x, 156 leaves : ill. ; 29 cm Notes Typescript. (Another copy on microfilm is located in Archives) Thesis (Ph.D.) -- University of Oregon Includes vita and abstract Bibliography: leaves 150-156

Para melhor entender a relação entre os oceanos e as variações climáticas são necessários registros destes eventos. O presente trabalho tem por objetivo principal estudar as variações climáticas e oceanográficas utilizando os registros de conteúdo de carbonato em dois sedimentos coletados na Bacia de Campos. A cronologia dos testemunhos foi primeiramente estabelecida através do conteúdo de carbonato. Sua validação foi feita através das análises de radiocarbono em duas amostras próximas do topo de cada testemunho. Outros métodos usados para corroborar a cronologia foram o biozoneamento com base nos foraminíferos planctônicos Globorotalia menardii e Pulleniatina obliquiloculata, executadas em ambos os testemunhos; análises de isótopos de oxigênio em foraminíferos planctônicos Globigerinoides ruber em amostras do KF-13; e dados de susceptibilidade magnética para o KF-14. Com exceção de radiocarbono, os outros métodos não fornecem idades absolutas Foi então necessário compará-los com estratos de idade conhecida. Para isso utilizaram-se dados do SPECMAP, tornando possível a inferência dos estágios isotópicos marinhos para estes testemunhos. Estabelecida a estratigrafia para os testemunhos com base no conteúdo de carbonato, identificamos as diferentes condições climáticas nas quais os sedimentos foram depositados. As curvas de conteúdo de carbonato para ambos os testemunhos, junto com os dados de isótopos de oxigênio para o KF-13 e a de susceptibilidade magnética para o KF-14 foram comparados com a curva de isótopos de oxigênio do SPECMAP, inferindo assim idades aproximadas para algumas das feições apresentadas. Também foram utilizadas as biozonas de foraminíferos planctônicos identificadas para estimar as idades aproximadas em pontos ao longo do testemunho, além dos dados de radiocarbono. Estabelecida essa cronologia foi possível fazer o cálculo das taxas de sedimentação. Os resultados aqui apresentados mostram a importância que o conteúdo de carbonato nos sedimentos tem para estudos de variações climáticas. / Records of climatic variations are necessary for better understanding of the relationship between the oceans and these events. The main objective of this work is to study climate and ocean variations using carbonate records in two sediment cores collected from the Campos Basin. The chronology of the sediment cores was established through carbonate content. Validation was achieved through radiocarbon analysis in two samples from the top of each core. Other methods used to corroborate chronology were the establishment of biozones based on the planktonic foraminifera Globorotalia menardii and Pulleniatina obliquiloculata, used in both sediment cores; oxygen isotope analysis on the planktonic foraminifera Globigerinoides ruber in samples from KF-13; and magnetic susceptibility data for KF-14. With the exception of radiocarbon, other methods do not provide absolute ages, making it necessary therefore to compare with other stratum of known ages. Data from SPECMAP were used enabling inference of marine isotopic stages for this sediment cores. Once the stratigraphy was established based on the carbonate content, it was possible to identify the climate conditions in which the sediments were deposited. Carbonate content curves for both cores along with the oxygen isotope data for the KF-13 and KF-14 magnetic susceptibility data were compared with the oxygen isotope curve from SPECMAP, inferring approximate ages for some of the features presented. Identified foraminiferal biostratigraphic zones were used to estimate the approximate ages in certain points along the core, along with radiocarbon dating. Once this chronology was established, it was possible to calculate sedimentation rates along the sediment cores. The results here presented demonstrate the importance of carbonate content variations in sediment cores as a means to understanding climate variations.

