Academic literature on the topic 'Altération des silicates'
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Journal articles on the topic "Altération des silicates":
Mosser, Chr, J. C. Leprun, and A. Blot. "Les éléments traces des fractions < 2 μm à kaolinite et smectite formées par altération de roches silicatées acides en Afrique de l'Ouest (Sénégal et Haute-Volta)." Chemical Geology 48, no. 1-4 (March 1985): 165–81. http://dx.doi.org/10.1016/0009-2541(85)90044-0.
Dissertations / Theses on the topic "Altération des silicates":
Dubernet, Stéphan. "Défauts ponctuels dans les silicates : élaboration, coloration, altération de verres archéologiques, caractérisation de défauts dans un luminiphore silicaté." Bordeaux 3, 1997. http://www.theses.fr/1997BOR30205.
Gudbrandsson, Snorri. "Experimental weathering rates of aluminium-silicates." Toulouse 3, 2013. http://thesesups.ups-tlse.fr/2225/.
The chemical weathering of primary rocks and minerals in natural systems has a major impact on soil development and its composition. Chemical weathering is driven to a large extent by mineral dissolution. Through mineral dissolution, elements are released into groundwater and can readily react to precipitate secondary minerals such as clays, zeolites, and carbonates. Carbonates form from divalent cations (e. G. Ca, Fe and Mg) and CO2, and kaolin clay and gibbsite formation is attributed to the weathering of aluminium- rich minerals, most notably the feldspars. The CarbFix Project in Hellisheiði SW-Iceland aims to use natural weathering processes to form carbonate minerals by the re-injection of CO2 from a geothermal power plant back into surrounding basaltic rocks. This process is driven by the dissolution of basaltic rocks, rich in divalent cations, which can combine with injected CO2 to form and precipitate carbonates. This thesis focuses on the dissolution behaviour of Stapafell crystalline basalt, which consists of three major phases (plagioclase, pyroxene, and olivine) and is rich in divalent cations. Steady-state element release rates from crystalline basalt at far-from-equilibrium conditions were measured at pH from 2 to 11 and temperatures from 5° to 75° C in mixed-flow reactors. Steady-state Si and Ca release rates exhibit a U-shaped variation with pH, where rates decrease with increasing pH at acid condition but increase with increasing pH at alkaline conditions. Silicon release rates from crystalline basalt are comparable to Si release rates from basaltic glass of the same chemical composition at low pH and temperatures =25°C but slower at alkaline pH and temperatures =50°C. In contrast, Mg and Fe release rates decrease continuously with increasing pH at all temperatures. This behaviour is interpreted to stem from the contrasting dissolution behaviours of the three major minerals comprising the basalt: plagioclase, pyroxene, and olivine. Element release rates estimated from the sum of the volume fraction normalized dissolution rates of plagioclase, pyroxene, and olivine are within one order of magnitude of those measured in this study. In addition, these experimental results show that during injection of CO2-charged waters with pH close to 3. 6, crystalline basalt preferentially releases Mg and Fe relative to Ca to the fluid phase. The injection of acidic CO2-charged fluids into crystalline basaltic rocks may therefore favour the formation of Mg and Fe carbonates rather than calcite at acidic to neutral conditions. Plagioclase is the most abundant phase in crystalline basalts and thus influences strongly its reactivity. Plagioclase dissolution rates based on Si release show a common U-shaped behaviour as a function of pH where rates decrease with increasing pH at acid condition but increase with increasing pH at alkaline conditions. Constant pH plagioclase dissolution rates increase with increasing anorthite content at acid conditions, in agreement with literature findings. Interpretation and data fitting suggests that plagioclase dissolution rates are consistent with their control by the detachment of Si-rich activated complexes formed by the removal of Al from the mineral framework. Most notably, compared with previous assumptions, plagioclase dissolution rates are independent of plagioclase composition at alkaline conditions, e. G. Anorthite-rich plagioclase dissolution rates increase with increasing pH at alkaline conditions. At such conditions rapid plagioclase dissolution rates likely dominate divalent metal release from crystalline basalts to the fluids phase due to its high Ca content. Gibbsite is commonly the first mineral formed during low temperature dissolution of plagioclase. Gibbsite is an aluminium-hydroxide that is found in various soils as well as the dominant phase in many bauxite ores. Gibbsite precipitation rates were measured in closed system reactors at alkaline condition, both at 25 °C and 