La composition chimique atmosphérique dépend principalement des émissions de polluants, de leurs précurseurs et de la météorologie. Les stratégies de gestion de la qualité de l’air ambitionnent des réductions substantielles d’émissions à long terme. Mais il est légitime d’évaluer si l’impact du changement climatique pourrait compenser ces efforts.Afin de répondre à cette problématique, on a recours à la modélisation qui permet de faire des projections à long terme, sous différents scénarios de sensibilité pour isoler les principaux facteurs. Se pose alors le problème des incertitudes dans la modélisation. L’approche privilégié pour les études d’impact du climat est la modélisation ensembliste. Cependant du fait de l'important coût de calcul, on constate qu’aucune étude passée d’impact du climat sur la qualité de l’air ne repose sur un ensemble large de projections climatiques. C’est pourquoi, nous avons développé une méthode statistique alternative, entraînée sur des grands ensembles de simulation, pour caractériser l'impact des émissions et de la météorologie sur la qualité de l'air dans un contexte de changement climatique.Nous avons montré qu'un modèle statistique permettait d'obtenir des réponses sur l'impact du climat sans forcément avoir à réaliser explicitement des modélisations d'ensemble. La méthode développée donne des résultats avec une incertitude faible sur le long terme, même si nous avons montré ses limites lorsqu'il s'agit de traiter des cas de pollution extrêmes.Afin de quantifier l'erreur induite par les données climatiques des modèles actuellement conservées de manière partielle, nous avons réalisé une étude de sensibilité à la résolution verticale des modèles climatiques régionaux. Nous avons montré qu'un minimum de dix niveaux verticaux, ainsi que des variables supplémentaires à l'existant étaient indispensables si l'on voulait que l'erreur de simulation reste inférieure au signal climatique étudié.Enfin, nous avons utilisé le modèle statistique pour confronter l’impact du changement climatique aux réductions d'émissions anthropiques attendues à l’avenir. Les résultats ont permis de mettre en évidence que le bénéfice climatique pour les particules fines, PM2.5, était du même ordre de grandeur que les baisses réalisées dans le secteur le plus influent de chaque pays étudié. Ces baisses d'émissions vont donc être renforcées par le changement climatique. Au contraire, pour le SOMO35, la pénalité climatique va contrebalancer les efforts de réductions d'émissions réalisés entre 2050 et 2010. Pour les pays analysés, on peut estimer la date approximative de l’émergence du signal induit par le changement climatique malgré la réduction des émissions attendue dans la législation actuelle. / The atmospheric composition is mainly driven by the emission of primary pollutants and precursors and meteorology. Because of its sensitivity to unfavorable weather patterns, air pollution is expected to be sensitive to climate change. That is why the aim of this work is to estimate the effect of climate change over air pollution in Europe at the end of the century. To achieve this we rely on modeling which allow to cover such timescales. To reduce uncertainties and quantify the effect of climate change on air quality, ensemble approaches should be applied. However, the computing cost of such methods is substantial. To overcome this issue we developed a statistical method which does not require forcing a chemistry and transport model with a large ensemble of climate projections. The results obtained with this statistical method are in good agreement with full chemistry-transport models when considering long time periods. But we point out the limits of the method when focusing on extreme pollution events. The statistical model can be used to assess the uncertainty of using a comprehensive ensemble of climate forcing in terms of air quality impacts. The statistical approach can also help identifying a subset of climate forcing that should be explored in priority to drive chemistry-transport models.Such a subset of climate models is however only available at a degraded vertical resolution on existing databases such as EuroCordex. To quantify the error induced when using a meteorological variables only saved for a few vertical levels, a sensitivity study focused on the impact of the vertical resolution of the meteorological data has been perfomed. We emphasized that a minimum of 10 vertical levels and some specific variables were required to study the impact of climate change on air quality to keep the error lower than the climate change signal.Finally, we use the statistical method to compare the climate change effect and the future emissions reduction impact estimated also with a surrogate model. We exhibit that the magnitude of climate benefit for PM2.5 will be comparable to the emissions reductions of the dominant sector in each country studied. These emissions decreases will therefore be reinforced the climate change. On the opposite, for SOMO35, the climate penalty will jeopardize the emission reductions between 2010 and 2050. We also evaluate that climate change will become more important than the expected reduction emissions signal.

Air quality degradation is emerging to be an issue of major concern in India. Recent investigations have shown that anthropogenic aerosols have significant impact on climate as well as on health. In fourth assessment report of IPCC, it has been mentioned that radiative effects of anthropogenic aerosols constitute one of the major uncertainties in assessing aerosol-induced climate impact. In addition to climate impacts, aerosol causes respiratory and cardiovascular diseases, air quality degradation, acidification of aquatic and terrestrial ecosystems. Characterization of anthropogenic aerosol fraction (defined as the fraction of anthropogenic aerosols to composite aerosols) is an appealing topic of research in current scenario. The first step towards achieving this goal is to separate natural aerosol from composite aerosols, which is a complex task. The main objective of this thesis work is the assessment of air quality and anthropogenic aerosol fraction over India using observations (ground-based as well as satellite-based) and chemistry-transport model. Specifically objectives are (a) assessment of air quality and anthropogenic aerosol fraction over Indian region (b) develop a method to derive natural aerosol properties over land and oceans using multi-satellite data analysis, which is first step towards separating natural aerosol effects from its anthropogenic counter parts and (c) evaluate performance of CHIMERE chemistry-transport model for Indian region and validate its suitability to air quality studies over India. In this thesis, different approaches have been followed such as ground-based observations, multi-satellite data analysis and CHIMERE transport model. We have used multi-year observations of particulate mass (PM) concentration, aerosol black carbon (BC) mass concentration and aerosol optical depth (AOD) from a network of observatories to make an assessment of ambient air quality over India. First, we have developed a method to estimate dust and sea-salt optical depth using multi-satellite data analysis. This enabled the determination of anthropogenic aerosol fraction over land and ocean and we have validated this method by comparing against observations. Surprisingly, even over desert locations in India and Saudi Arabia, the anthropogenic fraction were unexpectedly high (~0.3 to 0.4) and the regionally averaged anthropogenic fraction over India was 0.620.06 (for the year 2004). The CHIMERE chemistry-transport model was used to simulate PM, BC and AOD over India and are compared with measurements. Evaluation of CHIMERE output shows that diurnal and seasonal trends are captured reasonably well by the model. It was found that absolute magnitudes differ substantially during monsoon months. Model simulations are also used to estimate anthropogenic fraction over Indian region and are compared with observations. Implications of the results are discussed. Mineral dust constitutes the single largest contributor of natural aerosols over continents. The first step towards separating natural aerosol radiative impact from its anthropogenic counterparts over continents is to gather information on dust aerosols. The infrared (IR) radiance (10.5–12.5 mm) acquired from the Kalpana satellite (8-km resolution) was used to retrieve regional characteristics of dust aerosols over the Afro-Asian region during the winter of 2004, coinciding with a national aerosol campaign. Here, we used aerosol-induced IR radiance depression as an index of dust load. The regional distribution of dust over various arid and semi-arid regions of India and adjacent continents has been estimated, and these data in conjunction with regional maps of column aerosol optical depth (AOD) are used to infer anthropogenic aerosol fraction. Surprisingly, even over desert locations in India and Saudi Arabia, the anthropogenic fraction were relatively high (0.3 to 0.4) and the regionally averaged anthropogenic fraction over India was 0.62 ±0.06. Sea-salt constitutes the single largest contributor of natural aerosols over oceans. We derive sea-salt aerosol distribution using a method utilizing multi-satellite data analysis. This information was used in conjunction with dust aerosols retrieval to calculate anthropogenic fraction over land and ocean. First, we derived a relation between MODIS AOD and NCEP wind speed at the sea-surface. An exponential increase in AOD as a function of wind speed was observed from mid of southern ocean to northern Arabian Sea. Latitudinal variation of wind independent component of optical depth (τ0) and wind index (b) was used to estimate the sea-salt optical depth over Arabian Sea. The value of τ0 showed an exponential increase as we move towards north from 35°S while b showed linear increase. The derived relations for the τ0 and b have been used to derive the sea-salt AOD distribution over oceanic regions in the domain (Eq-30°N; 30°E-110°E). Then we subtract the natural aerosol contribution from composite AOD data from MISR to obtain anthropogenic aerosol fraction. Over Indian region, high anthropogenic fraction was observed over northern belt specifically Indo-Gangetic Plains (IGP). Annually averaged anthropogenic fraction over Indian domain (4N-29.5N; 67E-88.5E) is ~0.43. Further, we have investigated the impact of sea-surface winds on sea-salt radiative effect in visible and infrared region with the help of SBDART radiative transfer model. The SBDART simulations have shown that at 15 m s-1, sea-salt induced shortwave cooling at the sea-surface was -86 W m-2. Derivation of anthropogenic aerosol fraction over whole Indian domain has demonstrated the importance of anthropogenic aerosols. This observation motivated us to examine the air quality over Bangalore, a fast growing city in India. We have analyzed data from ground based measurements of particulate matter, observations from satellites and also model simulations. Comparison with national threshold indicates that more than 50% of observations were above the residential threshold. To represent the air quality of Bangalore we have calculated the air quality index (AQI) for air pollutants. Coarse spatial and temporal resolution of observational data is one major shortcoming in such analysis. Therefore, satellite observations are alternative to quantify the air quality over large area. We have used MODIS AOD and RSPM to develop an empirical relation between these two parameters. A reasonably good agreement was observed between measured RSPM and RSPM derived using satellite data (by applying empirical relation). The CHIMERE chemistry-transport model was used to simulate PM, BC and AOD over India and are compared with measurements. Evaluation of CHIMERE output shows that diurnal and seasonal trends are captured reasonably well by the model. It was found that absolute magnitudes differ substantially during pre-monsoon and monsoon months. Model simulations are also used to estimate anthropogenic fraction over Indian region and are compared with observations. Implications of the results and future scope are discussed. The validation of model results suggests that CHIMERE model is suitable for simulating air quality over India with reasonable accuracy. This would in turn help us to address the impacts of air pollution on regional climate and help policy makers in order to reduce the air pollution. In summary, we have developed a new method to infer natural aerosol (sea-salt and dust) properties using multi-satellite data analysis. This technique has been applied to derive anthropogenic aerosol fraction over Indian region. Surprisingly, even over desert locations in India and Saudi Arabia, the anthropogenic fraction were relatively high (0.3 to 0.4) and regionally averaged anthropogenic fraction over India was 0.62±0.06 in 2004. This study indicates that multi-satellite observations can provide a powerful tool in monitoring air quality. We have noticed that anthropogenic fraction was 0.62 in 2004 and reduced to 0.43 in 2008. Major anthropogenic aerosol over India is BC and decreasing trend in BC could be one of the reasons for the decrease in anthropogenic fraction from 2004 to 2008. The CHIMERE chemistry-transport model was used to simulate PM, BC and AOD over India and are compared with measurements. Evaluation of CHIMERE output shows that diurnal and seasonal trends are captured reasonably well by the model. It was found that absolute magnitudes differ substantially during pre-monsoon and monsoon months. Presence of elevated aerosol layers during these seasons could be one of the sources for such discrepancy. Model simulations of anthropogenic fraction over Indian region are compared with observations and found good agreement. Results from this thesis moves us one step forward to reduce the uncertainties involved in anthropogenic aerosol fraction, its spatial and temporal distributions and regional distribution of OC/BC ratio, which are most important parameters in order to assess the climate forcing by anthropogenic aerosols.

The overall goals of this dissertation are to advance the field of chemical data assimilation, and to develop efficient computational tools that allow the atmospheric science community benefit from state of the art assimilation methodologies. Data assimilation is the procedure to combine data from observations with model predictions to obtain a more accurate representation of the state of the atmosphere. As models become more complex, determining the relationships between pollutants and their sources and sinks becomes computationally more challenging. The construction of an adjoint model ( capable of efficiently computing sensitivities of a few model outputs with respect to many input parameters ) is a difficult, labor intensive, and error prone task. This work develops adjoint systems for two of the most widely used chemical transport models: Harvard's GEOS-Chem global model and for Environmental Protection Agency's regional CMAQ regional air quality model. Both GEOS-Chem and CMAQ adjoint models are now used by the atmospheric science community to perform sensitivity analysis and data assimilation studies. Despite the continuous increase in capabilities, models remain imperfect and models alone cannot provide accurate long term forecasts. Observations of the atmospheric composition are now routinely taken from sondes, ground stations, aircraft, and satellites, etc. This work develops three and four dimensional variational data assimilation capabilities for GEOS-Chem and CMAQ which allow to estimate chemical states that best fit the observed reality. Most data assimilation systems to date use diagonal approximations of the background covariance matrix which ignore error correlations and may lead to inaccurate estimates. This dissertation develops computationally efficient representations of covariance matrices that allow to capture spatial error correlations in data assimilation. Not all observations used in data assimilation are of equal importance. Erroneous and redundant observations not only affect the quality of an estimate but also add unnecessary computational expense to the assimilation system. This work proposes techniques to quantify the information content of observations used in assimilation; information-theoretic metrics are used. The four dimensional variational approach to data assimilation provides accurate estimates but requires an adjoint construction, and uses considerable computational resources. This work studies versions of the four dimensional variational methods (Quasi 4D-Var) that use approximate gradients and are less expensive to develop and run. Variational and Kalman filter approaches are both used in data assimilation, but their relative merits and disadvantages in the context of chemical data assimilation have not been assessed. This work provides a careful comparison on a chemical assimilation problem with real data sets. The assimilation experiments performed here demonstrate for the first time the benefit of using satellite data to improve estimates of tropospheric ozone. / Ph. D.

Halogen-driven ozone and nonmethane hydrocarbon losses in springtime Arctic boundary layer are investigated using a regional chemical transport model (CTM). Surface observation of O3 at Alert and Barrow and aircraft observations of O3 and hydrocarbons during the TOPSE experiment from February to May in 2000 are analyzed. We prescribe halogen radical distributions based on GOME BrO observations and calculated or observed other halogen radical to BrO ratios. GOME BrO shows an apparent anti-correlation with surface temperature over high BrO regions. At its peak, area of simulated near-surface O3 depletions (O3 LT 20ppbv) covers GT 50% of the north high latitudes. Model simulated O3 losses are in agreement with surface and aircraft O3 observations. Simulation of halogen distributions are constrained using aircraft hydrocarbon measurements. We find the currently chemical mechanism overestimate the Cl/BrO ratios. The model can reproduce the observed halogen loss of NMHCs using the empirical Cl/BrO ratios. We find that the hydrocarbon loss is not as sensitive to the prescribed boundary layer height of halogen as that of O3, therefore producing a more robust measure for evaluating satellite column measurement. Tropospheric tracer transport and chemical oxidation processes are examined on the basis of the observations at northern mid-high latitudes and over the tropical Pacific and the corresponding global 3D CTM (GEOS-CHEM) simulations. The correlation between propane and ethane/propane ratio is employed using a finite mixing model to examine the mixing in addition to the OH oxidations. At northern mid-high latitudes the model agrees with the observations before March. The model appears to overestimate the transport from lower to middle latitudes and the horizontal transport and mixing at high latitudes in May. Over the tropical Pacific the model reproduces the observed two-branch slope values reflecting an underestimate of continental convective transport at northern mid-latitudes and an overestimate of latitudinal transport into the tropics. Inverse modeling using the subsets of observed and simulated data is more reliable by reducing (systematic) biases introduced by systematic model transport model transport errors. On the basis of this subset we find the model underestimates the emissions of ethane and propane by 14 5%.

Ziel dieser Arbeit war es, Beziehungen zwischen den kristallchemischen Eigenschaften und dem beobachteten anomalen Verhalten im spezifischen elektrischen Widerstand (nicht-magnetischer Kondo-Effekt) aufzuzeigen und zusammenhängend zu interpretieren. Verbindungen, an denen dieser Effekt beobachtet wurde, werden aus einem Übergangs-, oder Actinidmetall mit je einem Vertreter der 15. (Pniktogene) und 16. Gruppe (Chalkogene) des Periodensystems gebildet und kristallisieren im PbFCl-Strukturtyp. Da zu ternären Actinidmetall-Pniktid-Chalkogeniden (z.B. ThAsSe, UPS) nur sehr wenige chemische und kristallographische Informationen existieren, wurden in dieser Arbeit umfassende Untersuchungen zur Kristallchemie ternärer Phasen aus den Systemen M-Pn-Q (M = Zr, Hf, La-Ce; Pn = As, Sb; Q = Se, Te durchgeführt. Der Schwerpunkt lag dabei auf der strukturellen Lokalisierung der beobachteten Widerstandsanomalie und der Erarbeitung chemisch-physikalischer Eigenschaftsbeziehungen. Die Darstellung der untersuchten ternären Phasen in Form von Einkristallen gelang über exothermen Chemischen Transport mit Jod. Da die erhaltenen Kristalle bis zu mehreren Millimetern groß sind, konnten an ein und demselben Kristallindividuum sowohl die stoffliche Charakterisierung (EDXS, WDXS, ICP-OES, LA-ICP-MS, CIC) und die strukturelle Charakterisierung, als auch die Messung der physikalischen Eigenschaften erfolgen. Es konnte u.a. gezeigt werden, dass ZrAs1,4Se0,5 und HfAs1,7Se0,2 ein ähnlich ungewöhnliches Verhalten im temperaturabhängigen elektrischen Widerstand zeigen, welches bereits an Thorium-Arsenid-Seleniden und Uran-Phosphid-Sulfiden beobachtet wurde. Desweiteren gelang es den beobachteten Verlauf im elektrischen Widerstand, mit seinem Minium bei etwa T = 15 K, auf intrinsische strukturelle Merkmale in der anionischen Arsen-Teilstruktur zurückzuführen. / The aim of this work was, to evaluate and interpret a relationship between the crystal-chemical properties and the observed unusual behavior in the electrical resistivity (non-magnetic Kondo-effect). Compounds, which show such an effect, are formed by a transition- or actinide-metal with both a group 15 element and a group 16 element of the periodic table. All these compounds crystallizing in the PbFCl type of structure. Because of less crystallographic and chemical information about actinide-metal-pnictide-chalcogenides (i.e. ThAsSe, UPS), intensive investigation were made concerning the crystal-chemistry of ternary phases of the systems M-Pn-Q (M = Zr, Hf, La-Ce; Pn = As, Sb; Q = Se, Te. Our studies were focused on the structurally localization of the observed anomaly in the electrical resistivity and the evaluation of chemical-physical relations of properties. The synthesis of the investigated ternary phases was realized by exothermically Chemical Transport with iodine as transport agent. The dimension of the synthesized crystals allowed a chemical (EDXS, WDXS, ICP-OES, LA-ICP-MS, CIC) and structurally characterization, as well as a determination of the physical properties on one large single crystal. It could be shown, that ZrAs1,4Se0,5 and HfAs1,7Se0,2 reveal a similar unusual behavior in the temperature dependent electrical resistivity, as it was observed in thorium-arsenide-selenides and uranium-phosphide-sulphides. In conclusion, the non-magnetic Kondo-effect, which was found in the low-temperature range (about 15 K), arises from structurally features of the anionic sublattice with arsenic.

Des détériorations importantes sont observées dans les réseaux d’assainissement en béton en raison de la présence d’hydrogène sulfuré (H2S). Différentes études ont montré qu’un environnement riche en hydrogène sulfuré entraîne, au contact de surfaces cimentaires, la sélection de bactéries sulfo-oxydantes (bactéries capables d’oxyder des composés soufrés réduits), menant à la production d’acide sulfurique. Cet acide détériore localement les réseaux par dissolution et recomposition minéralogique de la matrice cimentaire (formation de gypse et d’ettringite). Les réseaux ne collectent alors plus correctement les eaux usées et ce phénomène provoque donc des travaux de rénovation onéreux. Dans ce contexte, des solutions plus performantes que celles mises en place actuellement doivent être étudiées. L’objectif du projet FUI DURANET dans lequel s’inscrit cette thèse vise à proposer un essai accéléré et à développer un modèle.La mise en place d’essais abiotiques a permis de démontrer que cette première étape n’est pas l’étape limitante du phénomène de biodétérioration. En effet, le pH de surface des matériaux cimentaires adapté au développement microbien est rapidement atteint lorsqu’ils sont mis au contact de l’hydrogène sulfuré à une concentration élevée (100 ppm), quel que soit le matériau cimentaire considéré (mortiers à base de ciments CEM I, CEM III, CEM IV, CEM V, CAC et CSS). La modélisation de l’attaque par l’acide sulfurique et la mise en place d’un essai représentatif et accéléré ont ensuite été abordées pour prédire la durabilité des différents matériaux cimentaires de l’étude. Pour l’essai, différentes techniques d’ensemencement des microorganismes à la surface des matériaux cimentaires ont été comparées, afin de déterminer laquelle mène à la meilleure reproduction des conditions d’un réseau d’assainissement et à l’accélération des mécanismes de biodétérioration la plus importante. Ces essais permettent de préconiser l’utilisation de boues activées contenant un consortium de microorganismes, par rapport à l’utilisation de souches de collection, dont l’activité dépend trop fortement de leur adaptabilité aux conditions environnementales. L’ensemble des résultats, obtenus expérimentalement et par modélisation, montre une meilleure résistance des ciments d’aluminate de calcium et une dégradation très importante des ciments Portland face aux mécanismes mis en jeu, en accord avec les essais in-situ / Important deteriorations have been observed in concrete sewers, due to hydrogen sulfide (H2S) presence. H2S is used as nutrients for sulfur-oxidizing bacteria (bacteria able to oxidize the reduced sulfur compounds) and is oxidized into sulfuric acid. This acid attack of concrete leads to cementitious matrix dissolution and expansive products formation (gypsum and ettringite). This phenomenon disturbs the sewer system and conducts to expensive works of rehabilitation. In order to avoid this degradation, a French project named “FUI Duranet” was initiated to propose more efficient solutions. The aim of this thesis is to define a representative and accelerated test as well as a predictive model.Abiotic tests allow stating that this first stage of the biodeterioration mechanisms is not the limiting stage. Indeed, the adapted surface pH of the cementitious materials to bacteria development is quickly reached with a high H2S concentration (100 ppm), whatever the cementitious materials considered (mortars based on CEM I, CEM III, CEM IV, CEM V, CAC, and SSC cements). The chemical-transport modeling of the sulfuric acid attack of cementitious materials and the establishment of a representative and accelerated test have been proposed to predict their service life in these conditions. For the test, different seeding technics have been compared in order to determine which one lead to the better reproduction and acceleration of biodeterioration mechanisms. This test allows recommending the sludge use, which contains a microorganism’s consortium, rather than a collection strain use, whose activity is too dependent on environmental conditions. With the experimental test and the model, the better resistance of the calcium aluminate cement and the important degradation of the Portland cements are quickly confirmed, as highlighted during the field tests

Ziel dieser Arbeit war es, Beziehungen zwischen den kristallchemischen Eigenschaften und dem beobachteten anomalen Verhalten im spezifischen elektrischen Widerstand (nicht-magnetischer Kondo-Effekt) aufzuzeigen und zusammenhängend zu interpretieren. Verbindungen, an denen dieser Effekt beobachtet wurde, werden aus einem Übergangs-, oder Actinidmetall mit je einem Vertreter der 15. (Pniktogene) und 16. Gruppe (Chalkogene) des Periodensystems gebildet und kristallisieren im PbFCl-Strukturtyp. Da zu ternären Actinidmetall-Pniktid-Chalkogeniden (z.B. ThAsSe, UPS) nur sehr wenige chemische und kristallographische Informationen existieren, wurden in dieser Arbeit umfassende Untersuchungen zur Kristallchemie ternärer Phasen aus den Systemen M-Pn-Q (M = Zr, Hf, La-Ce; Pn = As, Sb; Q = Se, Te durchgeführt. Der Schwerpunkt lag dabei auf der strukturellen Lokalisierung der beobachteten Widerstandsanomalie und der Erarbeitung chemisch-physikalischer Eigenschaftsbeziehungen. Die Darstellung der untersuchten ternären Phasen in Form von Einkristallen gelang über exothermen Chemischen Transport mit Jod. Da die erhaltenen Kristalle bis zu mehreren Millimetern groß sind, konnten an ein und demselben Kristallindividuum sowohl die stoffliche Charakterisierung (EDXS, WDXS, ICP-OES, LA-ICP-MS, CIC) und die strukturelle Charakterisierung, als auch die Messung der physikalischen Eigenschaften erfolgen. Es konnte u.a. gezeigt werden, dass ZrAs1,4Se0,5 und HfAs1,7Se0,2 ein ähnlich ungewöhnliches Verhalten im temperaturabhängigen elektrischen Widerstand zeigen, welches bereits an Thorium-Arsenid-Seleniden und Uran-Phosphid-Sulfiden beobachtet wurde. Desweiteren gelang es den beobachteten Verlauf im elektrischen Widerstand, mit seinem Minium bei etwa T = 15 K, auf intrinsische strukturelle Merkmale in der anionischen Arsen-Teilstruktur zurückzuführen. / The aim of this work was, to evaluate and interpret a relationship between the crystal-chemical properties and the observed unusual behavior in the electrical resistivity (non-magnetic Kondo-effect). Compounds, which show such an effect, are formed by a transition- or actinide-metal with both a group 15 element and a group 16 element of the periodic table. All these compounds crystallizing in the PbFCl type of structure. Because of less crystallographic and chemical information about actinide-metal-pnictide-chalcogenides (i.e. ThAsSe, UPS), intensive investigation were made concerning the crystal-chemistry of ternary phases of the systems M-Pn-Q (M = Zr, Hf, La-Ce; Pn = As, Sb; Q = Se, Te. Our studies were focused on the structurally localization of the observed anomaly in the electrical resistivity and the evaluation of chemical-physical relations of properties. The synthesis of the investigated ternary phases was realized by exothermically Chemical Transport with iodine as transport agent. The dimension of the synthesized crystals allowed a chemical (EDXS, WDXS, ICP-OES, LA-ICP-MS, CIC) and structurally characterization, as well as a determination of the physical properties on one large single crystal. It could be shown, that ZrAs1,4Se0,5 and HfAs1,7Se0,2 reveal a similar unusual behavior in the temperature dependent electrical resistivity, as it was observed in thorium-arsenide-selenides and uranium-phosphide-sulphides. In conclusion, the non-magnetic Kondo-effect, which was found in the low-temperature range (about 15 K), arises from structurally features of the anionic sublattice with arsenic.

Tous les produits de construction ou les ouvrages qui sont en contact avec l’eau de pluie, sont susceptibles de relarguer des composants chimiques potentiellement dangereux pour la santé humaine et l’environnement. Actuellement, le relargage des substances dangereuses dans l’eau est évalué essentiellement par des méthodes expérimentales - généralement des essais de lixiviation réalisées à l’échelle du laboratoire. Par ailleurs, les impacts environnementaux des produits de construction et des bâtiments sont évalués par l’approche Analyse de Cycle de Vie (ACV), réalisées à partir de données propres aux fabricants et de données génériques existantes constituées en bases de données. Or, les émissions de polluants pendant la vie en oeuvre des produits de construction sont actuellement mal prises en compte dans ces mêmes bases de données existantes et dans les méthodes utilisées pour l’évaluation des performances environnementales des produits et des bâtiments.Dans ce contexte, les objectifs de ces travaux ont été : (i) de développer une méthodologie pour l’évaluation du comportement à la lixiviation de différentes matrices de produits de construction et (ii) d’intégrer les données de lixiviation dans les méthodes ACV à l’échelle du bâtiment. La méthodologie développée pour l’évaluation du comportement à la lixiviation des produits de construction est basée sur : (1) des essais de caractérisation à la lixiviation, selon les méthodes standardisées d’évaluation répondant au Règlement Produits de Construction (RPC), (2) la modélisation et la simulation des phénomènes couplés chimie-transport à l’échelle laboratoire et vraie grandeur et (3) l’intégration des données de lixiviation, obtenues par des simulations numériques en conditions d’exposition naturelle des produits de construction, dans les méthodes ACV, aux échelles produit et bâtiment.La méthodologie proposée a été appliquée et validée sur trois produits de construction : le bois traité CBA (Cuivre - Bore - Azole), la plaque fibrociment et la membrane bitumineuse. Les comportements à la lixiviation du bois traité CBA et de la plaque fibrociment a été simulé pour des conditions naturelles d’exposition à long terme, en utilisant le logiciel géochimique PHREEQC®. Les modèles chimiques développées permettent de considérer les matrices organiques et minérales et leurs interactions avec les polluants. Les phénomènes de transport des substances ont été également modélisés. Les modèles d’émission développés (couplage chimie-transport) permettent de simuler la lixiviation dynamique des produits considérés, pour différentes conditions d’exposition. Pour la membrane bitumineuse, seule la caractérisation expérimentale a été réalisée. Les données de lixiviation obtenues lors des simulations sur la durée de vie en oeuvre des produits ont été intégrées dans les inventaires respectifs du cycle de vie (ICV) des produits. Des méthodes d’impact spécifiques ont été utilisées en association avec les inventaires enrichis pour évaluer les impacts “pollution de l’eau”, “toxicité humaine” et “écotoxicité” des produits considérés. L’ACV d’une maison simplifiée a été réalisée en utilisant le logiciel ELODIE. La méthode d’évaluation à l’échelle bâtiment consiste à intégrer les nouvelles données construites sur la base de la méthodologie développée à l’échelle produit aux autres données d’ACV à l’échelle bâtiment. La méthodologie développée au cours de ces travaux permet donc l’intégration des données de lixiviation dans les outils ACV dédiés au bâtiment / Any construction product and building undergoing contact with water during its life cycle can release chemical compounds potentially hazardous for the human health and the environment. The release of dangerous substances is presently investigated especially by experimental approaches commonly by laboratory leaching tests while the environmental impacts of construction products and buildings are evaluated by a Life Cycle Assessment (LCA) approach. The dangerous substances release during use stage of construction products (leaching behaviour) is currently very poorly represented in the existing data bases and methods for environmental assessment of construction products and buildings.In this context, the main objectives of this study were: (i) to develop a methodology for the assessment of the leaching behaviour of various construction products and (ii) to integrate the leaching data in LCA approach at building scale. The methodology developed for the assessment of the leaching behaviour of construction products is based on: (1) characterisation leaching tests at lab scale, following the horizontal standardised assessment methods for harmonised approaches relating to dangerous substances under the Construction Products Regulation (CPR), (2) modelling and simulation of coupled chemical and transport phenomena at lab and field scale, and (3) utilisation of simulated leaching data for the construction products exposed in natural condition with the LCA method for the characterization of the hazardous effect during the use stage. The proposed methodology was applied and validated on three different classical construction products i.e. CBA (Copper-Boron-Azole) treated wood, fibre-cement sheets and bitumen membranes. The leaching behaviour of CBA treated wood and fibre-cement sheets was simulated over several years under natural