A Ãgua à um recurso natural de valor inestimÃvel. Mais que um insumo indispensÃvel à produÃÃo à um recurso estratÃgico para o desenvolvimento econÃmico. A regiÃo semiÃrida, assim como o resto mundo, sofre cada vez mais com as alteraÃÃes climÃticas, associadas ao aquecimento global. Essas mudanÃas climÃticas tÃm impactos tanto na oferta como na demanda por Ãgua nessa regiÃo. Na regiÃo Nordeste do Brasil, onde hà uma distribuiÃÃo irregular de chuvas, a produÃÃo agrÃcola à substancialmente melhorada atravÃs do uso da irrigaÃÃo. A adoÃÃo do uso da irrigaÃÃo nessas regiÃes semiÃridas causa modificaÃÃes no regime de umidade dos solos e pode ainda alterar suas propriedades e processos. O objetivo deste trabalho foi investigar os efeitos causados durante 23 anos de irrigaÃÃo sobre solos calcÃrios no semiÃrido cearense, com Ãnfase no estudo das alteraÃÃes pedogenÃticas proporcionadas pelo uso dessa prÃtica. As Ãreas escolhidas para o estudo estÃo localizadas no perÃmetro irrigado localizado na Chapada do Apodi no municÃpio de Limoeiro do Norte-CE. Foram realizadas 8 tradagens em cada Ãrea (na Ãrea irrigada e na Ãrea externa e limÃtrofe ao pivÃ). Posteriormente, em cada uma das Ãreas, foram abertas trincheiras para realizaÃÃo das descriÃÃes morfolÃgicas e coleta de amostras de solo para fins de caracterizaÃÃo fÃsica, quÃmica, mineralÃgica e micromorfolÃgica. Os resultados referentes Ãs tradagens indicam terem ocorrido diferenÃas significativas na Ãrea irrigada quando comparada à Ãrea nÃo irrigada, sendo verificadas a intensificaÃÃo da dissoluÃÃo de CaCO3 e o aumento dos teores de cÃlcio, sÃdio e fÃsforo. AlÃm disso, o solo irrigado sofreu alteraÃÃes dos seus atributos fÃsicos, sendo verificado aumento da sua densidade de partÃculas, diminuiÃÃo da permeabilidade do solo ao ar e a formaÃÃo de poros menos contÃnuos. Os resultados das anÃlises dos perfis mostraram que os 23 anos de irrigaÃÃo tiveram efeito no solo irrigado, tornando-o mais evoluÃdo em comparaÃÃo ao nÃo irrigado, isso foi verificado atravÃs dos resultados obtidos na morfologia com aumento da espessura do solum, na fÃsica com a menor relaÃÃo silte/argila e maior conteÃdo argila nesse solo, na mineralogia com indÃcios de aumento da caulinita e neoformaÃÃo de minerais interestratificados e na micromorfologia com o maior grau de pedalidade. O solo irrigado foi classificado como Chernossolo HÃplico carbonÃtico saprolÃtico, por apresentar horizonte A chernozÃnico seguido de horizonte B incipiente e possuir argila de atividade alta. / Water is a priceless natural resource. More than an essential input to production is a strategic resource for economic development. The semiarid region, as well as the rest of the world, suffer more with climate change associated with global warming. These climate changes have impacts on both supply and demand for water in this region. In northeastern Brazil, where there is an uneven distribution of rainfall, agricultural production is substantially improved through the use of irrigation. The adoption of the use of irrigation in these semiarid regions leads to changes in soil moisture regime and may even change its properties and processes. The objective of this study was to investigate the effects during 23 years of irrigation on calcareous soils in semiarid CearÃ, with emphasis on the study of pedogenetic changes provided by this practice. The areas chosen for study are located in Chapada do Apodi located in the city of Limoeiro do Norte - Ce. 8 amostrgens were performed in each area (in the irrigated area and the area outside and adjacent to the pivot). Subsequently, in each of the areas, trenches were opened to perform the morphological descriptions and collected soil samples for physical characterization, chemical, mineralogical and micromorphological. The results indicate significant differences have occurred in the irrigated area compared to non-irrigated area, and verified the increased dissolution of CaCO3 and increased levels of calcium, sodium and phosphorus. Furthermore, the flooded soil has changed its physical characteristics, and found an increase in density of particles decreased permeability of the soil air and the formation of pores less continuous. The analysis results showed that the profiles of 23 years of irrigation had effect on irrigated soil, making it more evolved in comparison to non-irrigated, it was verified by the results obtained in morphology with increasing soil thickness in physics with a lower silt / clay ratio and higher clay content in soil, mineralogy with evidence of increased neoformation of kaolinite and interstratified minerals, in micromorphology with the highest degree of pedalidade. The irrigated soil was classified as Chernosol by presenting chernozÃnico horizon followed by an incipient B horizon and possess high activity clay.

