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The scope of extreme-environment diving defined within this work encompasses diving modes outside of the generally accepted no-decompression, open-circuit, compressed-air diving limits on selfcontained underwater breathing apparatus (scuba) in temperate or warmer waters. Extreme-environment diving is scientifically and politically interesting. The scientific diving operational safety and medical framework is the cornerstone from which diving takes place in the scientific community. From this effective baseline, as evidenced by decades of very low DCS incidence rates, the question of whether compressed air is the best breathing medium under pressure was addressed with findings indicating that in certain depth ranges a higher fraction of oxygen (while not exceeding a PC 2 of 1.6 ATA) and a lower fraction of nitrogen result in extended bottom times and a more efficient decompression. Extremeenvironment diving under ice presents a set of physiological. equipment, training and operational challenges beyond regular diving that have also been met through almost 50 years of experience as an underwater research tool. Diving modes such as mixed-gas, surface-supplied diving with helmets may mitigate risk factors that the diver incurs as a result of depth, inert gas narcosis or gas consumption. A close approximation of inert gas loading and decompression status monitoring is a function met by dive computers, a necessity in particular when the diver ventures outside of the single-dive profile into the realm of multi-level, multi-day repetitive diving or decompression diving. The monitoring of decompression status in extreme environments is now done exclusively through the use of dive computers and evaluations of the performance of regulators under ice have determined the characteristics of the next generation of life-support equipment for extreme-environment diving for science. These polar, deep and contaminated water environments require risk assessment that analyzes hazards such as cold stress, hydration, overheating, narcosis, equipment performance and decompression sickness. Scientific diving is a valuable research tool that has become an integral methodology in the pursuit of scientific questions in extreme environments of polar regions, in contaminated waters, and at depth.

Water contaminations by many pollutants, especially heavy metals such as Pb(II), Hg(II), Cu(II), Cd(II), and Cr(VI) pose many public health and environmental concerns as reported in the list of hazardous substances compiled by the US Environmental Protection Agency due to their high toxicity, refractory degradation, and ease of entering food chain. Adsorption by chelating resins is proven to be the most effective method for the extraction of metal ions from polluted and wastewater. However, traditional absorbents such as activated carbon, activated alumina, clay, zeolite, etc., show limited adsorption abilities for these heavy metal ions. The major goal of this thesis is to develop efficient and cost-effective adsorbents for the extraction of heavy metals from wastewater. This dissertation will focus on the development of four chemically modified high surface area adsorbents with accessible chelating sites for capturing and retaining toxic metal ions from polluted water. The first adsorbent, Nitrogen Doped Carboxylated Activated Carbon (ND-CAC), is prepared by a polymerization reaction between melamine and formaldehyde to form the melamine formaldehyde resin (MF-R) followed by carbonization at 800 oC under nitrogen atmosphere to form nitrogen doped carbon (ND-C), and finally oxidation to form the ND-CAC adsorbent. The ND-CAC adsorbent shows high adsorption capacities of 750.5, 250.5, 98.2 mg/g for the extraction of Pb(II), Hg(II), and Cr(VI), respectively from aqueous solutions with a high selectivity to Pb(II). The second adsorbent, Melamine Zirconium Phosphate (M-ZrP) is prepared by a precipitation reaction between Melamine Phosphate (MP) and ZrCl4 in an aqueous solution. The M-ZrP adsorbent is used for the removal of Pb(II), Hg(II), and Cd(II) with maximum adsorption capacities of 680.4, 119.0, and 60.0 mg/g, respectively with a high selectivity to Pb(II). The third adsorbent is chemically functionalized metal organic framework (UIO-66-IT) was prepared by post-synthetic modification using the chelating ligand 2-Imino-4-Thioburit. The adsorbent was used to extract Hg(II) and (HPO4)- ions from aqueous solutions and the results revealed exceptionally high adsorption capacities toward mercury and phosphate ions of 700 and 160 mg/g, placing it among the top functionalized MOF known for the high capacity of Hg(II) removal from aqueous solutions. The fourth adsorbent, Melamine Thiourea Partially Reduced Graphene Oxide (MT-PRGO) prepared by the amidation reaction between chemically modified graphene oxide and melamine thiourea, is used for the effective extraction of Hg(II), Co(II) and Cu(II) from polluted water. The MT-PRGO adsorbent shows exceptional selectivity for the extraction of Hg(II) with a capacity of 651 mg/g, placing it among the top of carbon-based materials known for the high capacity of Hg(II) removal from aqueous solutions. Desorption studies demonstrate that the new adsorbents ND-CAC, M-ZrP, UIO-66-IT, and MT-PRGO are easily regenerated with the desorption of the heavy metal ions Hg(II), Pb(II), Cd(II), and Cr(VI) reaching 99 % - 100 % recovery from their maximum sorption capacities using different eluents. Moreover, all prepared adsorbents showed tremendous abilities to clean contaminated water from toxic heavy metals at trace concentrations. That prove the ability of using them at water contamination level when the concentration of heavy metals is very low. The new adsorbents ND-CAC, M-ZrP, UIO-66-IT, and MT-PRGO are proposed as top performing remediation adsorbents for the extraction of the heavy metals Pb(II), Hg(II), Cd(II), Cr(VI), and (HPO4)- from waste and polluted water.

