Trace element concentrations vary substantially during snowmelt runoff, with changes in the dissolved versus particulate fractions potentially impacting their movement at the catchment scale. To investigate trace element behavior in a snowmelt dominated stream, we measured concentrations in different size fractions in the Provo River (northern Utah, USA). We sampled the river at three locations during water years 2016-2018 and 2021-2023 for trace metal and major ion concentrations. During the final year, we collected three fractions (unfiltered, <0.45 µm filtered, and <0.22 µm filtered) for trace metal chemistry and calculated the particulate concentration as the difference between the unfiltered and 0.45 µm fraction. Stream measurements included pH, discharge, turbidity, and fluorescent dissolved organic matter (fDOM). We also sampled water sources (soil water, ephemeral streams, and snowpack) to compare trace metal concentrations across the watershed with the stream. Trace metal (Al, Be, Fe, Pb) and rare earth element (REE +Y) concentrations had the highest particulate and dissolved concentrations during snowmelt runoff. In contrast, major cations were primarily found in the dissolved fraction with lowest concentrations during snowmelt runoff. Major cation and particulate metal concentrations increased from upstream to downstream. The increased trace metal and REE + Y concentrations during snowmelt relative to baseflow may be explained by increased discharge and associated increased turbidity and fDOM. A comparison with water sources suggests that dissolved and particulate trace metals in the stream are sourced from flushed soil water, as trace metal transport through the watershed is facilitated by suspended sediment and dissolved organic matter. For most of the trace metals and REE +Y, concentrations were similar in the <0.45 µm and <0.22 µm fractions. Yet Al tended to have higher concentrations in the <0.45 µm fraction, suggesting a colloidal form of Al between 0.22 µm and 0.45 µm may exist. Differences from upstream to downstream may be related to changes in pH, from ~7 at the upper site to ~8 at the lower sites, which would change sorption capacity, saturation indices, or speciation. Our study demonstrates that trace metal concentrations are variable during snowmelt as the metals interact with suspended particles or dissolved organic matter and are influenced by changing water chemistry, with implications for understanding water quality impairments in snowmelt-dominated streams.

A aplicação do processo de fotoeletrocatálise à eliminação de interferentes orgânicos em baixa concentração na eletroanálise de metais foi abordada tomando o quelato Cu(II)-EDTA como sistema modelo e o restabelecimento da onda voltamétrica do cobre como indicador de efetividade. Desenvolveram-se células eletroquímicas de camada delgada (espessura de 600 micrômetros) nas quais alguns microlitros de amostra são tratados sobre um eletrodo modificado com TiO2 (tipo P25, rico em anatase), cuja superfície é irradiada através de uma janela por um LED (370 nm). Foram construídos e avaliados os seguintes eletrodos: pasta de carbono, TiO2 e óleo parafínico (CPE-TiO2), compósitos de grafite, TiO2 e adesivo epóxi ou de silicone e ouro com oclusão de TiO2 por eletrodeposição. Estudo do efeito de parâmetros como potencial aplicado ao eletrodo, composição do eletrólito e concentração de EDTA sobre a fotocorrente permitiu selecionar condições de trabalho e estabelecer algumas correlações. Por exemplo, observou-se linearidade entre a fotocorrente e a concentração de EDTA até 1,0 mmol/L, aparente limite superior do controle difusional do processo para potência radiante aplicada, acima do qual, a cinética de oxidação passa a sobrepujar o transporte no controle da velocidade de reação. O restabelecimento pleno da onda de Cu(II) 1,0 mmol.L-1 foi observado após a irradiação por 10 min quando a concentração de EDTA não excedia 0,94 mmol.L-1. Descobriu-se um procedimento mais rápido que consiste na aplicação do tratamento fotoeletrocatalítico simultâneo ao registro de voltamogramas cíclicos repetitivos (eletrodo de Au-TiO2, 0,3 a 0,7 V vs. Ag/AgCl, 100 mV.s-1). Após o sexto ciclo, a altura do pico de redissolução anódica do Cu (reduzido durante a varredura no sentido negativo) estabiliza, permitindo