Muitos organismos vivos, tal como seus constituintes, são formados por sistemas químicos complexos que envolvem a interação entre compostos orgânicos e inorgânicos ligados química e/ou fisicamente. Nestes sistemas as matrizes orgânicas são geralmente compostas por macromoléculas como polissacarídeos e proteínas. Essas moléculas têm o papel de direcionar a nucleação e o crescimento da porção inorgânica. O uso de superfícies metálicas adequadas recobertas por este tipo de filme híbrido tem potencial aplicação em implantes de substituição óssea, no qual são requeridas superfícies quimicamente inertes, mas que ao mesmo tempo estimulem processos de calcificação. Nesta tese estudou-se o crescimento de CaCO3 sobre superfícies metálicas de alumínio e aço inox recobertas por matrizes orgânicas compostas por diferentes poliânions e pelo policátion quitosana, na forma de filmes montados camada-a-camada (do inglês LbL), na presença ou não de fosfolipídeos (filmes Langmuir-Blodgett), formando um meio confinado para o crescimento do mineral. Diferentes técnicas foram utilizadas: microscopia eletrônica, microscopia de força atômica, espectroscopias de reflexão nas regiões do Uv-vis, e do infravermelho, Raman, espalhamento e difração de raios-X. Estudou-se a influência de diferentes grupos carregados dos fosfolipídeos e dos poliânions, tal como sua conformação, no crescimento de CaCO3. O tipo de interação entre o poliânion e a quitosana leva ao crescimento de matrizes poliméricas com diferenças em suas espessuras e capacidade de retenção de líquido, modificando as condições de supersaturação local e influenciando no tipo de estrutura de CaCO3. Puderam ser identificados dois polimorfos formados sobre os filmes orgânicos de poli(ácido acrílico) e quitosana, sugerindo que existem dois diferentes sítios onde a nucleação pode ser iniciada: a partir da solução de CaCl2 aprisionada na matriz polimérica e o outro a partir dos íons cálcio ligados como contra-íons aos grupos negativamente carregados do poliânion. Na presença do pré-recobrimento LB, a natureza da cabeça polar do fosfolipídeo direciona o tipo de ligação e crescimento da matriz polimérica, que levam ao crescimento de partículas de CaCO3 com morfologia e tamanho variados, explicados em termos da presença de ambientes com diferenças de concentrações locais de Ca2+. Além disso, verificou-se que a rugosidade superficial dos suportes metálicos pode favorecer a formação do polimorfo de CaCO3 cineticamente mais estável, mostrando que o processo de cristalização sobre estes suportes é um processo governado por difusão. A hidrofilicidade dos suportes é aumentada pela presença da matriz orgânica e pela presença de CaCO3 sobre as matrizes. O crescimento de CaCO3 em meios confinados tridimensionais, formados por membranas de policarbonato modificadas com filme finos de polieletrólitos, também foi estudado. Este tipo de molde leva à formação de estruturas cilíndricas que seguem a morfologia dos poros da membrana. A presença de poli(ácido acrílico) leva a formação de estruturas cilíndricas ocas, enquanto que cilindros completamente preenchidos foram formados nos poros contendo quitosana na última camada. Estes resultados foram explicados com base em diferenças na etapa de nucleação: na presença de PAA a nucleação de CaCO3 deve iniciar-se a partir dos íons Ca2+ ligados ao poliânion que, por sua vez, está ligado diretamente às paredes do molde; já na presença que quitosana, com maior capacidade de retenção de liquido e sem interação específica com Ca2+ a nucleação e seqüente cristalização devem ocorrer por todo o poro da membrana. As estruturas formadas são em sua maioria monocristais de calcita hexagonal orientadas na direção cristalográfica <2 -2 1>. / Some living organisms as well as their constituents are formed by complex chemical systems which involves the interaction among organic and inorganic compounds bounded physically or chemically. In these systems the organic matrices are usually composed by macromolecules like polysaccharides and proteins. These molecules have an important hole in tailoring the nucleation and the sequent growth of the inorganic portion. Metallic surfaces coated with these hybrid films have potential application as implants for bone substitution for which the surfaces must be chemically inert but at the same time they should stimulate calcification processes. In this present thesis we studied the growth of CaCO3 over aluminium and stainless steal surfaces coated with layer-by-layer films composed by different polyanions and chitosan as polycation, in the presence or not of phospholipids (Langmuir-Blodgett films). These organic matrices formed a confined medium within which CaCO3 particles were growth. Different techniques were applied in order to understand these systems: electronic microscopy, atomic force microscopy, UV-Vis and infrared reflection spectroscopy, Raman, and X-ray scattering and diffraction. We studied the influence of the different charged groups of the phospholipids and the polyanion as well as their conformation on