Human-caused emissions of CO2 and other greenhouse gases are an established reason for the climate changes that affect planet Earth. Negative emission technologies (NETs), for example, bio-accelerated silicate weathering bioreactors, seek to capture and store carbon from the atmosphere. Bio-acceleratedsilicate weathering utilizes microorganisms to increase natural silicate weathering processes.This project aimed to evaluate the potential bio-accelerated weathering of two silicate rock types, Basalt Lavagestine, and La Palma lapilli, using a mixture of microorganisms, Bacillus Subtilis, Cupriavidus Metallidurans, Aureobasidium Pullulans, and Suillus Variegatus. Straw was used as an organic carbon and nutrient source for the organisms. There were six types of reactors, biotic, abiotic,and mineral controls for each of the two minerals, with triplicates. The reactors were watered five times a week with 50 mL of autoclaved distilled water, after each week the leachate from each reactor wascollected. Geochemical analyses of all leachates were performed, these were pH, conductivity, alkalinity, and carbon analyses. After the experiment, the mineral grains and straw were examined in a scanning electron microscope (SEM) to observe the growth of organisms and the differences between reactor types.The biotic reactors for both minerals showed signs of enhanced weathering compared to their controls. The geochemical analyses showed that the alkalinity was doubled between the abiotic and biotic reactors for the basalt, and increased by roughly a third for the lapilli. The DIC was tripled for thebiotic basalt and doubled for the biotic lapilli. This indicated increased weathering rates and more sequestered carbon for the biotic reactors. SEM showed growth of fungi and bacteria in all biotic reactors. The extensive growth of fungi and biofilm formation was prominent in the basalt Lavagestineand a possible reason for the increased weathering compared to lapilli. The contrast in the surface structure of the minerals could be a second reason for the result. The two bacteria were colonizing one mineral each, which indicates differences in chemical composition. The C.Metallidurans were observed on the basalt grains and B.Subtilus on the lapilli. This report concludes that bio-enhanced weathering isa promising aspirant for NETs and that the selection of minerals is an important factor.

Phenol-formaldehyde (PF) resole and polymeric diphenylmethane diisocyanate (PMDI) are two commonly used exterior thermosetting adhesives in the wood-based composites industry. There is an interest in combining these two adhesives in order to benefit from their positive attributes while also neutralizing some of the negative ones. Although this novel adhesive system has been reportedly utilized in some limited cases, a fundamental understanding is lacking. This research serves this purpose by investigating some of the important aspects of this novel adhesive system. The adhesive rheological and viscometric properties were investigated with an advanced rheometer. The resole/PMDI blends exhibited non-Newtonian flow behavior. The blend viscosity and stability were dependent on the blend ratio, mixing rate and time. The adhesive penetration into wood was found to be dependent on the blend ratio and correlated with the blend viscosity. By using dynamic mechanical analysis, the blend cure speed was found to increase with the PMDI content. Mode I fracture testing of resole/PMDI hybrid adhesive bonded wood specimens indicated the dependence of bondline fracture energy on the blend ratio. The 75/25 PF/PMDI blend exhibited a high fracture energy with a fast cure speed and processable viscosity. Exposure to water-boil weathering severely deteriorated the fracture energies of the hybrid adhesive bondlines. More detailed chemistry and morphological studies were performed with cross-polarization nuclear magnetic resonance and 13C, 15N-doubly labeled PMDI. A spectral decomposition method was used to obtain information regarding chemical species concentration and relaxation behavior of the contributing components within the major nitrogen resonance. Different urethane concentrations were present in the cured blend bondlines. Water-boil weathering and thermal treatment at elevated temperatures (e.g. > 200°C) caused reduced urethane concentrations in the bondline. Solid-state relaxation parameters revealed a heterogeneous structure in the non-weathered blends. Water boil weathering caused a more uniform relaxation behavior in the blend bondline. By conducting this research, more fundamental information regarding the PF/PMDI hybrid adhesives will become available. This information will aid in the evaluation of, and improve the potential use of PF/PMDI hybrid adhesives for wood-based composites. / Ph. D.

