.

Under de senaste decennierna har i många länder, inkluderat Sverige, långt gångna planer utvecklats för ett djupförvar av högaktivt kärnavfall. Som en del i det svenska förvarskonceptet skall avfallet inneslutas i kopparkapslar som omslutes av återfyllnadsmaterial med mycket låg genomsläpplighet av vatten. Dessutom skall kapslarna förläggas på ca 500 meters djup i granitberggrunden, vilken fungerar som en naturlig barriär för transport av radionuklider till markytan. Dessa naturliga och konstruerade barriärer väljs och utformas så att förvarets funktion kan säkras under hundra tusentals år. En viktig fråga för säkerhetsanalysen för ett sådant förvar är utvecklingen av redoxförhållandena över långa tider. Korrosionen av kopparkapslarna går fortare under oxiderande förhållanden och rörligheten hos frisläppta radionuklider ökar. I den första delen av avhandlingen studerades förmågan hos berget att upprätthålla reducerande förhållanden på förvarsdjupet över långa tider. En modellstruktur har utvecklats med målet att ta hänsyn till alla processer som bedömts viktiga för utarmning av inträngande syre från markytan över långa tider. Förenklingar introducerades så att transparenta analytiska lösningar kunde erhållas som förenklar utvärdering av resultat och tillåter identifiering av osäkra parametrar. Komplexa system löstes numeriskt för fall då analytiska lösningar ej kunde erhållas, samt för att validera förenklingar som ligger till grund för de analytiska lösningarna. Resultat redovisades för rådande förhållanden samt för förhållanden som bedömdes rimliga under smältfasen av en glaciationsperiod. Det visade sig att de hydrauliska egenskaperna har stor påverkan på inträngningsdjupet av syre längs flödesvägar i berget. Kvoten mellan den flödesvätta ytan och flödet visade sig vara en viktig parameter som bestämmer omfattningen av interaktionen mellan löst syre i grundvattnet och reducerande mineral i berget. Resultaten visar att för korta tider, beroende på mängd reducerande mineral och reaktionshastighet, kan kemisk reaktionskinetik bestämma förbrukningshastigheten av syre. För längre tider begränsas förbrukningen av intern diffusion i stora partiklar och bergmatrisen. Det visade sig att hänsyn måste tas till många osäkerheter för att kunna göra tillförlitliga kvantitativa uppskattningar av omfattningen av syreinträngningen. I den andra delen av avhandlingen undersöktes konsekvenserna av inträngande syre på korrosion av kopparkapslarna. En mekanism föreslogs också för bildande av sulfid nära kapseln. Sulfid är en annan korrodent som kan bildas mikrobiellt i reducerande miljöer från sulfat och en organisk reduktant såsom metan. Beräkningarna visar att mer än 50 kg av koppar inte är sannolikt att korrodera över en miljon år. / Advanced plans for the construction of a deep geological repository for highly radioactive wastes from nuclear power plants have evolved during the past decades in many countries including Sweden. As part of the Swedish concept, the waste is to be encapsulated in canisters surrounded by low permeability backfill material. The copper canisters will be deposited at around 500 metres depth in granitic rock, which acts as a natural barrier for the transport of radionuclides to the ground surface. These natural and engineered barriers are chosen and designed to ensure the safety of the repository over hundred of thousands of years. One issue of interest for the safety assessment of such a repository is the redox evolution over long times. An oxidising environment would enhance the corrosion of the copper canisters, and increases the mobility of any released radionuclides. In the first part of the present thesis, the ability of the host rock to ensure a reducing environment at repository depth over long times was studied. A model framework was developed with the aim to capture all processes that are deemed to be important for the scavenging of intruding oxygen from the ground surface over long times. Simplifications allowing for analytical solutions were introduced for transparency reasons so that evaluation of results is straight-forward, and so that uncertain parameter values easily can be adjusted. More complex systems were solved numerically for cases when the analytical simplifications are not applicable, and to validate the simplifications underlying the analytical solutions. Results were presented for prevailing present day conditions as well as for conditions deemed to be likely during the melting phase of a period of glaciation. It was shown that the hydraulic properties have a great influence on the oxygen intrusion length downstream along flow-paths in the rock. An important parameter that determines the extent of interaction between the dissolved oxygen and the reducing minerals in the rock was shown to be the flow-wetted surface to flow-rate ratio. The results show that for an initial period of time, depending on the amount of reducing minerals and reaction rates, chemical reaction kinetics may control the rate of the overall depletion of oxygen. For longer times, internal diffusion resistance in large particles or in the rock matrix become rate limiting for the overall process. It was found that there are many uncertainties that have to be considered in order to make reliable quantitative predictions on the extent of oxygen intrusion. In the second part of the thesis, the impact of intruding oxygen on the corrosion of the copper canisters was explored. Also, a mechanism for the production of sulphide close to the deposition holes was studied. Sulphide is another corroding agent that may be produced microbially in a reducing environment from sulphate in the presence of organic reductants such as methane. From calculation results it was found that corrosion of more than 50 kg of copper is not likely over a period of one million years / QC 20100818

