Parmi les contaminants environnementaux reconnus pour leur toxicité et leur propagation à travers le monde, les métaux lourds sont certainement d'une première préoccupation. Des études démontrent que les métaux lourds peuvent altérer différents systèmes dont le système immunitaire. Ils peuvent induire des effets immunomodulateurs qui pourront avoir comme conséquences, l'augmentation de la susceptibilité à des agents infectieux, l'apparition de maladies néoplasiques et de maladies auto-immunes. Afin de se protéger de cette agression, les cellules immunitaires induisent des thiols (cystéines, glutathion, métalloprotéines) qui sont des molécules capables de neutraliser les métaux en s'y liant et ainsi protéger l'organisme des effets néfastes. La pré-activation de ces cellules augmenterait leur contenu intracellulaire en thiols et les rendrait donc plus résistantes à l'effet néfaste des métaux lourds. Dans cette étude, nous avons voulu démontrer, l'effet de la pré-activation des lymphocytes avec la concanavaline A sur la toxicité de certains métaux lourds tels que le mercure (organique et inorganique), le cadmium, le zinc et le sélénium. Nous avons mesuré la prolifération Iymphoblastique, la viabilité, l'apoptose ainsi que le niveau de thiols intracellulaires dans ces cellules pré-activées ou non pré-activées. Pour la prolifération lymphoblastique, les cellules pré-activées ont été significativement plus résistantes que les cellules au repos pour les deux formes de mercure, le cadmium et le zinc. Le niveau de thiols a été significativement augmenté chez les lymphocytes pré-activés de même que la viabilité, alors que l'apoptose a été augmentée dans les lymphocytes pré-activés par rapport à leur contrôle respectif en présence de mercure inorganique, de zinc et de sélénium. Les résultats suggèrent que la pré-activation des lymphocytes entraîne une augmentation du niveau de thiols intracellulaires leur procurant une meilleure protection contre l'effet néfaste des métaux lourds.

La contamination des eaux de surface par les polluants agricoles soulève des inquiétudes concernant les effets potentiels sur les organismes aquatiques. L'objectif général de ce projet de maîtrise était d'évaluer le statut physiologique du poisson d'eau douce exposé de façon chronique aux pesticides et autres polluants agricoles. Dans un premier volet, des truites arc-en-ciel (Oncorhynchus mykiss) ont été exposées durant 30 jours à un herbicide communément détecté dans les cours d'eau agricoles, le métolachlore, à des concentrations de 200, 500 et 800 µg/l. Une exposition au métolachlore en microplaque avec des cellules interrénales de truites arc-en-ciel (cellules qui sécrètent le cortisol) a aussi été réalisée. Dans un second volet, des perchaudes ont été capturées à trois reprises entre 2002 et 2003 dans la rivière Yamaska (Québec, Canada), qui est contaminée par les pesticides et autres polluants agricoles. À chacune des campagnes, un site non contaminé (lac Brome) ou très faiblement contaminé par les pesticides (rivière Yamaska Nord) était utilisé comme site de référence. Pour les deux volets, des fonctions biologiques ont été évaluées à l'aide de biomarqueurs: la fonction endocrinienne par le cortisol plasmatique; l'osmorégulation par l'activité de l'enzyme branchiale Na+/K+-ATPase et le métabolisme énergétique par le glucose plasmatique et le glycogène hépatique. L'activité de l'acétylcholinestérase plasmatique a été évaluée comme biomarqueur d'exposition aux inhibiteurs de cholinestérases. Enfin, des indices de condition tels que le facteur de condition, l'indice hépatosomatique et l'hématocrite ont permis de caractériser la condition générale des poissons. Les résultats obtenus pour le volet réalisé en laboratoire révèlent que les truites arc-en-ciel sont peu affectées par une exposition au métolachlore allant jusqu'à 800 µg/l. Une augmentation de l'hématocrite est toutefois notée à l'exposition de 200 µg/l de métolachlore. À 800 µg/l, les truites sont beaucoup plus sensibles au stress de capture. De plus, une perturbation du système d'osmorégulation est révélée par une hausse de l'activité Na+/K+ATPase des branchies, une diminution de l'hématocrite et des réserves énergétiques. L'exposition en microplaque montre que les cellules interrénales sont très résistantes au métolachlore en terme de viabilité cellulaire (concentration létale pour 50% des cellules CL50 = 1092 mg/l). Cependant, la concentration effective qui diminue de 50% la libération de cortisol est beaucoup plus faible (CE50 = 79 mg/l), ce qui suggère un potentiel de perturbateur endocrinien in vitro. Les résultats du volet réalisé en milieu naturel indiquent, pour la seconde campagne d'échantillonnage, que le milieu contaminé par les pesticides et autres polluants agricoles n'affecte pas significativement l'activité des cholinestérases plasmatiques, bien que celle-ci tende à baisser. Ce milieu affecte toutefois négativement la croissance des perchaudes et perturbe la réponse cortisolique. Les perchaudes ont une accumulation de glycogène hépatique et un indice hépatosomatique plus élevé. L'activité des enzymes Na+/K+-ATPase des branchies est plus élevée. Les résultats de ces études ont permis de dresser un portrait des effets des pesticides et autres polluants agricoles sur le statut physiologique du poisson. Ainsi, en approfondissant les différents biomarqueurs affectés, des études ultérieures pourront permettre d'évaluer l'état de santé des poissons. ______________________________________________________________________________ MOTS-CLÉS DE L’AUTEUR : Perchaude,Truite arc-en-ciel, Métolachlore, Pesticide, Cortisol, Perturbation endocrinienne, Osmorégulation, Hématocrite, Glycogène, Acétylcholinestérase, Rivière Yamaska.

