Microbial-Induced Calcium Carbonate (CaCO3) Precipitation (MICP) is a biological process in which microbial activities alter the surrounding aqueous environment and induce CaCO3 precipitation. Because the formed CaCO3 crystals can bond soil particles and improve the mechanical properties of soils such as strength, MICP has been explored for potential engineering applications such as soil stabilisation. However, it has been difficult to control and predict the properties of CaCO3 precipitates, thus making it very challenging to achieve homogeneous MICP-treated soils with the desired mechanical properties. This PhD study investigates MICP at both micro and macro scales to improve the micro-scale understandings of MICP which can be applied at the macro-scale for improving the homogeneity and mechanical properties of MICP-treated sand. A microfluidic chip which models a sandy soil matrix was designed and fabricated to investigate the micro-scale fundamentals of MICP. The first important finding was that, during MICP processes, phase transformation of CaCO3 can occur, which results in smaller and less stable CaCO3 crystals dissolving at the expense of growth of larger and more stable CaCO3 crystals. In addition, it was found that bacteria can aggregate after being mixed with cementation solution, and both bacterial density and the concentration of cementation solution affect the size of aggregates, which may consequently affect the transport and distribution of bacteria in a soil matrix. Furthermore, bacterial density was found to have a profound effect on both the growth kinetics and characteristics of CaCO3. A higher bacterial density resulted in a quicker formation of a larger amount of smaller crystals, whereas a lower bacterial density resulted in a slower formation of fewer but larger crystals. Based on the findings from micro-scale experiments, upscaling experiments were conducted on sandy soils to investigate the effect of injection interval on the strength of MICP treated soils and the effects of bacterial density and concentration of cementation solution on the uniformity of MICP treated soils. Increasing the interval between injections of cementation solution (from 4 h to 24 h) increased the average size of CaCO3 crystals and the resulting strength of MICP-treated sand. An optimised combination of bacterial density and cementation solution concentration resulted in a relative homogeneous distribution of CaCO3 content and suitable strength and stiffness of MICP-treated sand. This thesis study revealed that a microfluidic chip is a very useful tool to investigate the micro-scale fundamentals of MICP including the behaviour of bacteria and the process of CaCO3 precipitation. The optimised MICP protocols will be useful for improving the engineering performance of MICP-treated sandy soils such as uniformity and strength.

The Cutler Formation is composed of thick, arkosic, alluvial conglomerate, sandstone, and mudstone shed southwestward from the Uncompahgre Uplift into the Paradox Basin. More basin-ward the Cutler is recognized as a group consisting of differentiable formations. Discrete formations historically have not been distinguished near the uplift, but this study identified several separate successions in the Richardson Amphitheater. Research at the Richardson Amphitheater, ~12 km southwest of the uplift and ~30 km northeast of Moab, Utah, led to a systematic subdivision of the Permian Cutler Formation proximal to the uplift. Likely driven by channel cutting and migration across the alluvial fan, six 10-20 m thick successions are partially exposed. The dominant observed facies are basal conglomerate and channel-fill trough cross-stratified sandstone overlain by finer-grained distal sheetflood and frequently pedogenically altered sandstone. Down-warping of identified successions and the presence of additional sands within the area of flexure suggest that localized salt withdrawal created a sediment depocenter in the Richardson Amphitheater, ~6 km northwest of the Onion Creek salt diapir. The identified salt withdrawal feature is more proximal to the Uncompahgre Uplift than any of the major documented salt structures in the area and was not previously documented. Six measured stratigraphic sections and hundreds of high-precision differential GPS data points outlining major lateral erosional surfaces form the basis for interpretation. Five mapped erosional surfaces (bounding surfaces based upon differential GPS point interpolation) are laterally extensive within the approximately one square kilometer study area, and as such, represent stratigraphically significant surfaces. Within the generated structural geocellular model, stratigraphic data from measured sections informed facies modeling between major surfaces. This outcrop model may serve as an analogue for subsurface systems deposited in similar settings.

O hexaluminato de cálcio (CaAl12O19 ou CA6) poroso é um material promissor para aplicações de isolamento térmico pois combina baixa condutividade térmica (~0,33 Wm-1K-1 a 1400 °C), resistência mecânica razoável (2 – 8 MPa), inércia química, boa refratariedade (Tf ~1830 °C) e alta resistência ao choque térmico. Existem várias rotas para se obter o CA6 por meio de reações em temperaturas acima de 1300 °C, usando diversas fontes de Al2O3 e CaO, assim como diferentes métodos de processamento. No entanto, embora suas propriedades físicas tenham sido avaliadas, dois pontos principais ainda requerem investigação: o impacto das características das matérias-primas no desenvolvimento da microestrutura de sistemas porosos formados in situ, e a evolução da microestrutura e propriedades de sistemas obtidos a partir de CA6 pré-formado. Neste trabalho, foram produzidas peças de CA6 in situ a partir de diferentes fontes de Al2O3 (alumina calcinada e hidróxido de alumínio) e carbonato de cálcio (CaCO3) de diferentes granulometrias, processados por prensagem uniaxial e moldagem direta de suspensões e submetidas a diferentes tratamentos térmicos. As amostras (verdes e secas e após tratamento térmico) foram submetidas à análise microestrutural (MEV e DRX) e dilatométrica, ensaios para determinação das propriedades físicas (porosidade total, distribuição de tamanho de poros e condutividade térmica) e propriedades mecânicas (resistência à ruptura por compressão e módulo elástico). Estruturas à base de CA6 formado in situ obtidas por prensagem e moldagem direta apresentaram elevada porosidade (até 71 %) e uma resistência à compressão acima de 10 MPa. Verificou-se que o processo de conformação determinou a porosidade à verde inicial da peça, enquanto o tamanho de partícula de alumina induziu a um crescimento de grão assimétrico (partícula grossa) ou à densificação da peça (partícula fina). Dois mecanismos antagonistas acontecem ao mesmo tempo na reação in situ: a reação expansiva da formação de aluminatos intermediários (efeito porogênico) e a densificação das partículas de Al2O3. As partículas de carbonato tiveram uma grande influência no tamanho final dos poros. O efeito porogênico do hidróxido de alumínio foi efetivo até um conteúdo máximo de 50 %vol. / Porous calcium hexaluminate (CaAl12O19 or CA6) is a promising material for thermal insulation applications because it combines low thermal conductivity (~0,33 Wm-1K-1 at 1400° C), reasonable mechanical strength (2 – 8 MPa), chemical inertia, good refractoriness (Tf ~1830 °C) and high resistance to thermal shock. There are several routes to obtain CA6 by reactions at temperatures above 1300 °C, using various sources of Al2O3 and CaO, as well as different processing methods. However, although its physical properties have been studied, two main points still require investigation: the impact of the characteristics of the raw materials on the development of the microstructure of in situ formed porous systems, and the evolution of the microstructure and properties of systems obtained from preformed CA6. In this study, in situ CA6 bodies were produced from different sources of Al2O3 (calcined alumina and aluminum hydroxide) and calcium carbonate (CaCO3) of different granulometries, processed by uniaxial pressing and direct molding of suspensions and thermally treated at different temperatures. The samples (green and heat treated ones) were submitted to microstructural analysis (SEM and XRD) and dilatometry, also tests to determine the physical properties (total porosity, Hg porosimetry and thermal conductivity) and mechanical properties (compression strength and elastic modulus). In situ formed CA6-based structures obtained by pressing and direct molding showed high porosity (up to 71%) and a compressive strength above 10 MPa. It was found that the conformation process determined the initial porosity of the green body, while particle size of alumina may induce asymmetric grain growth (coarse particle) or densification of the ceramic body (fine particle). Two antagonistic mechanisms occur at the same time in the in situ reaction: the expansive reaction of the formation of intermediate aluminates (porogenic effect) and the densification of Al2O3 particles. The carbonate particles had a great influence on the final pore size. The porogenic effect of aluminum hydroxide was effective up to a maximum content of 50% vol.

This thesis examines functional relationships between the morphologic, hydrodynamic, ecological and sedimentological characteristics of the Warraber reef platform, an inter-tidal reef island system, Central Torres Strait, Australia (10[degrees] 12??? S, 142 [degrees] 49??? E). Hydrodynamic and sediment-transport experiments were conducted on the reef flat using current meters, water level recorders and directional sediment traps. Results showed dominantly SE flows during the dry season and more variable NW to SE flows during the wet season. Topography and reefal water levels modulated the direction and strength of currents and the generation of wind-waves on the reef flat as well as the passage of waves over the reef rim. These hydrodynamic conditions are sufficient to induce significant transport of moderately fast to slow settling sediment (&gt-5.25 symbol psi) on the reef flat, though the platform as a whole is a relatively closed transport system. Carbonate production was estimated based on the key ecological variables of live assemblage distribution and cover. Overall, only 24% of the reef flat was occupied by carbonate-producing organisms. The average estimated carbonate-production rate for the reef was 1.6 kgm -2y-1 (0.07-4.37 kgm-2y-1). Production is dominated by coral (73%), with subordinate proportions contributed by coralline algae (19%). And molluscs, foraminifera and Halimeda (&lt4%) though actual reef-flat sediments did not reflect this potential. Instead, they were dominated by molluscs (35-55%), coralline algae (16-26%), coral (8-13%), Halimeda (7-8%) and foraminifera (5-10%). Differential rates of carbonate to sediment conversion meant the reef-platform sediments were more closely related to the cover of live organisms than to the contribution of carbonate production by each parent organism. The settling properties of the least altered particles of the five commonest constituents were measured and these provided the basis for an eco-sedimentological model of the reef-platform system. Modelled textures were compared to the actual textures, indicating the degree of textural alteration resulting from a combination of biological and physical processes, including sediment production, hydraulic sorting and mechanical breakdown. This analysis, integrated with the hydrodynamic, exposure and other data, was used to determine reef-platform surface-sediment sources, sinks and transport pathways. In using both the textual and constituent compositional properties of sediments, as well as information on local biological and physical processes, the model approach developed offers progress towards an integrative, interdisciplinary analysis of carbonate environments.

Five folded ill. in pocket / Bibliography: leaves 141-152 / ix, 152, 12 leaves, [17] leaves of plates : ill. (some col.) ; 31 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, 1987

Le développement considérable réalisé ces dix dernières années dans les techniques de<br />diffraction sur des échantillons sous forme de poudre même très texturés (temps<br />d'enregistrement raisonnable et très bonne résolution) et les progrès fascinants des moyens de<br />calcul sur des machines individuelles rendent possible l'accès à des informations précises et<br />avec des temps de calcul raisonnablement courts. Dans ce travail, nous avons appliqué<br />l'analyse combinée basée sur la méthode de Rietveld pour étudier des échantillons de<br />carbonates de calcium naturels de coquilles de certaines espèces de mollusques (structure,<br />texture, tailles anisotropes...etc.) et synthétiques par biomimétisme dans le but de comprendre<br />l'influence des différents facteurs intervenants dans la croissance et la forme des grains des<br />différents polymorphes de CaCO3. Dans les échantillons naturels, nous avons clairement mis<br />en évidence l'existence de déformations de mailles cristallines dues à la présence des<br />macromolécules intra-cristallines et extra-cristallines, en complément d'études du même<br />genre réalisées sur des échantillons broyés. Dans les échantillons synthétiques obtenus par une<br />méthode de synthèse simple, nous avons analysé l'effet de l'ajout d'acide polyacrylique, en<br />termes de modulateur de croissance des polymorphes de CaCO3. La simulation des<br />digrammes de diffraction anisotropes réalisée sur ces deux types d'échantillons nous a permis<br />d'accéder aux informations pertinentes de façon précise (tailles anisotropes des cristallites,<br />structure, texture, proportion volumique des polymorphes).

Dans un cadre stratigraphique revu le remplissage miocène du bassin molassique rhodano-provençal (BMRP) a été découper en 10 séquences de dépôt (IIIrd). Trois grandes phases d'érosion fluviatile ont été caractérisées : entre l'Aquitanien et le Burdigalien inférieur et entre le Burdigalien terminal et le Langhien puis à la base du Tortonien. Les transgressions marines miocènes du BMRP sont contrôlées par l'existence de ces réseaux fluviatiles successifs. Un modèle séquentiel haute fréquence du remplissage par des carbonates bioclastiques de faciès « foramol » du premier complexe de vallées incisées est proposé. Ces réseaux miocènes qui alimentent la plate-forme et le talus du golfe du Lion permettent de mieux comprendre comment l'ouverture du Golfe du Lion, son ralentissement puis son arrêt interagissent avec le raccourcissement alpin. Les vallées aquitano-burdigaliennes sont généralement superposées et emboîtées dans les dépôts oligo-aquitaniens. Ils sont en relation direct avec l'héritage morphostructural de ce bassin d'avant-pays et signent une déformation régionale de grande longueur d'onde rapportée à une remise en compression à la base du Miocène. Les réseaux suivant en quasi-conformité avec les structures pyrénéo-provençales sont en relation avec l'activation des plis et des chevauchements et signent une déformation plicative de plus courte longueur d'onde associée pour le réseau du Burdigalien terminal à un soulèvement régional. Leur superposition souligne la pérennité d'un contrôle tectonique. Leur déboîtement est la conséquence de l'activation des plis et des chevauchements provoquant la migration des dépôts-centres et des réseaux successifs de vallées dont cette déformation amplifie le creusement.

Methane derived authigenic carbonate (MDAC) precipitation occurs within marine sediments as a byproduct of the microbial anaerobic oxidation of methane (AOM). While these carbonates form in chemical and isotopic equilibrium with the fluids from which they precipitate, burial diagenesis and recrystallization can overprint these signals. Plane polarized light (PPL) and cathodoluminescent (CL) petrography have allowed for detailed characterization of carbonate phases and their subsequent alteration. Modern MDACs sampled offshore in northern Cascadia (n =33) are compared with paleoseep carbonates (n =13) uplifted on the Olympic Peninsula in order to elucidate primary vs. secondary signals, with relevance to interpretations of the carbonate record. The modern offshore environment (S. Hydrate Ridge and Barkley Canyon) is dominated by metastable acicular and microcrystalline aragonite and hi-Mg calcite (HMC) that with time will recrystallize to low-Mg calcite (LMC). The diagenetic progression is accompanied by a decrease in Mg/Ca and Sr/Ca ratios while variation in Ba/Ca depends upon the Ba-concentration of fluids that spur recrystallization. CL images discern primary carbonates with high Mn/Ca from secondary phases that reflect the Mn- enrichment that characterizes deep sourced fluids venting at Barkley Canyon. Methane along the Cascadia continental margin is mainly of biogenic origin, where reported strontium isotopic values reflect a mixture of seawater with fluids modified by reactions with the incoming Juan de Fuca plate. In contrast, the Sr-isotopic composition of carbonates and fluids from Integrated Ocean Drilling Program (IODP) Site U1329 and nearby Barkley Canyon point to a distinct endmember (lowest ⁸⁷Sr/⁸⁶Sr = 0.70539). These carbonates also show elevated Mn/Ca and δ¹⁸O values as low as -12‰, consistent with a deep-source of fluids feeding thermogenic hydrocarbons to the Barkley Canyon seeps. Two paleoseep carbonates sampled from the uplifted Pysht/Sooke Fm. have ⁸⁷Sr/⁸⁶Sr values similar to those of the anomalous Site U1329 and Barkley Canyon carbonates (⁸⁷Sr/⁸⁶Sr = 0.70494 and 0.70511). We postulate that the ⁸⁷Sr-depleted carbonates and pore fluids found at Barkley Canyon represent migration by the same type of deep, exotic fluid as is found in high permeability conglomerate layers down to 190 mbsf at Site U1329, and which fed paleoseeps in the Pysht/Sooke Fm. These exotic fluids likely reflect interaction with the 52-57 Ma igneous Crescent Terrane, which is located down-dip from both Barkley Canyon and Site U1329. This previously unidentified endmember fluid in northern Cascadia may have sourced cold seeps in this margin since at least the late Oligocene. / Graduation date: 2012

This research was conducted in order to evaluate natural trace element (TE) contents and anthropogenic contamination in soils and vegetables in Chenggong County (Yunnan Province, China). In this way, trace element contents in soils have been analysed to assess TE contamination in soils and vegetables, and transfer of TE from soil to vegetables. Agricultural practises have been proposed to amend the quality of vegetables. We identified three geomorphopedological units: lacustrine unit, transition unit and mountain unit.  In the mountain unit, soil texture is clay more often from the weathering of limestone and marlstone. Soil colour is red or reddish brown with acid reaction.  In the transition unit, soil texture is loamy clay. Soil colour is red-brown with acid reaction.  In the lacustrine unit, soil texture mainly is sandy developed from lacustrine-alluvial deposits. Soil colour is brown and is slightly acid. Total TE contents in the topsoil are higher than usual and even Kunming Prefecture soil. TE contents indicate a high contaminated level when considered globally. Pb, Cd and Zn present however individually low contaminated levels, and Cu presents a medium contaminated level. TE contents decrease from northeast to southwest, which is consistent with the elevation gradient. Significant differences of TE contents are observed according to distance from Chenggong town in the lacustrine unit and with distance from the mountain in the transition unit. TE accumulation is usually observed along roads. TE contents in subsoil are related to soil colour, texture, parent materials and mottles. Accumulation of Pb and Zn in topsoil and of Cu and Cd in subsoil are observed. The highest contents are observed for Pb in cauliflower, Cd in lettuce and Chinese cabbage, and Cu and Zn in pea. The order of TE accumulation in plants varies according to the plant species and organ. According to relations between TE contents in Chinese cabbage and extraction sequential fractions of TE in soils, different soil fractions are suggested as soil assessment indicators. Lime and pig manure have been applied to modify the soil pH and to decrease the mobility of TE in situ. With increasing in lime rate and pH, contents of acetic-acid extractable TE fractions in soil decrease. Enrichment coefficients related to TE availability (AEC) of Pb and Cu are stable and are not changed by lime or pig manure. AEC of Cd and Zn which are high in low pH, decrease with increased pH and application rates of lime and pig manure. When application rates of lime and pig manure increase, TE contents in Chinese cabbage decrease and biomass of Chinese cabbage increases. Application rates of lime and pig manure are recommended, but their quality should also be taken into account. / Cette recherche a pour objet l'étude de la teneur naturelle en éléments traces métalliques (ET) et de la contamination anthropique des sols et des productions légumières dans le Comté de Chenggong (Province du Yunnan, RP de Chine). Pour cela, la variabilité des teneurs en fonction des conditions géomorphopédologiques a été analysée, ainsi que les transferts des ET du sol vers les végétaux. Cette approche a permis ensuite d'aborder l'évaluation de la qualité des sols et des légumes, puis de proposer des pratiques agricoles alternatives dans le but d'améliorer la qualité des légumes produits. La zone d'étude a été divisée en 3 unités géomorphopédologiques: unité de montagne où les sols brun rouge à rouge résultent notamment de l'altération de calcaires et de marnes. Une texture argileuse et une réaction acide dominent. unité de piedmont (dite de transition) où les sols de couleur jaune clair à jaune rougeâtre résultent principalement de l'altération de grès et de shales. Une texture limono-argileuse en surface et argileuse en profondeur, ainsi quune réaction acide dominent. unité lacustre, à proximité du Dianchi Lake, dont les sols de couleur brun foncé sont essentiellement développés à partir de sédiments lacustres. Une texture sableuse domine en surface, ainsi qu'une réaction faiblement acide à neutre. Les teneurs en ET rencontrées en surface des sols de la zone d'étude sont plus élevées que les teneurs moyennes observées dans les sols du monde ou même de la préfecture de Kunming. Evaluées séparément pour chaque ET, les teneurs rencontrées correspondent à des niveaux de contamination jugés faibles pour Pb, Cd et Zn, moyen pour Cu. Considérées simultanément, ces teneurs permettent de déterminer un indice de contamination global correspondant à un niveau de contamination élevé. Les teneurs en ET décroissent globalement du nord-est vers le sud-ouest, suivant le gradient d'altitude. Ces teneurs varient également de façon significative en fonction de l'éloignement de la montagne dans l'unité de transition et de l'éloignement de l'agglomération de Chenggong dans l'unité lacustre . Une accumulation en ET est souvent observée le long des routes. Dans le sous-sol, les teneurs en ET sont liées à la couleur, à la texture, au matériau parental, et aux marques d'altération. Les teneurs sont plus élevées en surface pour Pb et Zn, et en profondeur pour Cu et Cd. Les teneurs les plus élevées pour Pb sont observées dans le chou-fleur, pour Cd dans la laitue et le chou chinois, pour Cu et Zn dans le pois.L'ordre d'accumulation des ET dans la plante dépend de l'espèce et de l'organe considérés. En fonction des corrélations observées entre les teneurs du chou chinois et les résultats obtenus avec différentes modalités d'extraction des ET du sol, des indicateurs d'évaluation de la qualité du sol ont été proposés. Un amendement carbonaté et du fumier de porc ont été épandus afin de réduire in situ la mobilité des ET. L'augmentation de l'apport d'amendement carbonaté permet d'augmenter le pH du sol et de diminuer la fraction extraite avec l'acide acétique dilué (AA) pour chaque élément. Les AEC, rapports teneur dans la plante : teneur dans le sol extractible à lAA, sont stables pour Pb et Cu et ne sont modifiés par aucun des 2 apports. Cependant, les AEC de Zn et de Cu, élevés quand le pH du sol est acide, diminuent si le pH devient plus alcalin, ainsi qu'avec les apports d'amendement carbonaté et de fumier de porc. Quand les apports d'amendement carbonaté et de fumier de porc augmentent, les teneurs en ET du chou chinois diminuent et sa biomasse augmente. Un épandage d'amendement carbonaté est donc recommandé. Cependant la plus grande attention doit être portée à la qualité des fumiers de porcs dont les teneurs en Zn et Cu ne sont pas négligeables.

Among the obstacles for the commercialization of the MoltenCarbonate Fuel Cell (MCFC), the dissolution of thestate-of-the-art lithiated NiO cathode is considered as aprimary lifetime limiting constraint. Development ofalternative cathode materials is considered as a main strategyfor solving the cathode dissolution problem. LiFeO2and LiCoO2had earlier been reported as the most promisingalternative materials; however, they could not satisfactorilysubstitute the lithiated NiO. On the other hand, ternarycompositions of LiFeO2, LiCoO2and NiO are expected to combine some desirableproperties of each component. The aim of this work was todevelop alternative cathode materials for MCFC in the LiFeO2-LiCoO2-NiO ternary system. It was carried out byinvestigating electronic conductivity of the materials, firstin the form of bulk pellets and then in ex-situ sinteredporous-gas-diffusion cathodes, and evaluating theirelectrochemical performance by short-time laboratory-scale celloperations. Materials in the LiFeO2-NiO binary system and five ternary sub-systems,each with a constant molar ratio of LiFeO2:NiO while varying LiCoO2content, were studied. Powders withcharacteristics appropriate for MCFC cathode fabrication couldbe obtained by the Pechini method. The particle size of LiFeO2-LiCoO2-NiO powders considerably depends on thecalcination temperature and the material composition. Theelectrical conductivity study reveals the ability of preparingLiFeO2-LiCoO2-NiO materials with adequate electricalconductivity for MCFC cathode application. A bimodal pore structure, appropriate for the MCFC cathode,could be achieved in sintered cathodes prepared usingporeformers and sub-micron size powder. Further, this studyindicates the nature of the compromise to be made between theelectrical conductivity, phase purity, pore structure andporosity in optimization of cathodes for MCFC application. Cellperformance comparable to that expected for the cathode in acommercial MCFC could be achieved with cathodes prepared from20 mole% LiFeO2- 20 mole% LiCoO2- 60 mole% NiO ternary composition. It shows aniR-corrected polarization of 62 mV and a iR-drop of 46 mV at acurrent density of 160 mAcm-2at 650 °C. Altogether, this study revealsthe possibility of preparing LiFeO2-LiCoO2-NiO cathode materials suitable for MCFCapplication. Keywords: molten carbonate fuel cell (MCFC), MCFC cathode,LiFeO2-LiCoO2-NiO ternary compositions, electrical conductivity,porous gas diffusion electrodes, polarization, electrochemicalperformance, post-cell characterization.