CaCO3 growth. The type of interaction between the polycation and the polyanions tailors the growth of the organic matrices, forming films with different thickness and different water retention abilities which change the local supersaturation conditions changing the structure of the CaCO3 formed. Two types of CaCO3 polymorphs were growth over poly(acrylic acid) (PAA) and chitosan films suggesting that there are two sites where the nucleation can be started: the CaCl2 solution retained in the gel-like organic films and the Ca2+ ions bounded to the negative groups of the polyanion. In the presence of the LB pre-coating, the nature of the phospholipid polar head tailors the binding and the growth of the polymeric matrices leading to the formation of CaCO3 particles with difference in their sizes and morphologies. This result was explained in basis of the differences in the Ca2+ local concentrations in each situation. Moreover, it was observed that the surface roughness of the supports can favour the formation of vaterite, the kinetically most stable CaCO3 polymorph, showing that the crystallization may be guided by diffusion processes. The hidrophilicity of the supports was improved by the presence of both organic and hybrid films. The growth of CaCO3 in tridimentional confined mediums was done using LbL modified polycarbonate membranes as template. This template leads to the formation of cylindrical CaCO3 particles following the morphology of the membrane pores. CaCO3 tube-like structures were formed in presence of PAA, while rod-like structures were formed in presence of chitosan in the top LbL layer. These results were explained on basis of the difference in the nucleation stages: in the presence of PAA the nucleation starts on the Ca2+ ions bounded to the polyanion that is linked to the walls of the template; in the presence of chitosan that presents higher water retention ability and has no specific interaction with Ca2+ ions, the nucleation and sequent crystallization should occur through the entire pore of the membrane. The electron diffraction patterns showed that the CaCO3 structures are single crystals of the calcite polymorph oriented in < 2 -2 1> crystallographic direction.

Orientador: José Ricardo Pelaquim Mendes / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica e Instituto de Geociências / Made available in DSpace on 2018-08-23T21:31:12Z (GMT). No. of bitstreams: 1 Rigobello_AnaLuciaGodoy_M.pdf: 19440225 bytes, checksum: 976868faec9ffa0e37433dfbff01c239 (MD5) Previous issue date: 2013 / Resumo: Incrustações consistem em um subproduto indesejável na forma de depósitos cristalinos, provenientes da precipitação de sais presentes na água. Dependendo da natureza da incrustação e da composição do :fluido a deposição pode ocorrer no reservatório de petróleo, próximo ao poço causando dano à formação, ou em instalações de produção ocasionando graves problemas operacionais além do declínio da produtividade. O controle de incrustação atualmente tem sido um problema desafiador na indústria do petróleo além de impactar fortemente no valor econômico do produto final. A variedade e complexidade dos tipos de tal deposição formados aumentam a dificuldade de desenvolver métodos adequados para aliviar esses problemas. Anualmente as empresas de petróleo gastam milhões de dólares na manutenção de equipamentos e produção, e alguns dos mais altos custos ocorrem na prevenção da incrustação. São necessários estudos em diferentes áreas com o intuito de reduzir e combater a formação de depósitos destes sais, evitando assim perdas e danos à formação. A prevenção e mitigação da incrustação é de grande importância além de ser bastante complexa. Um método eficaz é através do cálculo do chamado índice de incrustação, representado neste trabalho por Is. A presente pesquisa visa o estudo de incrustação, em especial incrustações por carbonato de cálcio no sistema de produção como um todo, bem como o estudo das variáveis que influenciam em sua formação através do mapa do potencial de incrustação. Com o intuito de realizar tal estudo, foi utilizado um modelo termodinâmico previamente existente para realizar os cálculos do índice baseado em dados de poços hipotéticos, além de exemplos reais. O modelo mostrou-se válido, e, conforme esperado, obteve-se um comportamento de variação de pressão, temperatura e pH condizente ao descrito nas literaturas / Abstract: Scale consists in an undesirable product in the form of crystalline deposits from precipitation of salts in the water. Depending on the scale nature and the composition of fiuid deposition can occur in the oil reservoir, near the well damaging the formation, or in production facilities causing serious operational problems in addition to the decline of productivity. The control of scale currently has now been a challenging problem in the oil industry and also impact strongly on the economic value of the final product. The variety and complexity of this type of deposition increases the difficulty of developing suitable methods to relieve these problems. Each