Dans le cadre de la gestion de la ressource en eau et de l'aménagement de sites de stockages de déchets sûrs, une meilleure compréhension du devenir des contaminants dans les milieux souterrains est nécessaire. Dans les nappes souterraines, les contaminants sont transportés à travers des milieux poreux caractérisés par une forte hétérogénéité qui joue un rôle important sur leur migration et leur dispersion. D'autre part, le transport des contaminants dans les milieux poreux résulte du couplage de processus physiques, chimiques voire biologiques complexes et interdépendants. Ce travail s'intéresse à l'impact de l'hétérogénéité physique du milieu associée à la réactivité chimique sur le transport de contaminants. L'objectif est de trouver les lois macroscopiques du transport réactif dans les milieux poreux hétérogènes en commençant par les réactions d'adsorption. Nous avons développé un outil numérique modélisant le couplage physico-chimique. Ce modèle repose sur le principe d'une discrétisation de la phase liquide en paquets d'eau identiques, dits volumes élémentaires, caractérisés par leur concentration en soluté. La méthode consiste à suivre simultanément ces volumes élémentaires dans la grille par une méthode de transport dans le domaine des temps. L'intérêt de ce modèle est le découplage des processus physique et chimique à l'échelle du volume élémentaire. L'évolution de la concentration dans le volume est donnée par le flux chimique et est résolue à chaque traversée de maille par le volume élémentaire. Ainsi, cette méthode peut simuler toute sorte de réactions chimiques. Nous avons étudié le comportement d'un panache soumis à une adsorption cinétique, non linéaire de type Freundlich. Le développement du panache a principalement été caractérisé par sa vitesse moyenne et son coefficient de dispersion effectif. L'effet du couplage transport-cinétique-non linéarité a d'abord été étudié en milieu physiquement homogène. Nous avons étudié l'effet des conditions initiales ainsi que l'effet d'une hétérogénéité chimique du milieu. Nous avons montré que la cinétique influence le comportement du panache à court-terme, provoquant même dans certains cas l'apparition de double pics transitoires dans la distribution du panache en solution. Nous avons quantifié ces phénomènes. Le comportement asymptotique du panache est lui contrôlée par la non linéarité. Nous avons étudié ensuite le comportement d'un panache injecté sous forme de pulse dans un milieu physiquement hétérogène dans lequel la variation spatiale de la conductivité hydraulique est supposée aléatoire. Nos premiers résultats montrent que l'étalement du panache n'est que très peu influencé par l'hétérogénéité du milieu. Nous pouvons en conclure que les dimensions du panache sont contrôlées par l'effet de la non linéarité. Par ailleurs, une expérimentation en laboratoire a été initiée afin de valider les résultats des simulations numériques et étudier des processus réactifs plus complexes.

This manuscript based thesis examines and advances methods for constraining sources of atmospheric trace constituents with a Lagrangian particle dispersion model. The method of Bayesian inversion is demonstrated, and a new method is introduced to a class of similar problems where established methods are not applicable. First, A new regression based methodology was developed and applied to observations of atmospheric methanesulfonic acid mass concentrations at Alert, Nunavut. The methodology was used to compare the importance of phytoplankton blooms vs. the ice-free ocean as sources of the dimethylsulfide precursor, and to compare the importance of bromine monoxide vs. hydroxyl as agents oxidizing dimethylsul de to methanesulfonic acid. These issues are relevant to the application of methanesulfonic acid concentrations in ice cores to determine historic sea ice properties. The analysis indicated that source regions to Alert during the spring are primarily ice-free ocean with a significant contribution from ice edge blooms, and during the summer to be dominated by the ice-free ocean. The model also indicated that oxidation of DMS by BrO was the dominant source of MSA in the spring, while DMS oxidation by OH was the dominant source in the summer. Secondly, Bayesian inversion was applied to observations of atmospheric elemental carbon mass concentrations at Tsinghua University in Beijing, China. The analysis provided evidence that current bottom-up elemental carbon emissions estimates in northern China are likely underpredicted. Global chemical transport models show ubiquitous underestimates of the atmospheric burden of elemental carbon, especially near large sources of emissions. Northern China is among the regions with the most intensive elemental carbon emissions in the world, and an underestimate of emissions in this region may be partially responsible for the global chemical transport model underestimates.