O presente trabalho visou a construção de uma linhagem recombinante de levedura que apresentasse a proteína MerR ancorada à sua superfície celular externa. Para tanto, foi realizada a fusão gênica do gene codificador de MerR de C. metallidurans, que apresenta elevada afinidade e seletividade para íons mercúrio, com a sequência codificadora da região C- terminal da proteína Flo1p, utilizado como âncora. A fusão gênica foi inserida entre as sequência codificadoras do promotor e terminador de transcrição do gene da fosfoglicerato quinase (PGK) do vetor de expressão de levedura pMA91, obtendo-se o plasmídeo recombinante pMA91MF. Esse plasmídeo foi empregado na transformação genética da linhagem de S. cerevisiae YPH252. A linhagem de S. cerevisiae recombinante YPH252/pMA91MF apresentou a proteína MerR ancorada na superfície celular e mostrou ter capacidade aumentada de ligar Hg2+ em relação à linhagem de levedura controle YPH252/pMA91. Portanto, foi confirmada a funcionalidade do sistema de ancoragem da proteína MerR à superfície celular de levedura aumentando a biossorção de mercúrio pela linhagem recombinante, com potencial para ser utilizada como uma ferramenta biotecnológica para a biorremediação de águas contaminadas com mercúrio. / This work describes the construction of recombinant yeast strain by anchoring MerR on the cell wall, using the C-terminal region of the Flo1 protein as an anchor. Therefore, several molecular cloning steps resulted in the inserting of gene fusion SS-merR-Flo428 (-factor signal sequence, coding sequence of MerR and C-terminal region of the Flo1 protein) into a yeast expression vector, pMA91, under control of the S. cerevisiae 3-phosphoglycerate kinase (PGK) promoter, the resulting plasmid was named pMA91MF. This plasmid carrying the anchoring and expression cassette MerR was used to transform the S. cerevisiae YPH252 strain. The transformants were selected by genetic complementation the Leu+ phenotype. The display of MerR on the cell surface of recombinant strain YPH252/pMA91MF was confirmed by transmission electron microscopy (TEM).After 10 min of incubation with 5.0 mM HgCl2, recombinant strain YPH252/pMA91MF adsorbed 109.6 mg Hg2+/g dry cell weight, 54% higher than the Hg2+ binding capacity of control strain YPH252/pMA91. After 10 min of incubation with 10.0 mM HgCl2, recombinant strain adsorbed 173.8 mg Hg2+g dry cell weight, 84% higher than the Hg2+ binding capacity of control strain (94.5 mg de Hg2+/g dry cell weight). The rapid initial adsorption of Hg2+ suggests an instantaneous binding of Hg2+ to MerR anchored on the cell surface of the recombinant yeast strain. It was observed that the binding rate to Hg2+ showed saturation with increasing external ion concentrations and reached saturation of HgCl2 in 15.0 mM after 120 min of incubation. Probably the input Hg2+ inside the cells affected cell function, but detoxification mechanisms are still active, protecting the cells from the toxic effect of Hg2+. The results confirm the construction of the recombinant strain YPH252/pMA91MF and functionality of the anchoring system for MerR on the yeast cell surface, increasing the mercury biosorption by recombinant yeast strain, with potential for use as a biotechnological tool for the bioremediation of contaminated water with mercury.