a quantificação sem etapa prévia de abertura. / The photoelectrocatalysis process was investigated for the elimination of organic compounds interference on the electroanalysis of trace metals. Cu(II)-EDTA chelate was chosen as model system and the recovery of copper voltammetric peak, as effectiveness indicator. Thin layer cells (thickness of 600 micrometers) were designed for the treatment of some microliters of sample by irradiation (370 nm LED) of an electrode modified with TiO2 (P25, anatase rich). The following modified electrodes were prepared and evaluated: carbon paste with TiO2 and paraffin oil (CPE-TiO2), composites of graphite, TiO2 and epoxy or silicone binders and TiO2 occluded in electrodeposited gold on a gold substrate. The effect of parameters like potential bias, electrolyte composition and EDTA concentration on the photocurrent was evaluated to setup working conditions. Some correlations were observed, e.g., a linear dependence between photocurrent and EDTA concentration up to 1.0 mmol/L. For the irradiance applied, this concentration is possibly the upper limit of operation diffusion transport control, above which, the kinetics of the oxidation at the TiO2 modified electrode becomes the controlling process. For EDTA concentrations not exceeding 0.94 mmol.L-1, full recovery of 1.0 mmol.L-1 Cu(II) voltammetric peaks was observed after 10 min of irradiation. A faster procedure was discovered and consists in recording repetitive cyclic voltammograms (Au-TiO2 electrode, 0,3 to 0,7 V vs. Ag/AgCl scans, 100 mV.s-1) simultaneously with continuous irradiation. After the sixth cycle, the copper anodic stripping peak height stabilizes allowing quantification without previous sample pre-treatment step.

A aplicação do processo de fotoeletrocatálise à eliminação de interferentes orgânicos em baixa concentração na eletroanálise de metais foi abordada tomando o quelato Cu(II)-EDTA como sistema modelo e o restabelecimento da onda voltamétrica do cobre como indicador de efetividade. Desenvolveram-se células eletroquímicas de camada delgada (espessura de 600 micrômetros) nas quais alguns microlitros de amostra são tratados sobre um eletrodo modificado com TiO2 (tipo P25, rico em anatase), cuja superfície é irradiada através de uma janela por um LED (370 nm). Foram construídos e avaliados os seguintes eletrodos: pasta de carbono, TiO2 e óleo parafínico (CPE-TiO2), compósitos de grafite, TiO2 e adesivo epóxi ou de silicone e ouro com oclusão de TiO2 por eletrodeposição. Estudo do efeito de parâmetros como potencial aplicado ao eletrodo, composição do eletrólito e concentração de EDTA sobre a fotocorrente permitiu selecionar condições de trabalho e estabelecer algumas correlações. Por exemplo, observou-se linearidade entre a fotocorrente e a concentração de EDTA até 1,0 mmol/L, aparente limite superior do controle difusional do processo para potência radiante aplicada, acima do qual, a cinética de oxidação passa a sobrepujar o transporte no controle da velocidade de reação. O restabelecimento pleno da onda de Cu(II) 1,0 mmol.L-1 foi observado após a irradiação por 10 min quando a concentração de EDTA não excedia 0,94 mmol.L-1. Descobriu-se um procedimento mais rápido que consiste na aplicação do tratamento fotoeletrocatalítico simultâneo ao registro de voltamogramas cíclicos repetitivos (eletrodo de Au-TiO2, 0,3 a 0,7 V vs. Ag/AgCl, 100 mV.s-1). Após o sexto ciclo, a altura do pico de redissolução anódica do Cu (reduzido durante a varredura no sentido negativo) estabiliza, permitindo a quantificação sem etapa prévia de abertura. / The photoelectrocatalysis process was investigated for the elimination of organic compounds interference on the electroanalysis of trace metals. Cu(II)-EDTA chelate was chosen as model system and the recovery of copper voltammetric peak, as effectiveness indicator. Thin layer cells (thickness of 600 micrometers) were designed for the treatment of some microliters of sample by irradiation (370 nm LED) of an electrode modified with TiO2 (P25, anatase rich). The following modified electrodes were prepared and evaluated: carbon paste with TiO2 and paraffin oil (CPE-TiO2), composites of graphite, TiO2 and epoxy or silicone binders and TiO2 occluded in electrodeposited gold on a gold substrate. The effect of parameters like potential