<p>SO₂ and NO_x (NO+NO₂) are important trace gases in the atmosphere as they adversely affect air quality and are precursors to sulfate and nitrate aerosols in the atmosphere. However, there are significant uncertainties in the emission inventories and the atmospheric chemistry processes of both gases. Addressing these uncertainties will help us to 1) better regulate their emissions from anthropogenic activities, 2) understand the formation mechanism of aerosol pollution events, during which rapid accumulation of nitrate and sulfate aerosols are commonly observed, and 3) better constrain the impact of SO₂, NO_x, sulfate aerosols and nitrate aerosols to the global radiation balance. Stable isotopes of nitrogen and sulfur are useful tools in understanding both the origins and chemistry of SO₂ and NO_x since different emission sources usually display distinct sulfur and nitrogen isotopic compositions, and different SO₂ and NO_xoxidation pathways fractionate sulfur and nitrogen isotopes differently. In this dissertation, five studies are conducted to 1) use sulfur isotopes to investigate the sources and chemistry of atmospheric sulfur, and 2) improve our understanding of the isotopic fractionation processes associated with the atmospheric chemistry of reactive nitrogen. </p><p>Using stable sulfur isotopes, we first analyzed the sources of sulfate aerosols collected at Baring Head, New Zealand and atmospheric deposition at the Atacama Desert. At Baring Head, we found that the secondary sulfate, i.e., sulfate formed from atmospheric oxidation of SO₂, is mainly observed in fine aerosols (<1 µm) while the sulfate in coarse aerosols (>1 µm) is mostly sea salt sulfate. 73-77% of the secondary sulfate is sourced from biogenic emissions by ocean phytoplankton, and the rest is originated from anthropogenic activities. The sulfate deposition across the Atacama Desert, on the other hand, is a mixture of sea salt sulfate (only near the coast), anthropogenic SO₂ emissions, local soil, and lake salts. Then, sulfur isotopes were used to investigate the formation chemistry of sulfate aerosols collected during a strong winter haze episode in Nanjing, China, where the sources of SO₂ were well-understood. We found that, although the sources of sulfur remain unchanged during the haze episode, the sulfur isotopic compositions of sulfate vary significantly, suggesting isotopic fractionation occurred during the formation of sulfate aerosols. We interpreted the variation using a Rayleigh distillation model to evaluate the contribution of sulfate formation pathways. The model suggested that the Transition Metal Ion catalyzed O₂ oxidation pathway contributed 49±10% of the total sulfate production, while the O₃/H₂O₂ oxidations accounted for the rest. </p><p>Next, we conducted experiments in an atmospheric simulation chamber to determine the isotopic fractionations between NO and NO₂. This isotopic fractionation is controlled by a combination of two factors: 1) the equilibrium isotopic exchange between NO and NO₂ molecules, and 2) the kinetic isotope effects of the NO_x photochemical cycle, namely the Leighton Cycle Isotope Effect (LCIE). Our experiments showed that the fractionation factor during the isotopic exchange is 1.0289±0.0019, and the fractionation factor of LCIE is 0.990±0.005. A model was constructed to assess the relative importance of the two factors, showing the isotopic exchange should be the dominant factor when NO_x >20 ppb, while LCIE should be more important at low NO_x concentrations (<1 ppb) and high rates of NO₂photolysis. Last, we quantified the overall nitrogen isotopic fractionation during the formation of nitrate aerosols collected at Baring Head, New Zealand. Our results showed that significant and variable (0-15‰) isotopic fractionations occurred during the formation of nitrate aerosols. The isotopic fractionation factors are lower in the summer and higher in the winter, which is mainly caused by seasonal variations in nitrate formation pathways. </p><p>Overall, this dissertation first applied stable sulfur isotopes in aerosol samples collected in different environments, demonstrating that isotopes are excellent tools in identifying the origins and chemistry of atmospheric sulfur. Then, we investigated the isotopic fractionation processes during the atmospheric nitrogen chemistry, which can be useful for future studies aimed at understanding the origins and chemistry of atmospheric nitrogen using stable nitrogen isotopes.</p>

Nearly half of the electrical power produced in the United States is generated with coal. Coal power is inexpensive and reliable, but coal combustion releases harmful pollutants including NOx and SOx into the atmosphere if not controlled. CO2, a greenhouse gas, is also released during coal combustion and may contribute to global warming. A promising technology enabling carbon capture is oxy-coal combustion. During oxy-combustion, coal is burned in an atmosphere of O2 and recycled flue gas to eliminate nitrogen which makes up the majority of air-combustion flue gas. Oxy-combustion flue gas is mainly composed of CO2 and H2O. H2O can be condensed out of the gas, and the CO2 can then be captured and permanently stored relatively easily. The composition of the gas inside an oxy-fired boiler will be different due to the absence of nitrogen and the recycling of flue gas. Corrosive sulfur and chlorine gas species concentrations will be higher, and CO and NOx concentrations will be effected. An understanding of the differences in gas concentrations is critical to oxy-combustion boiler design. Four different pulverized coals were combusted in a reactor under staged and unstaged oxy-combustion conditions with warm recycled flue gas (420°F) to simulate conditions in an oxy-fired coal boiler. The gas composition was measured in the reducing and oxidizing zones for staged combustion, and in the same locations, 57 cm and 216 cm from the burner, for unstaged combustion. The results were compared to the results from similar staged air-combustion experiments using the same coals and burner. CO concentrations were higher for staged oxy-combustion compared to air-combustion, and the increase was more substantial for lower rank coals. H2S concentrations in the reducing regions were also higher, and the fraction of gas phase sulfur measured as H2S was higher for oxy-combustion. SO2 concentrations were 2.9 to 3.8 times as high as air-combustion concentrations. The measured conversion of coal sulfur to SO3 was lower for oxy-combustion, and ranged from 0.61% to 0.98%. The average fraction of coal sulfur measured in the gas phase was 84%, 80%, and 85% for staged oxy-combustion, unstaged oxy-combustion, and staged air-combustion respectively. HCl concentrations were 2.8 to 3.1 times higher in the staged oxy-combustion oxidizing zone, and a smaller fraction of coal chlorine was measured in the reducing zone. On average 70.8%, 79.5%, and 71.1% of the coal chlorine was measured as HCl for staged oxy-combustion, unstaged oxy-combustion, and staged air-combustion respectively. The fractions of coal chlorine and sulfur measured in the gas phase for staged combustion were not significantly affected by combustion media. Some staged oxy-combustion NO concentrations were lower than air-combustion concentrations while others were slightly higher, and NO emission rates were much lower due to recycling NO through the burner.

No description available.

Nine-week-old yellow-poplar and green and white ash were exposed to various concentrations of O₃ (0.00 to 0.15 ppm) and/or SO₂ (0.08 ppm), 4 hr/d, 5d/wk in combination with simulated rain (pHs 5.6, 4.3, 3.0), 1 hr/d, 2 d/wk, for 5 or 6 wk under controlled laboratory conditions. Pollutant exposures resulted in alterations in seedling biomass accumulation, growth rates, changes in carbon allocation among plant parts and modification in physiological processes associated with gas exchange. Ozone (0.010 ppm) and SO₂ together caused a significant decrease in height growth and biomass and an increase in leaf area ratio (LAR) in yellow-poplar. Ozone and SO₂ exposures resulted in linear decreases and increases, respectively, in root dry weight, leaf area increase, relative growth rates of all yellow-poplar plant parts and unit leaf rate with decreasing rain pH. Chlorophyll content increased in both O₃ and SO₂ treatments with increasing rain acidity. In green and white ash experiments height growth was inhibited by O₃, SO₂ and O₃ + SO₂ for green ash, whereas only leaf dry weight was decreased by O₃ exposure in white ash. Decreasing rain pH resulted in linear decreases in root/shoot ratio (RSR) and LAR, for white ash. In green ash, a quadratic response to rain pH occurred with these growth variables. Ozone and O₃ + SO₂-treated green ash exhibited a significant quadratic response in leaf weight ratio with increasing rain acidity. Leaf area ratio and RSR exhibited linear increases and decreases, respectively, for O₃ and rain acidity. In SO₂-treated white ash with increasing white ash and yellow-poplar seedlings exposed to various O₃ concentrations and simulated rain for 5 and 6 weeks, respectively, increasing O₃ concentrations caused linear decreases in height and biomass of white ash. Linear decreases in root growth rate and biomass and RSR occurred with decreasing rain pH, across O₃ treatments. Ozone (0.05 or 0.10 ppm) caused linear decreases in these variables in combination with increasing rain acidity. For yellow-poplar, increasing O₃ concentrations caused linear increases in RSR and specific leaf area. At 0.05 and 0.10 ppm O₃, stem and leaf biomass, their relative growth rates and leaf area all decreased with decreasing rain pH. Ozone (0.10 ppm) exposure caused a decrease in stomatal conductance, and decreasing variable. rain pH resulted in a linear decrease in this A linear decrease in net photosynthesis also occurred with increasing rain acidity in O₃-treated (0.10 ppm) plants. These results demonstrate that gaseous pollutants in combination with simulated acid rain can have detrimental effects on growth of three forest tree species, under controlled laboratory conditions. / Ph. D.

Ce travail se concentre sur le développement de systèmes catalytiques capable d’oxyder complètement le méthane à basse température. Le sujet principal concerne la conception d'une nouvelle génération de catalyseurs à base de palladium qui sont résistants aux composés soufrés et à l'eau.<p>Notre objectif a été atteint grâce à l'utilisation d'un support oxyde mixte produit par sol-gel. En effet, nos catalyseurs de palladium supporté sur un oxyde de silicium dopé au titane se sont révélés être résistants à l’empoisonnement au soufre et présentent des performances élevées pour la conversion du méthane.<p>En variant les quantités de TiO2, il a été montré que les performances atteignent un maximum pour une composition en masse de 10% TiO2. Les analyses structurelles et de surface ont montré que nos supports mixtes contiennent des liens Ti-O-Si. Nous pensons que ces liens sont responsables de l’activité accrue du catalyseur.<p>Par ailleurs, les catalyseurs contenant du titane présentent une tolérance supérieure vis-à-vis du SO2 lorsque celui-ci est ajouté aux réactifs ou que le catalyseur est exposé à une atmosphère de SO2 pur à 350°C pendant 15 heures. Nous avons mis en évidence par XPS que les sites Ti-O-Si sont également responsables de cette tolérance aux composés soufrés. Ceci est accompli par l'insertion du SO2 dans le support qui forme des liens soit Ti-O-SOx•••Si soit Si-O-SOx•••Ti. L’analyse XPS a également montré que sur le long terme, l’exposition au SO2 conduit à la formation d’une couche de PdSO4 de 18 à 20 Å. Étonnamment, les catalyseurs sont capables de récupérer entièrement leur activité initiale après ce traitement. Cette régénération se produit grâce à un mécanisme concerté avec le méthane permettant la décomposition totale du PdSO4. Par ailleurs, des études en présence d'eau ont montré que ces propriétés restent inchangées.<p>L'état du palladium a également été étudié et nous a permis de prouver qu’une activation/stabilisation du catalyseur est nécessaire. Celle-ci est réalisée en présence des réactifs par de légères modifications chimiques du support et de la phase de palladium. En effet, l'augmentation de l'activité du catalyseur a été corrélée avec une augmentation des quantités de Ti3+ et Pd0. La présence de palladium métallique dans le catalyseur semble être l'élément clé dans l'activation des liaisons C-H.<p>Enfin, nous avons étudié l'influence de la taille/la dispersion des particules de palladium sur la vitesse de réaction. L'utilisation de synthèses en phase liquide nous a permis de produire des solutions colloïdales de particules de palladium avec des tailles contrôlées. Cette étude a révélé que la combustion du méthane est une réaction sensible à la structure. Néanmoins, un meilleur contrôle de la forme des nanoparticules devrait être réalisé pour déterminer les facteurs structurels influençant la réaction./ The present work focuses on the development of highly efficient catalytic systems able to completely oxidize methane at low temperature in order to comply with modern environmental legislation. The main subject concerns the design of a new generation of palladium-based catalysts that are sulfur and water resistant. <p>Our goal was achieved through the use of a mixed oxide support produced by sol-gel. In fact, palladium-supported on titanium-doped silica catalysts have proven to be sulfur tolerant and exhibit high performances for the methane conversion. <p>Varying the amounts of TiO2 showed that the performance reached an optimum for a 10 wt.% TiO2 loading. According to the structural and surface analyses, the mixed oxides contained Ti-O-Si linkages, believed to be responsible for the better activity as compared to PdO supported on pure oxides. <p>Moreover, the titania-containing catalysts exhibited a superior tolerance towards SO2 when either adding it to the reactants or feeding it as a pure pretreatment atmosphere at 350°C (15 hour on stream). We evidenced using XPS that the Ti-O-Si sites are also responsible for the higher sulfur tolerance of the catalysts by the insertion of SO2 in the support forming either Ti-O-SOx•••Si or Si-O-SOx•••Ti. XPS analyses also evidenced that the long-term SO2-treatment leads to the formation of PdSO4 with a thickness of 18 to 20 Å. However, the catalysts can entirely recover their initial activity after this treatment. This regeneration was proven to be occurring through a concerted mechanism with methane leading to the total decomposition of PdSO4. Moreover, studies in presence of water showed that these properties remained unchanged.<p>The state of the palladium was also investigated and allowed us to evidence that an activation/stabilization of the catalyst is necessary. This is achieved in presence of the reactants by slight and subtle changes in both the support and the palladium phase. The increase of the catalyst activity was correlated with an increase of Ti3+ and Pd0 fractions. The presence of metallic palladium in the catalyst seems to be the key element in the activation of the C-H bonds. <p>Finally, we have studied the influence of the size/dispersion of the palladium particles on the reaction rate. The use of wet-chemistry synthesis allowed us to produce colloidal solutions of palladium with controlled particles sizes. This study revealed that the methane combustion is a structure sensitive or demanding reaction. Nevertheless, a better control of the shape of the nanoparticles should be achieved to determine the structural factor influencing the reaction.<p> / Doctorat en Sciences / info:eu-repo/semantics/nonPublished

