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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
151

Purification de polyoléfines artificiellement polluées : études de l’extraction de composés modèles par CO2 supercritique en autoclave et en extrudeuse bi-vis / Purification of polyolefins artificially contaminated : studies of the extraction of model compounds by supercritical CO2 in batch process and in twin-screw extruder

Ben Said, Anouar 10 March 2016 (has links)
En raison de leurs excellentes propriétés, les polyoléfines telles que le polypropylène et le polyéthylène sont largement utilisées dans des applications d'emballage alimentaire. Cependant, tout au long de leur cycle de vie ou de la première utilisation, les polyoléfines peuvent être exposées à des milieux contaminés qui limitent leur recyclabilité en contact alimentaire. Par conséquence, le recyclage de polyoléfines au contact alimentaire nécessite des niveaux de décontamination rigoureux et donc une technologie de décontamination avancée. L’objectif de ce travail consiste dans un premier temps à étudier la faisabilité et la potentialité de l’extraction par CO2 supercritique en mode batch pour la purification de polyoléfines (extraction d’additifs et de contaminants modèles). On s’est plus particulièrement attaché à étudier l’effet des paramètres du procédé sur la cinétique de l’extraction ainsi que l’influence de l’extraction supercritique sur les comportements rhéologique et thermique des matériaux purifiés. Dans un deuxième temps, on s’est intéressé au développement d’un nouveau procédé continu d’extraction par couplage de l’extraction supercritique et l’extrusion bi-vis. Les résultats les plus importants ont montré la potentialité de l’extraction par CO2 supercritique en mode batch pour la purification de polyoléfines sans influencer significativement les propriétés de la matrice / Due to their excellent properties, polyolefins such as polypropylene and polyethylene are widely used in food packaging applications to preserve and protect foodstuffs. However, throughout their lifecycle or first use, polyolefins can be exposed to contaminated media which limit their recyclability in food contact applications. Therefore, the recycling of polyolefins into direct food contact applications requires rigorous decontamination levels and thus effective and advanced recycling technology. The objective of this work is, at first hand, to study the feasibility and the potential of supercritical CO2 extraction in batch process for the purification of polyolefins (extraction of additives and model contaminants). In the whole, we investigated the effects of process parameters and contaminant structure on the extraction kinetic, and the influence of the supercritical CO2 extraction on the rheological and thermal behaviors of the purified materials. On the other hand, we aimed at the development of a novel continuous extraction process by coupling supercritical extraction technique and twin-screw extrusion. The most significant results showed the potential of supercritical CO2 extraction in batch mode for the purification of polyolefins without influence significantly the matrix properties
152

Air diffusion and solid contaminant behaviour in room ventilation v : a CFD based integrated approach

Einberg, Gery January 2005 (has links)
<p>One of the most fundamental human needs is fresh air. It has been estimated that people spend comparatively much time in indoor premises. That creates an elevated need for high-quality ventilation systems in buildings. The ventilation airflow rate is recognised as the main parameter for measuring the indoor air quality. It has been shown that the ventilation airflow rates have effects on respiratory diseases, on “sick building syndrome” symptoms, on productivity and perceived air quality. Ventilation is necessary to remove indoor-generated pollutants by diluting these to an acceptable level. The choice of ventilation airflow rate is often based on norms or standards in which the airflow rate is determined based on epidemiological research and field or laboratory measurements. However, the determination of ventilation flow rate is far more complex. Indoor air quality in the occupied zone can be dependent of many factors such as outdoor air quality, airflow rate, indoor generation of pollutants, moisture content, thermal environment and how the air is supplied into the human occupied zone. One needs to acknowledge the importance of air distribution which clearly affects the comfort of occupants. To design a ventilation system which considers all aspects of room ventilation can only be achieved by computer modelling. The objective of this thesis is to investigate air diffusion, indoor air quality and comfort issues by CFD (computational fluid dynamics) modelling. The crucial part of the CFD modelling is to adopt BCs (boundary conditions) for a successful and accurate modelling procedure. Assessing the CFD simulations by validated BCs enabled constructing the ventilation system virtually and various system layouts were tested to meet given design criteria. In parallel, full-scale measurements were conducted to validate the diffuser models and the implemented simplified particle-settling model. Both the simulations and the measurements reveal the full complexity of air diffusion coupled with solid contaminants. The air supply method is an important factor for distribution of heat, air velocity and solid contaminants. The influence of air supply diffuser location, contaminant source location and air supply method was tested both numerically and by measurements to investigate the influence of different parameters on the efficiency of room ventilation. As example of this, the well-known displacement ventilation is not fully able to evacuate large 10 μm airborne particles from a room. Ventilation should control the conditions in the human breathing zone and therefore the ventilation efficiency is an important parameter. A properly designed ventilation system could use less fresh air to maintain an acceptable level of contaminant concentration in the human breathing zone. That is why complete mixing of air is not recommended as the ventilation efficiency is low and the necessary airflow rate is relatively high compared to other ventilation strategies. Especially buoyancy-driven airflows from heat sources are an important part of ventilation and should not be hampered by supply airflow from the diffusers. All the results revealed that CFD presently is the only reliable method for optimising a ventilation system considering the air diffusion and contaminant level in all locations of any kind of room. The last part of the thesis addresses the possibility to integrate the CFD modelling into a building design process where architectural space geometry, thermal simulations and diffuser BCs could be embedded into a normal building design project.</p>
153