80 °C as a function of fluid saturation state. Analyses of the solids demonstrate that gibbsite precipitation occurred in all experiments. The comparison of gibbsite precipitation to the dissolution rates of plagioclase at pH 11 shows that the rates are close to equal. The precipitation rates of gibbsite, however, decrease faster with decreasing pH than plagioclase dissolution rates. As such it seem likely that plagioclase dissolution is faster than gibbsite precipitation at near to neutral pH, and the relatively slow rate of gibbsite precipitation influences plagioclase weathering in many Earth surface systems. Kaolinite is commonly the second secondary mineral formed during low temperature dissolution of plagioclase. Kaolinite precipitation rates were measured in mixed flow reactors as a function of fluid saturation state at pH=4 and 25 °C. In total eight long-term precipitation experiments were performed in fluids mildly supersaturated with respect to kaolinite, together with a known quantity of cleaned low defect Georgia Kaolinite as seeds. Measured kaolinite precipitation rates are relatively slow compared with plagioclase dissolution rates. This observation suggests that kaolinite formation during weathering is limited by its precipitation rates rather than by the availability of aqueous species sourced from plagioclase dissolution. Taken together the results of this study provide some of the fundamental scientific basic for predicting the rates and consequences of crystalline basalt and plagioclase dissolution at both the Earth's surface and during the near surface injection of CO2 as part of carbon storage efforts. Results indicate that although gibbsite precipitation rates are relatively rapid, the relatively slow precipitation rates of kaolinite may be the process controlling the formation of this mineral at the Earth's surface. This observation highlights the need to further quantify this secondary mineral precipitation rates at conditions typical at the Earth's surface. Moreover, as the composition of divalent metals released from crystalline basalts varies significantly with pH, CO2 carbonation in basalt should yield a systematic variation in the identity of carbonate and zeolite minerals precipitated with distance from the injection site. This latter conclusion can be tested directly as part of the currently on-going CarbFix project in Hellisheiði, Iceland
Aouad, Georges. "Influence de Pseudomonas aeruginosa sur la dégradation de silicates : Incidence sur la stabilité de matrices de confinement de déchets et d'un machefer industriel." Université Louis Pasteur (Strasbourg) (1971-2008), 2006. https://publication-theses.unistra.fr/restreint/theses_doctorat/2006/AOUAD_Georges_2006.pdf.
Today it is generally accepted that alteration of rocks as well as anthropogenic products is not only driven by the interaction with water or mineral aqueous solutions. Organic compounds and also microorganisms are of importance for material degradation together with secondary mineralization. However, the exact role of some bacteria in these processes remains unclear in such complex systems. There is no convincing experimental validation of such phenomenon for silicate phases. The goal of this thesis was to experimentally evaluate the effect of one type of bacteria largely widespread in nature and producing biofilm (Pseudomonas aeruginosa) during the alteration of some silicates of environmental interest. The tested materials are the french nuclear glass SON68, a basaltic glass, a vitrified industrial bottom ash (JAP) and a municipal solid waste incinerator bottom ash (MIOM). We elaborated a specific medium allowing both the growth of Pseudomonas aeruginosa and a precise measurement of trace elements solubilized from materials. The total solubilized mass are systematically higher in sterile condition than in biotic one in proportions going from 26 to 79% depending on element and material. The dissolution rate of MIOM is 5. 3 10-4 g. M-2. J-1 in biotic condition and 7. 6 10-4 g. M-2. J-1 in the sterile one. The vitrified bottom ash dissolution rate is 7. 7 10-4 g. M-2. J-1 in presence of P. Aeruginosa and 12. 8 10-4 g. M-2. J-1 without bacteria. Basalt deteriorates with a rate of 18. 3 10-4 g. M-2. J-1 in biotic and 29. 8 10-4 g. M-2. J-1 in sterile system. Finally SON68 glass has a dissolution rate of 17. 6 10-4 g. M-2. J-1 in biotic medium and 25. 0 10-4 g. M-2. J-1 in the sterile one. In addition, the biofilm trap large proportions of potentially toxic elements
Rassineux, François. "Altération des mortiers : étude expérimentale et analogues anciens." Poitiers, 1987. http://www.theses.fr/1987POIT2314.
Sterpenich, Jérôme. "Altération des vitraux médiévaux : contribution à l'étude du comportement à long terme des verres de confinement." Nancy 1, 1998. http://docnum.univ-lorraine.fr/public/SCD_T_1998_0211_STERPENICH.pdf.
Moquet, Jean-Sébastien. "Caractérisation des flux d'altération des contextes orogéniques en milieu tropical : cas des bassins andins et d'avant pays de l'Amazone." Toulouse 3, 2011. http://thesesups.ups-tlse.fr/1333/.
The weathering flux estimation of orogenic belts and the identification of critical parameters that control these processes is a major question in the study of the long term carbon cycle. The objective of this research is to estimate the weathering of the Andean (the second largest orogenic belt after Himalaya) and foreland basins of the Amazon (the world's largest river) and to discuss variability according to geographical characteristics (climate, vegetation cover, lithology, erosion). The weathering fluxes of the Andean and foreland parts of the Amazon basin were estimated at high time and spatial resolution scales in the PHICAB, HIBAM and ORE-HYBAM frameworks. The Andean and foreland basins control the production of around 70% of the Amazon dissolved load. The carbonates and evaporites weathering in Marañón and Ucayali basins contribute approximately 70% of the total. The first order dissolved load spatial variability is controlled by the runoff and lithology (carbonates/silicates) variability. With the exception of the evaporites dissolution load products, the temporal variability of the dissolved load is firstly controlled by the hydrological variability. The silicate weathering variability in the Andean domain is not associated with the erosion rates variability. The dissolved rates are somewhat higher in the recent sedimentation areas (which correspond to Madeira subsidence foreland areas) than those calculated in foreland areas subjected to erosion if we normalize by the runoff (Napo). The atmospheric CO2 consumption derived from silicate weathering (CO2 sil) of the Andes and Foreland part represents 50-73% of the total CO2 sil budget of the Amazon. The Solimões plain contributes significantly to the Amazon basin CO2 sil. The Upper Amazon's silicate CO2 consumption flux is commensurate with the Himalaya's basins for an area two times lower and a runoff value two times higher. This result points out the importance of the climate for the CO2 sil consumption by tropical orogenic belts. 80% of the Amazon basin silicate weathering intensity is controlled by the runoff spatial variability, independently of the mobil cation content
Wild, Bastien. "Changements microstructuraux et diversité microbienne associés à l'altération des silicates : influence sur les cinétiques de dissolution du laboratoire au terrain." Thesis, Strasbourg, 2017. http://www.theses.fr/2017STRAH004/document.
Chemical weathering of silicate minerals is central to numerous environmental and societal challenges. This study addresses the long-standing question of the inconsistency between field and laboratory estimates of dissolution kinetics, by revisiting current approaches of mineral reactivity. It is demonstrated that evolution of feldspar reaction rates are inaccurately describedby current kinetics rate laws, due to textural and structural changes occurring at the fluid-mineral interface over the course of the dissolution process. A novel method is developed to enable probing biogeochemical weathering rates in the field. Bacterial and fungal metagenomic data reveal that subtle reciprocal relationships are established between microorganisms and mineral substrates within the mineralosphere. This thesis emphasizes the impact of passivation phenomena on dissolution rates, under field-relevant reacting conditions and the incapacity of microorganisms to overcome the passivation barrier
Hemadi, Hallouma. "Les silicates et carbonates authigènes de diapirs du Nord de la Tunisie : signification chimique et thermique." Paris 11, 1987. http://www.theses.fr/1987PA112182.
Ruan, Xiaobai. "Géochimie des rivières du bassin de Chayu (Sud-est du Tibet) et altération du batholithe du Trans-Himalaya." Electronic Thesis or Diss., Université de Lorraine, 2023. http://www.theses.fr/2023LORR0053.