Physical activation of oil-sands fluid coke, a dense carbonaceous material, using sulfur dioxide (SO2) was investigated as a means of utilizing a plentiful and inexpensive waste for elemental mercury (Hg) removal. A new model was developed to elucidate physical activation of dense carbonaceous materials. Experiments and model simulations revealed that, during activation with SO2, a sulfur-rich porous layer is formed around the periphery of the coke particles; this porous layer reaches a maximum thickness as a result of diffusion limitations; the maximum porous layer thickness is controlled by activation conditions and determines the maximum achievable specific surface area (SSA). Pre-oxidation in air prior to activation, acid washing after activation and smaller coke particle size all result in higher SSA. The highest SSA achieved was 530 m2/g, the highest yet found for oil-sands fluid coke with physical activation. If present, oxygen out-competed SO2 for carbon during activation. SO2 activation and porous layer formation did not occur until oxygen was depleted. Sulfur added to coke through SO2 activation is mainly in reduced forms which are more thermally stable than elemental sulfur in commercial sulfur-impregnated activated carbons (SIACs). TGA and elemental analyses revealed that only 17% of sulfur was removed at 800°C from SO2-activated coke under inert conditions, compared with 100% from a commercial SIAC. The role of sulfuric acid (H2SO4) in vapor Hg capture by activated carbon (AC) was studied due to conflicting findings in the recent literature. In the absence of other oxidizing species, it was found that Hg could be oxidized by oxygen which enhanced vapor Hg adsorption by AC and Hg absorption in H2SO4 solution at room and elevated temperatures. At 200°C, AC treated with 20% H2SO4 reached a Hg loading of more than 500 mg/g, which is among the highest Hg capacities yet reported. When oxygen was not present, S6+ in H2SO4 was found to act as an oxidizer of Hg, thus enabling Hg uptake by H2SO4-treated AC at 200°C. Treating the AC with SO2 at 700°C improved the initial rate of Hg uptake, with and without subsequent H2SO4 treatment.

Physical activation of oil-sands fluid coke, a dense carbonaceous material, using sulfur dioxide (SO2) was investigated as a means of utilizing a plentiful and inexpensive waste for elemental mercury (Hg) removal. A new model was developed to elucidate physical activation of dense carbonaceous materials. Experiments and model simulations revealed that, during activation with SO2, a sulfur-rich porous layer is formed around the periphery of the coke particles; this porous layer reaches a maximum thickness as a result of diffusion limitations; the maximum porous layer thickness is controlled by activation conditions and determines the maximum achievable specific surface area (SSA). Pre-oxidation in air prior to activation, acid washing after activation and smaller coke particle size all result in higher SSA. The highest SSA achieved was 530 m2/g, the highest yet found for oil-sands fluid coke with physical activation. If present, oxygen out-competed SO2 for carbon during activation. SO2 activation and porous layer formation did not occur until oxygen was depleted. Sulfur added to coke through SO2 activation is mainly in reduced forms which are more thermally stable than elemental sulfur in commercial sulfur-impregnated activated carbons (SIACs). TGA and elemental analyses revealed that only 17% of sulfur was removed at 800°C from SO2-activated coke under inert conditions, compared with 100% from a commercial SIAC. The role of sulfuric acid (H2SO4) in vapor Hg capture by activated carbon (AC) was studied due to conflicting findings in the recent literature. In the absence of other oxidizing species, it was found that Hg could be oxidized by oxygen which enhanced vapor Hg adsorption by AC and Hg absorption in H2SO4 solution at room and elevated temperatures. At 200°C, AC treated with 20% H2SO4 reached a Hg loading of more than 500 mg/g, which is among the highest Hg capacities yet reported. When oxygen was not present, S6+ in H2SO4 was found to act as an oxidizer of Hg, thus enabling Hg uptake by H2SO4-treated AC at 200°C. Treating the AC with SO2 at 700°C improved the initial rate of Hg uptake, with and without subsequent H2SO4 treatment.