bias, electrolyte composition and EDTA concentration on the photocurrent was evaluated to setup working conditions. Some correlations were observed, e.g., a linear dependence between photocurrent and EDTA concentration up to 1.0 mmol/L. For the irradiance applied, this concentration is possibly the upper limit of operation diffusion transport control, above which, the kinetics of the oxidation at the TiO2 modified electrode becomes the controlling process. For EDTA concentrations not exceeding 0.94 mmol.L-1, full recovery of 1.0 mmol.L-1 Cu(II) voltammetric peaks was observed after 10 min of irradiation. A faster procedure was discovered and consists in recording repetitive cyclic voltammograms (Au-TiO2 electrode, 0,3 to 0,7 V vs. Ag/AgCl scans, 100 mV.s-1) simultaneously with continuous irradiation. After the sixth cycle, the copper anodic stripping peak height stabilizes allowing quantification without previous sample pre-treatment step.

Les lacs jouent un rôle particulier dans le cycle de l’eau dans les bassins versants urbains. La stratification thermique et le temps de séjour de l’eau élevé favorisent le développement phytoplanctonique. La plupart des métaux sont naturellement présents dans l’environnement à l’état de traces. Ils sont essentiels pour les organismes vivants. Néanmoins, certains métaux sont connus pour leurs effets toxiques sur les animaux et les humains. La concentration totale des métaux ne reflète pas leur toxicité. Elle dépend de leurs propriétés et de leur spéciation (fractions particulaires, dissoutes: labiles ou biodisponibles et inertes). Dans les systèmes aquatiques, les métaux peuvent être absorbés par des ligands organiques ou minéraux. Leur capacité à se complexer avec la matière organique dissoute (MOD), particulièrement les substances humiques, a été largement étudiée. Dans les lacs, le développement phytoplanctonique peut produire de la MOD non-humique, connue pour sa capacité complexante des métaux. Pourtant, peu de recherche sur la spéciation des métaux dans la colonne d’eau des lacs urbains a été réalisée jusqu’à présent.Les objectifs principaux de cette thèse sont (1) d’obtenir une base de données fiables des concentrations en métaux traces dans la colonne d’eau de lacs urbains représentatifs; (2) d’évaluer leur biodisponibilité via une technique de spéciation adéquate ; (3) d’analyser leur évolution saisonnière et spatiale et leur spéciation; (4) d’étudier l’impact des variables environnementales, en particulier de la MOD autochtone sur leur biodisponibilité; (5) de lier la concentration des métaux au mode d’occupation du sol du bassin versant.Notre méthodologie est basée sur un suivi in-situ des lacs en complément d’analyses spécifiques en laboratoire. L’étude a été conduite sur trois sites: le lac de Créteil (France), le lac de Pampulha (Brésil) et 49 lacs péri-urbains (Ile de France). Sur le lac de Créteil, plusieurs dispositifs de mesure en continu nous ont fourni une partie de la base de données limnologiques. Dans le bassin versant du lac de Pampulha, la pression anthropique est très importante. Le climat et le régime hydrologique des 2 lacs sont très différents. Les 49 lacs de la région d’Ile de France ont été échantillonnés une fois pendant trois étés successifs (2011-2013). Ces lacs nous ont fourni une base de données synoptique, représentative de la contamination métallique à l’échelle d’une région fortement anthropisée.Afin d’expliquer le rôle des variables environnementales sur la concentration métallique, le modèle Random Forest a été appliqué sur les bases de données du lac de Pampulha et des 49 lacs urbains avec 2 objectifs spécifiques: (1) dans le lac de Pampulha, comprendre le rôle des variables environnementales sur la fraction labile des métaux traces, potentiellement biodisponible et (2) dans les 49 lacs, comprendre la relation des variables environnementales, particulièrement au niveau du bassin versant, sur la concentration dissoute des métaux. L’analyse des relations entre métaux et variables environnementales constitue l’un des principaux résultats de cette thèse. Dans le lac de Pampulha, environ 80% de la variance du cobalt labile est expliqué par des variables limnologiques: Chla, O2, pH et P total. Pour les autres métaux, le modèle n’a pas réussi à expliquer plus de 50 % de la relation entre