Over the course of the past several decades the benefits of redeveloping brownfields have been widely recognized. Actions have been taken to foster sustainable redevelopment of brownfields by government, policy makers and stakeholders across the world. However, redevelopments encounter great challenges and risks related to environmental and non-environmental issues. In this work, we intend to build a comprehensive and practical framework to evaluate the hydrogeological and financial risks involved during redevelopment and to ensure developers reserve sufficient capital to cover unexpected future costs within the guarantee period. Punitive damages, which contribute to these costs, are in this thesis solely associated with the cost of repossessing a house within a development should the indoor air concentration of TCE exceed the regulatory limit at a later time. The uncertainties associated with brownfield remediation have been among the barriers to brownfield redevelopment. This is mainly caused by the lack of knowledge about a site’s environmental condition. In order to alleviate uncertainties and to better understand the contaminant transport process in the subsurface, numerical simulations have been conducted to investigate the role of controlling parameters in determining the fate and transport of volatile organic compounds originating from a NAPL source zone located below the water table in the subsurface. In the first part of this thesis, the numerical model CompFlow Bio is used on a hypothesized three-dimensional problem geometry where multiple residential dwellings are built. The simulations indicate that uncertainty in the simulated indoor air concentration is sensitive to heterogeneity in the permeability structure of a stratigraphically continuous aquifer with uncertainty defined as the probability of exceeding a regulatory limit. Houses which are laterally offset from the groundwater plume are less affected by vapour intrusion due to limited transverse horizontal flux of TCE within the groundwater plume in agreement with the ASTM (2008) guidance. Within this uncertainty framework, we show that the Johnson and Ettinger (1991) model generates overly-conservative results and contributes to the exclusion zone being much further away from the groundwater plume relative to either CompFlow Bio or ASTM (2008). The probability of failure (or the probability of exceedence of the regulatory limit) is defined and calculated for further study. Due to uncertainties resulting from parameter estimation and model prediction, a methodology is introduced to incorporate field measurements into the initial estimates from the numerical model in order to improve prediction accuracy. The principle idea of this methodology is to combine the geostatistical tool kriging with the statistical data assimilation method Kalman filter to evaluate the worth and effectiveness of data in a quantitative way in order to select an optimal sampling scenario. This methodology is also used to infer whether one of the houses located adjacent to affected houses has indoor air problems based on the measurements subject to the observation that the affected house is monitored and has problems and developers have liability if a problem occurs. In this part of the study, different sampling scenarios are set up in terms of permeability (1 – 80 boreholes) and soil gas concentration (2, 4 and 7 samples) and three metrics are defined and computed as a criterion for comparison. Financing brownfield redevelopment is often viewed as a major barrier to the development process mainly due to risks and liabilities associated with brownfields. The common way of managing the risk is to transfer it to insurers by purchasing insurance coverage. This work provides two different strategies to price the risk, which is equivalent to an insurance premium. It is intended to give an instructive insight into project planning and feasibility studies during the decision-making process of a brownfield project. The two strategies of risk capital valuation are an actuarial premium calculation principle and a martingale premium calculation principle accounting for the hydrogeological and financial uncertainties faced in a project. The data used for valuation are the posterior estimates of data assimilation obtained from the results of different sampling scenarios. The cost-benefit-risk analysis is employed as a basis to construct the objective function in order to find the least cost among sampling scenarios for the project. As a result, it shows that drilling seven boreholes to extract permeability data and taking soil gas samplings in four locations or seven locations alternatively give the minimum total cost. Sensitivity analysis of some influential parameters (the safety loading factors and the possible methods to calculate the probability of failure) is performed to determine their roles of importance in the risk capital valuation. This framework can be applied to provide guidance for other risk-based environmental projects.

Brownfields redevelopment has been encouraged by governments or the real estate market because of economic, social and environmental benefits. However, uncertainties in contaminated land redevelopment may cause massive investment risk and need to be managed so that contaminated land redevelopment is facilitated. This study was designed to address hydrogeological as well as economic uncertainty in a hypothetical contaminated land redevelopment project and manage the risk from these uncertainties through the integration of the hydrogeological and economic uncertainties. Hydrogeological uncertainty is derived from incomplete site information, including aquifer heterogeneity, and must be assessed with scientific expertise, given the short history of redevelopment projects and their unique hydrogeological characteristics. Hydrogeological uncertainty has not yet been incorporated in one framework with the economic uncertainty that has been relatively well observed in financial markets. Two cases of Non-Aqueous Phase Liquid (NAPL) contamination were simulated using a physically-based hydrogeological model to address hydrogeological uncertainty: one concerns the effect of an ethanol spill on a light NAPL (LNAPL) contaminated area in the vadose zone, and the other is regarding the vapour phase intrusion of volatile organic compounds, in particular, Trichloroethylene (TCE), a dense NAPL (DNAPL), into indoor air through a variably saturated heterogeneous aquifer. The first simulation replicated experimental observations in the laboratory, such as the capillary fringe depressing and the NAPL pool remobilizing and collecting in a reduced area exhibiting higher saturations than observed prior to an ethanol injection. However, the data gap, in particular, on the chemical properties between the model and the experiment caused the uncertainty in the model simulation. The second NAPL simulation has been performed based on a hypothetical scenario where new dwellings in a redeveloped area have the potential risk of vapour phase intrusion from a subsurface source into indoor air because remediation or foundation design might fail. The simulation results indicated that the aquifer heterogeneity seemed the most significant factor controlling the indoor air exposure risk from a TCE source in the saturated zone. Then, the exposure risk was quantified using Monte Carlo simulations with 50 statistically equivalent heterogeneous aquifer permeability fields. The quantified risk (probability) represents the hydrogeological uncertainty in the scenario and gives the information on loss occurrence intensity of redevelopment failure. Probability of failure (or loss occurrence intensity) was integrated with cost of failure (or loss magnitude) to evaluate the risk capital in the hypothetical brownfields redevelopment project. The term “risk capital” is adopted from financial literature and is the capital you can lose from high risk investment. Cost of failure involves economic uncertainty and can be defined based on a developer’s financial agreement with new dwellers to prevent litigation in the case of certain events, such as an environmental event where indoor air concentrations of pollutants exceed regulatory limits during periodic inspections. The developer makes such a financial agreement with new dwellers because new dwellings have been constructed founded on flawed site information, and municipalities may require it if a land use planning approval is required. An agreement was presumed that the developer would repurchase the affected houses from new dwellers immediately, if indoor air contamination exceeded the regulatory limit. Furthermore, the developer would remediate any remaining contamination, demolish the affected houses and build new houses if they were worth investing in. With this financial plan assumed, the stochastic housing price, stochastic inflation rate and stochastic interest rate have been considered to cause the uncertainty in the cost of failure, and the information on these stochastic variables was obtained from the financial market due to its long history of observations. This research reviewed appropriate risk capital valuation methods for hydrogeologists to apply straightforwardly to their projects, with integrating probability of failure (hydrogeological uncertainty) and cost of failure (economic uncertainty). The risk capital is essentially the probability of failure times the cost of failure with safety loading added to compensate investors against hydrogeological and financial uncertainty. Fair market prices of risk capital have been valuated using financial mathematics and actuarial premium calculations, and each method has a specific safety loading term to reflect investors’ level of risk aversion. Risk capital results indicated that the price of the risk capital was much more sensitive to hydrogeological uncertainty than financial uncertainty. Developers can manage the risk capital by saving a contingency fee for future events or paying an insurance premium, given that the price of this risk capital is the price of a contingent claim, subsequent to failure in remediation or in foundation design, and equivalent to an environmental insurance premium if there is an insurance company to indemnify the liability for the developer. The optimal framework of investment strategy in brownfields redevelopment can be built by linkage of addressing and integrating uncertainties and valuating risk capital from the uncertainties. This framework involves balancing the costs associated with each step while maximizing a net profit from land redevelopment. The optimal investment strategy, such as if or when to remediate or redevelop and to what degree, is given when the future price of the land minus time and material costs as well as the contingency fee or insurance premium maximizes a net profit.

Brownfields redevelopment has been encouraged by governments or the real estate market because of economic, social and environmental benefits. However, uncertainties in contaminated land redevelopment may cause massive investment risk and need to be managed so that contaminated land redevelopment is facilitated. This study was designed to address hydrogeological as well as economic uncertainty in a hypothetical contaminated land redevelopment project and manage the risk from these uncertainties through the integration of the hydrogeological and economic uncertainties. Hydrogeological uncertainty is derived from incomplete site information, including aquifer heterogeneity, and must be assessed with scientific expertise, given the short history of redevelopment projects and their unique hydrogeological characteristics. Hydrogeological uncertainty has not yet been incorporated in one framework with the economic uncertainty that has been relatively well observed in financial markets. Two cases of Non-Aqueous Phase Liquid (NAPL) contamination were simulated using a physically-based hydrogeological model to address hydrogeological uncertainty: one concerns the effect of an ethanol spill on a light NAPL (LNAPL) contaminated area in the vadose zone, and the other is regarding the vapour phase intrusion of volatile organic compounds, in particular, Trichloroethylene (TCE), a dense NAPL (DNAPL), into indoor air through a variably saturated heterogeneous aquifer. The first simulation replicated experimental observations in the laboratory, such as the capillary fringe depressing and the NAPL pool remobilizing and collecting in a reduced area exhibiting higher saturations than observed prior to an ethanol injection. However, the data gap, in particular, on the chemical properties between the model and the experiment caused the uncertainty in the model simulation. The second NAPL simulation has been performed based on a hypothetical scenario where new dwellings in a redeveloped area have the potential risk of vapour phase intrusion from a subsurface source into indoor air because remediation or foundation design might fail. The simulation results indicated that the aquifer heterogeneity seemed the most significant factor controlling the indoor air exposure risk from a TCE source in the saturated zone. Then, the exposure risk was quantified using Monte Carlo simulations with 50 statistically equivalent heterogeneous aquifer permeability fields. The quantified risk (probability) represents the hydrogeological uncertainty in the scenario and gives the information on loss occurrence intensity of redevelopment failure. Probability of failure (or loss occurrence intensity) was integrated with cost of failure (or loss magnitude) to evaluate the risk capital in the hypothetical brownfields redevelopment project. The term “risk capital” is adopted from financial literature and is the capital you can lose from high risk investment. Cost of failure involves economic uncertainty and can be defined based on a developer’s financial agreement with new dwellers to prevent litigation in the case of certain events, such as an environmental event where indoor air concentrations of pollutants exceed regulatory limits during periodic inspections. The developer makes such a financial agreement with new dwellers because new dwellings have been constructed founded on flawed site information, and municipalities may require it if a land use planning approval is required. An agreement was presumed that the developer would repurchase the affected houses from new dwellers immediately, if indoor air contamination exceeded the regulatory limit. Furthermore, the developer would remediate any remaining contamination, demolish the affected houses and build new houses if they were worth investing in. With this financial plan assumed, the stochastic housing price, stochastic inflation rate and stochastic interest rate have been considered to cause the uncertainty in the cost of failure, and the information on these stochastic variables was obtained from the financial market due to its long history of observations. This research reviewed appropriate risk capital valuation methods for hydrogeologists to apply straightforwardly to their projects, with integrating probability of failure (hydrogeological uncertainty) and cost of failure (economic uncertainty). The risk capital is essentially the probability of failure times the cost of failure with safety loading added to compensate investors against hydrogeological and financial uncertainty. Fair market prices of risk capital have been valuated using financial mathematics and actuarial premium calculations, and each method has a specific safety loading term to reflect investors’ level of risk aversion. Risk capital results indicated that the price of the risk capital was much more sensitive to hydrogeological uncertainty than financial uncertainty. Developers can manage the risk capital by saving a contingency fee for future events or paying an insurance premium, given that the price of this risk capital is the price of a contingent claim, subsequent to failure in remediation or in foundation design, and equivalent to an environmental insurance premium if there is an insurance company to indemnify the liability for the developer. The optimal framework of investment strategy in brownfields redevelopment can be built by linkage of addressing and integrating uncertainties and valuating risk capital from the uncertainties. This framework involves balancing the costs associated with each step while maximizing a net profit from land redevelopment. The optimal investment strategy, such as if or when to remediate or redevelop and to what degree, is given when the future price of the land minus time and material costs as well as the contingency fee or insurance premium maximizes a net profit.

Soil quality standards (SQSs) are one of the most important elements of management system for contaminated sites. In order to manage risks associated with soil contamination, risk based SQSs are used worldwide. However, in Turkey, the Soil Pollution Control Regulation in force was focusing mainly on the use of stabilized sludge on soil and was including standards for a limited number of parameters, mainly metals and some organic chemicals. Thus, existing SQSs were far away from providing common criteria for assessment of the soil quality. In this study, the aim was to develop human health risk based SQSs for Turkey. For derivation of risk based SQSs, the conceptual framework and technical infrastructure were established. SQSs were derived for 151 chemical substances and for three different land use types by incorporating generic site characteristics for Turkey. Since SQSs are highly sensitive to site conditions and chemical-specific data used in calculations, a Microsoft Excel based exposure model was developed as a technical tool. This tool serves for calculation of generic and site-specific SQSs and maintenance of the currency of the standards by allowing periodic update of data used in calculations. Besides, a hydrogeologic database was developed to provide information on the general soil and hydrogeologic characteristics that are used in derivation of SQSs. This database is ultimately, expected to serve for development of conceptual site models, sampling strategies, and derivation of dilution factors during risk assessment studies. As a result, this study presents a general perspective and approach for derivation of human health risk based SQSs. It is believed that the developed conceptual and technical infrastructure will contribute to contaminated site management and risk assessment studies conducted by the regulatory authorities and the other stakeholders in Turkey.

Over the course of the past several decades the benefits of redeveloping brownfields have been widely recognized. Actions have been taken to foster sustainable redevelopment of brownfields by government, policy makers and stakeholders across the world. However, redevelopments encounter great challenges and risks related to environmental and non-environmental issues. In this work, we intend to build a comprehensive and practical framework to evaluate the hydrogeological and financial risks involved during redevelopment and to ensure developers reserve sufficient capital to cover unexpected future costs within the guarantee period. Punitive damages, which contribute to these costs, are in this thesis solely associated with the cost of repossessing a house within a development should the indoor air concentration of TCE exceed the regulatory limit at a later time. The uncertainties associated with brownfield remediation have been among the barriers to brownfield redevelopment. This is mainly caused by the lack of knowledge about a site’s environmental condition. In order to alleviate uncertainties and to better understand the contaminant transport process in the subsurface, numerical simulations have been conducted to investigate the role of controlling parameters in determining the fate and transport of volatile organic compounds originating from a NAPL source zone located below the water table in the subsurface. In the first part of this thesis, the numerical model CompFlow Bio is used on a hypothesized three-dimensional problem geometry where multiple residential dwellings are built. The simulations indicate that uncertainty in the simulated indoor air concentration is sensitive to heterogeneity in the permeability structure of a stratigraphically continuous aquifer with uncertainty defined as the probability of exceeding a regulatory limit. Houses which are laterally offset from the groundwater plume are less affected by vapour intrusion due to limited transverse horizontal flux of TCE within the groundwater plume in agreement with the ASTM (2008) guidance. Within this uncertainty framework, we show that the Johnson and Ettinger (1991) model generates overly-conservative results and contributes to the exclusion zone being much further away from the groundwater plume relative to either CompFlow Bio or ASTM (2008). The probability of failure (or the probability of exceedence of the regulatory limit) is defined and calculated for further study. Due to uncertainties resulting from parameter estimation and model prediction, a methodology is introduced to incorporate field measurements into the initial estimates from the numerical model in order to improve prediction accuracy. The principle idea of this methodology is to combine the geostatistical tool kriging with the statistical data assimilation method Kalman filter to evaluate the worth and effectiveness of data in a quantitative way in order to select an optimal sampling scenario. This methodology is also used to infer whether one of the houses located adjacent to affected houses has indoor air problems based on the measurements subject to the observation that the affected house is monitored and has problems and developers have liability if a problem occurs. In this part of the study, different sampling scenarios are set up in terms of permeability (1 – 80 boreholes) and soil gas concentration (2, 4 and 7 samples) and three metrics are defined and computed as a criterion for comparison. Financing brownfield redevelopment is often viewed as a major barrier to the development process mainly due to risks and liabilities associated with brownfields. The common way of managing the risk is to transfer it to insurers by purchasing insurance coverage. This work provides two different strategies to price the risk, which is equivalent to an insurance premium. It is intended to give an instructive insight into project planning and feasibility studies during the decision-making process of a brownfield project. The two strategies of risk capital valuation are an actuarial premium calculation principle and a martingale premium calculation principle accounting for the hydrogeological and financial uncertainties faced in a project. The data used for valuation are the posterior estimates of data assimilation obtained from the results of different sampling scenarios. The cost-benefit-risk analysis is employed as a basis to construct the objective function in order to find the least cost among sampling scenarios for the project. As a result, it shows that drilling seven boreholes to extract permeability data and taking soil gas samplings in four locations or seven locations alternatively give the minimum total cost. Sensitivity analysis of some influential parameters (the safety loading factors and the possible methods to calculate the probability of failure) is performed to determine their roles of importance in the risk capital valuation. This framework can be applied to provide guidance for other risk-based environmental projects.

Thesis (M.S.)--Mississippi State University. Department of Geosciences. / Title from title screen. Includes bibliographical references.

Resumo: O fluxo das águas subterrâneas no SAG, em sua porção ocidental, é caracterizado pela existência de três áreas de recarga regional, localizadas em Mato Grosso do Sul e Goiás. A partir destas áreas de recarga o fluxo regional é radial direcionado para o centro da Bacia do Paraná. Em algumas porções das zonas de aforamento ocorrem fluxos localizados de descarga. As águas apresentam características químicas que permitem sua classificação em: bicarbonatadas cálcicas ou calco-magnesianas, bicarbonatadas sódicas e bicarbonatadas cloretadas/sulfatadas sódicas, representando, nesta ordem, a sua evolução hidroquímica. Os mecanismos envolvidos nesta evolução são: dissolução de feldspatos e remoção do cimento carbonático do arcabouço mineral dos arenitos, seguido por troca iônica, responsável pelo aumento nas concentrações de sódio e diminuição nas concentrações de cálcio e, finalmente, o enriquecimento em cloreto e sulfato, oriundos dos aqüíferos sotopostos ao SAG. Foram reconhecidas três unidades hidroestratigráficas distintas no SAG: superior, representada pelos arenitos eólicos limpos, da Formação Botucatu, intenuediária, representada por arenitos finos e argilosos, e inferior, por arenitos finos, pouco argilosos, estas duas últimas unidades pertencentes à Formação Pirambóia. / The groundwater flow pattern in the occidental portion of SAG (Guarani Aquifer System) is characterized by the existence of three regional recharge areas located in Mato Grosso do Sul and Goiás states. From these areas ofrecharge the regional flow is radial and directed toward the center of Paraná Sedimentary Basin. Local discharge flows occurs in portions of outcrop regions. The groundwater can be classified as calcium or calcium-magnesium bicarbonate type, sodium bicarbonate type and sodium bicarbonate/chloride/sulphate type, representing in this sequence its hydrochemical evolution. The mechanisms responsible for this evolution are dissolution of feldspars and remova! of the carbonate cement of the sandstones mineral framework, followed by ionic exchange, responsible for the increase in the sodium concentration and decrease of calcium, and, finally, the enrichment in chloride and sulphate derived from underlying aquifers units. Three distinct hydrostratigraphics units in the SAG have been recognized: the upper unit is represented by aeolian sandstones from Botucatu Formation, the intermediate, represented by the fine and argillaceous sandstones, and the lower unit is constituted by fine sandstones with low content in clays, these last two units belong to the Pirambóia formation. / Orientador: Chang Hung Kiang / Coorientador: Ian Hutcheon / Banca: Osmar Sineli / Banca: Ricardo César Aoki Hirata / Banca: Alexandre Campane Vidal / Banca: Ernani Francisco da Rosa Filho / Doutor

Made available in DSpace on 2014-06-11T19:32:17Z (GMT). No. of bitstreams: 0 Previous issue date: 2007-04-19Bitstream added on 2014-06-13T20:43:11Z : No. of bitstreams: 1 gastmans_d_dr_rcla.pdf: 6127390 bytes, checksum: ab710341c81fc6a1a52c3f6d1d493132 (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / O fluxo das águas subterrâneas no SAG, em sua porção ocidental, é caracterizado pela existência de três áreas de recarga regional, localizadas em Mato Grosso do Sul e Goiás. A partir destas áreas de recarga o fluxo regional é radial direcionado para o centro da Bacia do Paraná. Em algumas porções das zonas de aforamento ocorrem fluxos localizados de descarga. As águas apresentam características químicas que permitem sua classificação em: bicarbonatadas cálcicas ou calco-magnesianas, bicarbonatadas sódicas e bicarbonatadas cloretadas/sulfatadas sódicas, representando, nesta ordem, a sua evolução hidroquímica. Os mecanismos envolvidos nesta evolução são: dissolução de feldspatos e remoção do cimento carbonático do arcabouço mineral dos arenitos, seguido por troca iônica, responsável pelo aumento nas concentrações de sódio e diminuição nas concentrações de cálcio e, finalmente, o enriquecimento em cloreto e sulfato, oriundos dos aqüíferos sotopostos ao SAG. Foram reconhecidas três unidades hidroestratigráficas distintas no SAG: superior, representada pelos arenitos eólicos limpos, da Formação Botucatu, intenuediária, representada por arenitos finos e argilosos, e inferior, por arenitos finos, pouco argilosos, estas duas últimas unidades pertencentes à Formação Pirambóia. / The groundwater flow pattern in the occidental portion of SAG (Guarani Aquifer System) is characterized by the existence of three regional recharge areas located in Mato Grosso do Sul and Goiás states. From these areas ofrecharge the regional flow is radial and directed toward the center of Paraná Sedimentary Basin. Local discharge flows occurs in portions of outcrop regions. The groundwater can be classified as calcium or calcium-magnesium bicarbonate type, sodium bicarbonate type and sodium bicarbonate/chloride/sulphate type, representing in this sequence its hydrochemical evolution. The mechanisms responsible for this evolution are dissolution of feldspars and remova! of the carbonate cement of the sandstones mineral framework, followed by ionic exchange, responsible for the increase in the sodium concentration and decrease of calcium, and, finally, the enrichment in chloride and sulphate derived from underlying aquifers units. Three distinct hydrostratigraphics units in the SAG have been recognized: the upper unit is represented by aeolian sandstones from Botucatu Formation, the intermediate, represented by the fine and argillaceous sandstones, and the lower unit is constituted by fine sandstones with low content in clays, these last two units belong to the Pirambóia formation.