Miljöteknisk undersökning enligt MIFO : en studie på fastigheten Bodsjölandet 1:14 avseende den nedlagda tjärfabriken i Grötingen

Ed, Maria January 2006 (has links)
<p>During 40 years of industrial production, from the end of the 1890’s until the end of 1930’s, coal and wood distillation products were manufactured in AB Carbo’s tar factory along the River Gimån in Grötingen, in the county of Jämtland, Sweden. In accordance with the Swedish Environmental Protection Agency’s Methods for Inventories of contaminated sites, MIFO, the site in Grötingen has been identified as a potentially contaminated site. In order to determine whether toxic substances pose a threat to human health and ecological systems in the area, there was a need to investigate the presence of contaminants, their levels and potential for migration. Sensitivity and protection value regarding exposure of man and the environment at the site is high, since people live next to the site and River Gimån is a part of the Natura 2000 network.</p><p>The initial phase of the MIFO method includes a preliminary survey. Information regarding AB Carbo’s activities and production has been obtained by studying map and archive material, as well as by interviews and site inspections. Potential point sources have been identified around the factory forge, storage cellar, distillation building and the wooden channel for the discharge of tar and other condensates into the River Gimån.</p><p>Guided by the information gathered in MIFO phase 1, a preliminary site investigation was carried out at the site. It included sampling of soil, sediment, groundwater and surface water together with sample analysis of heavy metals and organic pollutants. The result of the analysis shows that very high levels of the contaminants PAH, aromatics and lead are found in both soil and groundwater. The sediment contamination level is high while that of surface water is very low. The distribution of contamination levels among the samples indicates a likely point source close to the distillation building due to very high contamination levels in soil and groundwater close to that point. The point source may represent a larger spillage or dumped waste products.</p><p>Two of the contaminants present at the site, phenantrene and phenol, were studied by using the model CHEMFLO-2000. The analysis focussed on mobility in unsaturated soils under conditions that prevail at the site in Grötingen. The adsorption of phenantrene is significantly higher in comparison to that of phenol.</p><p>Comprehensive assessment and risk classification results in risk class 2 for the site in Grötingen, which implies a need for further investigations and measurements. The risk of human exposure could be reduced by removing contaminated soil around the factory forge. Additional studies should focus on finding the location of the point source around the distillation building as well as contaminant migration from the wooden channel and the geographical spreading of heavy metal contamination.