Potential contamination from hazardous and solid waste landfills stemming from population increase, rapid industrialization, and the proliferation of assembly plants known as the maquiladoras, are of major concern in the U.S.-Mexican border area. Additionally, historical, current, and future stresses on the Hueco Bolson alluvial aquifer in the El Paso/Ciudad Juarez area due to excessive groundwater withdrawal can affect contaminant migration in the area. In the current study, an updated and improved threedimensional numerical groundwater flow and transport model is developed using a current Hueco Bolson groundwater availability model as its basis. The model with contaminant transport is required to access and characterize the extent of vulnerability of the aquifer to potential contamination from landfills in the El Paso/Ciudad Juarez border area. The model developed in this study is very capable of serving as the basis of future studies for water availability, water quality, and contamination assessments in the Hueco Bolson. The implementation of fate and transport modeling and the incorporation of the Visual MODFLOW® pre and post processor, requiring MODFLOW 2000 data conversion, enabled significant enhancements to the numerical modeling and computing capabilities for the Hueco Bolson. The model in the current research was also developed by employing MT3DMS©, ZONEBUDGET, and Visual PEST® for automated calibrations. Simulation results found that the Hueco Bolson released more water from storage than the aquifer was being recharged in response to increased pumping to supply the growing border area population. Hence, significant head drops and high levels of drawdown were observed in the El Paso/Ciudad Juarez area. Predictive simulations were completed representing scenarios of potential contamination from the border area sites. Fate and transport results were most sensitive to hydraulic conductivities, flow velocities, and directions at the sites. Sites that were located within the vicinity of the El Paso Valley and the Rio Grande River, where head differences and permeabilities were significant, exhibited the highest potentials for contaminant migration.

N-Nitrosamines are an emerging group of disinfection byproducts characterized by high carcinogenic risks at ng/L levels and by their frequent detection in water and wastewater treatment systems in the U.S. and other parts of the world. The overall goal of this research is to achieve a better understanding of the roles of common nitrosamine precursors in leading to N-nitrosamine formation in water and wastewater treatment systems. The specific objectives of this research are: (a) To probe the mechanisms of nitrosamine formation from commonly employed water treatment polymers, particularly polyDADMACs, during ozonation, (b) To evaluate the role of dithiocarbamate compounds as nitrosamine precursors in reaction with common water disinfection oxidants, and (c) To investigate the potential enhancement effect of activated carbons (AC) to promote transformation of amines to nitrosamines and identify the involved reaction mechanism. Results of this research show that, upon ozonation, polyDADMACs may yield N-nitrosodimethylamine (NDMA) at levels up to two orders of magnitude higher than current advisory guidelines for NDMA. Radical pathways may be responsible for the degradation of the quaternary ammonium ring groups in polyDADMACs to release of dimethylamine (DMA). Detection of significant amounts of nitrite after ozonation of polyDADMACs and DMA suggests the potential role of nitrosation pathway in NDMA formation. Study results also reveal dithiocarbamates as potent nitrosamine precursors with significant nitrosamine yields upon ozonation and monochloramination. Identification and quantification of reaction products suggest nitrosation and chlorinated-UDMH oxidation as primary reaction mechanisms in nitrosamine formation from ozonation and monochloramination of dithiocarbamates compounds, respectively. This research also demonstrates that many commercial AC materials may catalyze transformation of secondary amines to yield trace levels of N-nitrosamines under ambient aerobic conditions. This is a novel discovery with far-reaching implications because of the widespread usage of AC materials in numerous analytical and environmental applications. The study results show that the properties of AC materials and reaction conditions play a crucial role in the catalyzed nitrosamine formation and should be carefully selected to minimize analytical errors and undesirable nitrosamine formation in water samples. Overall, the mechanistic information obtained in this research will be useful for the water industry and research communities to develop more effective strategies to control undesirable nitrosamine formation in water and wastewater treatment systems and thus better protect the public health.