exposure conditions, using the geochemical software PHREEQC. The chemical models consider both the mineral and the organic matrixes and their interaction with treatmentcompounds. Mass transfer and transport phenomena were modelled. The developed coupled chemical-transport models are able to represent the dynamic leaching behaviour of the respective products in various leaching conditions. For bitumen membranes only experimental characterisation was possible. The leaching data obtained by simulation over the whole use stage of the products were integrated in the life cycle inventory (LCI) and the relevant life cycle impact assessment (LCIA) methods were applied with the enriched inventory. A simplified single-family house was modelled using a software designed to evaluate the intrinsic environmental performances of a building over its entire life cycle. ELODIE software was used in this work. The building scale assessment methodology is based on coupling the methodology developed for the product scale with the Life Cycle Assessment (LCA) at building scale. This methodology allows a proper integration of leaching data in LCA tools and answers several technical questions raised in the field

Accurate models to reliably predict sediment and chemical transport in watershed water systems enhance the ability of environmental scientists, engineers and decision makers to analyze the impact of contamination problems and to evaluate the efficacy of alternative remediation techniques and management strategies prior to incurring expense in the field. This dissertation presents the conceptual and mathematical development of a general numerical model simulating (1) sediment and reactive chemical transport in river/stream networks of watershed systems; (2) sediment and reactive chemical transport in overland shallow water of watershed systems; and (3) reactive chemical transport in three-dimensional subsurface systems. Through the decomposition of the system of species transport equations via Gauss-Jordan column reduction of the reaction network, fast reactions and slow reactions are decoupled, which enables robust numerical integrations. Species reactive transport equations are transformed into two sets: nonlinear algebraic equations representing equilibrium reactions and transport equations of kinetic-variables in terms of kinetically controlled reaction rates. As a result, the model uses kinetic-variables instead of biogeochemical species as primary dependent variables, which reduces the number of transport equations and simplifies reaction terms in these equations. For each time step, we first solve the advective-dispersive transport of kinetic-variables. We then solve the reactive chemical system node by node to yield concentrations of all species. In order to obtain accurate, efficient and robust computations, five numerical options are provided to solve the advective-dispersive transport equations; and three coupling strategies are given to deal with the reactive chemistry. Verification examples are compared with analytical solutions to demonstrate the numerical accuracy of the code and to emphasize the need of implementing various numerical options and coupling strategies to deal with different types of problems for different application circumstances. Validation examples are presented to evaluate the ability of the model to replicate behavior observed in real systems. Hypothetical examples with complex reaction networks are employed to demonstrate the design capability of the model to handle field-scale problems involving both kinetic and equilibrium reactions. The deficiency of current practices in the water quality modeling is discussed and potential improvements over current practices using this model are addressed.

This thesis presents the development of a numerical water quality model using a general paradigm of reaction-based approaches. In a reaction-based approach, all conceptualized biogeochemical processes are transformed into a reaction network. Through the decomposition of species governing equations via Gauss-Jordan column reduction of the reaction network, (1) redundant fast reactions and irrelevant kinetic reactions are removed from the system, which alleviates the problem of unnecessary and erroneous formulation and parameterization of these reactions, and (2) fast reactions and slow reactions are decoupled, which enables robust numerical integrations. The system of species transport equations is transformed to reaction-extent transport equations, which is then approximated with two subsets: algebraic equations and kinetic-variables transport equations. As a result, the model alleviates the needs of using simple partitions for fast reactions. With the diagonalization strategy, it makes the inclusion of arbitrary number of fast and kinetic reactions relatively easy, and, more importantly, it enables the formulation and parameterization of kinetic reactions one by one. To demonstrate the general paradigm, QAUL2E was recasted in the mode of a reaction network. The model then was applied to the Loxahatchee estuary to study its response to a hypothetical biogeochemical loading from its surrounding drainage. Preliminary results indicated that the model can simulate four interacting biogeochemical processes: algae kinetics, nitrogen cycle, phosphorus cycle, and dissolved oxygen balance.