</p> / <p>Från slutet av 1890-talet och fram till slutet av 1930-talet tillverkades träkol och trädestillationsprodukter vid AB Carbos kolugnsanläggning i Grötingen, Jämtlands län. En undersökning enligt MIFO-modellen motsvarande fas 1 och fas 2 har genomförts på området med syfte att fastställa vilka föroreningar som förekommer på området, föroreningsnivå, spridningsförutsättningar och sammanfattningsvis bedöma föroreningssituationen på området utifrån de miljö- samt hälsorisker som området ger eller kan ge upphov till. Objektsområdet har hög känslighet och högt skyddsvärde då människor bor permanent alldeles intill objektsområdet samt att det intilliggande vattendraget Gimån ingår i Natura 2000-nätverket.</p><p>Genom de orienterande studier som genomfördes i MIFO fas 1 har kart- och arkivstudier samt intervjuer resulterat i information om kolugnsanläggningens verksamhet samt tillverkade produkter. På fabriksområdet identifierades potentiella punktkällor vid fabrikens smedja, källare, reningsverk samt vid den träränna varigenom spilltjära släpptes ut till Gimån.</p><p>Utifrån den information som erhölls i den orienterande fasen genomfördes en riktad provtagning enligt MIFO fas 2 i såväl mark och sediment som grund- och ytvatten. Bedömning av uppmätta föroreningshalter baseras på riktvärden och skattas från mindre allvarliga till mycket allvarliga. Analysresultaten påvisar allvarliga till mycket allvarliga halter av PAH, aromater och bly i jorden och grundvattnet. Andra föroreningar som påvisas i högre halter på området är alifater och koppar. Föroreningsnivån med avseende på PAH i sedimenten bedöms som allvarlig medan analysresultaten från ytvattenprovtagningen påvisar mycket låga föroreningsnivåer. Provtagningsresultaten påvisar ett mycket förorenat grundvattenflöde från reningsverket, där en punktkälla i form av större spill eller nedgrävda förvaringskärl kan vara lokaliserad. Eventuell spridning av föroreningar från trärännan går inte att fastställa då föroreningsspridning även kan ske från det intilliggande området där kolugnar och kondenseringshus har varit lokaliserade.</p><p>Föroreningarna fenantren och fenol studerades genom modellering i CHEMFLO-2000 med avseende på deras rörlighet i omättad jord under de geohydrologiska förhållanden som råder på objektsområdet i Grötingen. Resultatet visar att fenantren adsorberas i marken i betydligt större grad än fenol. Koncentrationen fenantren i porvattnet minskar nästan lika mycket som den totala koncentrationen fenantren i marken, vilket tyder på att fenantren binds starkt genom adsorbtion i marken.</p><p>Den samlade riskbedömningen av objektet resulterar i att objektet bedöms tillhöra riskklass 2, vilket innebär att objektet ger upphov till en stor risk för människa och miljön. Fortsatta undersökningar på området i Grötingen bör fokusera på att hitta den punktkälla vid reningsverket som bedöms vara orsaken till de höga föroreningsnivåer som uppmättes i grundvattenrör V1. Den geografiska utbredningen av de ytliga föroreningarna som påträffades där smedjan har stått bör också utredas vidare och eventuellt avlägsna förorenad jord eller vidta åtgärder för att minska exponeringen. Vidare undersökningar bör även klarlägga spridningen från trärännan samt orsakerna till de höga föroreningsnivåer av bly som uppmättes på området.</p>
154

Kartering av markföroreningar inom Skutskärs Bruk samt utvärdering av spridningsrisker enligt Naturvårdsverkets MIFO fas 2