fraction labile et variables limnologiques. Dans les 49 lacs, le modèle Random Forest a donné un bon résultat pour le cobalt (60% de la variance expliquée) et un très bon résultat pour le nickel (86% de la variance expliquée). Pour Ni les variables explicatives sont liées au mode d’occupation du sol : « Activités » (Equipements pour l’eau et l’assainissement, entrepôts logistiques, bureaux…) et « Décharge ». Ce résultat est en accord avec le cas du lac de Créteil où la concentration en Ni dissous est très élevée et où les catégories d’occupation du sol « Activités » et « Décharges » sont dominantes / Lakes have a particular influence on the water cycle in urban catchments. Thermal stratification and a longer water residence time in the lake boost the phytoplankton production. Most metals are naturally found in the environment in trace amounts. Trace metals are essential to growth and reproduction of organisms. However, some are also well known for their toxic effects on animals and humans. Total metal concentrations do not reflect their ecotoxicity that depends on their properties and speciation (particulate, dissolved: labile or bioavailable and inert fractions). Trace metals can be adsorbed to various components in aquatic systems including inorganic and organic ligands. The ability of metal binding to dissolved organic matter (DOM), in particular humic substances, has been largely studied. In urban lakes, the phytoplankton development can produce autochthonous DOM, non humic substances that can have the ability of metal binding.. But there are few studies about trace metal speciation in lake water column.The main objectives of this thesis are (1) to obtain a consistent database of trace metal concentrations in the water column of representative urban lakes; (2) to access their bioavailability through an adapted speciation technique; (3) to analyze the seasonal and spatial evolution of the metals and their speciation; (4) to study the potential impact of environmental variables, particularly of dissolved organic matter related to phytoplankton production on metal bioavailability and (5) to link the metal concentrations to the land use in the lake watershed.Our methodology is based on a dense field survey of the water bodies in addition to specific laboratory analysis. The research has been conducted on three study sites: Lake Créteil (France), Lake Pampulha (Brazil) and a panel of 49 peri-urban lakes (Ile de France). Lake Créteil is an urban lake impacted by anthropogenic pollution. It benefits of a large number of monitoring equipment, which allowed us to collect a part of the data set. In Lake Pampulha catchment, the anthropogenic pressure is high. Lake Pampulha has to face with many pollution point and non-point sources. The climate and limnological characteristics of the lakes are also very different. The panel of 49 lakes of Ile de France was sampled once during three successive summers (2011-2013); they provided us with a synoptic, representative data set of the regional metal contamination in a densely anthropized region.In order to explain the role of the environmental variables on the metal concentrations, we applied the Random Forest model on the Lake Pampulha dataset and on the 49 urban lake dataset with 2 specific objectives: (1) in Lake Pampulha, understanding the role of environmental variables on the trace metal labile concentration, considered as potentially bioavailable and (2) in the 49 lakes, understanding the relationship of the environmental variables, more particularly the watershed variables, on the dissolved metal concentrations. The analysis of the relationships between the trace metal speciation and the environmental variables provided the following key results of this thesis.In Lake Pampulha, around 80% of the variance of the labile cobalt is explained by some limnological variables: Chl a, O2, pH, and total phosphorus. For the other metals, the RF model did not succeed in explaining more than 50% of the relationships between the metals and the limnological variables.In the 49 urban lakes in Ile de France, the RF model gave a good result for Co (66% of explained variance) and very satisfying for Ni (86% of explained variance). For Ni, the best explanatory variables are landuse variables such as “activities” (facilities for water, sanitation and energy, logistical warehouses, shops, office…) and “landfill”. This result fits with Lake Creteil where dissolved Ni concentration is particularly high and where the “activities” and “landfill” landuse categories are the highest

Parce qu’ils sont peu coûteux, faciles d’utilisation, et surtout très efficaces, les pesticides sont devenus une composante majeure de l’agriculture moderne et se sont imposés dans de nombreuses activités urbaines et domestiques. Ces molécules se retrouvent aujourd’hui dans tous les compartiments de l’environnement notamment dans les milieux aquatiques. Le suivi resserré des substances actives et de leurs résidus, présents dans l’environnement à des concentrations potentiellement dommageables pour les écosystèmes, apparaît aujourd’hui comme une nécessité. L’application de la Directive cadre sur l’eau, l’une des principales réglementations européenne ciblant les eaux, requiert des techniques d’échantillonnage et d’analyse performantes, alliant haute sensibilité, facilité de mise œuvre, coûts abordables, et surtout précision et fiabilité. Actuellement, la méthodologie employée consiste en des prélèvements ponctuels d’eau à pas de temps lâche (une fois par mois en général) suivi de l’analyse en laboratoire. Cette approche souffre d’un manque de représentativité temporelle, couplée à une sensibilité analytique souvent peu satisfaisante. Les techniques d’échantillonnage passif développées au cours des 20 dernières années pourraient être intégrées dans les réseaux de surveillance réglementaires afin de pallier ces manques, mais des questions subsistent encore quant à leur opérationnalité. Ces travaux de thèse visent à développer puis tester les échantillonneurs passifs sur le terrain afin de déterminer leur adéquation avec les exigences de la Directive cadre sur l’Eau, et le cas échéant, mettre en évidence les principaux verrous scientifiques résiduels. L’originalité de ce travail réside dans:- la variété des outils évalués : trois échantillonneurs différents ont été étudiés (Le Polar Organic Chemical Integrative Sampler (POCIS), le Chemcatcher et le Diffusive Gradient in Thin film (DGT). Les méthodes classiques de prélèvement ponctuels ont également été mise en œuvre.- la variété des environnements étudiés : deux bassins versant très différents ont été considérés, l’un présentant une contamination en pesticides forte, l’autre une contamination modérée.- La mise en en œuvre des échantillonneurs passifs dans un réel contexte réglementaire, les cours d’eau choisis faisant l’objet d’un contrôle opérationnel. Les données acquises avec les échantillonneurs passifs ont ainsi pu être comparées avec les suivis de l’Agence de l’Eau. / The intensive use of pesticides in agriculture and urban activities since the 1950s has led to diffuse contamination of environmental compartments (air, soil, water). The presence of these molecules can lead to toxic effects for biota. The implementation of the Water Framework Directive (WFD) requires the use of an efficient monitoring network, based on reliable sampling and analytical techniques. Nowadays, grab sampling followed by extraction of analytes and chromatographic analysis is the most widespread strategy because of its simplicity of implementation but it also has numerous drawbacks. The crux of the issue lies in the lack of temporal representativeness and the low analytical sensibility. An alternative strategy to overcome some of these problems could be the use of passive samplers. This contribution aims at discuss about the possible application of passive samplers in regulatory monitoring programs. The originality of this work lies in :The variety of tested devices: three different samplers was studied (The Polar Organic Chemical Integrative Sampler (POCIS), the Chemcatcher and the Diffusive Gradient in Thin Film (DGT). Conventional grab sampling strategies were also evaluated.The variety of studied environments: two very different watersheds were selected. The first one presented a high level of contamination; the second had a low contamination in pesticides.The implementation of passive samplers in a real regulatory context, as the selected streams were monitored by the Water Agency for operational control. Data from the Water Agency could therefore be compared with passive sampler data.