Silicate minerals are the most common mineral group in the earth's crust so it is not surprising that their weathering reactions dominate the chemistry of many earth surface processes. This project used forsterite as a model system to identify the important factors that affect silicate mineral dissolution rates and grain lifetimes in the weathering environment. I determined an empirical rate law for forsterite dissolution of forsterite in oxalic acid solutions: based on a series of 124 semi-batch reactor experiments over a pH range of 0 to 7 and total oxalate concentrations between 0 and 0.35 m at 25°C. These experiments show that oxalate-promoted dissolution rates depend upon both oxalate concentration and pH. I propose a reaction mechanism in which a hydrogen ion and an oxalate ion are simultaneously present in the activated complex for the reaction that releases H4SiO4 into solution. By analogy, I propose that water acts as a ligand in the absence of oxalate. I also ran 82 batch reactor experiments in magnesium and sodium sulfate and magnesium and potassium nitrate solutions. These experiments show that ionic strength up to 12 m, log mMg up to 4 m, and log mSO4 up to 3 m have no effect on forsterite dissolution rates. However, decreasing aH2O slows forsterite dissolution rates. The effect of decreasing dissolution rates with decreasing aH2O is consistent with the idea that water acts as a ligand that participates in the dissolution process.Forsterite dissolution rate data from previously published studies were combined with results from my experiments and regressed to produce rate laws at low and high pH. For pH < 5.05 or and for pH > 5.05 or I then developed a diagram that shows the effect rate-determining variables on the lifetime of olivine grains in weathering environments using these rate laws. / Ph. D.

Sun protection has gained worldwide attention because repetitive overexposure to ultraviolet radiation can result in harmful effects on human skin, including sunburn, premature skin ageing, and in the worst case, skin cancer (Eckhardt and Rohwer, 2000; Sengupta and Blain, 2001). The diminishing stratospheric ozone layer, due to environmental degradation in the past few decades, combined with the modern outdoor-oriented lifestyles, are leading to unexpected levels of skin cancer (Davis, Capjack, Kerr, and Fedosejevs, 1997). Wearing Ultraviolet protective clothing is a simple way of practicing sun safety; however, regular cotton generally has very low ultraviolet protection and it is one of the most environmentally damaging crops despite of it is commonly used to make summer clothing. With the increased interest of public awareness related to sustainability and environmental issues, naturally colored cotton was recommended as it provides better ultraviolet protection than regular cotton. In addition, the production of naturally colored cotton is more environmentally friendly than regular cotton. Although several studies have been conducted on the UVR protection of naturally colored cotton, many questions regarding the factors that influence the UVR protection of fabrics remain unanswered. The primary purpose of the study was to examine the effects of perspiration application, weathering exposures, washing action of automatic home clothes washers, and repeated laundering on the UVR protection of a NC lightweight cotton fabric. In addition, five fabric property changes in the test specimen after the treatments of perspiration, weathering exposure, washing action, and repeated laundering (i.e., fabric count change, thickness change, weight change, color change and dimensional change) were included in this study to serve as secondary dependent variables to examine if the four treatment factors (i.e., perspiration application, weathering exposures, washing action of automatic home clothes washers, and repeated laundering) will cause changes in these five fabric properties, and if these changes will lead to changes of UVR protection of NC lightweight cotton fabric. Based on the purpose and objectives of the study, a split-plot repeated measures experimental design was used for the current study. In this study, the whole plot treatment was the weathering exposure, which contained three levels (i.e., semi-tropical climate without water spray, semi-arid climate, and standard conditioning), and the split plot treatments were the combinations of two treatment factors. In order to understand the effects of repeated laundering on the UVR protection and the five fabric properties, except for the control group, all test specimens were laundered after being treated with the three treatment factors (i.e., perspiration, weathering exposure, and washing action), and this process was repeated 15 times. The UVR protection (i.e., express in UPF value change in current study) and the five fabric properties of these treated test specimens were measured before laundering, and after each laundering cycle. The results of UPF value change showed that test specimens treated with perspiration had a lower change in UPF value than the specimens without treatment. The test specimens exposed to Florida condition had the most UPF value change, followed by Arizona and Standard textile testing conditions. A significant difference also found in test specimens that laundered in a traditional washer after ninth cycle and the UPF value decreased as the number of laundering cycle increased. However, test specimens that laundered in a front-loading HE washer showed no significant UPF value change. For the five fabric properties that listed in secondary objective, all four treatments significantly influenced fabric count, fabric thickness and fabric weight. However, perspiration treatment had no significant effect on the dimensional change in warp direction of test specimens, and washing action had no significant effect on the dimensional change in filling direction of the test specimen as well as both Delta E and Delta L of color change. For testing the relationship between the changes of the five fabric properties and UPF value change, Delta E and Delta L of color change had the highest correlation coefficient with UPF value change. Therefore, it is possible that the changes of these two properties caused by the four treatments and lead to the UPF value change. Future research is needed to confirm this relationship. In conclusion, of perspiration application, weathering exposures, washing action of automatic home clothes washers, and repeated laundering do have influence on the ultraviolet protection of the naturally colored cotton. The color change of the test specimens caused by these four treatments possible lead to the change of the ultraviolet protection of the test specimens. More studies are needed to confirm this relationship. / Ph. D.

