The Dinantian West Lothian Oil-Shale Formation of the Midland Valley, Scotland, is a laterally variable lacustrine sequence, deposited in an overall humid climatic period. The sequence comprises non-marine limestones, dolostones, oil-shales, mudrocks and deltaic sandstones. Thin marine bands and the thick freshwater Burdiehouse Limestone are the most reliable stratigraphic markers. Eight individual outcrops of microbial carbonatesa, ll stratigraphically close to the Burdiehouse Limestone, are correlatable, and therefore important in helping to clarify the Asbian stratigraphy of the eastern Midland Valley of Scotland. The microbial carbonates were deposited in varied shallow lake settings. Lake waters had a long residence time, suggested by fairly positive stable carbon and oxygen isotope ratios. Petrography and geochemistry suggest the primary carbonate was high-Mg calcite. Isotopic variations are mainly controlled by depositional water depth, diagenetic fluid temperaturesl,o calised magmatica ctivity and in-situ organicm atterd ecay. A regional dolornitisation event affected the lithologies, with high Fe" and Mg2+ concentrations suggesting early diagenetic dolomitisation under phreatic conditions. High Sr dolomite suggestst hat the lake and / or regional groundwaters were Sr enriched. Both the Sr ions and the Mg ions for dolomitisation were probably derived from chemically-enriched, seaward flowing groundwaters, that originated on a westerly situated volcanic plateau. The microbial carbonates represent regional and localised regressive sequences, lake, and in volcanically-isolated depositional sub-basins. The carbonates probably correspond to a regionally-significant period of aridity within the Asbian of south-east Scotland, similar to fluctuating seasonal semi-arid and humid conditions identified in the Dinantian of England and Wales.

L’analyse de sûreté des réacteurs à neutrons rapides refroidis au sodium de Génération IV nécessite l'étude des conséquences d'un accident grave en cas de rejet dans l'environnement du sodium et des radionucléides qu'il transporte (terme source chimique et radiologique). Le terme source global dépend donc à la fois de la spéciation chimique des aérosols de sodium, issus de la combustion du sodium dans l'enceinte, et de leurs interactions avec les radionucléides. Au cours de cette thèse, les interactions entre le carbonate de sodium et les produits de fission gazeux iodés (I2 et HI) ont été étudiées aux échelles atomique et macroscopique, via une double approche théorique et expérimentale. Une expression analytique de l'isotherme d'adsorption a été développée. La stabilité relative des surfaces du carbonate de sodium a été déterminée par des calculs ab initio utilisant la théorie de la densité fonctionnelle. La réactivité de l'iode a été étudiée pour les surfaces les plus stables et les isothermes d'adsorption évaluées. En parallèle, la cinétique de capture de l'iode moléculaire par le carbonate de sodium a été déterminée expérimentalement pour différentes conditions. L'ensemble des résultats montrent une capture efficace de l'iode moléculaire par le carbonate de sodium à 373 K, variant selon la pression partielle d'iode et la surface du carbonate. Pour les conditions représentatives d'un accident grave, les sites d'adsorption de la surface de carbonate de sodium la plus favorable seront majoritairement vides ou doublement occupés selon la pression partielle d'iode moléculaire, conduisant à une pression d'équilibre inférieure à 2x10-4 bar à 373 K. / The safety analysis of Generation IV sodium-cooled fast neutron reactors requires the study of the consequences of a severe accident in case of release into the environment of sodium and the radionuclides it carries (term chemical and radiological source). The global source term therefore depends on both the chemical speciation of sodium aerosols, resulting from the combustion of sodium in the containment, and their interactions with radionuclides. During this thesis, the interactions between sodium carbonate and iodinated gaseous fission products (I2 and HI) were studied at the atomic and macroscopic scales, via a combined theoretical and experimental approach. An analytical expression of the adsorption isotherm has been developed. The relative stability of the sodium carbonate surfaces was determined by ab initio calculations using density functional theory. The reactivity of iodine has been studied for the most stable surfaces and the adsorption isotherms evaluated. In parallel, the kinetics of capture of molecular iodine by sodium carbonate has been determined experimentally for different boundary conditions.The results show an effective capture of the molecular iodine by sodium carbonate at 373 K, varying according to the partial pressure of iodine and the surface of the carbonate sorbent. For the representative conditions of a severe accident, the adsorption sites of the most favorable sodium carbonate surfaces will be mostly bare or doubly occupied depending on the partial pressure of molecular iodine; leading to an equilibrium pressure of less than 2x10-4 bar at 373 K.

