Increasing awareness about the presence and ecological ramifications of toxic, persistent and bioaccumulative contaminants within the Great Lakes system spurred the implementation of numerous bans and emissions restrictions over the past few decades. Due to their high trophic status in food webs and the critical link they serve with human consumers, fish species have historically been monitored to assess the relative success of such remedial efforts within the region and to simultaneously ascertain the current risks posed to local humans. Using Bayesian dynamic linear modelling, this project first aimed to evaluate temporal trends of various organochlorine contaminants within Lake Erie fish communities, the results of which generally indicated decreasing trends through time. The second half of this study used a similar Bayesian approach to propose a framework for updating fish consumption advisories, with specific attention paid to the acknowledgment of uncertainty and natural variability when producing such consumption guidelines.

The focus of this thesis was to investigate developmental neurotoxic effects of different persistent and non-persistent environmental pollutants, alone or in binary mixtures, when exposure occurs during a critical period of brain development, in mice. The compounds investigated included a perfluorinated compound, perfluorohexane sulphonate (PFHxS), and four different pesticides, endosulfan, cypermethrin, chlorpyrifos and carbaryl. Both persistent and non-persistent pollutants are detected in the environment and in humans, which shows that exposure to these compounds is occurring in real life. Humans can therefore be exposed to various pollutants during their whole lifetime, starting from the gestational period to adulthood. Furthermore, exposure to environmental pollutants is rarely exclusive to a single compound, but rather occurs through combinations of various pollutants present in the environment. Exposure to environmental pollutants during human brain development have been suggested to be a possible cause for neuropsychiatric disorders, such as autism spectrum disorder (ASD) and attention deficit hyperactivity disorder (ADHD). Previous studies have shown that chemicals can induce irreversible disorders in brain function when exposure to these chemicals occurs during a critical defined period of the brain development known as the brain growth spurt (BGS). The BGS is characterized by a rapid growth and development of the immature brain. In humans, and mice, this period also overlaps the lactation period indicating that newborns and toddlers can be exposed via mothers’ milk as well. This thesis has shown that a single oral exposure to PFHxS, endosulfan, cypermethrin, chlorpyrifos or carbaryl can induce developmental neurotoxic effects in mice, when exposure occurs during a critical period of brain development. These effects are manifested as persistent altered adult spontaneous behavior in a novel home environment, modified habituation, altered susceptibility of the cholinergic system and changed levels of neuroproteins in the mouse brain. Furthermore, a single neonatal co-exposure to a binary mixture of carbaryl/chlorpyrifos or PFHxS/endosulfan can interact and exacerbate the adult behavioral effects. These effects were seen at dosages were the single compound did not elicit a response or induced a much weaker behavioral effect. This indicates that risk assessments conducted on single compounds might underestimate interaction effects of mixtures when co-exposed.

Nearly 250,000 sites with past and present potentially polluting activities need urgent remediation within Europe. Major pollutants include organochlorines (OCls), e.g. chlorinated ethenes (CEs) and hexachlorocyclohexanes (HCHs), mainly used as industrial solvents and pesticides, respectively. Due to improper handling and disposal, OCls contaminants are present in the soil or groundwater surrounding sites, where they have been produced or used. CEs and HCHs can undergo degradation by microorganisms indigenous to the soil or groundwater. Therefore natural attenuation (NA), relying on the in situ biodegradation of pollutants, is considered as a cost effective remediation strategy, yet it requires accurate monitoring methods. Compound specific isotope analysis (CSIA) is a powerful tool to provide information on the extent of degradation and, when combining two isotope systems (2D-CSIA), such as carbon (δ13C) and chlorine (δ37Cl), on reaction mechanisms. The diagnostic reaction-specific isotope enrichment factors (εC and εCl) were determined in laboratory experiments for the anaerobic degradation of PCE, TCE (Paper II) and α-HCH (Paper III) by mixed bacterial cultures enriched from CEs and HCHs contaminated sites, respectively. The related mechanism-specific εCl/εC ratios were calculated as 0.35 ± 0.11 (PCE), 0.37 ± 0.11 (TCE) and 0.52 ± 0.23 (α-HCH). These values are smaller than previously reported values for pure cultures. This is explained by the microbial community composition changes observed during degradation of PCE and α-HCH, which also reflect the variability of the microbial community at the field level. Furthermore, εCl/εC ratio might be bacteria specific. These values allowed the estimation of the extent of contaminant degradation at the respective study sites (Paper III and IV). Application of both isotope systems (δ13C and δ37Cl) led to comparable estimates. However the choice of representative ε values is crucial for an accurate assessment. These studies show that CSIA is useful to quantify in situ degradation of OCls contaminants and identify reaction pathways, by combining δ13C and δ37Cl. / <p>At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 3: Submitted. Paper 4: Manuscript.</p>

Made available in DSpace on 2016-06-02T19:32:09Z (GMT). No. of bitstreams: 1 5793.pdf: 2202297 bytes, checksum: 747359b5bd140047bbb32daf90dd91aa (MD5) Previous issue date: 2014-02-27 / Financiadora de Estudos e Projetos / Environmental contamination by pesticides in agriculture has caused many irreparable damage environmental to the ecosystem. Pentachlorophenol (PCP), the class of organochlorines, is a phenolic compound and a dangerous pollutant, that although banned in Brazil since 1985, there are many contaminated areas. This pesticide is the subject of much concern because it has high toxicity and power of persistence in the environment due to their resistance to biotic and abiotic degradation. The use of microorganisms as degrading agents of several chemical is considered an effective method to reduce the adverse effects of contaminants on the environment. The fungi derived from marine environment are adapted to extreme conditions, developing attributes that give them the ability to produce various of biologically active compounds differentes of their respective representatives who inhabit the land environment. In addition, marine fungi present an excellent bioenzimatic potential to be explored in the biotransformation of xenobiotics such as, for example, pesticides. In this work, fifteen strains of fungi isolated from a marine invertebrate, the ascidian Didemnun ligulum were evaluated according to their resistance, ability to grow in the presence of the pentachlorophenol (PCP) pesticide and its enzymatic potential against biodegradation of the pesticide and its metabolites. Concentrations were evaluated 10, 25, 30, 40 and 50 mgL-1 in solid media 3% malt. Nine among the tested strains showed growth in at least one concentration, but the DL2B strain (identified as Trichoderma harzianum) obtained optimal growth in most (50 mgL-1), proving be resistant to its toxicity and suggesting its potential for biodegradation. Therefore, it was selected for reactions in liquid medium in the presence of the pesticide with an initial concentration of 20 mgL-1 of PCP, to measure biodegradation. he biodegradation were evaluated after 7, 14 and 21 days of incubation. In 7 days of incubation it was no longer detected the presence of PCP in the samples, indicating the biodegradation of the pesticide by the fungus. The pentachloroanisole (PCA) metabolites and 2,3,4,6- tetrachloroanisole (2,3,4,6-TeCA) were identified by gas chromatography coupled with mass spectrometry (GC-MS), indicating degradation of the pesticide by the fungus. In a second step, the strain of Trichoderma harzianum was subjected to biodegradation reactions in liquid medium containing metabolites PCA and 2,3,4,6-TeCA. It was observed that these compounds possibly cause some toxic effect on this micro-organism, but not enough to cripple the biodegradation by fungi. The fungus didn't degrade these compounds completely as occured with the PCP, but got reduce the concentrations of metabolites in the samples. These results confirm the efficiency of fungi derived from marine environment to biodegrade persistent compounds and enables the improvement methodologies using these microorganisms in techniques for decontamination of polluted environments with xenobiotics. / A contaminação ambiental pelo uso de pesticidas na agricultura tem causado muitos danos ambientais irreparáveis ao ecossistema. O pentaclorofenol (PCP), da classe dos organoclorados, é um composto fenólico e um perigoso poluente. Este pesticida é objeto de muita preocupação por possuir elevada toxicidade e poder de persistência no meio ambiente, devido à sua resistência à degradação biótica e abiótica. Apesar de proibido no Brasil desde 1985, existem ainda muitas áreas contaminadas por ele. A utilização de micro-organismos como agentes degradadores de diversas substâncias químicas é considerada uma forma eficiente para reduzir os efeitos adversos dos contaminantes sobre o ambiente. Os fungos derivados do ambiente marinho são adaptados à condições extremas