This work presents the use of numerical modeling and simulation for the analysis of transport phenomena in engineering systems including zero boil-off (ZBO) cryogenic storage tanks for liquid hydrogen, refrigerated warehouses, and human-occupied air-conditioned spaces. Seven problems of medium large spaces in these fields are presented. Numerical models were developed and used for the simulation of fluid flow and heat and mass transfer for these problems. Governing equations representing the conservation of mass, momentum, and energy were solved numerically resulting in the solution of velocity, pressure, temperature, and species concentration(s). Numerical solutions were presented as 2-D and 3-D plots that provide more insightful understanding of the relevant transport phenomena. Parametric studies on geometric dimensions and/or boundary conditions were carried out. Four designs of ZBO cryogenic liquid hydrogen storage tank were studied for their thermal performance under heat leak from the surroundings. Steady state analyses show that higher flow rate of forced fluid flow yields lower maximum fluid temperature. 3-D simulation provides the visualization of the complex structures of the 3-D distributions of the fluid velocity and temperature. Transient analysis results in the patterns of fluid velocity and temperature for various stages of a proposed cooling cycle and the prediction of its effective operating term. A typical refrigerated warehouse with a set of ceiling type cooling units were modeled and simulated with both 2-D and 3-D models. It was found that if the cooling units are closer to the stacks of stored packages, lower and more uniform temperature distribution can be achieved. The enhancement of thermal comfort in an air-conditioned residential room by using a ceiling fan was studied and quantified to show that thermal comfort at higher temperature can be improved with the use of ceiling fan. A 3-D model was used for an analysis of thermal comfort and contaminant removal in a hospital operating room. It was found that if the wall supply grilles are closer to the center, the system has better performance in both contaminant removal and thermal comfort. A practical guideline for using CFD modeling in indoor spaces with an effective meshing approach is also proposed.

Many potential small wind turbine locations are near obstacles such as buildings and shelterbelts, which can have a significant, detrimental effect on the local wind climate. This thesis describes the creation of a new model which can predict the wind speed, turbulence intensity, and wind power density at any point in an obstacle’s region of influence, relative to unsheltered conditions. Artificial neural networks were used to learn the relationship between an obstacle’s characteristics and its effects on the local wind. The neural network was trained using measurements collected in the wakes of scale models exposed to a simulated atmospheric boundary layer in a wind tunnel. A field experiment was conducted to validate the wind tunnel measurements. Model predictions are most accurate in the far wake region. The estimated mean uncertainties associated with model predictions of velocity deficit, power density deficit, and turbulence intensity excess are 5.0%, 15%, and 12.8%, respectively. / Industrial collaborators: Weather INnovations Inc., Wenvor Technologies Inc. / Ontario Centre of Excellence for Energy

This manuscript based thesis examines and advances methods for constraining sources of atmospheric trace constituents with a Lagrangian particle dispersion model. The method of Bayesian inversion is demonstrated, and a new method is introduced to a class of similar problems where established methods are not applicable. First, A new regression based methodology was developed and applied to observations of atmospheric methanesulfonic acid mass concentrations at Alert, Nunavut. The methodology was used to compare the importance of phytoplankton blooms vs. the ice-free ocean as sources of the dimethylsulfide precursor, and to compare the importance of bromine monoxide vs. hydroxyl as agents oxidizing dimethylsul de to methanesulfonic acid. These issues are relevant to the application of methanesulfonic acid concentrations in ice cores to determine historic sea ice properties. The analysis indicated that source regions to Alert during the spring are primarily ice-free ocean with a significant contribution from ice edge blooms, and during the summer to be dominated by the ice-free ocean. The model also indicated that oxidation of DMS by BrO was the dominant source of MSA in the spring, while DMS oxidation by OH was the dominant source in the summer. Secondly, Bayesian inversion was applied to observations of atmospheric elemental carbon mass concentrations at Tsinghua University in Beijing, China. The analysis provided evidence that current bottom-up elemental carbon emissions estimates in northern China are likely underpredicted. Global chemical transport models show ubiquitous underestimates of the atmospheric burden of elemental carbon, especially near large sources of emissions. Northern China is among the regions with the most intensive elemental carbon emissions in the world, and an underestimate of emissions in this region may be partially responsible for the global chemical transport model underestimates.