Le développement économique et l'industrialisation pendant les dernières années ont créés de nombreuses zones de déchets dangereux qui contribuent à une contamination généralisée des eaux souterraines à travers le monde. Les chercheurs ont tourné leur attention à trouver de méthodes d'efficace et moins coûteux pour l’assainissement, prenant en compte que les principaux polluants (les métaux lourds) ne sont pas biodégradables et qu’ils ont tendance plutôt à s'accumuler dans les organismes vivants, en déterminant des troubles des différentes fonctions vitales et des graves maladies. En raison de ces inconvénients il est envisagé le développement des technologies permettant la restauration de l'environnement d’une manière efficace à la fois écologique et biologique ainsi qu’en termes de coûts impliqués. Dans le cadre de cette thèse, nous avons proposé d'obtenir des matériaux avec une grande efficacité pour la décontamination des eaux continentales et océaniques. La structure du travail présent comprend quatre chapitres et présente des propriétés générales et spécifiques de matériaux nanométriques. Le premier chapitre présente des concepts généraux des matériaux céramiques et oxyhydriques utilisés pour remédier l'environnement. Le deuxième chapitre présente des méthodes générales pour la préparation des matériaux céramique et oxyhydriques ainsi que des méthodes adaptées au laboratoire pour obtenir ces matériaux à l'échelle nanométrique afin d'améliorer les propriétés d'adsorption des différents polluants. Dans le cadre de ce chapitre sont présentées aussi les techniques pour la caractérisation des matériaux à l'échelle nanométrique qui fait l’objectif de notre étude. Les deux chapitres suivants sont consacrés à la présentation des résultats expérimentaux originaux obtenus suite à la caractérisation physico-chimique, cinétique et biologiques des matériaux céramiques et oxyhydriques utilisés dans l'assainissement des eaux contaminées. / He economic development and industrialization from recent years have created many areas of hazardous waste that contributed to the contamination of groundwater worldwide. The researchers turned their attention to finding cost-effective methods for decontamination, taking into account that the main pollutants (heavy metals) are not biodegradable and they tend to accumulate in living organisms, determining disorders of different vital functions and serious illness. Because of these drawbacks the development of technologies for environmental restoration effectively both ecologically and biologically are of a great interest. As part of this thesis, we proposed to obtain materials with high efficiency for the decontamination of continental and oceanic waters. The structure of this work consists of four chapters and provides general and specific properties of nanoscale materials. The first chapter presents the general concepts of ceramic materials and iron oxide based materials used in environmental applications. The second chapter provides general methods for the preparation of ceramic materials and iron oxides and the adapted laboratory methods used for obtaining these materials at the nanoscale in order to improve their adsorption properties of different pollutants. This chapter also presents the techniques used for the characterization of the obtained materials. The next two chapters are devoted to the presentation of original experimental results obtained from the physico-chemical characterization, kinetics and biological investigations of the ceramics and iron oxide based materials used in the remediation of contaminated waters.

O presente trabalho visou a construção de uma linhagem recombinante de levedura que apresentasse a proteína MerR ancorada à sua superfície celular externa. Para tanto, foi realizada a fusão gênica do gene codificador de MerR de C. metallidurans, que apresenta elevada afinidade e seletividade para íons mercúrio, com a sequência codificadora da região C- terminal da proteína Flo1p, utilizado como âncora. A fusão gênica foi inserida entre as sequência codificadoras do promotor e terminador de transcrição do gene da fosfoglicerato quinase (PGK) do vetor de expressão de levedura pMA91, obtendo-se o plasmídeo recombinante pMA91MF. Esse plasmídeo foi empregado na transformação genética da linhagem de S. cerevisiae YPH252. A linhagem de S. cerevisiae recombinante YPH252/pMA91MF apresentou a proteína MerR ancorada na superfície celular e mostrou ter capacidade aumentada de ligar Hg2+ em relação à linhagem de levedura controle YPH252/pMA91. Portanto, foi confirmada a funcionalidade do sistema de ancoragem da proteína MerR à superfície celular de levedura aumentando a biossorção de mercúrio pela linhagem recombinante, com potencial para ser utilizada como uma ferramenta biotecnológica para a biorremediação de águas contaminadas com mercúrio. / This work describes the construction of recombinant yeast strain by anchoring MerR on the cell wall, using the C-terminal region of the Flo1 protein as an anchor. Therefore, several molecular