This thesis presents a comparison of the development of the concentrations of nitrogen oxides and sulfur dioxide in the air in the Usti region. The work described generally air pollution and related terms such as the sources of pollution emission, immission and atmospheric deposition. The study also evaluated pollution nitrogen oxides and sutur dioxide in the Usti region. This work describes the methods that were used in the calculations and evaluations. It also deals with the selecting appropriate measuring stations to handle the development of the concentrations of these substances in the air. The aim of this work is to find trends in time series of concentrations of NOx and SO2 and statistical evaluation of development levels in selected cities Ústí Region. The next section is evaluated spatial analysis of the concentration of nitrogen oxides and sulfur dioxide in the air in the Ústí Region. This area was chosen primarily because it is characterized by significant air pollution.

Sulfur dioxide (SO2) is a gas typical of high temperature magmatic degassing, being its<p>third most abundant constituent after water vapor and carbon dioxide. SO2 flux measurements<p>are used to characterized and monitor volcanic degassing. This thesis presents advanced<p>methods for measuring the SO2 emitted in the troposphere by passive degassing volcanoes.<p>These methods are based on the absorption of infrared (IR) and ultraviolet (UV) light by SO2<p>molecules. They make use of the data acquired by satellite borne sensors (ASTER, OMI and<p>MODIS), and collected in the field using a UV camera equipped with filters<p>ASTER is a multispectral sensor observing the Earth in the thermal IR with a 90 m<p>ground resolution. The developed retrieval algorithm works with band ratios<p>(B10+B12)/2B11 and B14/B11, to avoid spectral interference from other variables than SO2.<p>With this algorithm, the impact of interferers such as atmospheric water vapor, sulfate<p>aerosols and ground emissivity is minimal, as demonstrated by radiative transfer simulations<p>by applying of the algorithm to real ASTER images and by comparing the results with ground<p>based data. ASTER is a kind of unifying thread for this thesis because its high ground<p>resolution fills the gap existing between highly localized ground based SO2 measurements and<p>the global coverage of other satellites with coarser pixels such as OMI and MODIS.<p>OMI is an imaging spectrometer operating in the UV, with a daily global coverage, a<p>high sensitivity to SO2 and a ground resolution of 13x24km. The OMI-ASTER comparison<p>shows that the SO2 columns measured on OMI pixels are two orders of magnitude smaller<p>than those of ASTER, because of the huge difference in the pixel size of the two satellites.<p>The flux measurements however are generally in good agreement. The analysis of a large<p>number of images shows that ASTER is better for cloud free scenes while OMI has an<p>optimal signal to noise ratio when the plume is lying above a low cloud cover. A practical<p>detection limit for SO2 flux measurements in tropospheric plumes has also been established:<p>5kg/s.<p>The comparison between ASTER measurements of SO2 column amounts with those of<p>MODIS (a multispectral IR imager with 1km ground resolution) shed light on systematic<p>errors in MODIS measurements. These errors were quantified and their origins were separated<p>and identified. This work demonstrates the limitations of MODIS for SO2 measurements.<p>A UV camera equipped with filters has also been developed to achieve 2D SO2 from the<p>ground at a high spatial and temporal resolution. The potential provided by this new type of<p>instruments has been demonstrated during a field campaign on Turrialba Volcano (Costa<p>Rica). The integration of measurements obtained using the camera, ASTER and OMI revealed<p>a high and sustained SO2 flux, which can be explained only by the degassing of a recently<p>intruded magma body. The slow decrease of SO2 flux since January 2010 suggests a<p>progressive exhaustion of the volatile content of the magma.