[pt] Este trabalho apresenta resultados de um estudo, executado em laboratório, da mobilidade do herbicida Paraquat, realizado a partir de sua percolação através de amostras de solos retiradas do Campo Experimental de Bom Jardim, RJ. Foram determinadas as propriedades físicas, químicas e mineralógicas das amostras coletadas de maneira a formar um perfil do solo local. Para estes solos, através dos ensaios realizados, tais como o ensaio ADS (em coluna) e o de adsorção em batelada, foi possível determinar parâmetros de transporte do contaminante. Na análise para a quantificação do Paraquat foi adotado um método de coloração por determinação espectrofotométrica. No ensaio ADS foi possível, para apenas um dos solos, a determinação dos parâmetros de transporte em solo saturado, enquanto que no ensaio de adsorção em batelada foi determinada, para todos os solos, a isoterma de adsorção bem como os parâmetros referentes aos modelos de Freudlich e Langmuir. A partir dos resultados do ensaio ADS, verificou-se, a alta capacidade de retenção do Paraquat ao solo, chegando-se à conclusão de que, possíveis problemas de contaminação de águas pelo mesmo venham a estar associados a processos erosivos. / [en] This paper presents results of a study, performed in the laboratory, on the mobility of the herbicide Paraquat, investigated from its percolation through soils samples withdrawn from the Experimental Field of Bom Jardim, RJ. It was determined the physical, chemical and mineralogical properties of samples collected in such manner to form a profile of ground local soil. For these soils, through testings, such as the ADS test (in a special column) and the batchadsorption test, it was possible to determine parameters of the transport of the contaminant. In the analysis for the quantification of Paraquat was adopted a method of staining by spectrophotometric determination. In the ADS test it was possible, for only one of the soil samples, the determination of the parameters of transport with the batch- adsorption test it was determined, for all soils, the isotherm of adsorption as well as the parameters related to the models of Freudlich and Langmuir. From the results the ADS test it was found a high retention of Paraquat to the soil, leading to the conclusion that potential problems of contamination of superficial water at the sitemay be associated with erosive processes.