Lundell, Lisa January 2005 (has links)
<p>With the prospect of future construction on the Skutskär Pulp Mill property, Stora Enso Fine Paper has initiated an investigation of soil contaminants and a risk assessment of these contaminants. A soil and groundwater investigation has therefore been conducted on an open area of about 16 000 square meters, situated between the current wood room and digester house. To be able to integrate this study into an investigation for the whole industrial property, the study has been carried out as a phase 2 study according to the Swedish Environmental Protection Agency’s Methods of Inventories of Contaminated sites (MIFO).</p><p>The site investigation has involved soil and groundwater sampling, together with the analysis of heavy metals and organic contaminants. The degree of hazard posed by the contaminants, the level of contamination, the potential for migration of the contaminants, as well as the degree to which protection of human health and the environment is required in the area, have been weighed together for an overall risk assessment of the area with regard to human health and the environment.</p><p>The investigated area was built up by filling in the coastal waters. The fill material consists mainly of sand that becomes finer below the groundwater surface at the depth of about 2.3 m.</p><p>Above the groundwater surface pyrite cinders was encountered. Underneath the cinders, lime sludge, bark and wood fiber were found at different depths. The deepest layer encountered consists of moraine.</p><p>The results showed that most of the heavy metals in the soil originate from the pyrite cinders. The level of contamination was assessed as very high for Zn, Pb, Cu, Cd and Hg. In the groundwater, the level of contamination was assessed as high for Al and moderate for Pb and Cr. The level of organic contaminants was in general low. Heavy oils were encountered in shallow soil layers. Mercury was analysed due to risk of migration from an earlier factory that produced chlorine alkali. The metal was encountered in both the shallow and the deeper layers of soil. Only three of 56 soil samples exceeded the Swedish Environmental Protection Agency’s guideline value for less sensitive land use of 7 mg Hg/kg dry weight.</p><p>The investigation indicates that the metals still are bound to the pyrite cinders and that most of the leachable parts were mobilized during the years when the ground was not covered with asphalt.</p><p>Most of the contaminant migration is assumed to take place through groundwater advection. The groundwater flows in the direction of the dock and was calculated to about 3 m3 per day. The gradient in the area is about 0.5 %. The average linear groundwater velocity was computed to about 5 m per year. The transport of the pollutants might be slower due to adsorption and precipitation. Groundwater sampling indicates that the transport to the dock is up to 100 g Zn, 10 g Cr, 8 g Pb and 0.02 g Hg per year.</p><p>The site was assigned to risk class 3, i.e. moderate risk regarding human health and environment and relatively low urgency concerning additional investigations.</p> / <p>Inför framtida ombyggnationer inom industrifastigheten vill Skutskärs Bruk, Stora Enso, kartlägga markföroreningar och utvärdera vilken spridningsrisk de utgör. En undersökning av mark- och grundvattenförhållanden har därför utförts på en ca 16 000 m2 stor yta, belägen mellan dagens renseri och kokeri. Undersökningen har utförts enligt Naturvårdsverkets Metodik för Inventering av Förorenade Områden (MIFO) för att i framtiden kunna integreras i en fas 2- undersökning för hela fastigheten.</p><p>Arbetet har inneburit provtagning av mark- och grundvatten som analyserats med avseende på tungmetaller och organiska föroreningar. Föroreningarnas farlighet, föroreningsnivån, spridningsförutsättningarna samt objektets känslighet och skyddsvärde har vägts samman för att bedöma områdets risk för människors hälsa och miljö.</p><p>Området utgörs av utfylld havsbotten. Massorna består främst av sand som blir siltigare under grundvattenytan på ca 2,3 m djup under markytan. Ovan grundvattenytan påträffades kisaska. Därefter hittades mesa, bark och träfiber på varierande djup. Fyllningen underlagras av morän.</p><p>Resultatet visade att huvuddelen av tungmetallerna i marken härstammade från kisaskan. Föroreningsnivån bedömdes som mycket stor för Zn, Pb, Cu, Cd och Hg. I grundvattnet bedömdes föroreningsnivån som stor för Al och måttlig för Pb och Cr. Halten organiska föroreningar var generellt sett låg. Tyngre oljor påträffades i ytliga marklager.</p><p>Kvicksilver har analyserats eftersom risk för spridning från en före detta kloralkalifabrik uppströms området förelåg. Ämnet påträffades både i ytnära marklager och på större djup. Endast tre av 56 markprover översteg Naturvårdsverkets gränsvärde för mindre känslig markanvändning på 7 mg/kg TS.</p><p>Undersökningen tyder på att metallerna fortfarande är bundna till kisaskan och att stora delar av den lakbara delen transporterades bort under de år som ytan var oasfalterad.</p><p>Huvuddelen av föroreningstransporten antas ske genom advektion. Grundvattnet flödar i riktning mot hamnbassängen och beräknas uppgå till ca 3 m3/dygn. Områdets gradient är ca 0,5 %. Vattenpartiklarnas hastighet beräknades till ca 5 m/år. Föroreningstransporten kan vara lägre på grund av adsorption och utfällning. Grundvattenprovtagningen tyder på att den årliga transporten till hamnbassängen skulle kunna uppgå till 100 g Zn, 10 g Cr, 8 g Pb och 0,02 g Hg.</p><p>Objektet bedömdes tillhöra riskklass 3, det vill säga måttlig risk för människa och miljö samt relativt låg angelägenhet för vidare undersökningar.</p>
155

