Depuis plusieurs décennies, l'environnement arctique est en proie à de nombreux changements notamment dus à l'activité humaine. L'Arctique est en effet très sensible aux espèces polluantes issues de l'industrie de masse ainsi qu'au réchauffement global accéléré par les émissions anthropogéniques. Leurs impacts sur les écosystèmes boréaux, visibles dès les années 1970, (Schindler et Smol, 2006) ont motivé de nombreuses études. Ainsi a été démontrée l'importance des sources ponctuelles et du transport atmosphérique longue distance sur la pollution des zones arctiques. Un des composants clés de l'écosystème arctique est le manteau neigeux saisonnier, car en directe interaction avec l'atmosphère, le sol et les systèmes aquatiques. La neige contient de nombreuses espèces chimiques, microorganismes, particules et impuretés qui en font un milieu chimiquement et biologiquement dynamique, siège de réactions et d'interactions diverses. L'important interface atmosphère - neige (milieu poreux) donne notamment lieu à de nombreuses réactions d'oxydoréduction photo-induites impliquées dans des cycles chimiques complexes. Néanmoins, peu de choses sont connues sur l'interaction entre les différentes espèces contenues dans le manteau neigeux, et si on sait désormais que les microorganismes y ont une activité significative, on ignore tout ou presque des interactions chimiques éventuelles. Lors de la fonte du manteau neigeux, ce sont toutes les espèces qui y ont été stockées et formées in situ qui seront libérées dans l'écosystème aquatique. Ainsi le manteau neigeux saisonnier constitue un réservoir et réacteur crucial d'espèces chimiques, biologiques et contaminantes pour l'environnement arctique. Le cycle du mercure est dominé par deux systèmes de réactions majeurs : 1) l'oxydo-réduction (Hg0 Hg2+) ; et 2) la méthylation-déméthylation (Hg2+ CH3Hg+ CH3HgCH3). Les espèces formées par méthylation sont le monométhylmercure CH3Hg+ (aussi appelé méthylmercure, noté MMHg) et le diméthylmercure CH3HgCH3 (noté DMHg). Dans les régions polaires, le mercure élémentaire gazeux atmosphérique est rapidement oxydé et déposé en très grande quantité lors d'épisodes appelés AMDEs (Atmospheric Mercury Depletion Events) survenant au printemps polaire (Schroeder et al., 1998; Steffen et al., 2008). Durant ces épisodes, la neige se comporte comme une " éponge " à mercure et retient des concentrations en mercure très élevées (de l'ordre de la centaine de ng/L). Plusieurs campagnes de terrain ont montré que le mercure pouvait être soit oxydé soit réduit dans le manteau neigeux (Lalonde et al., 2002; Dommergue et al., 2003; Poulain et al., 2004) bien qu'il soit admis que la plus grande partie du mercure divalent déposé dans le manteau neigeux est réduit puis réémis dans l'atmosphère (Poulain et al., 2004; Kirk et al., 2006). Le mercure stocké par le manteau neigeux est libéré dans les eaux de fontes en période de réchauffement, en partie sous forme monométhylée (MMHg) (Loseto et al., 2004; St. Louis et al., 2005). Un récapitulatif de la chimie du mercure ainsi que de sa réactivité en arctique et dans le manteau neigeux est présenté en chapitre introductif de cette thèse. L'objectif des travaux présentés dans ce manuscrit est de clarifier l'influence de la chimie du manteau neigeux saisonnier arctique sur la réactivité du mercure qu'il contient, en particulier celle de sa forme méthylmercure. Comment s'y retrouve-t-il ? Est-il transporté dans la neige ou s'y forme-t-il à partir d'autres espèces mercurielles ? Quel rôle joue le manteau neigeux sur la boucle méthylée du cycle du mercure ? Les résultats présentés ci-après exploitent les données d'échantillons de neige saisonnière, collectés entre avril et juin 2011 autour du site côtier de Ny-Ålesund, dans la région du Kongsfjorden (Svalbard). La thèse est divisée en six parties, subdivisées en chapitres. La première partie présente les connaissances de la biogéochimie du mercure ainsi que de la physico-chimie du manteau neigeux nécessaires à la compréhension des parties de développement qui suivent. La deuxième partie présente les différentes méthodes analytiques utilisées pour obtenir notre jeu de données à partir des échantillons de terrain. Il comprend aussi la description d'un dispositif de dosage d'ultra-traces de MMHg que nous avons développé au laboratoire, bien qu'il n'ait pas eu l'aboutissement nécessaire pour analyser nos échantillons. Ce travail de développement analytique fait partie intégrante du travail de thèse et a mobilisé beaucoup de temps et de moyens ; il permet aujourd'hui un dispositif fonctionnel dont les performances doivent encore être précisées. La mise en place de ce dispositif est décrite de manière très complète en abordant un point de vue très pratique sur problèmes rencontrés et leurs solutions. Suit un court mais indispensable chapitre de description du site d'étude, de la méthodologie de terrain et des conditions géochimiques et météorologiques du milieu étudié. Dans la troisième partie, dédiée à l'étude de la chimie de la neige, nous commencerons par quelques observations sur la dynamique du mercure dans le manteau neigeux avant d'aborder dans un deuxième chapitre la chimie du manteau neigeux saisonnier avec une méthodologie nouvelle dans ce domaine, impliquant des rapports de concentrations d'espèces chimiques (Robinson et al., 2006). Cette approche a permis d'identifier les principales sources d'espèces chimiques dans le manteau neigeux côtier, et notamment d'y identifier les principales sources de MMHg. Le troisième chapitre de cette partie s'appuie sur les résultats sur la chimie de la neige pour discuter de la nature de la source principale de MMHg, en raisonnant sur la chimie globale de la neige et des traceurs de source. Nous y développons une nouvelle explication de l'apport de MMHg dans la neige étudiée - basée sur nos résultats et étayée par une littérature fournie - clarifiant ainsi le faisceau d'hypothèses habituellement évoqué pour expliquer la présence de MMHg dans le manteau neigeux. Nous n'identifions pas de formation de MMHg in situ dans le manteau neigeux côtier étudié. En réponse et en complément à la partie précédente, la quatrième partie traite de la dynamique du MMHg dans la neige et l'eau de fonte. Dans un premier chapitre sont présentés les résultats d'une étude d'un puits de neige sur le glacier Kongsvegen (une année d'accumulation), un site éloigné de la côte du Kongsfjorden. En utilisant la même méthodologie que précédemment, nous observons un processus chimique reliant le MMHg à d'autres espèces chimiques, qui est certainement identifiable uniquement en raison des faibles concentrations et de la stabilité de ce manteau neigeux dans le temps. En se basant sur les résultats d'une étude de laboratoire sur la formation de MMHg (Gåardfeldt et al., 2003), nous attribuons les relations entre ces espèces chimiques à une réaction de méthylation du mercure in situ. L'importance de cette réaction dans le budget de MMHg du manteau neigeux ainsi que les implications potentielles de cette observation préliminaire y sont évaluées et discutées. Un dernier chapitre présentera les observations concernant le méthylmercure dans l'eau de fonte, en complément des résultats présentés plus tôt. Les cinquième et sixième parties sont constituées respectivement d'une discussion conclusive et des annexes.