Le développement de l’industrie et de l’agriculture a entraîné l’accumulation d’éléments métalliques dans les sols. Dans ces écosystèmes, la fraction vivante intervient de façon importante dans la modification de la rétention des contaminants. Parmi les techniques de décontamination, la phytoremédiation apparaît comme un outil de choix. Si un des inconvénients majeurs de cette technique réside dans des durées de traitement pouvant atteindre plusieurs années, l’ajout de micro-organismes couplé aux plantes améliorerait les prélèvements et réduirait les temps de décontamination. Cette étude s’est intéressée aux possibilités de développer des procédés de phytoremédiation associés à des bactéries productrices de sidérophores, molécules ayant une forte affinité pour le fer mais également pour d’autres métaux. Dans ce contexte, un système de complexité croissante, jusqu’au modèle complet comprenant les constituants du sol, les bactéries, les métaux contaminants et les plantes, a été étudié avec pour objectif la compréhension des processus intervenant dans ces différentes interactions. Ces travaux ont conduit, dans un premier temps, à la compréhension, notamment par une approche de biologie moléculaire, des interactions intervenant entre des minéraux du sol, des argiles et des oxy-hydroxydes de fer, et une bactérie productrice de sidérophores, Pseudomonas aeruginosa. Les résultats ont mis en évidence le rôle majeur de l’un de ces sidérophores, la pyoverdine, ainsi que du biofilm, dans la dissolution des minéraux par cette bactérie. Une étude en fluorimétrie et dosages des métaux a, quant à elle, montré que la pyoverdine était capable de complexer des métaux contaminants adsorbés sur les argiles ou présents dans la structure cristalline des oxy-hydroxydes de fer. Enfin, ces travaux ont abouti à la mise en place du système d’étude dans sa globalité. Si la pyoverdine ou les bactéries productrices de sidérophores n’ont pas amélioré le prélèvement par les plantes du cadmium et du nickel, des résultats prometteurs ont cependant été obtenus pour le cuivre. De plus, les bactéries productrices de sidérophores s’avèrent être des cibles intéressantes en phytostabilisation. / The industrial and agricultural development caused a metallic element accumulation in the soils. In these ecosystems, the living fraction significantly operates in the changes of contaminants retention. Among the decontamination techniques, the phytoremediation appears as a tool of choice. If one of major disadvantages of this technique is the long-term remediation process, the addition of microorganisms with the plants could enhance the uptakes and decrease the time to remediate. This work focused on the possibility to develop processes for siderophore-producing bacteria-assisted phytoremediation, siderophores being molecules with a high affinity for iron and also able to chelate other metals. In this context, a system with an increasing complexity until a complete model including the soil constituents, the bacteria, the contaminant metals and the plants, has been studied to understand the processes involved in these different interactions. The understanding of the interactions between the soil minerals, clays and iron oxydydroxides, and a siderophore-producing bacteria, Pseudomonas aeruginosa, have been first performed with, in particular, a molecular biology approach. These results have highlighted the major role of the one of siderophores, the pyoverdine, and also the biofilm in the mineral dissolution by this bacteria. Fluorimetry and metal quantification assays showed that the pyoverdine was able to chelate the contaminant metals adsorbed on the clays or present in the crystal structure of the iron oxyhydroxides. Lastly, the global system has demonstrated that if the pyoverdine or the siderophore-producing bacteria do not enhance the cadmium and nickel uptake by plants, promising results were obtained for copper. Moreover, siderophore-producing bacteria turn out to be interesting asset for the phytostabilization.

In many cities, groundwater is essential for human consumption. However, urban aquifers coexist with the constant risk of contamination by the various types of pollutants from heterogeneity of activities. Nitrate is the main pollutant found in aquifers in terms of abundance, and may be able to promote much harmful to human health and the aquatic environment. In this context, this study goal to evaluate the nitrate contamination plume in part of the Metropolitan Region of Maceió City and looking for evidence of the effect of recharging on pollutant dynamics. To do this, we used the MODFLOW code to simulate the steady state distribution of hydraulic load, the MODPATH for tracking particles and MT3DMS to describe the transport and fate of nitrate. The results show that the seasonality of precipitation introduced no significant influence on the water level variations in deep sedimentary aquifer as well as the contaminant dispersion. Furthermore, there is a probability that disposal of sewage in long-term on soil govern the dynamics of the nitrate concentration in 87.5% of monitoring wells. / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Em muitas cidades as águas subterrâneas são imprescindíveis para o abastecimento humano. Porém, os aquíferos urbanos convivem com o constante risco de contaminação em virtude dos diversos tipos de poluentes originados da heterogeneidade das atividades que acorrem na superfície do solo. Um dos principais poluentes encontrados em termos de abundância é o nitrato, e que pode ser capaz de promover diversos danos à saúde humana e ao ambiente aquático. Neste contexto, este trabalho teve por objetivo avaliar a pluma de contaminação do nitrato em parte da Região Metropolitana de Maceió e buscar por evidências do efeito da recarga na dinâmica do poluente. Para tal, foi utilizado o código MODFLOW para simular o estado de equilíbrio da distribuição da carga hidráulica, o MODPATH para o rastreamento de partículas e o MT3DMS para descrever o transporte e destino do nitrato. Os resultados evidenciam que a sazonalidade da precipitação não apresentou influência significativa nas variações do nível de água em aquífero sedimentar profundo assim como na dispersão do contaminante. Além disso, há probabilidade que a disposição de dejetos sanitários no solo em longo prazo governe a dinâmica da concentração de nitrato em 87,5% dos poços de monitoramento.