cloning steps resulted in the inserting of gene fusion SS-merR-Flo428 (-factor signal sequence, coding sequence of MerR and C-terminal region of the Flo1 protein) into a yeast expression vector, pMA91, under control of the S. cerevisiae 3-phosphoglycerate kinase (PGK) promoter, the resulting plasmid was named pMA91MF. This plasmid carrying the anchoring and expression cassette MerR was used to transform the S. cerevisiae YPH252 strain. The transformants were selected by genetic complementation the Leu+ phenotype. The display of MerR on the cell surface of recombinant strain YPH252/pMA91MF was confirmed by transmission electron microscopy (TEM).After 10 min of incubation with 5.0 mM HgCl2, recombinant strain YPH252/pMA91MF adsorbed 109.6 mg Hg2+/g dry cell weight, 54% higher than the Hg2+ binding capacity of control strain YPH252/pMA91. After 10 min of incubation with 10.0 mM HgCl2, recombinant strain adsorbed 173.8 mg Hg2+g dry cell weight, 84% higher than the Hg2+ binding capacity of control strain (94.5 mg de Hg2+/g dry cell weight). The rapid initial adsorption of Hg2+ suggests an instantaneous binding of Hg2+ to MerR anchored on the cell surface of the recombinant yeast strain. It was observed that the binding rate to Hg2+ showed saturation with increasing external ion concentrations and reached saturation of HgCl2 in 15.0 mM after 120 min of incubation. Probably the input Hg2+ inside the cells affected cell function, but detoxification mechanisms are still active, protecting the cells from the toxic effect of Hg2+. The results confirm the construction of the recombinant strain YPH252/pMA91MF and functionality of the anchoring system for MerR on the yeast cell surface, increasing the mercury biosorption by recombinant yeast strain, with potential for use as a biotechnological tool for the bioremediation of contaminated water with mercury.

Per- and polyfluoroalkyl substances (PFAS) are synthetic compounds that have beenaround since 1940. They can be used in a variety of products such as fire-fighting foam, food packaging and cosmetic products. Many PFAS have potential toxic effects on both humans and animals which poses a problem due to their wide distribution and persistency. Another problem concerns the remediation of PFAS, where the substances ends up circulating between the different disposal types (landfills, wastewater treatment and incineration). Active methods are therefore needed to remove or retain the contaminants. Some examples of these remediation technologies can be biomaterials, organoclays and more advanced methods such as activated carbon and ion exchange. The more advanced being suited for remediation of drinking water. In this study, the sorption efficiency of two pine bark fractions has been studied and also compared to the efficiency of activated carbon. The evaluation was done for both target analysis (PFAS-11) and non-specific analysis of extractable organofluorine (EOF) compounds in contaminated water from a hazardous waste management facility. The two pine bark fractions indicated similar sorption efficiencies, for both the PFAS-11 and the EOF compounds. The sorption efficiency ranged from 10% up to 75% for perfluorinated sulfonic acids (PFSA) and from below zero up to 40% for perfluorinated carboxylic acids (PFCA). A general pattern can be seen, the sorption efficiency increases with increasing length of the PFAS chain. The activated carbon had a higher sorption efficiency, where the majority of PFAS had an average sorption of 100%. In comparison, the PFAS-11 and total EOF analysis displayed high concentrations of unidentified EOF compounds. These compounds indicated a negative sorption, which might imply that non-targeted PFAS or other fluorinated organic compounds desorb from the bark. Therefore, the pine bark might be suitable as a rough remediation of long-chain PFAS (≥8C), but further studies on the sorption of unidentified fluorinated organic compounds are of interest.

Batch equilibrium and dynamic column studies were undertaken to compare the metal-removal capabilities of two natural, low-cost materials (dried, crushed brown seaweed and shrimp shells) with a commercially available strong acid cation exchange resin (CER). All media maintained structural and hydraulic integrity over the duration of the column experiments. The batch tests showed that the low-cost materials demonstrated high adsorption capacities and affinities to Pb, Cu, Cd and Zn, but were slightly outperformed by the CER. Metal removal by each media was far superior to that reported for other types of low cost materials. Fixed beds of each media reduced concentrations of the target metals in a synthetic drainage water solution to levels below reference values measured at a case study site. This result suggests that any of the materials tested have the potential to completely remove impacts of a point source of metal contamination on the local water regime at the site. The CER column sustained the longest service time without large-scale breakthrough of any metal.