Hydrophobic organic contaminants (HOCs) often reside in sediments sorbed to particles, most tightly to particles with high content of organic carbon. If persistent, such pollutants can accumulate in the sediment for many years and constitute a contamination risk for sediment-living organisms and organisms at higher trophic levels, including humans. Since traditional remediation techniques are associated with complications (e.g. release of contaminants during dredging operations, disturbance of benthic faunal communities), or constraints (handling of large amounts of contaminated sediment and water, limitations due to depth and size of the area, high costs), there is a need for new alternative methods. In situ remediation through thin-layer capping (a few centimeter cover) with a sorbing material such as activated carbon (AC) has been proposed as an alternative remediation method. Compared to traditional remediation techniques, AC amendment in a thin layer means less material handling and lower costs and is assumed to be less disruptive to benthic communities. The objectives of this thesis were to investigate the ecological effects from thin layer capping as well as the efficiency in contaminant retention. Thin layer capping amended with AC proved to reduce availability of HOCs to the tested organisms, the gastropod Nassarius nitidus (Paper II), the clam Abra nitida (Paper III) and to polychaete worms  (Paper II and III). The remediation technique also decreased the sediment-to-water fluxes of the contaminants (Paper II and III). However, AC amended thin-layer capping was also found to cause negative biological effects. In laboratory studies with only a few species the negative effects were minor, or difficult to discern with the endpoints used (Paper II and III). In a larger multi-species mesocosm (boxcore) study, on the other hand, the negative effects were more prominent (Paper I) and in a large scale field study the benthic community was found to be profoundly disturbed by the AC amendment, with the effects persisting or even worsening ca one year (14 months) post amendment (Paper IV). / <p>At the time of the doctoral defence the following papers were unpublished and had a status as follows: Paper 3: Manuscript; Paper 4: Manuscript.</p> / Carbocap / Opticap / Thinc

The contamination of seafood with methylmercury (MeHg) is a global health issue, as MeHg is a well known neurotoxin. Since dietary nutrients may interact with MeHg toxicity, and oxidative stress is one of the primary mechanisms underlying MeHg neurotoxicity, we characterized dietary antioxidant-MeHg interactions. Firstly, we used an ethnobotanical study to confirm the antioxidant activity of Northern Labrador Tea, Rhododendron tomentosum ssp. subarcticum (Tea), for the Canadian Inuit, a population with elevated MeHg exposure. Secondly, we determined the ability of Tea to ameliorate MeHg-induced toxicity in a rat perinatal exposure study. MeHg exposure (2 mg/KgBW/d) was associated with perturbed development and behaviour, elevated brain N-methyl-D-aspartate receptors, and serum lipid peroxidation. Surprisingly, Tea co-exposure (100 mg/KgBW/d) modulated MeHg’s effects on brain NMDA-R levels and lipid peroxidation, but also increased mercury serum concentrations. Thirdly, using a toxicogenomics approach we determined that MeHg exposure caused the down-regulation of Nr4a2 and its protein product Nurr1. These novel MeHg targets are implicated in developmental learning functions and were corrected with MeHg + Tea co-exposure. Lastly, we conducted a risk assessment survey and cross-sectional dietary epidemiology study in Costa Rica to further investigate dietary nutrient-MeHg interactions. Costa Rica is a Central American country with multiple sources of Hg and a high per capital fish consumption. Here, 5 of the 14 populations we studied exceeded the recommended MeHg provisional tolerable daily intake (pTDI) of 0.2 µg/KgBW/d. In Heredia the pTDI was exceeded by 34% of woman participants, primarily associated with canned tuna consumption. Interestingly, we detected that Hg body burden was significantly reduced by the consumption of antioxidant-rich dietary items. Considering our collective results, we hypothesized that MeHg toxicokinetics may be altered by dietary nutrients at the site of intestinal absorption from the disruption of gut flora, or at the site of cellular demethylation in tissues from the improvement of cellular redox state. The interaction of dietary nutrients on MeHg outcomes has a large impact on risk assessment and may provide a public health approach for managing the risk associated with MeHg exposure without reducing local fish consumption.

Fully-dynamic, continuous fugacity-based fate and transport models have been developed to examine all natural processes and interactions in the aquatic water systems. Within a body of surface water such as a lake or a river, a dynamic interaction among different media takes place. Chemical compounds are continuously dissolving, adsorbing into solid particles, attaching to suspended particles, resuspending, reacting, diffusing, and advecting. As the inclusion of all these interactions into a model is complex, the use of fugacity concept instead of concentration, renders the modeling task relatively easy. Fugacity, which is described as the escaping tendency of a chemical from a medium, is continuous among different phases, thus easier to follow the movement of the chemical. The first model has been developed to be used as an emergency response model by decision makers, which models the fate and transport of any contaminant in a lake. Due to uncertainties involved in the analysis, Monte Carlo simulations are performed. The fate of three representative contaminants; polychlorinated biphenyls (PCBs), atrazine, and benzene in air, water, and sediment compartments are examined. The second model developed is a continuous, dynamic river fugacity-based water quality model. In order to develop a continuous model, the hydrodynamics of the river system is solved first. Water depth and velocity at each point along the river are used in the advection-dispersion equation to determine the fate and transport of a contaminant. Interactions between different phases are also incorporated into the advection-dispersion equation which is solved numerically and coupled with a mass balance equation derived for the same contaminant in the sediments. The third model is a multispecies contaminant fate and transport model which can be used for the fate of a single contaminant and its daughter products. Trichloroethylene (TCE) and its daughter products, dichloroethylene (DCE) and vinyl chloride (VC), are used as representative of multispecies contaminants. The fate and transport of TCE and its daughter products has been analyzed first in a lake environment, and then in a river environment with the addition of a biofilm compartment where all biotransformations take place.