Au Québec, l'esturgeon jaune (Acipenser fulvescens) fait l'objet d'une pêche commerciale importante malgré le fait qu'à l'échelle mondiale la plupart des espèces d'esturgeons sont menacées de disparition. Si les données dont disposent les intervenants dans la gestion de cette ressource les informent sur l'état des stocks, en terme de quantité, elles ne les renseignent pas sur la qualité des individus pêchés. Des doutes subsistent sur le potentiel réel de régénération et de subsistance à long terme de cette espèce. Ce travail vise à élargir nos connaissances sur l'esturgeon jaune du Québec, une espèce de poissons qui affiche des traits biologiques particuliers dont une forte longévité et une reproduction tardive à longue périodicité. L'hypothèse principale de la recherche est que certains indicateurs biologiques pourraient signaler une atteinte potentielle à la santé des esturgeons, ce qui pourrait conduire à un examen plus approfondi des phénomènes détectés. Des relevés physionomiques (âge, sexe, indices somatiques, relevés d'irrégularités morpho-pathologiques) et des analyses en laboratoire (concentrations de lipides, protéines et glycogène hépatiques, histologie du foie, cycle cellulaire des splénocytes) ont été effectuées sur des esturgeons jaunes (n=122) provenant de trois stations d'échantillonnage. Des analyses de contaminants environnementaux furent également effectuées (mercure, biphényles polychlorés (BPC), dioxines, furanes, éthers de diphényles polybrominés (PBDE), biphényles polybrominés (BPB)). Deux stations se trouvent dans le fleuve Saint-Laurent (lac Saint-Louis et archipel du lac Saint-Pierre), et la troisième se trouve en Abitibi (lac Berthelot). Un indice intégré d'examen de la santé, traité tel qu'il le fut dans le présent travail, ne constitue pas un signal préventif adéquat. Les résultats concernant les lipides hépatiques totaux ainsi que certaines observations histologiques indiquent que le suivi de l'indice hépatosomatique constitue un signal préventif d'atteinte potentielle à la santé. Les fluctuations spatiales et temporelles de la proportion d'individus présentant une valeur supérieure à 3.15 pour cet indice constitue un outil de suivi. ______________________________________________________________________________ MOTS-CLÉS DE L’AUTEUR : Poisson, Indicateurs biologiques, Histologie, Contaminants lipophiles, Esturgeon jaune.

El transporte de solutos no conservativos en medios porosos o fracturados es altamente influenciado por su heterogeneidad. Complejidad adicional se agrega al proceso de transporte, debido a la presencia de diferentes tipos de reacciones químicas que controlan la evolución de las concentraciones de las especies en el medio. Muchas de esas reacciones químicas están gobernadas por la mezcla de aguas con diferente calidad geoquímica. La mezcla produce desequilibrio químico instantáneo en el agua mezclada resultante, y las reacciones dan lugar para que se re-equilibre el sistema.Esta disertación doctoral estudia el transporte en medios heterogéneos cubriendo diferentes y tipos de acuíferos. Primero, el flujo y el transporte se analizan en rocas fracturadas, las cuales poseen baja permeabilidad. Estas formaciones son estudiadas usando como modelo conceptual las Redes Discretas de Fracturas, donde se considera el medio como una densa red de fracturas que se interconectan y conducen agua. Este modelo de es una alternativa válida para conceptualizar el transporte de solutos en el medio fracturado, pero tradicionalmente no se ha utilizado para analizar ni el transporte ni el flujo en una modelación de tipo problema inverso, debido a su alto costo computacional.El transporte de solutos conservativos en medios heterogéneos puede modelarse con una ecuación efectiva que involucre un término de transferencia de masa entre la zona móvil y la zona inmóvil. La segunda parte de la disertación explora la posibilidad de extender esta idea para tener en cuenta las especies reactivas. Se parte de la consideración de que las especies están en equilibrio químico local, el cual es alcanzado instantáneamente. El impacto de la heterogeneidad del medio en el transporte efectivo es representado por un modelo de tasa de transferencia múltiple de masa (MRMT), el cual aproxima el medio a un multicontinuo de una región móvil y varias regiones inmóviles, las cuales se relacionan por una transferencia de masa cinética. Partiendo del hecho de que todas las regiones están bien mezcladas, el equilibrio global no se preserva. Esta imposición implica que las reacciones tomen lugar en todo el dominio, y sean dominadas tanto por la dispersión local como por la transferencia de masa. Se derivaron expresiones explícitas para calcular las tasas de reacción en las regiones móvil e inmóvil y se estudió el impacto de la transferencia de masa en el transporte reactivo. Las tasas de reacción pueden cambiar significativamente comparadas con aquellas que se obtendrían en un medio homogéneo. Para una amplia distribución de tiempos de residencia en las zonas inmóviles, el sistema podría tomar mucho más tiempo para equilibrar globalmente el medio comparado que para un medio homogéneo.El último tema abordado en esta disertación es el análisis del transporte de especies bajo condiciones de cinética química o equilibrio no instantáneo. El transporte reactivo a escala local es analizado bajo dos situaciones: (i) con una reacción sencilla y (ii) con dos reacciones simultáneas: una considerada instantánea y la otra como lenta respecto al tiempo característico de transporte. En la primera situación de las dos planteadas, es posible concluir que el problema puede ser reescrito sólo en términos del estado inicial del sistema más una ecuación diferencial para la tasa de reacción. El resultado clave es que la tasa de reacción en equilibrio depende de un término relativo a la mezcla y a la reacción cinética, la cual es de hecho el factor que controla la disponibilidad de reactantes en el sistema, y la distribución de las combinaciones lineales de las concentraciones acuosas de las especies, llamadas componentes tanto conservativas como cinéticas. Desde un punto de vista operacional, estas expresiones permiten el cálculo directo de las tasas de reacción en equilibrio sin la necesidad de calcular las concentraciones de las especies acuosas. / Transport of non-conservative species or solutes in porous or fractured media is highly influenced by heterogeneity. Additional complexity is added to the processes due to the presence of different types of chemical reactions that control the fate of species concentrations in the medium. Many of these chemical reactions are governed by mixing of waters with different geochemical signature. Mixing yields instantaneous chemical disequilibrium in the resulting mixed water, and reactions take place to re-equilibrate the system.This dissertation studies transport in heterogeneous media covering different problems (flow, conservative transport and reactive transport) and in different aquifer types. First, we analyze flow and transport in low permeable highly fractured massifs. These are studied using the Discrete Fracture Network (DFN) approach, where a dense network of water-conducting intersecting fractures is considered. The DFN approach traditionally has lacked the possibility of analyzing transport (as well as flow) in an inverse problem framework. The actual tracer test, performed with a conservative solute (deuterium), evidences Non-Fickian behavior, characterized by tailing in the breakthrough curve.As a consequence, transport of conservative solutes in heterogeneous media can be modeled with an effective equation involving a mass transfer term between the mobile and some immobile zones. In the second part of the thesis we explore the possibility of extending this idea to account for transport of reactive species. We start by considering species where local chemical equilibrium conditions are reached instantaneously. The impact of the medium heterogeneity on effective transport is represented by a multi rate mass transfer approach, which models the medium as a multiple continuum of one mobile and multiple immobile regions, which are related by kinetic mass transfer. Even though all regions (mobile and immobile) are assumed to be well mixed (local equilibrium), globally equilibrium is not preserved. The imposition of local equilibrium at all points implies the need for reactions to take place all through the domain, driven by both local dispersion and mass transfer. We derive explicit expressions for the reaction rates in the mobile and immobile regions and study the impact of mass transfer on reactive transport. The reaction rates can change significantly compared with the ones that would be obtained in a homogeneous media. For a broad distribution of residence times in the immobile zones, the system may take much more time to equilibrate globally than for a homogeneous medium.The last topic addressed in this Thesis is the analysis of transport of species undergoing non-instantaneous (kinetic) chemical equilibrium. Reactive transport at the local scale is analyzed under two situations: (i) with a single kinetic reaction and (ii) with two simultaneous reactions: one considered instantaneous and the other one being slow related to the transport characteristic time. In the first problem of these problems, we find that the problem can be rewritten only in terms of the initial state of the system plus a non-linear partial differential equation for the reaction rate.The key result is that the equilibrium reaction rate depends on a mixingrelated term, the kinetic reaction rate, which is actually controlling the availability of reactants in the system, and the distribution of (conservative and kinetic) linear combinations of aqueous species concentrations. From an operational standpoint, our expressions allow direct computation of equilibrium reaction rates without the need to calculate aqueous species concentrations. To illustrate the results, the dissolution of calcite in the presence of precipitating gypsum in a one-dimensional fully saturated system is analyzed. The example highlights the highly nonlinear and non monotonic response of the system to the controlling input parameters.

The ability of supersaturated water injection (SWI) to recover non-aqueous phase liquids (NAPLs) was studied at the field scale as part of an ongoing program to evaluate its applicability to groundwater remediation. SWI uses Gas inFusionTM technology to efficiently dissolve gases into liquids at elevated pressures. SWI has been shown to both volatilize and mobilize residual NAPL ganglia (Li, 2004). During SWI pressurized water containing high concentrations of CO2 is injected into the subsurface below the zone of contamination. Once the injected water is in the aquifer the pressure drops substantially and the concentration of CO2 is no longer in equilibrium with the water and as a result CO2 bubbles nucleate. These bubbles then migrate upwards through the contaminated zone towards the water table. As they move they come into contact with residual NAPL ganglia and they either volatilize this NAPL, resulting in a bubble comprised of CO2 and gaseous NAPL, or mobilize this NAPL, resulting in a film of NAPL surrounding the bubble. In either case the bubbles continue to rise until they reach the water table at which point they are removed by a dual phase extraction system. In this work, a known amount of NAPL was emplaced below the water table at residual concentrations to represent a residual source of weathered gasoline. The source was created in a hydraulically isolated cell in an unconfined sand aquifer at CFB Borden, Ontario. After the source was emplaced SWI was used to remove as much of the contaminant mass as possible in 22.25 days of operation over three months. The goal of this project was to determine if SWI was capable of removing residual NAPL at a field site. It was successful in removing volatile NAPL but not non-volatile NAPL. 64% of the volatile compounds were removed but contaminant mass was still being removed when the system was shut down so with continued operation more mass would have been removed. There is no way of knowing how much more would have been removed had the project continued. These results indicate that continued development of the technology is warranted.

This study was initiated to overview the sediment contaminant monitoring data of Kaohsiung Harbour areas collected between 92-97 for assessing the discharge sources of pollution and manipulating the effective management on the dredging of sediment. The harbour areas are surrounded with major industry and become the receiving sites with sewages from the populated city besides the shipping activities. These have impacted the harbour environment and its development for competing against other world shipping harbours. The present research intends to evaluate the proper strategy for dealing with the reduction of pollution source to prevent from further complicated environmental impacts. Approaches for the data assessment include the distribution of heavy metal concentration and its types of contaminants associated the discharge of industrial sources. A total of 20 monitoring stations were examined for the interrelation of metals. The Principal Component Analysis (PCA) of heavy metals in sediment result shows specific site related contaminant point sources and the localization of pollution at the enclosed areas. Lowest contaminant concentrations were observed at the exit of harbour, area A. The B Area including the estuary of Love River, between Love River and the fifth ship irrigation ditch, and the fifth ship irrigation ditch, dominated the highest element concentrations of Hg, Cd, Pb, Zn, As, Al. The C area, including the former town river to the sea, had highest Cr concentration.The sources of pollution are related to electrical plating, metal polishing factory, leather industries and other industrial production. The D area including the heavy industries i.e., Taiwan Ship Building, Taiwan Steel Manufacturing, Ta-Lin Power Station and the major shipping channel, had the highest Cu concentrations. Similarly the E area as the A area, located at the end exit of harbour, had the lowest metal concentrations. These two areas are more subjected to the tide flow than the other survey stations (B, C, D areas) which have the highest contaminant concentrations. Although the harbour authority has carried out the dredging and monitoring annually, there is no enforcement on regulating the discharge of contaminants from the surrounding industrial sites or the lack of the appropriate strategy of pollution reduction for incorporating with the clean up program. This is owing to the non unified authorization between the municipality and harbour bureau. The present study suggests that four steps are needed to cope with harbour sediment contamination to achieve the sustainable harbour development; 1. appropriate pollution reduction program, 2.long term environmental monitoring, 3.an unified authority and 4.a sediment management strategy with proper guidelines to prevent from land based pollution source discharge.