This thesis aims to understand better why and how the climate cooling, CO₂ drawdown and the marine Sr isotopic ratio increase all happened during Eocene/Oligocene. I checked the possibility of Trans-Himalaya weathering as the candidate for explaining the early change in marine ⁸⁷Sr/⁸⁶Sr and atmospheric CO₂ during Eocene/Oligocene, by studying the modern chemical weathering of the Trans-Himalaya batholith under monsoon climate. We choose the Chayu River Catchment locating in the SE Tibet as the study area for three reasons: 1) this catchment is mostly covered by the granitoid rocks of the Trans-Himalaya batholith, 2) it is now under the monsoon climate and 3) it is experiencing intense tectonic activity. Besides, the alpine part of the catchment is under periglacial environment, and there is a lack of knowledge about alpine periglacial weathering especially in active mountain ranges. Combining the above, we set two objects of the thesis: first, to study the periglacial weathering process in active alpine mountain of the Chayu Catchment, and second to study the weathering budget and the ⁸⁷Sr/⁸⁶Sr ratios of the catchment, in order to figure out the atmospheric CO₂ sinks and sources, the climatic dependency of chemical weathering rates and the Sr systematics of the Chayu Catchment. Samplings for the main river, tributaries and seepages of mass wasting deposits were conducted at the end of monsoon season in 2019. To study the alpine periglacial weathering processes, we compared the seepages from mass wasting deposits generated by freeze-thaw processes under periglacial environment and landslide under monsoon climate, and the nearby streams of these two climatic conditions. The landslide seepages under monsoon climate are more concentrated than nearby streams, and the seepages under periglacial environment are as concentrated as the landslide seepages but exhibit negligible differences than nearby streams. Our analyses on elemental ratios indicate that the freeze-thaw process provide an exposure mechanism similar to landslide to facilitate the weathering of reactive mineral phases of calcite, biotite and sulphide. The similarity between periglacial seepages and streams may indicate the widespread periglacial mass wasting deposits has a decisive influence on the river chemistry in alpine periglacial areas. To discuss the weathering budgets of the Chayu River Catchment, we first identified and corrected the river composition for the influences of secondary calcite precipitation (SCP). It is found that the weathering budget is dominated by carbonate weathering even though the lithology is mostly granitoid, and the degree of SCP is higher in the periglacial North Chayu than in the South Chayu, and is closely related to the carbonate weathering contribution. The δ¹³CDIC and sulphate proportion together tell that the chemical weathering of the Chayu catchment is mostly driven by carbonic acid, although sulphuric acid weathering is widespread. Combining the budgets of substrates and acids, the chemical weathering of the modern Chayu River Catchment is a CO₂ source rather than a CO₂ sink. After estimating the relative discharge of each tributary by δ¹⁸O of the river water, the carbonate and silicate weathering rates in each tributary basin are calculated. The carbonate weathering rates are basically irrelevant to climatic factors while the silicate weathering rates are positive correlated with basin MAT and runoff. The ⁸⁷Sr/⁸⁶Sr ratios of the main river is around 0.735, suggesting the impact from radiogenic carbonate. Combining the results, the silicate weathering of Trans-Himalaya might be more important than today during Eocene/Oligocene with warmer and wetter climate, and it is also possible that the weathering at that time was thus reversed to a CO₂ sink. The radiogenic Sr signals of the Chayu River suggest the weathering of Trans-Himalaya was capable of rising the marine ⁸⁷Sr/⁸⁶Sr before Himalayan exhumation
Galai, Leila. "Les mécanismes réactionnels régissant les interactions verre-fer en solution aqueuse." Thesis, La Rochelle, 2021. http://www.theses.fr/2021LAROS029.
The geological disposal of high-level waste (HLW) developed by ANDRA, in France, is based on a multi-layer concept. The vitrified radioactive waste is placed in a stainless-steel container itself placed in a carbon steel overpack and disposed in Callovo-Oxfordian (Cox) claystone. The proximity between iron, glass and groundwater should involve a chemical interaction between them which can impact the long-term behaviour of nuclear vitrified waste. Previous study on the glass-iron system in geological storage conditions have highlights the phenomenology linked to this interaction. Iron has been almost unanimously described as increasing the alteration of glass. However, in the experimental setups chosen, the simultaneous alteration of glass and iron makes it difficult to identify the mechanisms prevailing at the interface of each material. In this thesis, we have therefore chosen to decompose the real and complex Glass / Steel / Clay / Solution system into two model study systems in order to better characterize the different mechanisms at each interface. The first experiments were about the corrosion of iron powder in the presence of Si. These experiments have shown that an increase in [Si] promotes the formation of Fe silicates at the expense of Fe oxides, but without leading to an increase in the amount of corroded iron. Kinetic investigations revealed that a complex germination-growth mechanism is behind the formation of Fe silicates. A simplified kinetic model has also been proposed. Then, the experimental system has been complexified with iron corrosion experiments in the presence of CJ1 simple glass and ISG glass. These experiments have shown that the presence of iron certainly leads to the deterioration of the glass, but this increase is strongly limited by three main parameters : the glass composition, the iron flux associated with the corrosion kinetics of the metal and pH. The chosen simplification approach therefore made it possible to dissociate the effect of each parameter and to locate the effect of Si on the corrosion of iron, to dissociate the effect of iron from the effect of pH on alteration of the glass and above all to highlight the importance of parameters such as the iron flow and the initial composition of the glass on the effect that the iron will have on the deterioration of the glass