year oil companies spend millions of dollars in equipment maintenance and production, and some of the highest costs occur in the scale prevention. Several studies are needed in different areas in order to reduce and control the formation of deposits of these salts, thus avoiding damages to the formation. The scaling prevention and mitigation are of great importance as well as being quite complex. An effective method is by calculating the index scale, represented in this work by Is. This research aims to study scale, specially calcium carbonate scale into the production system as a whole, as well as the study of the variables that infiuence its formation through the map of scale potential. ln order to accomplish this study, we used a previously existing thermodynamic model to perform calculations of the index based on data from hypothetical wells and real examples. The model proved to be valid, and, as expected, there was obtained one behavior of variation of pressure, temperature and pH consistent to that described in the literature / Mestrado / Explotação / Mestra em Ciências e Engenharia de Petróleo

Lake basins contain depositional systems whose stratigraphy and sedimentology are highly influenced by allogenic and authigenic processes. Identifying the relative roles of these controls is complicated in settings where both tectonic and climate influences control sediment inputs and accommodation availability. In order to identify how these controls may interact in carbonate lake basins the lacustrine Mayrán Formation, northeast México was investigated. The Mayrán Formation is well exposed and the strata geometries are well preserved. The necessary data needed to unravel these complexities was obtained using field based techniques (geological and structural mapping, sedimentary logging and sampling), combined with optical and electron optical microscopy, mineralogical (XRD), and geochemical (oxygen and carbon stable isotopes, total organic carbon [TOC], organic carbon isotopes, and U-Pb carbonate dating) techniques, to characterise the lake basins. These data reveal that the Mayrán Formation was deposited in four, northerly, down-stepping, broadly coeval, hydrologically linked, carbonate-dominated lake subbasins (the Mayrán Basin system), that formed at different elevations spanning ~500 m. Subbasin geomorphology was controlled by the inherited topography of the exhumed and eroded Parras foreland fold-and-thrust belt, as a result, the subbasins are compartmentalized by prominent sandstone ridges that form sills between subbasins. Sedimentary infill of the subbasins consists of a fluvio-lacustrine succession (carbonate and clastic) that overly an angular unconformity truncating the folded and faulted Cretaceous bedrock. Clastic sediments were preferentially trapped in the most proximal subbasin in the south, adjacent to the mountain front. In more distal settings to the north, carbonate production resulted in deposition of horizontally bedded lacustrine limestones with subordinated siliciclastics and evaporite minerals. Carbonate deposition occurred during overfilled to balance filled conditions. Prominent aggradational to progradational tufa clinoforms form at the spillover points between the subbasins, and interfinger up- and down-dip with the horizontally bedded lacustrine limestones. The tufas consist of steeply dipping clinoforms that prograde northwards. They formed by inorganic and biogenically mediated calcite precipitation as waters from the topographically upper lake overflowed the sill. U-Pb dating of speleothem cements formed in the tufas yield a Pliocene age (3.06 ± 0.2 Ma). The horizontally bedded limestones that predominantly fill the subbasins are composed of nine lithofacies. These are: ostracode mudstone-wackestone, clotted boundstone, gastropod wackestone-packstone, oncoid wackestone-packstone, stromatolite, charophyte wackestone-packstone, marlstones, crystalline carbonate and evaporite minerals. These lithofacies contain variable proportions of production-derived components, with subordinated detrital and diagenetic components. They overall contain inorganic and organic calcite (average 91%), organic matter (average 12.6 % TOC) and subordinated detrital quartz, feldspar and clay. Stable isotope conditions from stromatolite laminations (δ13C -6.3‰ and δ18O -8.0‰), and micritic matrix from samples in all the subbasins (δ13C -5.7‰ and δ18O -8.4‰), indicate that overall calcite deposition occurred in freshwater lakes, under predominantly oxic conditions. Carbonate particles deposited mainly by in situ disaggregation and by settling. Significant preservation of the organic matter likely occurred because of the fine grained carbonate matrix, and because of moderate rates of both carbonate sediment and organic matter production. Stacking patterns in the lake successions show an overall shallowing upward cyclicity. It is considered, that the effects of inherited basin geomorphology and climate, ultimately controlled facies variability and strata geometries in these subbasins.