Arizona Drinking Water Well Contaminants

Uhlman, Kristine, Rock, Channah, Artiola, Janick 11 1900 (has links)
4 pp. / This short fact sheet is taken from "Arizona Well Owner's Guide to Water Supply" currently in print. We plan to complete part 2 of this fact sheet by the end of July, 2009. Please note that the text has already been incorporated into the eXtension Community of Practice web page - - I am the author for the COP/Drinking Water group text on chemistry of naturally occurring water contaminants. / Arizona well water is often contaminated with elevated concentrations of naturally occurring constituents that are a human health concern. This short fact sheet is the first in a two-part series about what naturally occurring contaminants may be found in your water supply well and includes a brief discussion on environmental pollutants that originate from land use activities. If you own a well in Arizona, you have the sole responsibility for checking to see if your drinking water is contaminated. Arizona state law does not require private well owners to test or treat their water for purity. The second part of this series outlines what to sample for and how to understand your analytical results.
156

Bioaccumulation of Heavy Metals from Soils to Plants in Watersheds Contaminated by Acid Mine Drainage in SE Arizona

Eddleman, Katherine January 2012 (has links)
Current concerns about inorganic contaminants in food products have raised consumer awareness of anthropogenic sources of heavy metal contamination in ecosystems and their potential threat to human health. Mining and exploration of mineralized zones is a major source of such contamination. Mining throughout the Patagonia Mountains, Arizona, has left a legacy of surface water contamination by acid mine drainage (AMD). This study assessed the impacts of AMD on soils and plants throughout the study area. Concentrations, transport, and loading of heavy metals (Ag, As, Cd, Co, Cr, Cu, Fe, Mn, Mo, Ni, Pb, Sb, and Zn) in soils and plants was quantified using total concentrations, suggested toxic levels, and plant and soil pollution indices. Pollution indices were modified to include antimony and molybdenum. Pollution indices greater than 100 were found in areas disturbed by mining, remediation sites and beyond. Cattle grazing on grasses contaminated by metals were documented.
157

Évaluation de la métallothionéine comme biomarqueur d'effets toxiques chez le bivalve d'eau douce Pyganodon grandis dans un environnement aquatique contaminé par les métaux traces

Perceval, Olivier January 2004 (has links)
Thèse numérisée par la Direction des bibliothèques de l'Université de Montréal.
158

Attenuation of Trace Organic Compounds by Physical and Chemical Processes in Water Reuse

Park, Minkyu, Park, Minkyu January 2016 (has links)
Realized and potential threats of water scarcity due in part to global climate change have increased the interest in potable reuse of municipal wastewater. Recalcitrant trace organic compounds (TOrCs), including pharmaceuticals, steroid hormones and industrial compounds in wastewater are often not efficiently removed by conventional wastewater treatment processes, thereby ubiquitously occurs in natural and wastewater effluents. Advanced water treatment processes including advanced oxidation processes (AOPs), activated carbon adsorption and membrane separation processes have been demonstrated to efficaciously attenuate many classes of TOrCs. In this dissertation, attenuation of TOrCs by ozone oxidation, powdered activated carbon (PAC) and nanofiltration membrane and their monitoring strategies were demonstrated in water reuse applications. Particularly, the first main chapter attempted to elucidate the use of indicator/surrogate for predicting TOrC attenuation by ozone oxidation in a theoretical basis. A semi-empirical model was developed, which successfully predicted many TOrCs with various oxidation kinetics simultaneously. The following chapter was pertaining to development of exploratory models to predict TOrC abatement by ozone. It was concluded that principal component (PC) analysis in conjunction with artificial neural network (ANN) resulted in precise and robust prediction of TOrC attenuation. In addition to oxidation process, kinetic of TOrC adsorption by PAC was scrutinized subsequently. It was found that the initial-phase adsorption was controlled by surface reaction due to hydrophobic interaction. In addition, correlation between surrogate reduction and TOrC attenuation was independent upon water quality at the early phase of adsorption, which was explained theoretically. In the last chapter, synergistic effects of NF membrane in conjunction with pre-ozonation was investigated for TOrC abatement in brine. As a result, all the tested TOrCs were efficaciously attenuated and not quantifiable due to their concentration below limit of quantification. In addition, ozonation also alleviated organic fouling potential substantially.
159