When an accident involving the possibility of a plutonium contaminated wound occurs, the contamination is often quantified using sodium iodide (NaI(Tl)) and high purity germanium (HPGe) detection systems. The NaI(Tl) system is used to quantify the amount of contamination, while HPGe is used to gauge the depth of contamination in the wound. Assessment of plutonium contaminated wounds is difficult due to the lowenergy and yield of the uranium L-shell x rays used for the measurement, which can be effected by source distance, shape, and tissue attenuation. These effects on wound counting systems used at Los Alamos National Laboratory (LANL) were characterized experimentally using common source shapes (disk, point, and line) and acrylic plastic as a tissue substitute. Experiments were conducted to characterize detector responses as a function of tissue attenuation, source distance, and source depth in tissue. The computer code MCNP5 was used to model both systems for wound counting and better examine angular displacement of a line source in tissue. The NaI(Tl) detector response was characterized using absolute detector efficiency for all experimental measurements. Measurements showed that the NaI(Tl) system is significantly effected by the source to detector position and depth in tissue. Characterization of the HPGe detection system was done utilizing the peak-to-peak ratio from the two low-energy x rays. HPGe peak-to-peak ratios were not affected by source to detector distance, but showed an increased response to source depth in tissue. MCNP results suggested that small incident angles from the plane of the detector face can cause significant effects on the response of both detectors. In summary, the response of both systems showed dependence on source geometry and depth of contamination in tissue. Correction values and uncertainties were determined based on these dependencies.

Analysis of the radiation produced by Z-machine nuclear experiments at Sandia National Laboratory and the materials irradiated indicate that the majority of produced radionuclides can easily be detected. One significant exception is volumetric contamination of stainless steel by iron-55. Detecting iron-55 in Z-machine components presents a particular problem due to its low-abundance and the low-energy (5.9 keV) xray it emits. The nuclide is often below the minimum detectable activity (MDA) threshold and resolution criteria of many standard radiation detection devices. Liquid scintillation has proven useful in determining iron-55 presence in loose contamination at concentrations below that of regulatory guidelines, but determination of volumetric iron- 55 contamination remains a significant challenge. Due to this difficulty, an alternate method of detection is needed. The use of radioactive surrogates correlating to iron-55 production is proposed in order to establish an estimate of iron-55 abundance. The primary interaction pathways and interaction probabilities for all likely radionuclide production in the Z-machine were tabulated and radionuclides with production pathways matching those of iron-55 production were noted. For purposes of nuclide identification and adequate detection, abundant gamma emitters with half-lives on the order of days were selected for use as surrogates. Interaction probabilities were compared between that of iron-55 production and a chosen surrogate. Weighting factors were developed to account for the differences in the interaction probabilities over the range of the known energy spectra produced on the device. The selection process resulted in cobalt-55, cobalt-57 and chromium-51 as optimal surrogates for iron-55 detection in both deuterium and non-deuterium loaded interactions. A decay corrected correlation of the surrogates (chromium-51, cobalt-57 and cobalt-55) to iron-55 for deuterium and non-deuterium loaded Z-machine driven reactions was derived. The weighting factors presented here are estimates which are based on rough comparisons of cross-section graphs. Analysis considering factors such as energy spectrum criteria to provide refined weighting factors may be utilized in future work.

I examined genetic variation for two populations of Black-crowned Night Herons using a 467 base pair region of the mitochondrial DNA. One population inhabits an environment highly impacted by industrial waste, heavy metals, and urbanization; while the other, a reference population, comes from a contaminant-free area. I observed a total of 10 haplotypes, three of which the two populations share. One individual from the contaminated site was ostensibly heteroplasmic. I found no evidence of significant genetic differentiation between the two populations. Coalescent simulation results provided evidence that both populations have undergone or are currently undergoing population expansion. The results of the biological marker I developed showed a high diversity for the ND-6 gene, making it a useful biomarker of population effects.

Thesis (M.Sc.)(Microbiology))--University of Pretoria, 2009. / Summary in English. Includes bibliographical references.