e possuem atributos que lhes conferem a capacidade de produzir compostos biologicamente ativos diferentes dos seus respectivos representantes que habitam o meio terrestre. Além disso, os fungos marinhos apresentam um excelente potencial bioenzimático a ser explorado na biotransformação de xenobióticos como, por exemplo, os pesticidas. Neste trabalho, quinze linhagens de fungos isoladas de um invertebrado marinho, a ascídia Didemnun ligulum, foram avaliadas segundo sua resistência à toxicidade, habilidade de crescer e biodegradar o pesticida pentaclorofenol (PCP) e seus metabólitos. Foram avaliadas as concentrações 10, 25, 30, 40 e 50 mgL-1 de PCP, em meio de cultura sólido Malte 3%. Nove, dentre as linhagens avaliadas, apresentaram crescimento em pelo menos uma das concentrações, mas a linhagem DL2B (identificada como Trichoderma harzianum) apresentou ótimo crescimento na concentração mais drástica (50 mgL-1), mostrando ser resistente à sua toxicidade e sugerindo seu potencial para biodegradação do composto. Sendo assim, foi selecionada para reações em meio líquido na presença do pesticida com concentração inicial de 20 mgL-1 de PCP, para quantificar sua biodegradação. As avaliações da biodegradação foram realizadas após 7, 14 e 21 dias de incubação. Com 7 dias de incubação já não foi detectada a presença do PCP nas amostras. Os metabólitos pentacloroanisol (PCA) e 2,3,4,6-tetracloroanisol (2,3,4,6-TeCA) oriundos das biotransformação do PCP foram identificados por cromatografia a gás acoplada ao espectrômetro de massas (CG-EM), indicando a biotransformação do pesticida pelo fungo. Em uma segunda etapa, a linhagem de Trichoderma harzianum foi submetida à reações de biodegradação em meio líquido contendo os metabólitos PCA e 2,3,4,6-TeCA. Observou-se que esses compostos possivelmente causam algum efeito tóxico sobre este micro-organismo, mas não o suficiente para inviabilizar a biodegradação pelo fungo. O fungo não degradou esses compostos completamente no período de 21 dias, como ocorreu com o PCP, mas conseguiu reduzir as concentrações dos metabólitos nas amostras. Estes resultados confirmam a eficiência de fungos derivados do ambiente marinho em biodegradar compostos persistentes e possibilitam o aprimoramento de metodologias utilizando esses micro-organismos em técnicas para descontaminação de ambientes poluídos com xenobióticos.

This thesis examines fatty acid (FA) and polychlorinated biphenyl (PCB) dynamics in a marine top predator, the grey seal (Halichoerus grypus,) and their transfer during lactation from mother to offspring. It examines regional and annual variations in FA composition and PCB loads, and also how the physical and chemical characteristics of these molecules (e.g. their polarity and size) can affect the rates of accumulation, mobilization and transfer of specific FAs or PCBs. Two UK grey seal colonies (North Rona (NR) and Isle of May (IOM) were studied during three consecutive years (1996-1998 and 2004-2006). Lactating grey seals and their pups were repeatedly captured during the lactation period and sampled for blubber, serum and milk and analysed for FAs and PCBs. Overall, the two colonies were clearly distinguished from each other, suggesting that the main prey species had different FA composition, and possibly that the seals from these colonies had different diets . These differences are probably a direct consequence of differences in prey community structure in the two regions where seals from these two colonies are thought to feed. Within each colony, annual differences could be detected between some years but not between others. During 1996-98, IOM seals showed a clear change in their FA profiles while NR seals did not. In contrast, during 2004-2006 NR seals showed a clear change while IOM seals did not. The changes observed in IOM during 1996-1998 are consistent with the large-scale regime shift that occurred in the North Sea during the 1990‟s. The relative proportions of each FA that were mobilized from blubber and transferred to the milk during lactation were very similar between colonies, and could be explained to a large degree by their physico-chemical properties. For a given carbon chain length the mobilization increased with increasing number of double bonds; and for a given number of double bonds the mobilization decrease with increasing carbon chain length. However, the mobilization also appeared to be influenced by the specific nutritional requirements of the growing pups. For instance, FAs that are considered essential for pup development or efficient energy storage (e.g. saturated FAs) were more highly mobilised than expected. This selectivity was also reflected in the FA composition of the different body compartments (maternal blubber and milk, pup blubber) that persisted throughout lactation. These changes were also similar between the colonies. Colonies could also be clearly distinguished