Vers une compréhension mécanistique de la biocatalyse des composés pharmaceutiques dans des matrices complexes par traitement fongique (Trametes hirsuta)

Haroune, Lounès January 2016 (has links)
La présence des contaminants organiques dans l’environnement est une problématique aux enjeux aussi bien scientifiques que politiques. Le caractère diffus et continu (différentes et multiples sources) de cette contamination ne permet pas à ces molécules biologiquement actives d’être soumises à une législation. Ces molécules, pouvant être très récalcitrantes, ne sont pas systématiquement éliminées par les systèmes de traitement des eaux conventionnels. Actuellement, de nouveaux procédés biotechnologiques basés sur des enzymes extracellulaires (e.g. Laccase) ou des champignons lignivores permettent l’élimination des composés les plus récalcitrants. Notre compréhension des mécanismes impliqués dans cette élimination reste incomplète. En effet, la biosorption et l’activité des enzymes extracellulaire sont les mécanismes les plus souvent mis en avant pour expliquer l’efficacité des procédés d’élimination fongique, mais ne sont pas capables d’expliquer les performances obtenues pour certains composés pharmaceutiques. Ces lacunes dans nos connaissances sur les mécanismes responsables de l’élimination fongique des contaminants organiques sont un frein à la pleine exploitation de ces procédés de traitement. De plus, il est forcé d’admettre qu’un grand nombre de travaux portant sur l’élimination fongique de contaminants organiques ont été réalisés dans des conditions de hautes concentrations, qui peuvent être peu représentatives des matrices environnementales. Ainsi, les effets observés à plus forte concentration peuvent etre le résultat dû au stress de l’organisme au contact des contaminants (toxicités). Cette thèse adresse deux questions ; ainsi quelle est l’influence des concentrations traces sur de tels procédés ? Et comment expliquer l’élimination de certains contaminants organiques lors des traitements fongiques ? Afin d’apporter des éléments de réponse sur les mécanismes mis en jeux lors de l’élimination fongique, les travaux présentés ici ont été réalisés sur un modèle de champignon lignivore connu pour ses propriétés en bioremediation. Dans un premier temps, un développement analytique permettant la quantification d’une sélection de contaminants organiques à l’état de traces a été réalisé. Cette méthode a permis d’effectuer des analyses de ces molécules à partir d’un seul échantillon environnemental de faible biomasse et à partir d’une seule injection instrumentale. Les résultats de cette thèse démontrent que l’élimination fongique de contaminants organiques résulte de mécanismes plus complexes que précédemment décrits. Notamment, la dégradation est fortement dépendante d’une étape initiale d’internalisation du contaminant par l’organisme ciblé et de la dégradation intracellulaire. Les mécanismes impliqués peuvent ainsi donnés lieux à des réactions de conjugaison intracellulaire des molecules (glucuronide, glutathione). Les résultats démontrent également que ces procédés d’élimination fongique sont efficaces sur une large gamme de concentration en contaminants organiques. Cependant, les faibles concentrations modifient les propriétés physico-chimiques et biologiques de l’organisme testé (i.e. un changement de la morphologie et du profil de la production enzymatique). La réponse biologique n’étant pas directement proportionnelle a l’exposition en contaminant. Cette étude a permis d’accroitre notre compréhension des mécanismes impliqués dans la dégradation fongique de contaminants organiques. Ceci ouvre la voie à de nouvelles études portant sur les interactions entre processus intra — et extracellulaires. Cette thèse contribue également à l’amélioration des connaissances en offrant des outils de compréhension nécessaire à l’optimisation et au développement du potentiel de ces procédés biotechnologiques (ciblage et role des enzymes réeellement impliquées dans les réactions de biocatalyse).
160

Réponses du tilapia Sarotherondon melanotheron aux stress multiples (contaminants chimiques et salinité) : approche multi-paramétrique / Reponses of tilapia Sarotherondon melanotheron to multiples stress(chemical pollutants and salinity) : multi-parameter approach