[pt] Foi investigada a determinação de Ni e Pb por GFAAS em n-hexano, n-heptano, n-octano, n-decano, n-hexadecano e misturas de n-octano + acetona (99+1, v/v), n-octano + bromofórmio (99+1, v/v) e n-octano + disulfeto de carbono (99+1, v/v). Com relação à estabilidade foram preparadas soluções com concentração (ao nível de ng.mL-1) por dissolução direta de padrões orgânicos nos diferentes líquidos orgânicos, apresentando perdas significativas de Ni e Pb depois de alguns minutos. Não foi observado padrão algum relacionado com o comprimento da cadeia carbônica, apesar das perdas menores quando substâncias contendo O, S e Br estiveram presentes. Foi observada uma excelente estabilidade nos diferentes meios orgânicos estudados com a formação de microemulsões. As microemulsões foram preparadas pela mistura de 6,5 mL de propan- 1-ol com 3,3 mL de líquido orgânico e 0,1 mL de HNO3 50% v/v. Foram adicionados Ni e Pb na forma aquosa ou orgânica. Foram aplicadas modificação química convencional e permanente no presente estudo. As etapas de secagem e rampa apresentaram influência na sensibilidade e tiveram que ser otimizadas. Curvas analíticas aquosas apresentaram maiores sensibilidades que aquelas em meio orgânico. Entretanto, foi observada a mesma sensibilidade para os diferentes meios estabilizados com microemulsão. Assim, curvas analíticas em microemulsão, preparadas com um solvente orgânico puderam ser utilizadas. Foram analisadas amostras de gasolina e diesel comercial, depois de sua estabilização na forma de microemulsão e por um procedimento comparativo, observando-se boa concordância entre ambos os procedimentos. Os limites de detecção da determinação de amostras de gasolina e diesel comercial foram derivados de 10 medidas do branco, sendo estes de 4,5 e 3,6 µg.L-1 para Ni e Pb respectivamente. / [en] The behaviour of Ni and Pb in different organic liquids relatively to their determination by GFAAS was investigated. The following organic liquids were studied: n- hexane, n-heptane, n-octane, isooctane, toluene, n-decane, hexadecane and mixtures of n-octane + acetone (99+1, v/v), n-octane + bromoform (99+1, v/v), and n-octane + carbon disulfide (99+1, v/v). Concerning stability, ng ml-1 solutions prepared by direct dissolution of organic standards in the different organic liquids showed significant Ni and Pb losses after only few minutes. No clear loss pattern related to chain length or form could be observed, although the losses were systematically slower when the O, S and Br compounds were present. Excellent long term sample stabilization was observed for the different organic media investigated if microemulsions are used. Microemulsions were prepared by mixing 6.5 ml of propan-1-ol with 3.3 ml of the organic liquid and 0.1 ml of 50% v/v HNO3. Ni and Pb could be added in the aqueous or aqueous forms. Conventional aqueous modification was allowed as well as Ir as permanent modifier. The dry and ramp steps showed to influence sensitivity, and must be carefully optimized. The same sensitivity was observed for the different microemulsion stabilized organic media. Thus, calibration with microemulsions prepared with a single organic solvent was possible. Commercial gasoline and diesel samples were analyzed after microemulsion stabilization and by a comparative procedure. Good concordance between both procedures was observed. Detection limits (k=3) in the original gasoline or diesel samples, derived from ten blank measurements were 4.5 and 3.6 µgl-1 for Ni and Pb, respectively, well above the values found in the analyzed samples.