by their blubber PCB profiles. IOM seals had higher total concentrations on average than NR seals (1327.9 vs. 680.2 ng/g lipid in 2005 and 1199.7 vs. 819.0 ng/g lipid in 2006). IOM seals also had higher total amounts in both years (79.2 vs. 38.0 mg in 2005 and 61.7 vs. 53.4 mg in 2006). One of the main differences between colonies was that females from IOM had higher concentrations of highly chlorinated congeners than NR seals. PCB concentrations in blubber increased towards the end of lactation. Serum and milk PCB concentrations also increased rapidly, especially for the highly chlorinated congeners. These results were consistent with other studies showing the increase in concentrations as a result of lipid loss. Serum concentrations stayed constant during the first part of lactation and increased at late lactation. This was also observed in milk PCB concentrations. The changes in the PCB profiles in the three body compartments were very similar between colonies. However IOM seals always had higher total concentrations of PCBs in all of the body compartments. The concentrations of individual congeners relative to PCB-153 showed that blubber contained higher proportions of the highly chlorinated PCBs relative to other tissues. There were no clear changes in these proportions in blubber during lactation, but the relative proportions of highly chlorinated PCB In serum and milk increased throughout lactation while the less chlorinated PCBs stayed constant. The highly chlorinated PCBs were found in lower concentration in the milk compared to the less chlorinated compounds suggesting a selective release from blubber to blood and a selective transfer of PCBs to the milk.

Introduction : La présente étude explore pour la première fois en Afrique, l'association entre l'exposition aux pesticides organochlorés (POC) et le risque de diabète de type 2. L’étude se déroule dans la région du Borgou, au nord du Bénin, où l’utilisation intense de pesticides pour la culture du coton coïncide avec une prévalence élevée du diabète par rapport aux autres régions du pays. Objectifs: 1) Décrire le niveau d’exposition de la population des diabétiques et non diabétiques du Borgou par le taux sérique de certains pesticides organochlorés ; 2) Explorer la relation entre le risque de diabète de type 2 et les concentrations sériques des POC; 3) Examiner l’association entre l’obésité globale, le pourcentage de masse grasse et l’obésité abdominale avec les concentrations sériques des POC; 4) Explorer la contribution de certaines sources d’exposition alimentaire et non-alimentaire aux concentrations sériques des POC. Méthodes : Il s'agit d'une étude cas-témoin qui concerne 258 adultes de 18 à 65 ans identifiés par deux valeurs glycémiques capillaire et veineuse au seuil de 7 mmol/l pour les diabétiques et 5,6mmol/l pour les témoins non diabétiques. Les 129 témoins ont été appariés aux 129 cas selon les critères suivants : l’ethnie, l’âge ± 5ans, le sexe et la localité de résidence. Les informations personnelles et celles portant sur les modes d’exposition ont été recueillies par questionnaire. Les concentrations sériques des POC ont été obtenues par chromatographie gazeuse couplée d’une spectrométrie de masse. L’obésité globale est déterminée par l’IMC ≥ 30 kg/m2. L’obésité abdominale est obtenue par le tour de taille selon les critères consensuels d’Alberti et al. pour la définition du syndrome métabolique. Le pourcentage de masse corporelle a été mesuré par bio-impédance électrique et été considéré comme élevé au seuil de 33% chez les femmes et 25% chez les hommes. Résultats: En comparant les 3ème et premier terciles des concentrations de p,p’-DDE et p,p’-DDT, les sujets du 3e tercile étaient deux à trois fois plus susceptibles de présenter du diabète que ceux du 1er tercile. La probabilité d’obésité abdominale ou de l’obésité générale (en contrôlant pour le statut diabétique) était accrue de trois à cinq fois dans le dernier tercile pour trois des quatre POC qui étaient détectables soit p,p’-DDT, β-HCH et trans-Nonachlore. Les facteurs socioéconomiques associés aux POC sériques sont le niveau d’éducation élevé, un meilleur revenu et la résidence en milieu urbain. Les sources d’exposition non alimentaire significativement associées aux concentrations sériques de POC étaient l’exposition professionnelle mixte (primaire et secondaire) aux pesticides et la consommation de tabac local. L’achat en opposition à l’autoproduction de plusieurs groupes de denrées alimentaire était associé à de plus fortes teneurs de POC. La fréquence de consommation hebdomadaire du poisson, des légumes, du fromage, de l’igname séchée ainsi que du mil, de l’huile de palme et de certaines légumineuses comme le soya, le néré, le niébé et le voandzou était significativement associées aux POC sériques. Conclusion : L’étude a mis en évidence la relation entre le niveau sérique de pesticides organochlorés d’une part, du diabète ou de l’obésité d’autre part. Les concentrations de POC observées au Borgou sont assez élevées et méritent d’être suivies et comparées à celles d’autres régions du pays. Les facteurs contribuant à ces teneurs élevées sont le niveau d’éducation élevé, un meilleur revenu, la résidence en milieu urbain, l’achat et la fréquence de consommation de plusieurs aliments. La contribution du mélange des polluants auxquels les habitants de cette région sont exposés à la prévalence croissante du diabète mérite d’être examinée, notamment les pesticides utilisés actuellement dans la région pour les productions de rente et autres polluants persistants. Ces résultats contribuent à accroître les connaissances sur les facteurs de risque émergents pour le diabète que sont des polluants environnementaux comme les pesticides. Les implications pour la santé publique sont importantes tant pour la prévention des maladies chroniques que pour la sensibilisation des autorités politiques du pays pour une politique agricole et sanitaire adéquate visant la réduction de l’exposition aux pesticides. / Background: The present study examines for the first time in sub-Saharan Africa, the association between exposure to organochlorine pesticides (OCPs) and the risk of type 2 diabetes. The study took place in the Borgou area in the northern part of Benin, where the intensive use of pesticides for cotton production coincides with a high prevalence of diabetes compared to other areas of the country. Objectives: 1) To describe in a sample of subjects with diabetes and in non-diabetic control subjects of Borgou serum levels of some OCPs; 2) To assess the relationship between the risk of type 2 diabetes and serum concentrations of OCPs; 3) To examine the association between overall obesity, the percentage of body fat and abdominal obesity with serum concentrations of OCPs; 4) To explore the contribution of some potential sources of exposure to serum concentrations of OCPs. Methods: This is a case-control study of 258 adults aged 18 to 65 years, identified on the basis of a diabetes prevalence study. Subjects were detected by capillary and venous fasting blood glucose at the threshold of 7mmol /l for diabetic subjects and 5.6mmol / l for the controls. The 129 controls were matched with 129 cases for ethnic group, age ± 5 years, sex and residence location. Personal data and information on potential sources of pesticide exposure were collected by questionnaire. Serum OCPs were determined by gas chromatography coupled with mass spectrometry. Overall obesity was determined by a BMI ≥ 30kg/m2. Abdominal obesity was defined according to waist circumference using the Alberti et al. consensual criteria for metabolic syndrome. The percentage of body fat was measured by bioelectrical impedance and was higher at the threshold of 33% in women and 25% in men. Results: Comparing the third and first tertiles of p,p'-DDE and p,p'-DDT serum concentrations, we observed a two to threefold higher odds ratio for diabetes. The likelihood of abdominal obesity or general obesity was three to five times higher in the upper compared to lower tertile for three of the four detected OCPs, that is: p,p'-DDT, β-HCH and trans-Nonachlor. The socioeconomic factors associated with serum OCPs are high level of education, high income and residence in urban area. The non-food sources of exposure were mixed occupational exposure (primary and secondary) and consumption of local tobacco. The food sources of exposure were purchased foods that are greater source of exposure to pesticide than self-production. The frequency of weekly consumption of fish, vegetables, cheese, dried yam as well as millet, oil palm and some legumes such as soybeans, locust bean, cowpea and Bambara groundnut was significantly associated with serum concentrations of OCPs. Conclusion: The study highlighted the relationship between the serum level of organochlorine pesticides on the one hand, diabetes or obesity on the other. Levels of OCPs observed in Borgou are high enough and need to be monitored and compared to others areas in the country. Factors associated with high levels of OCP in Borgou are high levels of education, high income, residence in urban area, purchase and consumption frequency of several foods. The contribution of the mixture of pollutants, to the increasing prevalence of diabetes in Borgou need to be examined, especially pesticides used currently for commercial productions in agriculture and other persistent pollutants. These results contribute to increase the knowledge on emerging risk factors for diabetes that are environmental pollutants such as pesticides. The implications for public health are important in terms of chronic diseases prevention and sensitization of national policies makers, for proper agricultural and health policy aimed at reducing exposure to pesticides.

En Afrique, la contamination des zones humides par les métaux et les pesticides va se poursuivre durablement. Pour autant, le statut toxicologique de ces milieux reste trop peu documente. Le but du présent travail est d’estimer la valeur du varan du Nil (Varanus niloticus) en tant qu’espèce sentinelle pour la contamination des zones humides continentales d’Afrique sub-Saharienne. Plomb, cadmium, et pesticides organochlorés et organophosphorés ont été quantifies, par spectrométrie d’absorption atomique et chromatographie gazeuse (respectivement), dans plusieurs tissus provenant de 71 spécimens issus de quatre sites (au Mali et au Niger) juges a priori inégalement contamines. Bien que des différences claires apparaissent, la contamination environnementale s’avère modérée sur les quatre sites, et ne semble pas constituer un risque notable pour les varans ni pour les humains qui s’en nourrissent occasionnellement. Toutefois la variabilité interindividuelle est importante. Les organotropismes des polluants détectés sont cohérents avec ceux préalablement décrits. Si l’on n’a pu mettre en évidence de différence liée au sexe en ce qui concerne les pesticides, les femelles présentaient des charges en métaux supérieures. La relation entre d’autres facteurs (taille, proportion de graisse) et les concentrations tissulaires a également été considérée. Les varans sont susceptibles de révéler des différences subtiles de contamination environnementale entre sites, et la résolution spatiale de l’outil semble très fine. La possibilité pratique d’utiliser cet indicateur se trouve donc validée. Un travail expérimental sur des varans captifs a par ailleurs été mené pour approfondir l’étude / In Africa, metal and pesticide contamination of wetlands is supposed to continue on a permanent basis. However, the ecotoxicological status of these ecosystems remains poorly documented. The aim of the present work is to assess the value of the Nile monitor (Varanus niloticus) as a sentinel species for the environmental contamination of continental wetlands in sub-Saharan Africa. Lead and cadmium on the one hand, and organochlorine and organophosphate pesticides on the other, have been quantified in several tissues by atomic absorption spectrophotometry and gas chromatography, respectively. Samples come from 71 specimens originating from four sites considered unequally contaminated (in Mali and Niger). Although clear differences appear between sites, the environmental contamination turns out to be moderate at the four sites, and does not seem to represent a significant risk neither for the monitors themselves, nor for occasional human consumers. However, the interindividual variability is important. The organotropisms relative to the detected pollutants are consistent with those described in previous studies. Concerning the pesticides, no gender effect has been found, whereas females were more contaminated by metals. The relation between other factors (size, proportion of fat) and tissue concentrations has been considered too. Nile monitors can reveal subtle differences in local pollution and the spatial resolution of this tool seems to be very sharp. Its practical relevance is thus validated. Additionally, an experimental work has been carried out on captive monitors to go into the subject in greater depth

Algumas ilhas oceânicas como o Arquipélago de São Pedro e São Paulo podem ser consideradas áreas remotas e preservadas devido a sua distância do continente. Entretanto, essas regiões não estão isentas da influência de agentes antrópicos oriundos das regiões costeiras, como é o caso dos poluentes orgânicos persistentes (POPs). A presente proposta visou determinar a ocorrência e distribuição de POPs na biota marinha, do Arquipélago de São Pedro e São Paulo. As extrações das amostras foram realizadas em micro-ondas e os pesticidas organoclorados e os PCBs/PBDEs foram analisados respectivamente por cromatografia a gás com detecção por captura de elétrons e espectrometria de massas. Os compostos predominantes foram os PCBs e os DDTs que apresentaram, respectivamente, as concentrações máximas de: 127,7 e 34,37 ng g-1 para Exocoetus volitans (Peixe-voador), 98,15 e 8,89 ng g-1 para Sula leucogaster (Atobá-marrom) e 90,5 e 18,86 ng g-1 Grapsus grapsus (Aratu). Os baixos valores dos contaminantes sugerem um relativo grau de isolamento e preservação, porém a ocorrência e o perfil de distribuição dos PCBs sustenta a hipótese de que a principal fonte de contaminação em áreas remotas é o transporte atmosférico de longa distância, e demonstra a ubiquidade desses poluentes no ambiente marinho. / Some oceanic islands, such as São Pedro e São Paulo Archipelago may be considered remote areas and preserved due to its distance from the mainland. However, these areas are not exempt from the influence of anthropogenic agents from coastal regions, such as persistent organic pollutants (POPs). This proposal aimed to determine the occurrence and distribution of POPs in marine biota of São Pedro e São Paulo Archipelago. Samples extractions were performed with microwave and organochlorine pesticides and PCBs/PBDES was respectively analysed by gas chromatography with electron capture detection and mass spectrometry. The predominant compounds were PCBs and DDTs that presented, respectively, the maximum concentrations 127.7 and 34.37 ng g-1 to Exocoetus volitans (Flying fish), 98.15 and 8.89 ng g-1 to Sula leucogaster (Brown Booby) and 90.5 and 18.86 ng g-1 to Grapsus grapsus (Sally Lightfoot crab). The low levels of contaminants suggest a relative degree of isolation and preservation, but the occurrence and distribution profiles of PCBs supports the hypothesis that the main source of contamination in remote areas is long range atmospheric transport, and demonstrates the ubiquity of those pollutants in the marine environment.

L'activité humaine est responsable de pollutions diffuses des sols entrainant des dommages sur l'écosystème. Afin d'éviter des déséquilibres importants comme la diminution de la biodiversité ou bien la contamination des chaînes trophiques par des polluants, il est nécessaire de restaurer les écosystèmes. Les différentes techniques utilisées à l'heure actuelle sont couteuses, diminuent la fertilité du sol et ont un effet négatif sur la fonctionnalité des écosystèmes. A contrario, la phytoremédiation ou dépollution grâce aux plantes, apparaît comme une solution digne d'intérêt. Néanmoins, elle nécessite d'être améliorée puisque de nombreux mécanismes restent inexpliqués. L'originalité de notre travail est d'étudier la fonctionnalité de la rhizosphère du maïs (Zea mays) exposée à des pesticides organochlorés (OCPs), le lindane et la chlordécone, interdits respectivement en 1998 et 1993 et persistants dans l'environnement. Cette étude a été réalisée en présence ou absence de microorganismes afin de préciser les mécanismes mis en jeux par les microorganismes et les matrices végétales. Ce travail a mis en évidence les mécanismes impliqués dans la phytotoxicité des deux organochlorés sur les cellules racinaires. Les réponses cellulaires sont dose-dépendantes et montrent un effet des OCPs sur le cycle cellulaire (induction de l'endoréplication et de la ploïdie) et la mort cellulaire (induction de ROS, du calcium cytosolique, des caspase-3-like, de l'apoptose) lors d'expositions extrêmes (correspondant à des cas particuliers comme les friches industrielles). A de plus faibles expositions ayant une réalité environnementale, les racines exposées montrent une perturbation importante de leur métabolome primaire. Ces modifications mesurées sur la production des sucres, des acides organiques, des acides aminées et des lipides peuvent être induites par le stress oxydant produit par les OCPs. Par ailleurs, de tels changements dans le métabolome peuvent provoquer une modification de la composition des exsudats racinaires, jouant sur la relation plante/microorganismes de la rhizosphère. Nos résultats montrent que la fonctionnalité globale de la rhizosphère (allocation des ressources en carbone et azote, catabolisme des microorganismes) n'est pas modifiée sur le long terme en présence des OCPs. Enfin, nous avons démontré l'implication de la rhizosphère (rétention/métabolisation des OCPs) sur l'absorption des OCPs par Zea mays. Le lindane semble être en partie minéralisé par la microflore rhizosphèrique puis les métabolites libérés sont absorbés par les racines, où ils sont majoritairement bioconcentrés. Ces connaissances fondamentales mettent en évidence l'adaptation de la rhizosphère à la pression chimique des OCPs et montrent que la rhizosphère reste fonctionnelle en présence de matrices contaminées par les OCPs. / Human activities lead to diffuse pollution causing damages to the ecosystem. To avoid major disturbances such as biodiversity loss or contamination of trophic chains by pollutants it is necessary to restore these ecosystems. The classical techniques used in depollution are expensive, reduce soil fertility and have a negative effect on ecosystem functionality. In contrast, the use of plants to clean up soils called phytoremediation seems to be a more effective solution. However, it needs to be improved because many biological mechanisms remain unexplained. The originality of our work is to study the functionality of the rhizosphere of maize (Zea mays) exposed to organochlorine pesticides (OCPs), lindane and chlordecone, banned in 1998 and 1993 respectively and persistent in the environment. This study will be conducted in the presence or absence of microorganisms to clarify the relationships between microorganisms and plant matrices. In this study, the mechanisms involved in the phytotoxicity of OCPs in root cells were analyzed. The cytotoxicity was dose-dependent and showed effects on the cell cycle (induction of endoreduplication and level of ploidy) and on cell death (induction of ROS, cytosolic Ca2+, caspase-3-like, apoptosis) under higher doses of exposure (particular case of former industrial sites). Lower exposures usually detected in the environment showed great disturbances in the root metabolome. These changes in sugars, organic acids, amino acids and lipids syntheses could be induced by oxidative stress provided by OCPs. Moreover, metabolome changes might cause modifications in root exudate composition which is involved in plant-microbe relationships. Ours results demonstrate that the overall rhizosphere functionality (resource allocation, carbon and nitrogen contents and microorganism's catabolism) was not disturbed by OCPs long-term exposure. Finally, we demonstrated rhizosphere positive impact on uptake of OCPs by Zea mays. Lindane seems to be partially mineralized by rhizospheric microorganisms. Then, these produced metabolites were uptaken by roots where they were bioconcentrated. These findings highlighted the rhizosphere adaptation to chemical pressure by OCPs and showed the good rhizosphere functionality despite of the OCPs contamination.

Algumas ilhas oceânicas como o Arquipélago de São Pedro e São Paulo podem ser consideradas áreas remotas e preservadas devido a sua distância do continente. Entretanto, essas regiões não estão isentas da influência de agentes antrópicos oriundos das regiões costeiras, como é o caso dos poluentes orgânicos persistentes (POPs). A presente proposta visou determinar a ocorrência e distribuição de POPs na biota marinha, do Arquipélago de São Pedro e São Paulo. As extrações das amostras foram realizadas em micro-ondas e os pesticidas organoclorados e os PCBs/PBDEs foram analisados respectivamente por cromatografia a gás com detecção por captura de elétrons e espectrometria de massas. Os compostos predominantes foram os PCBs e os DDTs que apresentaram, respectivamente, as concentrações máximas de: 127,7 e 34,37 ng g-1 para Exocoetus volitans (Peixe-voador), 98,15 e 8,89 ng g-1 para Sula leucogaster (Atobá-marrom) e 90,5 e 18,86 ng g-1 Grapsus grapsus (Aratu). Os baixos valores dos contaminantes sugerem um relativo grau de isolamento e preservação, porém a ocorrência e o perfil de distribuição dos PCBs sustenta a hipótese de que a principal fonte de contaminação em áreas remotas é o transporte atmosférico de longa distância, e demonstra a ubiquidade desses poluentes no ambiente marinho. / Some oceanic islands, such as São Pedro e São Paulo Archipelago may be considered remote areas and preserved due to its distance from the mainland. However, these areas are not exempt from the influence of anthropogenic agents from coastal regions, such as persistent organic pollutants (POPs). This proposal aimed to determine the occurrence and distribution of POPs in marine biota of São Pedro e São Paulo Archipelago. Samples extractions were performed with microwave and organochlorine pesticides and PCBs/PBDES was respectively analysed by gas chromatography with electron capture detection and mass spectrometry. The predominant compounds were PCBs and DDTs that presented, respectively, the maximum concentrations 127.7 and 34.37 ng g-1 to Exocoetus volitans (Flying fish), 98.15 and 8.89 ng g-1 to Sula leucogaster (Brown Booby) and 90.5 and 18.86 ng g-1 to Grapsus grapsus (Sally Lightfoot crab). The low levels of contaminants suggest a relative degree of isolation and preservation, but the occurrence and distribution profiles of PCBs supports the hypothesis that the main source of contamination in remote areas is long range atmospheric transport, and demonstrates the ubiquity of those pollutants in the marine environment.