Atualmente, os consumidores valorizam produtos com garantia de qualidade e que sejam obtidos de cadeias ecologicamente corretas e socialmente justas. A rastreabilidade da cadeia produtiva possui importância fundamental para o aumento do consumo de pescado. Um dos principais gargalos da cadeia produtiva é o reduzido aproveitamento do resíduo do processamento. A elaboração de silagem de pescado é uma alternativa para minimizar os problemas ambientais e de sanidade, provenientes do resíduo de pescado, porém esta deve ser preparada com agentes acidificantes sustentáveis e que sejam selecionados através de análise de mercado levando em consideração os riscos ambientais e para a saúde humana, o custo e a facilidade de compra do agente acidificante, um dos objetivos dessa pesquisa. A utilização do ácido cítrico aparentou ser a melhor escolha. Avaliou-se o desempenho de 180 alevinos de sargo (Diplodus sargus) (21,30 ± 0,87 g) alimentados com 6 dietas isoenergéticas (3.941 kcal/kg), contendo dois níveis de proteína bruta PB (35 e 45%) e três níveis de inclusão (0, 10 e 20%) de silagem de resíduos provenientes da indústria conserveira da cidade do Porto, Portugal. Não houve mortalidade e as dietas experimentais foram bem aceitas. Não houve diferença (P<0,05) no consumo das rações, fator de condição, índice hepatossomático, índice de conversão alimentar e ganho de peso. É possível a inclusão de até 20% de silagem em dietas para o sargo e sugere-se a utilização das rações formuladas contendo 45% de PB por apresentarem menor custo de produção e empregarem maior quantidade de material residual proveniente do processamento de pescado. Em Portugal, o setor pesqueiro ocupa espaço destacado entre as atividades econômicas. A relevância desta cadeia produtiva resulta, essencialmente, do fato de que o pescado é componente fundamental da alimentação e responsável por elevado número de empregos da população. No Brasil, com o aumento do número de indústrias beneficiadoras, o resíduo desta atividade tornou-se um sério problema. Buscou-se classificar o resíduo do beneficiamento da tilápia do Nilo (Oreochromis niloticus), conforme a Associação Brasileira de Normas Técnicas (ABNT NBR 10004:2004), foram coletadas vinte e quatro amostras; três em cada período (ago/07, set/2007, out/2007, dez/2007, fev/2008, mai/2008, jul/2008, ago/2008). Todas as amostras foram classificadas como Classe II, do tipo Não Inerte devido aos teores de chumbo, manganês, surfactantes e ferro. Esses resíduos devem ser destinados a aterros sanitários construídos conforme normas específicas. Entretanto, estão sendo descartados de forma irregular, diretamente em recursos hídricos ou enterrados sem tratamento com riscos ao ambiente e à saúde humana e animal pela possibilidade de lixiviação de metais / Currently, consumers value products with assurance of quality and obtained from environmentally friendly and socially just chain. The traceability of the commodity chain has fundamental importance to increase the fish consumption. One of the main bottlenecks in the commodity chain is the reduced utilization of processing residue. The elaboration of fish silage is an alternative to minimize the environmental and sanity problems from fish residue. In order to select the most appropriate acid for the preparation of chemical fish silage, market analysis considering environmental and human risks, cost and supply of acidifying agent was performed. The use of citric acid seems to be the best choice. The performance of 180 bream fingerlings (21.30 ± 0.87 g) fed six isoenergetic diets (3,941 kcal/kg) containing two levels of crude protein - CP (35 and 45%) and three levels of inclusion of silage (0, 10 and 20%) was evaluated. There was no mortality and the experimental diets were well accepted. There was no difference (P<0.05) in diets intake, condition factor, hepatosomatic index, food conversion ratio and weight gain. Weight gain and food conversion ratio were 9.61 g and 2.77, 9.23 g and 2.99, 9.95 g and 3.04, 11.81 g and 2.86, 13.41 g and 2.14, and 11.36 g and 2.41 for treatments 1 (35% CP; 0% inclusion), 2 (35% CP, 10% inclusion), 3 (35% CP, 20% inclusion), 4 (45% CP; 0% inclusion), 5 (45% CP, 10% inclusion) and 6 (45% CP, 20% inclusion), respectively. Therefore, it is possible to include up to 20% of fish silage in diets for bream and suggests the use of diets containing 45% CP because of their lower cost of production and for using higher amount of residual material from fish processing. The fisheries sector occupies an important position in the economic activities in Portugal. Its relevance is due to fish being a fundamental component of food and responsible for employment opportunities. In Brazil, the increasing number of fish processing industries, the residue of this activity has become a serious problem. The residue from the processing of Nile tilapia (Oreochromis niloticus) was classified according to the Brazilian Association of Technical Standards (ABNT NBR 10004:2004). A total of twenty-four samples were collected, three in each period (Aug/07, Sep/2007, Oct/2007, Dec/2007, Feb/2008, May/2008, Jul/2008, Aug/2008). All analyzed samples were classified as Class II, Non Inert, due to the lead, manganese, iron and surfactants levels. These wastes should be disposed of in landfills constructed according to environmental standards. However, they are being improperly disposed, dumped directly into water or buried without proper treatment, providing risk to the environment and human and animal health due to possible leaching of metals

