Mn, Mo, Pb, Sb, Sn and Zn. The risk index was less than 1 for the Cd, Cu, Pb and Zn in Benguela urban soils, representing an insignificant non-carcinogenic risk. The carcinogenic risk through ingestion for Pb exceeded the acceptable maximum set by the USEPA for children, but Pb is only considered potentially carcinogenic. The urban soil of Benguela was polluted in Cd, Cu, Pb and Zn. These were added to soils by anthropic activities and are controlled by soil type and pH. Although the urbanization processes are similar in the three cities, the urban soils of Benguela presented higher pollution in Cd, Cu, Pb, Sb, Sn and Zn. This is due to the geographic, climatic and geological characteristics of the Benguela region, which condition the soil type.

A prevalência das alergias e intolerâncias alimentares tem vindo a aumentar com o passar dos anos, constituindo um problema de saúde publica na nossa sociedade derivada da inexistência de uma cura para este tipo de patologias. A única forma de controlar reações adversas é a evicção do alimento em questão. O facto de certas substâncias poderem causar este tipo de reações em certos indivíduos pode impactar a sua qualidade de vida tornando se assim alvo de preocupação em todo o mundo. Em estabelecimentos de restauração a probabilidade de ocorrência de contaminação cruzada por alergénios é elevada sendo difícil assegurar que a rotulagem do produto é adequada, podendo induzir o consumidor em erro. Com o objetivo de servir refeições seguras ao consumidor foi realizada uma avaliação de risco, avaliando as condições estruturais, os pré-requisitos na unidade de produção, os conhecimentos dos colaboradores referente a boas práticas e alergénios alimentares, a qualidade microbiológica do ar e a eficácia da higienização das superfícies e alergénios alimentares. A avaliação de pré-requisitos respeitantes ao estado de conservação dos equipamentos de confeção, bancadas e utensílios evidenciou uma taxa de conformidade de apenas 30%. Existia a possibilidade de potenciais contaminações cruzadas em 20% das unidades por contatos indevidos de alimentos com os utensílios, superfícies e manipulações dos colaboradores. Apesar de todos os colaboradores apresentarem registos de formação, a mesma, não abrangia na sua maioria a temática dos alergénios alimentares. Na avaliação do conhecimento dos colaboradores (n=50), as principais lacunas identificadas foram relativas à identificação dos alergénios e à forma de eliminação dos mesmos, sendo possivel concluir que existem ainda muitas dúvidas que advêm do facto de apenas 28% dos inquiridos possuir uma formação em alergénios alimentares. Os resultados obtidos para a validação da qualidade do ar e higienização das superfícies, revelam globalmente, que 73% das amostras foram satisfatórias. De acordo com os dados recolhidos a generalidade apresenta falhas nos processos de higienização, falta de formação por parte dos manipuladores, existindo também a necessidade de incidir na reabilitação de equipamentos e aumento da periodicidade da manutenção preventiva. Com base nas avaliações realizadas foram propostas sugestões e oportunidades de melhoria, tendo em conta o objetivo de implementação de um plano de controlo de alergénios.<br>The prevalence of food allergies and intolerances has been increasing over the years, constituting a public Health problem in our society due to the lack of a cure for this type of pathology. The only way to control adverse reactions is to avoid the food in question. The fact that certain substances can cause this type of reaction in certain individuals can impact their quality of life and thus become a concern worldwide. In catering establishments, the likelihood of allergen cross-contamination is high, and it is difficult to ensure that product labelling is adequate and could mislead the consumer. In order to serve the consumer safe meals, a risk assessment was carried out, evaluating the structural conditions, the prerequisites in the production unit, the knowledge of the employees regarding good practices and food allergens, the microbiological quality of the air and the effectiveness hygiene of surfaces and food allergens. The assessment of prerequisites regarding the state of conservation of cooking equipment, benches and utensils showed a compliance rate of only 30%. There was the possibility of potential cross-contamination in 20% of the units due to improper food contact with the utensils, surfaces and manipulations of the employees. Even though all employees present training records it did not mostly cover the theme of food allergens. In assessing the knowledge of employees (n=50), the main gaps identified were related to the identification of allergens and how to eliminate them, and it is possible to conclude that there are still many doubts arising from the fact that only 28% of respondents have an training in food allergens. The results obtained for the validation of air quality and cleaning of surfaces, reveal globally, that 73% of the samples were satisfactory. According to the data collected, most of them present flaws in the hygiene processes, lack of training on the part of the handlers, and there is also the need to focus on the rehabilitation of equipment and increase the frequency of preventive maintenance. Based on the evaluations carried out, suggestions and opportunities for improvement were proposed, considering the objective of implementing an allergen control plan.