The Toarcian Oceanic Anoxic Event (T-OAE; ~183 million years ago) represents an interval during the Mesozoic when the emplacement of the Karoo-Ferrar Large Igneous Province (LIP) is thought to have resulted in significant environmental change. Associated with this interval was the widespread deposition of organic-rich sediments, carbon cycle and seawater chemistry changes, global warming, the development of marine anoxia, and major extinction events. The majority of studies of this event that have documented these responses have come from the Boreal and Tethyan regions of Europe, thus casting some doubt to the regional versus global significance of the event. Thus my dissertation has sought to reconstruct biogeochemical and paleoenvironmental changes across the T-OAE from a sedimentary succession that was deposited on the margins of a different ocean basin away from the well-studied European successions. Specifically, I have studied the chemostratigraphy of the Fernie Formation of the Western Canada Sedimentary Basin (WCSB), which was deposited on the eastern margin of the Panthalassa Ocean. The Toarcian carbon isotope excursions (CIEs) in the WCSB confirm that these features are global phenomena. I have suggested a new driver for small-scale CIEs observed during the event: the release of wetland-derived methane during progressive global warming. The osmium isotope record and numerical modeling of the osmium cycle suggests that continental weathering rates increased during the T-OAE by 230 – 540%. Rhenium abundance data also suggests that the increased geographic extent of marine anoxia during the T-OAE caused a global drawdown in the seawater rhenium inventory. Iron speciation data are used to reconstruct redox conditions within the WCSB, which suggest ferruginous conditions developed in the more distal locations at the onset of the T-OAE before returning to euxinic (anoxic and sulfidic) conditions. This is likely related to enhanced pyrite burial on a global scale, which caused the drawdown of the seawater sulfate inventory, thus limiting pyrite formation in the distal locations. The proximal setting remained euxinic across the T-OAE, and in all locations the iron speciation data suggest anoxic conditions persistent well after the interval that has been traditionally called the end of the T-OAE. / Ph. D.

No / One of the major roles lichens play in shaping the natural world, both physically and biologically, is as agents in soil development: formerly considered only in a geological context, recent research has shown that they are capable of biodeteriorating stone substrata within a relatively short timescale. Chemical alteration of the substratum is achieved by the disruptive action of many species, particularly those capable of producing an oxalate at the thallus–substratum interface . The oxalate contributes significantly to the bulk and composition of the thallus itself and persists as an obvious encrustation after the lichen’s death. In the past, these disfiguring oxalate residues on ancient monuments have been variously interpreted as resulting from former mechanical/chemical renovation treatments, atmospheric pollution , and climatic weathering. The origin and nature of oxalate accretions, the factors involved in pedogenesis , and the development of lichen mosaics are reviewed. Aesthetic disfigurement versus physical damage to stonework is considered, and various aspects of stonework conservation are discussed.

The Kukkal basin, Tamil Nadu, India, receives most of its rain from the southwest monsoon (SWM). A sediment core from Kukkal Lake preserves a continuous sediment record from the early-Holocene to present (9000 yr BP to present). The present lake is situated at an elevation of similar to 1887m a.s.l., in a small basin that appears to have alternated between a and wetland depositional environment. Climate proxies, including sediment texture, total organic carbon (TOC), total nitrogen (TN), C/N, pollen and geochemical composition indicate a steady progression to wetter conditions, with two stepwise changes at about 8000, and between 3200 and 1800 yr BP. The change at 8000 yr BP appears to correspond to a brief (100-150years) dry spell recorded elsewhere in India. The change at 3200-1800 yr BP consisted in a rapid intensification of the SWM, and may correlate with the initiation of the Roman Warm Period'. There is no clear evidence of changes at the times of the Medieval Warm Period' (MWP') and the Little Ice Age' (LIA'). The C/N ratio of the sediments ranges from 14.02 to 8.31, indicating that the organic matter originated from a mixture of lacustrine algae, vascular and terrestrial plants. Chemical weathering indices (Chemical Index of Alteration (CIA), Chemical Index of Weathering (CIW), and Plagioclase Index of Alteration (PIA)) are consistent with extreme silicate weathering. Pollen data show a development from savanna vegetation prior to about 8000 yr BP, followed by grassland with palms, the appearance of ferns just prior to 3200 yr BP and the establishment of the tropical humid forest between 3200 and about 1800 yr BP.

Ce travail est une analyse des conséquences de la présence de roches altérées, les altérites, sur les instabilités littorales du Labourd (Pays Basque). Le contexte environnemental des mouvements de terrain qui mobilisent ces matériaux méconnus est étudié afin de mieux appréhender les processus de rupture. Pour cela, d’une part, les altérites sont caractérisées d’un point de vue géologique ; d’autre part, les propriétés géotechniques et les circulations hydrogéologiques sont déterminées. Ces études permettent de mettre en évidence les différents facteurs prédisposant et déclenchant les instabilités, validés par modélisation numérique. La connaissance des processus ainsi améliorée, un outil d’estimation de l’aléa dans les altérites est proposé. / This work is an analysis of the consequences of the presence of weathered rocks, called alterites, on the coastal landslides of the Labourd (Basque country). The environmental context (geological, hydrogeological and morphological) of the landslides is studied to a better understanding of the failure processes. These studies allow to highlight the main triggering factors of the landslides, which are validated by numerical modelling. The knowledge of the processes so improved, a tool to estimate landslide hazards in the alterites is proposed.

Ce travail concerne l'étude des interactions bactéries /silicates grâce à de nouveaux matériaux ou gels de silice hybrides dopés en particules colloïdales de smectites (GSH). Les deux objectifs principaux sont la caractérisation physicochimique des GSH et l'amélioration des connaissances sur les mécanismes de l'altération minérale grâce aux GSH. Dans le premier volet de la thèse, nous avons ainsi pu mettre en évidence que le gel est constitué d'une matrice siliceuse particulaire de nature fractale dans laquelle les particules minérales sont dispersées. La structure des GSH est stabilisée par le traitement hydrothermal choisi (type autoclave). Dans le second volet de la thèse, l'altération minérale est étudiée pour des GSH à concentration variable en particules minérales, à teneur élevée (NAu-2) ou basse (SWy-2) en fer. Il est ainsi montré que la diffusion des acides organiques et des sidérophores dans le GSH, hors adhésion ou formation d'un biofilm en surface des minéraux, est suffisante pour altérer efficacement les particules minérales. La mise en évidence de gradients de protons locaux produits par la bactérie en interaction avec les GSH peut également expliquer l'efficacité biotique de la dissolution minérale par rapport à des conditions abiotiques. En conclusion, les points forts et les limites de l'utilisation d'un matériau hybride type GSH pour cibler les interactions minéral/microorganismes sont discutés / This work deals with the study of bacteria/silicate interactions by using new hybrid materials, i.e. hybrid silica gel dopped with colloidal smectite particles (HSG). The aims are (1) to characterize HSG physicochemical properties and (2) to get a better knowledge about mineral/bacteria interactions. In a first part of the thesis, it is shown that HSG is a fractal silica network containing well-dispersed mineral particles. Hydrothermal treatment is necessary to stabilize the HSG structure. In the second part, it is shown that diffusion of organic acids and siderophores is sufficient to explain the high efficiency of bacterial action compared to abiotic treatments. Preventing bacterial adhesion or biofilm formation at the mineral surface permits to enhance the influence of metabolites diffusion. To conclude, the advantages and limits of using HSG in environmental studies are discussed

Cette thèse a les objectifs suivants :1. Mieux comprendre comment les isotope du bore dans les sédiments fluviaux modernes enregistrent le régime d’altération à l'échelle du bassin versant. 2. Mieux comprendre comment le « signal » d’altération porté par les sédiments fluviaux est transféré des zones sources vers l’environnement de dépôt. 3. Déterminer si les isotopes du B dans les dépôts sédimentaires (paléo-canaux) peuvent être utilisés pour reconstituer les conditions paléo-climatiques et paléo-environnementales et ainsi révéler comment l’altération continentale au sens large (production et transport de sédiments) a réagi à la variabilité climatique au cours du dernier cycle glaciaire-interglaciaire (derniers 100 ka). Ces objectifs ont été examinés en étudiant les matériaux fluviaux des fleuves Gandak (Himalaya) et Murrumbidgee (NSW, Australie) et des dépôts de sédiments fluviaux de la Riverine Plain (basin versant de Murrumbidgee). La connaissance des paramètres qui contrôlent le fractionnement isotopique du bore des sédiments fluviaux au cours de la formation et du transport a d'abord été acquise dans les systèmes modernes, puis appliquée à d'anciens dépôts de paléochenaux. / This thesis has the following objectives: 1) To better understand how boron isotopes in modern fluvial sediments record the weathering regime at the catchment scale. 2) To better understand how the weathering “signal” carried by river sediments is transferred from source areas to the depositional environment. 3) To determine if boron isotopes in sediment deposits (paleochannels) can be used to reconstruct paleo-weathering and paleo-environmental conditions and reveal how continental weathering at large (production and sediment transport) responds to climatic variability over the last glacial-interglacial cycle (last 100 ka). These objectives were addressed by studying fluvial material from the Gandak (Himalayas) and Murrumbidgee (NSW, Australia) Rivers and fluvial sediment deposits from the Riverine Plain (Murrumbidgee catchment, Australia). Knowledge of the parameters that control boron isotope fractionation of river sediment during formation and transport was first gained in the modern systems and then applied to ancient paleochannel deposits.