Ndiaye, Awa 03 December 2012 (has links)
Sarotherodon melanotheron est un poisson euryhalin endémique d'Afrique de l'ouest, qui vit et se reproduit dans tous les milieux aquatiques. Dans cette région où le changement climatique a provoqué l'apparition d'estuaires hypersalés, cette espèce est la seule à survivre en milieu hyperhalin, et constitue donc un excellent modèle biologique. Les milieux aquatiques côtiers sont aussi impactés par de nombreux contaminants issus de l'activité humaine. L'objectif de cette thèse était d'évaluer l'impact des effets croisés de la salinité et des contaminants chez S. melanotheron dans des milieux très contrastés au Sénégal en utilisant une approche multi-multiparamétrique. Des indicateurs physiologiques (taux de croissance, facteur de condition) et une batterie de biomarqueurs en lien avec l'osmorégulation (pompe NKA), le métabolisme des xénobiotiques (EROD et GST), la protection vis-à-vis du stress (TBARS), la transmission de l'influx nerveux (AChE) et la reproduction (vitellogénine et histopathologie gonadique) ont été mesurés. Ils ont été complétés par une étude de la diversité génétique et de la forme des otolithes pour différencier les populations. Un dosage préalable de la contamination des sédiments a permis de caractériser précisément les sites échantillonnés. L'induction de l'activité EROD sur le site le plus impacté en HAP et celle de la NKA sur les sites de salinité plus élevée ont montré la sensibilité de ces biomarqueurs. Des expérimentations sur S. melanotheron en milieu contrôlé ont permis d'appréhender l'impact des effets combinés de la salinité et du DDT, et de caractériser l'activité NKA et les transporteurs protéiques (NKA et CFTR) mis en jeu lors de l'osmorégulation. L'immunofluorescence prononcée des transporteurs et leur abondance au niveau des branchies suggèrent leur implication fonctionnelle dans l'osmorégulation. L'analyse de la forme des otolithes et de la génétique des populations de S. melanotheron échantillonnées ont montré que la distance géographique semble être discriminante pour les variations morphométriques des otolithes, alors que la variabilité génétique observée traduisait l'histoire de la colonisation postglaciaire et les évènements démographiques affectant les populations les plus isolées. Tous les résultats montrent l'intérêt de l'utilisation d'une approche multi-paramétrique pour caractériser l'impact de perturbateurs environnementaux multiples. Des travaux complémentaires permettraient d'affirmer que ce tilapia est un très bon indicateur utilisable dans l'évaluation de la qualité des écosystèmes côtiers en milieu tropical. / The euryhaline black-chinned tilapia Sarotherodon melanotheron heudelotii is endemic in West Africa and able to adapt to changes of salinity, to survive and to reproduce in different natural conditions. It is one of rare species to survive in hyperhaline area. Increased of the salinity levels is one of the consequences of climate change in West Africa coastal environments. However coastal zones are also the ultimate sink of chemical contaminants. The aim of this study was to assess the impact of the combined effects of salinity and pollutants in the black-chinned tilapia for evaluate the Senegalese aquatic habitat quality. In accord to this objective physiological marker (condition factor and growth rate) and several biochemical biomarkers to link with osmoregulatory (NKA), xenobiotic metabolisation (EROD, GST), oxidative stress (TBARS), neurotoxicity (AChE) and reproduction (VTG and gonad histopathology) were assessed. Field studies revealed that EROD and NKA can discriminate different sampling site and could be used as biomarkers on pollutants and salinity exposure respectively. The combined effects of salinity and DDT on osmoregulatory were characterized in laboratory conditions. Results showed that influenced the osmoregulatory mechanisms with differential abundance of transport proteins (NKA and CFTR) in gill and induction of NKA. The results showed that a set of biomarkers to assess effects of multiple stressors can be useful in S. melanotheron. In addition, the S. melanotheron population structure using morphologic and genetic analysis revealed that otolith shape analysis provides a geographical discrimination and microsatellites analysis allow genetic pool discrimination. Results show the absence of correspondence between the morphologic and genetic patterns. The present study demonstrated that importance of use multi-parametric approach to assess impact of multiple stressors, such as salinity and contaminants on black-chinned tilapia. Further studies should be realized for a better characterize this set of biomarker responses.

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