Toxoplasma gondii, un protozoaire très répandu dans le monde, peut infecter de nombreuses espèces homéothermes incluant les mammifères et les oiseaux qui développent alors une toxoplasmose. L’impact de la toxoplasmose en termes de santé publique est majeur, particulièrement chez les personnes immunodéprimées et les foetus. Les niveaux d’infection humaine dans certaines régions de l’Arctique Canadien sont parmi les plus élevés au monde et ce, malgré l’absence de félidés qui sont les seuls hôtes capables d’excréter T. gondii. Plusieurs études ont suggéré la consommation de viande crue de mammifères marins et notamment de phoques comme source d’infection des Inuits. Notre travail de recherche visait à comprendre les mécanismes de dispersion de T. gondii dans les écosystèmes aquatiques menant à la contamination du milieu marin de l’Arctique par des oocystes, et à évaluer l’importance de cette voie de dispersion dans l’infection des phoques et conséquemment dans celle des Inuits. Notre hypothèse était que les oocystes de T. gondii, excrétés durant l’hiver par des félidés dans le Subarctique et transportés par les rivières pendant la fonte printanière, contaminaient les estuaires de l’Arctique Canadien. Dans un premier temps, une étude transversale de séroprévalence chez les phoques de l’Arctique Canadien a montré que ces populations étaient infectées par T. gondii et pouvaient ainsi a priori constituer une source d’infection pour les Inuit. Des variations spatio-temporelles de la séroprévalence étaient observées suggérant un lien potentiel avec des variations dans la contamination environnementale par les oocystes. Un schéma conceptuel explicitant les mécanismes de transport et de devenir des oocystes de T. gondii, du phénomène de la fonte de la neige jusqu’à l’exposition des organismes marins, a été proposé dans le chapitre suivant. Des interactions entre les différents mécanismes identifiés, qui agissent sur des échelles spatio-temporelles variées, devraient favoriser l’apparition de concentrations relativement élevées aux estuaires permettant ainsi l’exposition et potentiellement l’infection de phoques. Pour évaluer la contamination environnementale par les oocystes excrétés par la population de lynx du bassin versant de l’Arctique Canadien (les seuls félidés majoritairement distribués dans ce vaste territoire), nous avons mené une étude sérologique de type transversale dans cette population. Cette étude a permis de montrer que des lynx étaient infectés par T. gondii et a également suggéré que la dynamique des cycles de populations lynx-lièvres pouvait être un processus important dans la transmission de T. gondii. Finalement, la modélisation du transport hydrique des oocystes a indiqué que les concentrations hypothétiques d’oocystes dans l’eau de la fonte pourraient être suffisantes pour permettre l’exposition au niveau des estuaires de bivalves filtreurs, qui sont des proies pour les phoques et donc potentiellement des sources infectieuses pour ces derniers. Dans des écosystèmes nordiques en pleine mutation, la compréhension des mécanismes de transmission d’agents pathogènes d’origine hydrique comme T. gondii est plus que nécessaire, notamment dans le but de protéger les populations fragilisées de ces régions.<br>Toxoplasmosis results from infection with Toxoplasma gondii, a widespread protozoan that can infect many species including warm-blooded mammals and birds. The public health impact of toxoplasmosis is important, particularly in immunocompromised individuals and the foetus. Levels of human infection in parts of the Canadian Arctic are among the highest in the world, despite the absence of felids that are the only hosts that can excrete T. gondii. Several studies have suggested that consumption of raw meat of marine mammals including seals is a source of infection for the Inuit. Our research sought to understand the dispersal mechanisms of T. gondii in aquatic ecosystems leading to contamination of the marine environment of the Arctic by oocysts, and to assess the importance of this route of dispersion for infection in seals and consequently in the Inuit. We hypothesized that the T. gondii oocysts excreted during the winter by felids in the subarctic area and transported by rivers during spring melt contaminated the estuaries of the Canadian Arctic. Initially, a cross-sectional study of seroprevalence in seals from the Canadian Arctic showed that these populations were infected with T. gondii and thus a priori could be a source of infection for Inuit. Spatio-temporal variations in seroprevalence were observed suggesting a potential link with variations in environmental contamination by oocysts. A conceptual diagram of the possible mechanisms of transport and fate of T. gondii oocysts, from the melting snow to the exposure of marine organisms, is proposed in the following chapter. Interactions between the various mechanisms identified, which act on various temporal and spatial scales, should favour the appearance of relatively high concentrations in estuaries allowing exposure and potential infection of seals. To assess environmental contamination by oocysts excreted by the lynx population living in the watershed of the Canadian Arctic (the only felines largely distributed in this vast territory), we conducted a serological cross sectional study in this population. This study showed that lynx were infected with T. gondii and also suggested the dynamics of lynx-hare population cycles as an important process in the transmission of T. gondii. Finally, the modeling of hydrological transport of oocysts indicated that the hypothetical concentrations of oocysts in meltwater could be sufficient to permit significant exposure in estuarine filter-feeding bivalves on which seals prey and therefore potentially representing sources of infection for them. In changing northern ecosystems, understanding the mechanisms of transmission of waterborne pathogens, including T.gondii is essential, especially in order to protect vulnerable populations that live in these regions.