É crescente a demanda por materiais que atendam as exigências para construção de barreiras selantes (liners) em obras para disposição de resíduos. A utilização de solos tropicais para esta finalidade só não é maior por falta de conhecimento sobre muitas de suas características técnicas, principalmente a migração de contaminantes. Tentativas de melhoria das qualidades de solos supostamente inadequados também são importantes. Esta tese apresenta estudos sobre a migração dos íons \'CD POT.2+\', \'K POT.+\', \'CL POT.1-\' e \'F POT.-\' em latossolos residuais das formações Botucatu e Serra Geral e três diferentes misturas destes solos, com ênfase nos processos de sorção e difusão molecular. O potencial de retenção dos íons é avaliado através da construção de 33 isotermas de sorção resultantes de ensaios de equilíbrio em lote. Seus parâmetros são obtidos da adequação dos modelos linear, Freundlich e Langmuir as isotermas. O potencial de transporte dos íons é avaliado através de ensaios de difusão em colunas estanques, onde curvas teóricas produzidas no programa POLLUTE são ajustadas aos dados de concentração para a estimativa dos parâmetros de difusão. Os resultados dos estudos de retenção mostram que o \'CL POT.-\' experimenta sorção sob certas condições, o \'K POT.+\' e \'F POT.-\' possuem taxas semelhantes de retenção, e que a sorção do \'CD POT.2+\' se mostrou altamente dependente da composição da solução contaminante. Os ensaios de difusão resultaram em vários valores para o coeficiente de difusão efetiva (D*), mostrando que o fluxo difusivo dos íons diminui para solos mais argilosos. / There is a growing demand for materials that can be used in lining systems for waste disposal facilities. The use of tropical soils for this purpose is restricted due to the lack of technical knowledge about this type of material. Attempts to improve the quality of supposed unsuitable soils play also an important role. This thesis presents studies concerning the migration of the ions \'CD POT.2+\', \'K POT.+\', \'CL POT.-\' and \'F POT.-\' in latosoils from the Botucatu and Serra Geral formations and three different mixtures of these soils, with emphasis on sorption and molecular diffusion. Batch equilibrium tests were conduced to examine the retention capacity of the soils, and the sorption parameters are estimated by fitting the linear, Freundlich and Langmuir models to the experimental isotherm plots. The potential for these soils to transport ions is evaluated by diffusion tests, where theoretical curves produced in the POLLUTE code are used to estimate the effective diffusion coefficients (D*). The results show that the \'CL POT.-\' is sorbed under specific conditions and, therefore, it can not always be used as a conservative ion (i.e. nonreactive ion), \'K POT.+\' and \'F POT.-\' are sorbed in similar amounts, and that the \'CD POT.2+\' sorption is highly dependent on the contaminant solution composition. Several D* values are reported, showing that the diffusion rates are decreased for soils with more clay.

Certain types of waste, e.g. bottom ash originating from municipal solid waste incineration (MSWI bottom ash) can be used as road construction materials. A potential problem is the possibility of substances leaching out of the road and spreading in the surrounding groundwater. The aim of this master’s thesis is to conclude whether hydrogeological type settings can be employed to, based on local conditions, provide an estimate of the probable spreading of these substances in the surrounding groundwater, and whether certain types of soils can be identified as being less suitable for the localization of a MSWI bottom ash road. A hydrogeological type setting is defined as a mappable unit with similar hydrogeological properties. An advantage of this approach would be that mainly existing maps and surveys could form the basis for the assessment. The work has been performed by placing a hypothetical road construction in different hydrogeological type settings. The expected patterns of spreading has then been evaluated using theoretical reasoning and analytical and numerical models. The method can be used. In the report various type settings are defined. In several cases further information will be required to render possible a more exact estimate of the spreading. By locating the road on less permeable soils to reduce the local spreading of substances in groundwater, a greater proportion of the water will be drained as surface water. Thus it becomes important to take into account surface water transport aswell. In the report a procedure to estimate the maximum concentrations in groundwater at locations situated downstream the road is presented. This estimate could be used as basis for a more balanced valuation of appropriateness, e.g. by relating the estimated concentrations to background values. / Vissa typer av avfall, exempelvis slaggrus (sorterad bottenaska från avfallsförbränning), kan användas som vägbyggnadsmaterial. Ett potentiellt problem är möjligheten att ämnen lakas ut ur vägen och sprids i omgivande grundvatten. Syftet med detta examensarbete är att avgöra om hydrogeologiska typmiljöer kan användas för att, utifrån omgivningens förutsättningar, ge en bild av hur den vidare spridningen av dessa ämnen i omgivande grundvatten sannolikt ser ut, och om vissa typer av mark kan pekas ut som mindre lämpade för lokalisering av en slaggrusväg. En hydrogeologisk typmiljö definieras som ett område möjligt att avgränsa med avseende på karakteristiska hydrogeologiska förhållanden. En fördel med angreppssättet skulle vara att underlagsmaterialet till bedömningen då kan utgöras av i huvudsak befintligt kartmaterial. Studien har utförts genom att en hypotetisk vägkonstruktion placerats in i olika hydrogeologiska typmiljöer. De troliga spridningsscenarierna har sedan utvärderats genom teoretiska resonemang, samt genom användande av analytiska och numeriska modeller. Metodiken går att använda och i rapporten definieras olika typmiljöer. I flera fall kommer platsspecifik kunskap behöva inhämtas för en närmare beskrivning av spridningsbilden. Genom placering av vägen på tätare mark för att minska lokal spridning av ämnen i grundvatten kommer en större andel av vattnet att avledas som ytvatten. Därmed blir det viktigt att även inhämta kunskap om transport med ytvatten. I rapporten presenteras också en metod för uppskattning av maximala halter i grundvatten nedströms en väg. Denna metod kan användas som underlag för en mer nyanserad värdering av lämplighet, genom att de uppskattade halterna relateras till bakgrundsvärden eller lämpliga riktvärden.