Magister Scientiae - MSc (Chemistry) / In this study, graphene oxide was synthesized by oxidizing graphite using the modified Hummer's method. The graphene oxide was characterized by Raman Spectroscopy, Fourier Transform Infrared Spectroscopy, High Resolution Transmission Electron Microscopy, Scanning Electron Microscopy and X-Ray Diffraction for structural and morphological properties. The graphene oxide was electrochemically reduced on a carbon paste electrode followed by the in situ deposition of mercury thin films to achieve electrochemically reduced graphene oxide modified carbon paste metal film electrodes (ERGO-CP-MEs). The experimental parameters (amplitude, deposition time, deposition potential, frequency and rotation speed) were optimized, and the applicability of the modified electrode was investigated towards the simultaneous and individual determination of TI1+ and In3+ at the low concentration levels (?g L-1) in 0.1 M acetate buffer (pH 4.6) using square wave anodic stripping voltammetry (SWASV). The detection limit values for individual analysis at electrochemically reduced graphene oxide modified carbon paste mercury film electrode (ERGO-CP-HgE ) was 2.4 and 1.1 ?g L-1 for TI1+ and In3+, respectively. The detection limit values for simultaneous analysis at ERGO-CPE was 1.32 and 1.33 ?g L-1 and individual analysis was 0.975 and 1.04 ?g L-1 for TI1+ and In3+, respectively.

No description available.

Au Liban, 65% de la population résident à Beyrouth et au Mont Liban particulièrement dans la zone côtière et dans une bande étroite du flanc ouest du Mont Liban. Cette occupation engendre une forte pression anthropique sur les ressources hydriques. En effet environ 330 Mm3 d'eaux usées par an sont rejetés dans la Méditerranée par 53 émissaires distribués sur les villes côtières. Ces eaux, rejetées en grande majorité sans traitement, représentent le vecteur principal de pollution du milieu récepteur que représente la Mer Méditerranée (MOE/UNDP/ECODIT, 2011).Cette étude avait pour objectif principal de déterminer la qualité des eaux usées au Liban et d'établir une comparaison entre les contextes Libanais (en s'appuyant sur Beyrouth) et Français (cas de l'agglomération parisienne). Un suivi ponctuel des eaux usées provenant de 4 sites de prélèvement représentatifs de la région de Beyrouth et ses banlieues (sites d'Al Ghadir, Fleuve Beyrouth, Antelias et Jounieh) a été conduit. Deux sites ont été sélectionnés pour un suivi en continu de l'évolution des eaux usées aux échelles journalière et hebdomadaire : Jounieh et Al Ghadir. En France, une série de campagnes ont été réalisées sur les principaux émissaires des stations d'épuration de Marne Aval, Seine Amont, Seine Centre et Seine Aval, au sein de la STEP Seine Centre (au niveau des traitements primaire et secondaire), et en Seine. Ensuite les résultats à Beyrouth et Paris ont été confrontés pour déterminer l'impact sur l'environnement qu'aurait la mise en place de traitements adaptés aux effluents libanais. Les niveaux de contamination pour les paramètres globaux sont comparables pour le prélèvement ponctuel entre les bassins versants d'Al Ghadir et de Jounieh. Cependant les niveaux relevés à Al Ghadir et Jounieh sont plus élevés que ceux d'Antelias et Fleuve Beyrouth. Par ailleurs, le suivi en continu a permis de mettre en évidence que les niveaux en MES, MVS, DCOT et DBO5 sont généralement comparables sur les deux sites Al Ghadir et Jounieh. La comparaison avec les émissaires parisiens montre des différences significatives pour les MES, MVS et DBO5, ces paramètres sont significativement plus élevés sur les sites libanais. Pour la DCOT, les concentrations sont comparables entre les deux pays. En comparant les ETM totaux (Cr, Zn, Cu, Cd et Pb), on trouve que la concentration en cuivre des émissaires parisiens est plus élevée que celle du Liban pour les bassins versants d'Al Ghadir et Jounieh. Pour le plomb et le zinc, les concentrations sont comparables entre les deux pays. Enfin les concentrations en cadmium et chrome sont beaucoup plus élevées à Beyrouth qu'à Paris. Les flux en ETM au Liban exportés vers la Mer Méditerranée