<p>Finally, we applied the band ratio algorithm to a series of ASTER images of the recent<p>eruption of Eyjafjallajökull in April-May 2010. The SO2 measurements provide interesting<p>insights into the complex eruptive dynamics and into the control of hydromagmatic<p>interactions on eruptive gas release into the atmosphere. /<p><p>Le dioxyde de soufre (SO2) est un gaz typique du dégazage magmatique de haute<p>température, dont il est le troisième composant le plus abondant derrière H2O et CO2. Le flux<p>de SO2 est un excellent paramètre pour caractériser le dégazage volcanique et surveiller son<p>évolution dans le temps. Cette thèse présente de nouvelles méthodes de mesures des flux de<p>SO2 émis par l’activité volcanique. Ces méthodes se basent sur l’absorption de la molécule de<p>SO2 dans l’infrarouge (IR) et l’ultraviolet (UV). Elles utilisent les données prises par des<p>senseurs embarqués sur des satellites (ASTER, OMI et MODIS) ou opérés depuis le sol<p>(caméra UV munie de filtres).<p>Le senseur ASTER opère dans l’IR thermique avec une résolution spatiale de 90 m par<p>pixel. L’algorithme de mesure développé pour ce satellite n’est sensible qu’à la concentration<p>en SO2 et pratiquement pas aux paramètres interférents qui posaient problèmes aux méthodes<p>existantes :la vapeur d’eau atmosphérique, les aérosols de sulfate dans le panache et<p>l’émissivité de la surface sous-jacente. ASTER est un peu le fil conducteur de cette thèse, car<p>sa haute résolution spatiale lui permet de faire le lien entre des mesures au sol et les mesures<p>faites par d’autres satellites comme OMI et MODIS.<p>Le satellite OMI est un spectromètre imageant qui opère dans l’UV, avec une<p>couverture globale journalière, une haute sensitivité au SO2 et une résolution spatiale de<p>13x24km. La comparaison OMI-ASTER montre que les colonnes mesurées sur les pixels<p>d’OMI sont de deux ordres de grandeur inférieurs à celles d’ASTER, à cause de la différence<p>de résolution spatiale entre les deux satellites. Les mesures de flux, par contre, montrent une<p>très bonne concordance. L’analyse d’un grand nombre d’images a permis d’établir qu’ASTER<p>est meilleur pour des scènes sans nuages tandis qu’OMI est meilleur quand une couverture<p>nuageuse présente sous le panache augmente son rapport signal sur bruit. Une limite de<p>détection pratique a aussi été établie pour les flux de SO2 dans les panaches volcaniques dans<p>la basse troposphère :5kg/s.<p>La comparaison des mesures d’ASTER avec celle de MODIS a permis de démontrer les<p>limites de MODIS pour la mesure du SO2. Des erreurs systématiques sur les mesures de<p>MODIS on été mises en évidence et quantifiées. Ces erreurs sont dues aux interférents<p>spectraux que sont la vapeur d’eau atmosphérique et les aérosols sulfatés. L’émissivité est<p>aussi un important facteur d’erreur pour MODIS.<p>Une caméra UV équipée d’un système de filtres a également été développée pour<p>mesurer le SO2 en 2D, à haute résolution spatiale et temporelle. Le potentiel offert par ce<p>nouveau type d’instrument a été démontré lors d’une campagne de mesures sur le volcan<p>Turrialba (Costa Rica). La combinaison de mesures de SO2 réalisée avec la caméra, ASTER<p>et OMI a permis de mettre en évidence des flux très élevés (30-50kg/s) qui ne peuvent<p>s’expliquer que par une intrusion récente de magma juvénile en cours de dégazage.<p>Enfin, les mesures de SO2 ont réalisées à partir des images ASTER pendant l’éruption<p>du volcan Eyjafjallajökull en avril-mai 2010. Ces mesures fournissent des informations<p>intéressantes sur les dynamismes éruptifs qui se sont succédé et sur le contrôle des émissions<p>de SO2 dans l’atmosphère par les interactions magma-eau. / Doctorat en Sciences / info:eu-repo/semantics/nonPublished

This diploma thesis describes research and following development of lightweight cement mortars with alternative raw materials. Attention was focused on study of the effects of extreme influences such as high temperature (up to 1200 °C), freeze-thaw and agressive sulfur dioxide. Verification of durability of developed mortars was realized using physical and mechanical tests (density and strength), physical and chemical methods (computed tomography) and scanning electron microscopy. Assessment of durability was realized in a longer period of time (90 days).