The rate of biodegradation of hydrocarbon contaminated soils can be studied using the radiocarbon (14C) content of CO2 efflux from the ground surface over an impacted area.14C is used as a tracer to distinguish modern 14C CO2 from natural respiration processes and 14C depleted CO2 derived from petroleum degradation. Studies have shown that this analysis provides reliable, quantifiable data and an effective means of correcting for background CO2 which may present some natural depletion from older subsurface organics. The study area for this project is a remote community in Northern Yukon where organic rich sediments overlying continuous permafrost are contaminated by diesel oil. An objective of this study was to evaluate the use of 14C to quantify background CO2 in permafrost soils with abundant, older labile organics. A second objective was to test a new sampling technique to facilitate sample shipment from remote sites, which traps soil CO2 in small sealed exetainers as a solid barium carbonate. Data obtained from established radiocarbon sampling procedures and this new novel approach were shown to be comparable and reproducible. This technique facilitated both sample collection and shipment as well as analysis by accelerator mass spectrometry (AMS), allowing for rapid, efficient sampling techniques to be deployed in remote areas. Results of this study show the carbonate method to be an economical and effective sampling method, and used at the Old Crow site, demonstrated that under current climate conditions, older organics in the subsurface do not confound the use of 14CO2 for source zone biodegradation assessment at this hydrocarbon impacted permafrost site.

Most of the hydrocarbon reservoirs in the world are carbonates, and most of these carbonate reservoirs are fractured. Fractures can form due to tectonic activity, mainly associated with fold and faults, and as a result of diagenesis. In many cases, the fractures in carbonates are cemented due to fluid flow, where these fluids precipitate cements. The presence of fractures can enhance reservoir fluid flow if the fractures were open and connected. This thesis focuses on carbonate reservoir fractures, and understanding the evolution of fluids from the cements that have precipitated within them. This thesis relates regional tectonic events to the formation of fractures, and of the environment and temperature of the fluids of precipitation in cement fractures the Early Cretaceous Thamama Group, in the United Arab Emirates (UAE). First, samples were studied from the subsurface in a highly faulted oil Field (A) located in South East Abu Dhabi. Core samples were taken from wells close to major faults in the field in both oil and water legs. Second, fractures in outcrop in Wadi Rahaba, Ras Al Khaima (RAK) in the Northern Emirates were studied where the Upper Thamama Group is exposed. The field study in the outcrop included the fracture orientation and cement types. The fractures in the outcrop were divided into two main generations, F1, (en-echelon) and F2 and they were both fully or partially cemented. The main tectonic events that affected the fracture formation in the Thamama Group are foreland autochthon in the Precambrian to Lower Cretaceous, a frontal triangle zone in Neogene and Dibba zone which consists of Hawasina units (Triassic to Cretaceous), and the Sumeini units (Lower to Middle Cretaceous). F1 is related to the NS orientation fracture system consistent to the Arabian Trend sets caused by Cenozoic compression. F2 is related to the EW orientation fracture system matching Tethyan extensional trend sets. Petrographic analysis of the subsurface thin sections revealed the presence of three main sets of fractures. Fracture Set 1 (cemented), Fracture Set 2 (open) and Fracture Set 3 (cemented, only in Lower Thamama). The fracture cement included equant and blocky calcite as well as saddle dolomite. Cathodoluminescence (CL) analysis assigned the number of cement zones in each cement type in the fractures, and revealed more cement zones in the Lower Thamama reservoirs than the Upper. The most important diagenetic events were cementation and dissolution, which took place towards the end of the paragenetic sequence. The reservoirs contained significant amounts of stylolites, dissolution seams and bitumen, which were associated with most of the dissolution events. mMg/mCa obtained from in situ elemental analysis showed variation through the calcite and dolomite cement zones in the different reservoirs of the Thamama Group. This was inferred to be due to temperature changes. The Upper Thamama Reservoirs (A, B, and C) show lower mMg/mCa (0.072-0.48) than the Lower Thamama reservoirs (F,G) (0,4-1.3), meaning that the Upper Thamama fracture calcite cements were precipitated at higher overall temperatures than the Lower Thamama reservoirs. Mn-Fe analysis allowed an understanding of the redox index through the different cement zones, in both Fracture Set 1 and Fracture Set 3. Analysis of Sr showed the absence of exotic fluids role in the diagenetic system. In-situ (SIMS) δ18OVPDB values were obtained for the calcite cementation history of the two fracture sets in the five reservoirs of the Thamama Group. The δ18OVPDB analysis indicated that Fracture Set 1 has a longer cementation history than Fracture Set 3, and has wider range of temperatures (58-128°C). A comparison of the outcrop analysis results and the subsurface reservoir was established at the end to distinguish the similarities and differences between the subsurface and outcrop in fracture types, fracture cement types and characteristics of the elemental analysis curve behaviours. The fracture cement in both subsurface and outcrop seemed to be precipitated at deep burial environment.

The Middle Cambrian Spence Shale Member of the Langston Formation of northern Utah and southern Idaho is a fossil-rich unit that exhibits distinct cyclicity at the parasequence (meter) scale. At least seven discrete, shallowing-upwards parasequences, or cycles, can be found at the Miners Hollow and Antimony Canyon localities, each composed of calcareous shale capped by limestone. Within each cycle and within the member as a whole, predictable patterns of faunal distribution are evident. Sampling and identification of fossils from two localities have revealed that observed changes in fauna track changes in sea level throughout the section. Through cluster and principal components analyses it has been determined that those rocks of the Spence Shale representing a transgressive systems tract are home to a particular community of organisms, while those rocks of the highstand systems tract are home to another. It logically follows that the rocks of the transgressive tract represent a distinct biofacies, while those of the highstand tract represent another. The transgressive biofacies is composed of species such as agnostid and oryctocephalid trilobites and inarticulate brachiopods that are commonly found in deeper ramp settings. The highstand biofacies is distinguished by such taxa as Zacanthoides and other larger trilobite genera such as Glossopleura and Kootenia, and the eocrinoid Gogia, among others. The difference in ramp position between the Miners Hollow and Antimony Canyon localities implies a water depth gradient, with Antimony Canyon representing shallower water and Miners Hollow representing deeper water. This relationship is also reflected in the biofacies and community assignments. The stratigraphic trends explored in this study may be applied to other Spence Shale localities and possibly other Cambrian fossil deposits, such as the Burgess Shale of British Columbia. (151 pages)

Philosophiae Doctor - PhD / Search for an ideal scaffold for guided tissue/bone (GTR/GBR) regeneration continues as till now none of the commercially available GTR/GBR membrane fulfils the desired criteria. Currently, a variety of new materials and techniques have been investigated all over the world to improve the properties of GTR/GBR membranes. In the recent past three dimensional bioactive scaffolds composed of natural polymers have gained enormous popularity as potential future GTR/GBR devices. Electrospinning has emerged as one of the relatively simple, cost effective and efficient technique to fabricate three dimensional nanofibrous scaffolds in the field of tissue engineering. The rationale of this project is to investigate the natural polymers based bioactive nanofibrous scaffolds for GTR/GBR applications in the field of Periodontology.

The hydrolysis of urea by the widely distributed enzyme urease is special in that it is one of the few biologically occurring reactions that can generate carbonate ions without an associated production of protons. When this hydrolysis occurs in a calcium-rich environment, calcite (calcium carbonate) precipitates from solution forming a solid-crystalline material. The binding strength of the precipitated crystals is highly dependent on the rate of carbonate formation and under suitable conditions it is possible to control the reaction to generate hard binding calcite cement (or Biocement). The objective of this thesis was to develop an industrially suitable cost-effective microbial process for the production of urease active cells and investigate the potential for urease active cells to act as a catalyst for the production of Biocement. The biocementation capability of two suitable strains was compared. Sporosarcina pasteurii (formally Bacillus pasteurii) produced significantly higher levels of urease activity compared to Proteus vulgaris, however the level of urease activity was variable with respect to biomass suggesting that the enzyme was not constitutive as indicated by the literature, but subject to regulation. The environmental and physiological conditions for maximum urease activity in S. pasteurii were investigated and it was found that the potential urease capacity of the organism was very high (29 mM urea.min-1.OD-1) and sufficient for biocementation without additional processing (e.g. concentration, cell lysis). The regulation mechanism for S. pasteurii urease was not fully elucidated in this study, however it was shown that low specific urease activity was not due to depletion of urea nor due to the high concentrations of the main reaction product, ammonium. pH conditions were shown to have a regulatory effect on urease but it was evident that another co-regulating mechanism existed. Despite not fully exploiting the urease capability of S. pasteurii, sufficient urease activity to allow direct application of the enzyme without additional processing could still be achieved and the organism was considered suitable for biocementation. Urease was the most expensive component of the cementation process and cost-efficient production was desired, thus an economic growth procedure was developed for large-scale cultivation of S. pasteurii. The organism is a moderate alkaliphile (growth optimum pH 9.25) and it was shown that sufficient activity for biocementation could be cultivated in non-sterile conditions with a minimum of upstream and downstream processing. The cultivation medium was economised and expensive components were replace with a food-grade protein source and acetate, which lowered production costs by 95%. A high level of urease activity (21 mM urea hydrolysed.min-1) was produced in the new medium at a low cost ($0.20 (AUD) per L). The performance of urease in whole S. pasteurii cells was evaluated under biocementation conditions (i.e. presence of high concentrations of urea, Ca2+, NH4 +/NH3, NO3 - and Cl- ions). It was established that the rate of urea hydrolysis was not constant during cementation, but largely controlled by the external concentrations of urea and calcium, which constantly changed during cementation due to precipitation of solid calcium carbonate from the system. A simple model was generated that predicted the change in urea hydrolysis rate over the course of cementation. It was shown that whole cell S. pasteurii urease was tolerant to concentrations of up to 3 M urea and 2 M calcium, and the rate of urea hydrolysis was unaffected up to by 3 M ammonium. This allowed the controlled precipitation of up to 1.5 M CaCO3 within one treatment, and indicated that the enzyme was very stable inspite of extreme chemical conditions. A cost-efficient cementation procedure for the production of high cementation strength was developed. Several biocementation trials were conducted into order to optimise the imparted cementation strength by determining the effect of urea hydrolysis rate on the development of strength. It was shown that high cementation strength was produced at low urea hydrolysis rates and that the development of cementation strength was not linear over the course of the reaction but mostly occurred in the first few hours of the reaction. In addition, the whole cell bacterial enzyme had capacity to be immobilised in the cementation material and re-used to subsequent applications, offering a significant cost-saving to the process. An industry-sponsored trial was undertaken to investigate the effectiveness of Biocement for increasing in-situ strength and stiffness of two different sandy soils; (a) Koolschijn sand and (b) 90% Koolschijn sand mixed with 10% peat (Holland Veen). After biocementation treatment, Koolschijn sand indicated a shear strength of 1.8 MPa and a stiffness of 250 MPa, which represents an 8-fold and 3-fold respective improvement in strength compared to unconsolidated sand. Significantly lower strength improvements were observed in sand mixed with peat. In combination, trials of producing bacteria under economically acceptable conditions and cementation trials support the possibility of on-site production and in-situ application of large field applications.

Recently, we reported the extraction, purification and amino acid sequence of ansocalcin, the major goose eggshell matrix protein. In vitro studies showed that ansocalcin induces spherical calcite crystal aggregates. We designed two peptides using the unique features of the sequence of ansocalcin and the role of these peptides in CaCO₃ crystallization was investigated. The peptides showed similar activities as compared to ansocalcin, but at a higher concentration. The full characterization of the peptides and a rational for the observed morphology for the calcite crystals are discussed in detail. / Singapore-MIT Alliance (SMA)

Reliable measurements of the thermodynamics of the carbonate system are needed to better understand the CO2 system in natural waters. New measurements of the carbonic acid pK1* and pK2* in seawater have been made over a wide range of temperatures (1 to 50°C) and salinities. The commonly used CO2 constants of Mehrbach et al., (1973) were limited to salinities (19 to 43) and temperatures (2 to 35°C). They cannot be used to study estuarine or fresh waters. The results of these measured pK1* and pK2* values are in good agreement with those determined using the Miami Pitzer equations (Millero and Pierrot, 1998). The results in this dissertation can be demonstrates the validity of the model that can be used to study the carbonate system in most natural waters. The so called Miami model is presently being used to examine the effect of ocean acidification on natural waters. The boric acid effect on the dissociation constants in seawater and NaCl solutions was tested. The addition of boric acid has little or no effect on pK1* values. However, the values of pK2*, decreases with the addition of small amounts of boric acid to ASW in agreement with the work of Mojica-Prieto and Millero, (2002). The addition of larger concentrations of boric acid cause the values of pK2* to increase. These effects have been attributed to the interactions of boric acid with the carbonate ion (CO32-) in seawater (Mojica-Prieto and Millero, 2002). The addition of boric acid to NaCl solutions in contrast, caused the values of pK1* and pK2* to decrease. This has been attributed to the interactions of borate ions with Mg2+ and Ca2+ in seawater. Further measurements in Na-Mg-Cl and Na-Ca-Cl solutions are needed to prove that this is the case. The boric acid effect on the carbonate constants indicate that an increase in boric acid has no affect on pK1*, but does change the values of pK2*. At low concentrations of boric acid, pK*2 decreases, and at higher concentrations it increases. These results indicate that boric acid has some ionic interactions with the carbonate ion. Similar studies in NaCl indicate that both pK1* and pK2* decrease when boric acid is added. The differences between seawater and NaCl may be related to the interactions of Mg2+ and Ca2+ with borate anions. Further studies of NaCl with additions of MgCl2 and CaCl2 are needed to examine the effects in detail. Preliminary studies on the effect of DOC on the carbonate constants are not definitive. The change of the DOC concentration from 50 to 100 µmol kg-1 has little effect on the values of pK1* and pK2*. Dilutions of seawater with artificial seawater are complicated by changes in the concentration of boric acid. Earlier studies indicated that DOC may cause the 8 mu-mol kg-1 increase in total alkalinity of seawater needed to balance the thermodynamics of the system (Millero et al., 2002). This may be partially due to the new values for the B/Cl ratio in seawater found by Lee et al., (2010) that increases the TA by ~ 6 µmol kg-1. Further studies are needed to examine the effect of humic compounds in estuarine waters on the carbonate system. Measurements of pH or pCO2 along with TA and TCO2 can be used to separate the effect of organic ligands on TA. If DOC measurements are also made, one can relate the effect to organic ligands that can accept a proton. The cruises in the Little Bahama Banks show for the first time the active precipitation of CaCO3 (Bustos-Serrano et al., 2009). This causes measured decreases of TA, TCO2 and pH and increases in pCO2 in the whitings. This is in contrast to earlier studies on the Grand Bahama Banks where no active precipitation of CaCO3 was every found (Morse et al., 2003; Millero et al., 2005). The differences appear to be due to the movement of fresh saturated seawater from the Gulf Stream into the LBB. The Gulf Stream water enters the GBB in the winter, and the precipitation occurs on the suspended sediment over the year. Observations are needed on the Grand Bahama Banks in the winter and throughout the year to prove that this is the case.

The use of neural networks in the field of development geology is in its infancy. In this study, a neural network will be used to identify flow units in Happy Spraberry Field, Garza County, Texas. A flow unit is the mappable portion of the total reservoir within which geological and petrophysical properties that affect the flow of fluids are consistent and predictably different from the properties of other reservoir rock volumes (Ebanks, 1987). Ahr and Hammel (1999) further state a highly "ranked" flow unit (i.e. a good flow unit) would have the highest combined values of porosity and permeability with the least resistance to fluid flow. A flow unit may also include nonreservoir features such as shales and cemented layers where combined porosity-permeability values are lower and resistance to fluid flow much higher (i.e. a poor flow unit) (Ebanks, 1987). Production from Happy Spraberry Field primarily comes from a 100 foot interval of grainstones and packstones, Leonardian in age, at an average depth of 4,900 feet. Happy Spraberry Field is unlike most fields in that the majority of the wells have been cored in the zone of interest. This fact more easily lends the Happy Spraberry Field to a study involving neural networks. A neural network model was developed using a data set of 409 points where X and Y location, depth, gamma ray, deep resistivity, density porosity, neutron porosity, lab porosity, lab permeability and electrofacies were known throughout Happy Spraberry Field. The model contained a training data set of 205 cases, a verification data set of 102 cases and a testing data set of 102 cases. Ultimately two neural network models were created to identify electrofacies and reservoir quality (i.e. flow units). The neural networks were able to outperform linear methods and have a correct classification rate of 0.87 for electrofacies identification and 0.75 for reservoir quality identification.