Accurate prediction of colloid deposition rates in porous media is essential in several applications. These include natural filtration of pathogenic microorganisms such as bacteria, viruses, and protozoa, transport and fate of colloid-associated transport of contaminants, deep bed and river bank filtration for water treatment, fate and transport of engineered nanoparticles released into the environment, and bioremediation of contaminated sites. Colloid transport in porous media is a multi-scale problem, with length scales spanning from the sub-pore scale, where the particle-soil interaction forces control the deposition, up to the Darcy scale, where the macroscopic equations governing particle transport are formulated. Colloid retention at the Darcy scale is due to the lumped effect of processes occurring at the pore scale. This requires the incorporation of the micro-scale physics into macroscopic models for a better understanding of colloid deposition in porous media. That can be achieved through pore-scale modeling and the subsequent upscaling to the Darcy scale. Colloid Filtration Theory (CFT), the most commonly used approach to describe colloid attachment onto the soil grains in the subsurface, is found to accurately predict the deposition rates of micron-sized particles under favorable conditions for deposition. But, CFT has been found to over predict particle deposition rates at low flow velocity conditions, typical of groundwater flow, and for nanoscale particles. Also, CFT is found to be inapplicable at typical environmental conditions, where conditions become unfavorable for deposition, due to factors not considered in CFT such as deposition in the secondary minimum of the interaction energy profile, grain surface roughness, surface charge heterogeneity of grains and colloids, and deposition at grain-to-grain contacts. To the best of our knowledge, mechanistic-based models for predicting colloid deposition rates under unfavorable conditions do not exist. Currently, fitting the colloid breakthrough curve (BTC), obtained from the laboratory column-or field-scale experiments, to the advection-dispersion-deposition model is used to estimate the values of deposition rate coefficients. Because of their small size (less than 100 nm), nanoparticles, a sub-class of colloids, may interact with the porous medium in a different way as compared to the larger colloids, resulting in different retention mechanisms for nanoparticles and micron-sized particles. This emphasizes the need to study nanoparticles separately from larger, micrometer-sized colloids to better understand nanoparticle retention mechanisms. The work reported in this thesis contributes towards developing mathematical models to predict nanoparticle movement in porous media. A comprehensive mechanistic approach is employed by integrating pore-scale processes into Darcy-scale models through pore-network modeling to upscale nanoparticle transport in saturated porous media to the Darcy scale, and to develop correlation equations for the Darcy-scale deposition parameters in terms of various measurable parameters at Darcy scale. Further, a one-dimensional mathematical model to simulate the co-transport of viruses and colloids in partially saturated porous media is developed to understand the relative importance of various interactions on virus transport in porous media. Pore-network modeling offers a valuable upscaling tool to express the macroscopic behavior by accounting for the relevant physics at the underlying pore scale. This is done by idealizing the pore space as an interconnected network of pore elements of different sizes and variably connected to each other, and simulating flow and transport through the network of pores, with the relevant physics implemented on a pore to pore basis (Raoof, 2011). By comparing the results of pore-network modeling with an appropriate mathematical model describing the macro-scale behavior, a relationship between the properties at the macro scale and those at the pore scale can be obtained. A three dimensional multi-directional pore-network model, PoreFlow, developed by Raoof et al. (2010, 2013) is employed in this thesis, which represents the porous medium as an interconnected network of cylindrical pore throats and spherical pore bodies, to upscale nanoparticle transport from pore scale to the Darcy scale. The first step in this procedure is to obtain relationships between adsorbed mass and aqueous mass for a single pore. A mathematical model is developed to simulate nanoparticle transport in a saturated cylindrical pore by solving the full transport equation, considering various processes such as advection, diffusion, hydrodynamic wall effects, and nanoparticle-collector surface interactions. The pore space is divided into three different regions: bulk, diffusion and potential regions, based on the dominant processes acting in each of these regions. In both bulk and diffusion regions, nanoparticle transport is governed by advection and diffusion. However, in the diffusion region, the diffusion is significantly reduced due to hydrodynamic wall effects. Nanoparticle-collector interaction forces dominate the transport in the potential region where deposition occurs. A sensitivity analysis of the model indicates that nanoparticle transport and deposition in a pore is significantly affected by various pore-scale parameters such as the nanoparticle and collector surface potentials, ionic strength of the solution, flow velocity, pore radius, and nanoparticle radius. The model is found to be more sensitive to all parameters under favorable conditions. It is found that the secondary minimum plays an important role in the deposition of small as well as large nanoparticles, and its contribution is found to increase as the favorability of the surface for adsorption decreases. Correlation equations for average deposition rate coefficients of nanoparticles in a saturated cylindrical pore under unfavorable conditions are developed as a function of nine pore-scale parameters: the pore radius, nanoparticle radius, mean flow velocity, solution ionic strength, viscosity, temperature, solution dielectric constant, and nanoparticle and collector surface potentials. Advection-diffusion equations for nanoparticle transport are prescribed for the bulk and diffusion regions, while the interaction between the diffusion and potential regions is included as a boundary condition. This interaction is modeled as a first-order reversible kinetic adsorption. The expressions for the mass transfer rate coefficients between the diffusion and the potential regions are derived in terms of the interaction energy profile between the nanoparticle and the collector. The resulting equations are solved numerically for a range of values of pore-scale parameters. The nanoparticle concentration profile obtained for the cylindrical pore is averaged over a moving averaging volume within the pore in order to get the 1-D concentration field. The latter is fitted to the 1-D advection-dispersion equation with an equilibrium or kinetic adsorption model to determine the values of the average deposition rate coefficients. Pore-scale simulations are performed for three values of Péclet number, Pe = 0.05, 5 and 50. It is found that under unfavorable conditions, the nanoparticle deposition at pore scale is best described by an equilibrium model at low Péclet numbers (Pe = 0.05), and by a kinetic model at high Péclet numbers (Pe = 50). But, at an intermediate Pe (e.g., near Pe = 5), both equilibrium and kinetic models fit the 1-D concentration field. Correlation equations for the pore-averaged nanoparticle deposition rate coefficients under unfavorable conditions are derived by performing a multiple-linear regression analysis between the estimated deposition rate coefficients for a single pore and various pore-scale parameters. The correlation equations, which follow a power law relationship with nine pore-scale parameters, are found to be consistent with the column-scale and pore-scale experimental results, and qualitatively agree with CFT. Nanoparticle transport is upscaled from pore to the Darcy scale in saturated porous media by incorporating the correlations equations for the pore-averaged deposition rate coefficients of nanoparticles in a cylindrical pore into a multi-directional pore-network model, PoreFlow (Raoof et al., 2013). Pore-network model simulations are performed for a range of parameter values, and nanoparticle BTCs are obtained from the pore-network model. Those curves are then modeled using 1-D advection-dispersion equation with a two-site first-order reversible deposition, with terms accounting for both equilibrium and kinetic sorption. Kinetic sorption is found to become important as the favorability of the surface for deposition decreases. Correlation equations for the Darcy¬scale deposition rate coefficients under unfavorable conditions are developed as a function of various measurable Darcy-scale parameters, including: porosity, mean pore throat radius, mean pore water velocity, nanoparticle radius, ionic strength, dielectric constant, viscosity, temperature, and surface potentials on the nanoparticle and grain surface. The correlation equations are found to be consistent with the observed trends from the column experiments available in the literature, and are in agreement with CFT for all parameters, except for the mean pore water velocity and nanoparticle radius. The Darcy-scale correlation equations contain multipliers whose values for a given set of experimental conditions need to be determined by comparing the values of the deposition rate coefficients predicted by the correlation equations against the estimated values of Darcy-scale deposition parameters obtained by fitting the BTCs from column or field experiments with 1-D advection-dispersion-deposition model. They account for the effect of factors not considered in this study, such as the physical and chemical heterogeneity of the grain surface and nanoparticles, flow stagnation points, grain-to-grain contacts, etc. Colloids are abundant in the subsurface and have been observed to interact with a variety of contaminants, including viruses, thereby significantly influencing their transport. A mathematical model is developed to simulate the co-transport of viruses and colloids in partially saturated porous media under steady state flow conditions. The virus attachment to the mobile and immobile colloids is described using a linear reversible kinetic model. It is assumed that colloid transport is not affected by the presence of attached viruses on its surface, and hence, colloid transport is decoupled from virus transport. The governing equations are solved numerically using an alternating three-step operator splitting approach. The model is verified by fitting three sets of experimental data published in the literature: (1) Syngouna and Chrysikopoulos (2013) and (2) Walshe et al. (2010), both on the co-transport of viruses and clay colloids under saturated conditions, and (3) Syngouna and Chrysikopoulos (2015) for the co-transport of viruses and clay colloids under unsaturated conditions. The model results are found to be in good agreement with the observed BTCs under both saturated and unsaturated conditions. Then, the developed model was used to simulate the co-transport of viruses and colloids in porous media under unsaturated conditions, with the aim of understanding the relative importance of various processes on the co-transport of viruses and colloids. The virus retention in porous media in the presence of colloids is greater under unsaturated conditions as compared to the saturated conditions due to: (1) virus attachment to the air-water interface (AWI), and (2) co-deposition of colloids with attached viruses on its surface to the AWI. A sensitivity analysis of the model to various parameters showed that virus attachment to AWI is the most sensitive parameter affecting the BTCs of both free viruses and total mobile viruses, and has a significant effect on all parts of the BTC. The free and the total mobile virus BTCs are mainly influenced by parameters describing virus attachment to the AWI, virus interactions with mobile and immobile colloids, virus attachment to solid-water interface (SWI), and colloid interactions with SWI and AWI. The virus BTC is relatively insensitive to parameters describing the maximum adsorption capacity of the AWI for colloids, inlet colloid concentration, virus detachment rate coefficient from the SWI, maximum adsorption capacity of the AWI for viruses, and inlet virus concentration.

Les matériaux énergétiques résiduels de l’entraînement militaire peuvent être dommageables pour la santé publique et pour l’environnement. Des critères environnementaux existent pour chacun de ces contaminants qui doivent être respectés afin d’assurer la qualité des eaux et des sols. Ainsi, à proximité des bases militaires, leur concentration respective doit être constamment sondée afin de respecter ces limites. Cependant, comme les méthodes de mesure actuelles sont compliquées et longues, elles ne permettent pas de suivre réellement ces concentrations. L’intérêt envers des capteurs usant de résonance de plasmons de surface (SPR) a grandement crû au cours des dernières décennies grâce à leur haute sensibilité et la rapidité de mesure. Les liquides ioniques polymériques à empreinte moléculaire représentent une nouvelle classe de polymères prometteuse qui pourrait permettre une approche novatrice et adaptable pour l’extraction de contaminants organiques dans l’eau. Ces polymères combinent les propriétés extractrices des liquides ioniques et la sélectivité adaptable des polymères à empreinte moléculaire (MIP). Le monomère de liquide ionique peut être conçu pour obtenir des interactions optimales avec l’analyte. De plus, les MIPs ont l’avantage d’être hautement modulables : le simple changement de l’empreinte utilisée lors de sa polymérisation conduisant à une nouvelle sélectivité, d’où le potentiel prometteur de la méthode présentée. Différents MIPs à base de liquide ionique ont été utilisés pour fonctionnaliser des surfaces d’or pour tester, via la SPR, leur capacité à quantifier le cyclotriméthylènetrinitramine (RDX). Les résultats obtenus montrent que ces MIPs présentent un bon effet d’empreinte. Cependant, quelques problèmes persistent concernant la reproductibilité de la fonctionnalisation des surfaces d’or. Les résultats semblent toutefois montrer que cette combinaison de liquides ioniques polymériques à empreinte moléculaire avec l’analyse par SPR est une alternative prometteuse pour la détection et la quantification de contaminants présents en quantité dans l’ordre du picomolaire. / Energetic material residues from military training munition are potentially harmful and need to be constantly surveyed in order to never exceed the environmental criterion. Yet, current methods are tedious and fail to provide real-time concentration of these contaminants. Surface plasmon resonance (SPR) based sensors have gained high interest in the past decade due to their great sensitivity and the possibility of rapidly assessing samples. Molecularly imprinted polymeric ionic liquids are a promising new class of polymer that could bring a novel and adaptable approach for selective extraction of organics in water. They combine the ionic liquid’s extraction properties to molecularly imprinted polymer’s (MIP) tunable selectivity. The ionic liquid monomer is designed for optimal interaction with the energetic material, as its anion greatly affects he monomer’s solubility and interaction. Chemically, MIPs have the great advantage of being very versatile. In other words, changing the template is enough to modify the MIP’s selectivity. Hence, the potential of the method presented here is highly promising. Various molecularly imprinted polymeric ionic liquids grafted on gold thin films have been tested via SPR for the quantification of energetic materials. The results show that the molecularly imprinted polymers film displayed good imprinting effect. Yet there still are issues concerning the reproducibility of the gold’s surface functionalization. The results in the following experiments suggested that a combination of SPR sensing with molecularly imprinted polymeric ionic liquids is a promising alternative method for subnanomolar detection of energetic materials in aqueous media.