Le procédé industriel pour purifier des solutions concentrées de chlorure de sodium consiste en la précipitation des ions calcium sous forme de carbonate de calcium et des ions magnésium sous forme d'hydroxyde de magnésium. Ces impuretés étant en faible concentration, la précipitation est menée en réacteur à lit fluidisé en présence d’une forte charge solide. La maîtrise de la qualité du précipité, constitué. Dans un premier temps, une méthode analytique fiable est développée pour déterminer quantitativement la composition d’un mélange de polymorphes : la spectroscopie Raman associée à une méthode de résolution de courbes. Ensuite, la précipitation du carbonate de calcium en réacteur fermé permet d’identifier les paramètres clés du procédé pour maîtriser la composition polymorphique. A partir de ces résultats, un nouveau procédé de purification en réacteur continu à lit fluidisé est conçu et mis en œuvre. L’étude expérimentale réalisée dans celui-ci permet de définir les paramètres opératoires conduisant à une parfaite maîtrise de la qualité du précipité et une conduite optimale de la purification / The purification process of sodium chloride solutions consists of the precipitation of Ca2+ and Mg2+ ions as calcium carbonate and magnesium hydroxide. The impurity content is low, so the best results can be obtained when the precipitation takes place in a fluidized bed reactor where the solid concentration is high. The improvement of the precipitate quality, mainly composed of CaCO3, is necessary for the good running of the process, thus the control of the calcium carbonate polymorphism is essential. First, a reliable method for the quantitative determination of the polymorphic composition using Raman spectroscopy combined with multivariate curve resolution is developed. Then the key parameters which control the polymorphic. composition are identified through the experiments carried out in a batch reactor. Based on these results, a new process using a fluidized bed reactor is designed and experimentally tested. From these experiments, the optimal operating conditions allowing a high level of purification and a very good solid/liquid separation are determined

Scaling due to calcium carbonate precipitation is a major problem in cooling water circuits in many of Eskom power stations. Some earlier studies have suggested that the natural organic matter (NOM) present in the cooling water may reduce the amount of scaling by limiting the formation of calcium carbonate precipitation. It is therefore the interest of this study to investigate further the role of the NOM in calcium carbonate precipitation at Hendrina power station. The raw water and cooling water were analysed for the major metal ions, anions, alkalinity, conductivity and total organic matter to determine the precipitation potentials of calcite and aragonite using MINTEQA2 speciation program. The NOM was isolated from the raw and cooling water using ion exchange resins, XAD-8/XAD-4 resins and ultrafiltration membranes with molecular weight cut-offs of 100 kDa, 10 kDa and 1 kDa. The isolated fractions were then characterized by ultraviolet and visible absorbance methods and high performance size exclusion chromatography. The effect of the isolated fractions of the NOM from the cooling water on calcium carbonate precipitation was then investigated. The results indicated the presence calcium carbonate precipitation in the cooling water, but the raw water was undersaturated with calcium carbonate. The NOM isolated from the raw water indicated the predominance of the hydrophobic acid NOM (74.17 %) and to a lower extent the presence of hydrophilic acid NOM (34.49%). The NOM isolated from the cooling water also showed the predominance of the hydrophobic acid NOM (69.25 %) and to a lower extent the presence of the hydrophilic neutral acid NOM (20.13 %) and minimal presence of hydrophilic acid NOM (9.51 %). The results obtained from high pressure size exclusion chromatography analyses indicated that in both the raw water and cooling water the NOM was having a low molecular weight (<13.2030 kDa). The specific ultraviolet absorbance (SUVA) of the raw water was high (>4) which also suggested that it contained predominantly hydrophobic NOM and that of the cooling i water was in the range 2-4 suggesting that it contained a mixture of the hydrophobic and hydrophilic acid NOM. The hydrophobic acid, hydrophilic acid and hydrophilic neutral acid NOM fractions isolated from the cooling water reduced the amount of calcium carbonate precipitate formed in synthetic water sample. This effect was more pronounced with hydrophobic and hydrophilic acid NOM fractions than with the hydrophilic neutral acid NOM fraction. / Dr. M. Shumane

The world’s 7 billion inhabitants depend on chemical fertilizers to meet the growing demand for food. The phosphorus used in fertilizer is sourced from ancient sedimentary deposits of Phosphate Rock (PR), largely in the form of carbonate calcium phosphate, called carbonate apatite, which resembles bone. PR is non-renewable and Canada’s reserves are extremely limited; currently, all 1,400,000 tonnes of phosphorus products used annually are imported. This project investigates a novel method to recycle phosphorus from municipal wastewater in a form that will enable its reuse as a fertilizer, through a reaction with CaCO3 from limestone and waste CO2 (g). This will contribute to the nascent circular nutrient economy within Canada. A review of the current state of phosphorus and nutrient recycling is presented, including a plan for establishing the Canadian Nutrient Platform. A series of inorganic phosphate (PO4-, or Pi) solutions was prepared to simulate the concentrations found in Ottawa’s municipal wastewater, between 2.5-30 mM Pi. These solutions were mixed with CaCO3 solutions that were highly supersaturated through a carbon capture technique. Batch tests successfully reduced the [Pi] and [Ca2+], as measured by colorimetry, and precipitate formed. These results were subsequently repeated in a continuous stirred lab-scale reactor. These precipitation products were characterized using Scanning Electron Microscopy, Raman Spectroscopy, X-Ray Diffraction, and carbon coulometry to measure carbonate content. This analysis confirmed the presence of both Pi and CO3 in a bone-like, carbonate apatite. Although other technologies are being explored to recycle phosphorus from wastewater streams, this is the first indication that it may be possible to precipitate a carbonate apatite by mixing two waste streams, municipal waste water and CO2 (g), with cost-effective CaCO3.

Carbonate diagenesis encapsulates a wide range of water rock interactions that can occur within many environments and act to modify rock properties such as porosity, permeability, and mineralogical composition. These rock modification processes occur by the supply of reactant-laden fluids to areas where geochemical reactions are thermodynamically and kinetically favoured. As such, understanding the development of diagenesis requires an understanding of both palaeohydrology and geochemistry, both of which have their own complexities. However, within geological systems, both the conditions that control fluid migration and the distribution of thermodynamic conditions can change through time in response to external factors. Furthermore, they are often coupled, with rock modification exercising a control on fluid flow by altering the permeability of sediments. Numerical methods allow the coupling of multiple complex processes within a single mathematical formulation. As such, they are well suited to investigations into carbonate diagenesis, where multiple component subsystems interact. This thesis details the application of four separate types of numerical forward modelling to investigations of diagenesis within two Carboniferous carbonate platforms, the Derbyshire Platform (Northern England) and the Tengiz Platform (Western Kazakhstan). Investigations of Derbyshire Platform diagenesis are primarily concerned with explaining the presence of Pb-mineralisation and dolomitisation observed within the Dinantian carbonate succession. A coupled palaeohydrology and basin-development simulation and a series of geochemical simulations was used to investigate the potential for these products to form as a result of basin-derived fluids being driven into the platform by compaction. The results of these models suggest that this mechanism is appropriate for explaining Pb-mineralisation, but dolomitisation requires Mg concentrations within the basin-derived fluids that cannot be attained. Geothermal convection of seawater was thus proposed as an alternative hypothesis to explain the development of dolomitisation. This was tested using an advanced reactive transport model, capable of considering both platform growth and dolomitisation. The results of this suggests that significant dolomitisation may have occurred earlier on in the life of the Derbyshire Platform than has previously been recognised. An updated framework for the development of diagenesis in the Derbyshire Platform is proposed to incorporate these new insights. The Tengiz platform forms an important carbonate oil reservoir at the northeastern shore of the Caspian Sea. The effective exploitation of any reservoir lies in an understanding of its internal distributions of porosity and permeability. Within carbonate systems, this is critically controlled by the distribution of diagenetic products. A model of carbonate sedimentation and meteoric diagenesis is used to produce a framework of early diagenesis within a sequence stratigraphic context. The studies mentioned above provide a broad overview of the capabilities and applicability of forward numerical models to two data-limited systems. They reveal the potential for these methods to guide the ongoing assessment and development of our understanding of diagenetic systems and also help identify key questions for the progression of our understanding in the future.