pour le site d'Al Ghadir sont 20,7; 20,8; 2,42; 0,6; et 1,5 kg/jour respectivement pour le CrT, ZnT, CuT, CdT et PbT et pour l'émissaire de Jounieh 0,66; 3,7; 0,38; 0,045 et 0,33 kg/jour. En s'appuyant sur l'efficacité des STEP parisiennes, les niveaux rejetés diminueraient de 90 à 98% pour les MES, de 84 à 95% pour la DCOT et de 63 à 97 % suivant l'ETM concerné / In Lebanon, 65 % of the population lives in Beirut and Mount Lebanon particularly along the coastal area and a narrow band of the western side of the Lebanon Mount. This occupation generates a strong anthropic pressure on the water resources. Indeed approximately 330 mm3 of waste waters a year are rejected into the Mediterranean by 53 trunks distributed along the coastal towns. In fact, these wastewaters are released to natural media without any significant treatment and These effluents, released in great majority without treatment, are considered as the primary vector of the Mediterranean Sea pollution (MOE/UNDP/ECODIT, 2011).This study aimed at determining the quality of wastewaters in Lebanon and at establishing a comparison between the Lebanese (with respect to Beirut) and French (case of the urban area of Paris) contexts. A specific monitoring of wastewaters was led on 4 representative sampling sites of the area of Beirut and its suburbs (Al Ghadir sites, Beirut River, Antelias and Jounieh). Two sites were selected to follow the evolution of the wastewater quality both at the daily and weekly scale: Jounieh and Al Ghadir. In France, a series of campaigns were carried out on the main trunks of several wastewater treatment plants, e.g., Marne Aval, Seine Amont, Seine Aval and Seine Centre, in the Seine Centre WWTP (within the primary and secondary treatments), and in the Seine River. Then the results in Beirut and Paris were confronted to determine the environmental impact of the installation of treatments adapted to the Lebanese effluents.Contamination levels for the water quality parameters were comparable for the punctual sampling between the Al Ghadir and Jounieh watersheds. However, the levels found in Al Ghadir and Jounieh were higher than those of Antelias and Beirut River. In addition, continuous monitoring helped to highlight the levels of TSS, VSS, BOD5 and CODT were generally comparable at both sites: Al Ghadir and Jounieh. The comparison with the Parisian trunks showed significant differences for TSS, BOD5 and VSS, these parameters were significantly higher on Lebanese sites. For CODT, concentrations were comparable between the two countries. By comparing the total ETM (Cr, Zn, Cu, Cd and Pb), we found that Cu concentrations in Parisian trunks were higher than those of Lebanese Al Ghadir and Jounieh watersheds. For lead and zinc concentrations were comparable between the two countries. Finally, the concentrations of cadmium and chromium were much higher in Beirut than in Paris. Trace metal flows to the Mediterranean Sea from the Al Ghadir site were of 20,7; 20,8; 2,42; 0,6; and 1,5 kg/day for CrT, ZnT, CuT, CdT and PbT respectively, and for Jounieh they were of 0,66; 3,7; 0,38; 0,045 and 0,33 kg/day, respectively. Based on the effectiveness of the Parisian WWTPs, released levels would decrease by 90-98 % for TSS, 84-95 % for CODt and 63-97 % depending on the ETM concerned

This study reports the synthesis of graphene by oxidizing graphite to graphite oxide using H2SO4 and KMnO4 and reducing graphene oxide to graphene by using NaBH4. Graphene was then characterized using FT-IR, TEM, AFM, XRD, Raman spectroscopy and solid state NMR. Nafion-Graphene in combination with a mercury film electrode, bismuth film electrode and antimony film electrode was used as a sensing platform for trace metal analysis in 0.1 M acetate buffer (pH 4.6) at 120 s deposition time, using square-wave anodic stripping voltammetry (SWASV). Detection limits were calculated using 3σblank/slope. For practical applications recovery studies was done by spiking test samples with known concentrations of metal ions and comparing the results to inductively coupled plasma mass spectrometry (ICPMS). This was then followed by real sample analyses.