The enormous rate of increase in waste generation across the world is a serious threat to the future generation, if not handled properly, due to the creation of health hazards and global warming. This was awakened many engineers and researchers to find an appropriate solution for efficient management of waste. The land filling of the waste is the most widely adopted method for its disposal, whose efficiency mainly depends on the engineered barrier system in place. Though possessing many limitations, clay liner solely or along with Geo-membrane is often used to avoid ground and surface water contamination. The thickness of the liner of a given breakthrough time depends on the transport rates of the selected contaminants. To estimate the transport rate of any given contaminant, it is necessary to understand the different migration processes of contaminants through the liner material. It was observed from the literature that, the transport rate of contaminants mainly depends on Dispersion coefficient (D) and Distribution coefficient (K) which are the main contaminant transport parameters. The amount of contaminant transport through the liner system for a desired time period is thus estimated from these contaminant transport parameters using the Advection-Dispersion Equation (ADE). The unregulated open dumps are another cause of serious environmental problem, where the contaminants are free to migrate in any direction through the underground soil. The percolation rate and the accumulation of leachate increase during the rainy season, which picks up more contaminants from the waste and thus the threat of the leachate increases. The leachate normally migrates in vertical and lateral directions, causing contamination of ground and surface water resources, and hence, there is a need to estimate the transport rates of contaminants in the porous media. These transport rates are not only useful for designing barrier systems, but also useful to find a suitable remediation technique for the removal of contaminants from a contaminated site. Thus, determination of transport rate is very important in effective waste management systems. Most of the researchers have obtained the contaminant transport parameters through the column tests to simulate one dimensional flow. Often, it is a lengthy process and there is a need to find an easy and effective method of determining these parameters which can reduce the time and effort. Generally, the metallic contaminants such as Cadmium (Cd), Copper (Cu), Lead (Pb), Mercury (Hg), Nickel (Ni) and Zinc (Zn) which are most hazardous are considered for the contaminant migration studies. In the present study, the transport rates of two heavy metals Copper and Zinc through locally available Black Cotton soil and Red soil were studied. Column experiments were conducted to simulate the field conditions under two types of test conditions i.e., Constant and Decreasing source concentrations. For Black Cotton soil as the hydraulic conductivity was very less and was taking a long time for achieving complete breakthrough, the soil sectioning method was used to get the depth versus concentration. The soil sectioning method involves the determination of pore water concentration of any given contaminant in different sections of the soil column. The depth versus concentration profile can serve as the same purpose as that of complete column test after breakthrough. The column experiments can be done only up to a relative concentration (C/C0) of about 0.2 instead of 0.8 or more. The soil samples were compacted to different densities to know the effect of density on transport parameters. The Black Cotton Soil samples were compacted to 0.76-0.97 times of maximum dry density and Red Soil samples were compacted to 0.81-0.98 times of maximum dry density. The samples were compacted to lesser densities to reduce the experimentation time. The transport parameters for field densities can be determined by setting „Forecast Trend Lines‟ to the density versus dispersion coefficient and density versus distribution coefficient plots. The contaminant transport was modeled by various methods i.e., Analytical, Semi-analytical, Explicit Finite Difference and Implicit Finite Difference methods. These models can be extended to predict the contaminant migration through soil liners constructed with similar soils. During the lifetime of a landfill, it may be subjected to both constant and decreasing source concentration conditions and thus the contaminant transport parameters determined by both constant and decreasing tests will be useful to estimate the optimum thickness of soil liner. The disposal of waste solutions and sludges by industries has led to problems with the contamination of both soil and groundwater. Much research work has not been carried out in the past for the remediation of contaminated soils in India. Thus an attempt has been made to study in detail the different remediation techniques on various contaminated soils. Three heavy metal contaminated soils were studied with two remediation techniques i.e., Soil washing and immobilization. As a case study, Zinc contaminated soil was collected from Hindustan Zinc Limited located near Udaipur in Rajasthan State, India and column leach tests were conducted on this soil with different leaching solutions to study the efficiency of the soil washing technique. The leaching solutions used for removing zinc from this soil were 0.1N HCl, 0.1N EDTA, 0.1N HCl+0.1N EDTA and 0.1N FeCl3. It was found that 0.1N FeCl3 was more efficient to remove zinc from this soil. The removal efficiency was also high with 0.1N HCl+0.1N EDTA solution. The transport rates were determined by matching the theoretical elution curves with experimental elution curves. The contaminant transport for column leach tests was modeled using analytical solution based on the Leaching Mass Ratio approach. These transport rates are useful to estimate the rate of treatment as well as the amount of flushing solution required to remove Zinc knowing the area of contamination and in-situ soil conditions. One of the potential sources of soil and ground water contamination with toxic metal ions is Effluent Treatment Plant sludge (ETP Sludge). The efficiency of soil washing technique was also studied on ETP Sludge using five leaching solutions i.e., distilled water, 0.1N HCl, 0.1N EDTA, 0.1N HCl+0.1N EDTA and 0.1N FeCl3. ETP sludge was collected at a filter press, KIADB industrial area, Doddaballapur, Bangalore. The removal efficiencies of these leaching solutions for removal of different metal ions (Copper, Zinc, Iron, Nickel, Cadmium, Lead and Chromium) were studied. The highest removal efficiencies were observed with 0.1N FeCl3 and 0.1N HCl+0.1N EDTA. The transport rates of different metals were determined which will be useful to estimate the quantity of leaching solution required in the field to remediate this sludge using soil washing technique. Even though soil washing technique is more effective than immobilization, for less permeable soil with more clay content, it is not a cost effective method. In such cases immobilization technique can be used to remediate the contaminated soil. The immobilized metals will not migrate through soil to groundwater and will not give adverse environmental hazards in their treated state. In the present study, immobilization technique was studied on two materials, (i) contaminated soil from open dump and (ii) ETP Sludge. The contaminated soil was collected from an open dump located at the Bingipura dumping yard, Bangalore and was tested for the presence of heavy metal ions. The efficiency of treatment to immobilize the metals was studied with different additives. The chemical agents with which can decrease the solubility product will be effective to immobilize the metal ions. The stabilizing agents used for treating these materials were lime water, NaOH and cement. These stabilizing agents were selected after preliminary batch tests. Since most of the heavy metals in soils become less mobile with increase in pH, the lime water / NaOH was added to the soil/sludge to adjust the pH of the mixture to 7.0, 8.5 and 10.0. The cement: soil ratios used were, 1:100 (pH=6. 8), 1:50 (pH=8. 1) and 1:25 (pH=9. 8) by weight. Leaching tests were conducted on the amended soils to know the long term efficiencies of the chemical agents for immobilizing the metal ions. The work carried out in this thesis is presented in different chapters as given below: For the design of the liner system, it is necessary to know the different contaminant transport processes, the determination of their rates and modeling. For remediation of contaminated soil, it is required to find the suitable remediation technique based on the amount and type of pollutants, the type of soil and other geological conditions. The detailed information about sources of heavy metals, effects of heavy metal contamination on health and the environment, contaminant transport processes, methods of determining transport rates, and different modeling techniques for contaminant transport are explained in Chapter 1. The Background information along with the scope and objectives of this study are presented in this chapter. The extensive review of literature related to column experiments, various solutions to Advection-Dispersion Equation, and different remediation techniques to treat the contaminated soil, is also presented in this chapter. Chapter 2 gives detailed information about various materials and methods used in this study. The characteristics of soils used in the present study and preparation of different chemical solutions were explained. The experimental procedures of batch tests, column tests and soil sectioning to determine the contaminant transport parameters were given in detail. The experimental procedures that are required for assessing the efficiency of soil washing technique i.e., Batch leach tests and column leach tests were also explained. The laboratory assessment of immobilization efficiency through leaching test was explained briefly. The analytical and numerical solutions used for this study were discussed in detail. This chapter also includes a method of prediction of breakthrough curves from the incomplete column test data. The contaminant transport parameters of metal ion Copper in two locally available soils i.e., Black cotton soil and Red soil were determined by various techniques i.e., Analytical (using MATLAB v7 software), semi-analytical (using POLLUTE v7 software), Explicit Finite Difference Method with two software tools (MATLAB v7 and M.S.EXCEL 2010), Implicit Finite Difference method with three schemes (BTCS, UPWIND & CRANK NICOLSON) using two software tools (MATLAB v7 and M.S.EXCEL 2010). Modifications were done in the spreadsheet solution of non-reactive solute available from the literature to incorporate the retardation factor as the solutes used in this study are reactive in nature. These results are presented in Chapter 3. The contaminant transport parameters determined for different test conditions (constant and variable source concentrations) and for different densities of soil are reported in this chapter. Determination of transport rates corresponding to maximum dry density using trend lines and preparation of design charts to estimate the thickness of the liner are also discussed in this chapter. The contaminant transport parameters were also determined for metal ion Zinc in the same soils with the same techniques as that of Copper and the migration rates were compared for both the ions. These models and comparative results are presented Chapter 4. It was observed that with increase in density, the dispersion coefficient decreases and Distribution coefficient increases. It was also found that the dispersion coefficient of Black Cotton Soil was lower than that of Red Soil whereas the distribution coefficient of Black Cotton soil is much higher than that of Red Soil. Further, it was observed that the dispersion coefficient of Copper was less than that of Zinc whereas the distribution coefficient of Copper was higher than Zinc. The design of liner thickness, based on transport rates of Zinc is briefly discussed in this chapter. A case study has been explained for the remediation of Zinc contaminated sandy soil using soil washing technique. The undisturbed soil samples collected from four locations of waste disposal site of Hindustan Zinc Limited located near Udaipur in Rajasthan State of Western India were assessed to find the suitable leaching solution and number of pore volumes for the effective removal of Zinc from this soil. The chelates/ solvents used for this soil were 0.1N HCl, 0.1N EDTA, 0.1N HCl+0.1N EDTA and 0.1N FeCl3. The contaminant transport parameters were also determined from the column leach tests based on the Leaching Mass Ratio approach and the results are presented in Chapter 5. From the experimental study it was observed that 0.1N FeCl3 and 0.1N HCl+0.1N EDTA are the most suitable leaching solutions to treat this soil. The Chapter 6 contains the sludge analysis of an industrial ETP sludge, column leach test results of this sludge with different leaching solutions, removal efficiencies of different solutions used and the transport rates of different contaminants. The leaching solutions used for this sludge were distilled water, 0.1N HCl, 0.1N EDTA, 0.1N HCl+0.1N EDTA and 0.1N FeCl3. It was observed that 0.1N FeCl3 and 0.1N HCl+0.1N EDTA are the most suitable leaching solutions to treat this sludge. Other solutions have also removed the contaminants by more than 50%, but the number of pore volumes required to leach out the contaminants was high. The order of removal efficiencies of different solutions is presented below: 0.1N FeCl3 > 0.1N HCl + 0.1N EDTA > 0.1N EDTA > 0.1N HCl > distilled water. The transport rates of different contaminants (Cu, Zn, Cd, Fe, Ni, Pb and Cr) were determined using analytical solution and are presented in this chapter. These transport rates are useful to estimate the quantity of leaching solution required in the field to remediate the sludge using soil washing technique. A contaminated soil collected from an open dump site within Bangalore city and ETP Sludge were analyzed to know the efficiency of immobilization/ solidification technique of remediation using three chemical agents lime, NaOH and cement. The soil samples were mixed with different proportions of these chemicals to adjust the pH of the mixtures to 7.0, 8.5 and 10.0. Leaching tests were conducted on the modified soils to know the long term efficiency of these chemical agents to immobilize the contaminants and these results are discussed in Chapter7. The results showed that highest immobilization efficiencies can be achieved with lime for this contaminated soil and cement is the most suitable chemical agent to treat this sludge. The immobilization efficiencies of different stabilizing agents for various metals were studied and the results analyzed. The Chapter 8 includes the major observations and conclusions of the present research work which will be useful for Geotechnical and Geo-environmental engineers to estimate the transport rates of contaminants, to design the soil liners, to assess the efficiency of soil washing technique to remediate the contaminated soil, to estimate the quantity of leaching solution required in the field for soil washing and to find the suitable chemical agent for remediating the contaminated soil by immobilization technique.