Le présent travail porte sur la photodégradation de polluants aqueux utilisant des catalyseurs à base de ZnO. La première étape a consisté à fonctionnaliser ZnO avec des nanoparticules d'argent. Deux méthodes ont été utilisées : la photodéposition et l'imprégnation des particules d'argent sur ZnO. L’activité des catalyseurs obtenus vis-à-vis de la dégradation du bisphenol-A, du triclosan et de la rhodamine-B a été ensuite étudiée. L'effet du pH, des concentrations du photocatalyseur et du polluant et de la longueur d'onde sur la dégradation du bisphenol-A a été analysée et la constante cinétique déterminée. L'optimisation a montré qu'une teneur faible en argent et un pH alcalin, tant pour la fonctionnalisation de ZnO que pour la photodégradation, maximisent la constante cinétique de dégradation du bisphenol-A. Un modèle a également prédit que le système obtenu par photodéposition présente une activité photocatalytique supérieure à celle de celui obtenu par imprégnation. D'autre part, pour surmonter des problèmes d'agrégation, les particules d’Ag/ZnO ont été immobilisées grâce à leur incorporation dans une matrice d'acide polyacrylique réticulé. La surface des particules de catalyseur a, au préalable, été modifiée grâce à un agent de couplage silané qui a permis (i) la dispersion et l'ancrage par estérification des nanoparticules sur la matrice polyacrylique (ii) de promouvoir la cristallisation du polymère. Les composites obtenus ont été testés avec succès sous rayonnement UV avec une efficacité comparable à celle des particules non-immobilisées. L'immobilisation permet par ailleurs d'empêcher la photocorrosion du catalyseur et d'utiliser ces composites en mode continu / The present work concerns photodegradation of water contaminants using ZnO-based catalysts. The first step consisted in designing a new catalytic system by functionalizing ZnO with silver nanoparticles. Two methods were used: photodeposition and impregnation of silver nanoparticles (AgNPs) on ZnO. The photocatalytic activity of the resulting catalyst towards the degradation of bisphenol-A, triclosan and rhodamine-B was studied. The effect of pH, photocatalyst and contaminant concentrations and wavelength, on bisphenol-A degradation was studied and the kinetic rate constant was determined. The optimization showed that a low silver content and an alkaline pH, during both functionalization of ZnO and photodegradation, maximized the kinetic rate constant of bisphenol-A degradation. A model also predicted that Ag/ZnO obtained by photodeposition showed higher photocatalytic activity that of Ag/ZnO obtained by impregnation.On the other hand, to overcome aggregation problems, Ag/ZnO were immobilized owing to their incorporation in a cross-linked poly(acrylic acid) matrix . The surface of Ag/ZnO was previously modified, using a silane coupling agentwhich allowed (i) dispersing and anchoring NPs on the polyacrylic matrix by formation ester bonds (ii) promoting crystallization of the polymer. The composites were successfully tested under UV light with an efficiency comparable to that of non-immobilized NPs. The immobilization provides additional advantages e.g. hindrance of catalyst photocorrosion and possible use of the composite in continuous mode

Per- and polyfluoroalkyl substances (PFAS) are synthetic compounds that have beenaround since 1940. They can be used in a variety of products such as fire-fighting foam,food packaging and cosmetic products. Many PFAS have potential toxic effects on bothhumans and animals which poses a problem due to their wide distribution and persistency.Another problem concerns the remediation of PFAS, where the substances ends upcirculating between the different disposal types (landfills, wastewater treatment andincineration). Active methods are therefore needed to remove or retain the contaminants.Some examples of these remediation technologies can be biomaterials, organoclays andmore advanced methods such as activated carbon and ion exchange. The more advancedbeing suited for remediation of drinking water. In this study, the sorption efficiency oftwo pine bark fractions has been studied and also compared to the efficiency of activatedcarbon. The evaluation was done for both target analysis (PFAS-11) and non-specificanalysis of extractable organofluorine (EOF) compounds in contaminated water from ahazardous waste management facility. The two pine bark fractions indicated similarsorption efficiencies, for both the PFAS-11 and the EOF compounds. The sorptionefficiency ranged from 10% up to 75% for perfluorinated sulfonic acids (PFSA) and frombelow zero up to 40% for perfluorinated carboxylic acids (PFCA). A general pattern canbe seen, the sorption efficiency increases with increasing length of the PFAS chain. Theactivated carbon had a higher sorption efficiency, where the majority of PFAS had anaverage sorption of 100%. In comparison, the PFAS-11 and total EOF analysis displayedhigh concentrations of unidentified EOF compounds. These compounds indicated anegative sorption, which might imply that non-targeted PFAS or other fluorinated organic compounds desorb from the bark. Therefore, the pine bark might be suitable as a roughremediation of long-chain PFAS (≥8C), but further studies on the sorption of unidentifiedfluorinated organic compounds are of interest.Keywords: