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Estudo do processo geoquímico de obstrução de filtro de barragens; Not available.

Maciel Filho, Carlos Leite
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 01/06/1983 PT
Relevância na Pesquisa
26.48%
Esta tese apresenta o desenvolvimento dos estudos para explicar o processo de cimentação de filtros de barragens com a conseqüente diminuição de sua permeabilidade. Os casos que estariam preocupando o meio geotécnico e que motivaram este estudo são principalmente o da barragem do Rio Grande, em São Paulo capital, e o da barragem de Xavantes, no Rio Paranapanema. As conclusões estão baseadas no tripé: revisão da teoria e publicações específicas; levantamentos de campo; experiências de laboratório. Para estas, foram desenvolvidos métodos e aparelhos próprios chegando-se a ensaios que permitiriam: primeiro, medir com aproximação o volume de ar contido nos poros de uma areia sob fluxo não saturado; segundo, verificar a absorção de oxigênio pela água sob fluxo não saturado e comprovar uma diminuição dessa absorção com o prolongamento do ensaio; terceiro, verificar a deposição de hidróxido férrico na franja capilar e zona earada de uma areia sob fluxo aproximadamente horizontal após passar por camada de argila: quartzo, verificar a mesma deposição em areia sob a capa de argila e sob fluxo, de cima para baixo, não saturado. Em todos eles a água usada era deareada e nos dois últimos continha bicarbonato ferroso. Preliminarmente desenvolveram-se ensaios que permitiram controlar a variação da permeabilidade a longo prazo...

Estudo em tempo real da migração de etanol na zona vadosa em experimento de campo

Schneider, Ana Cláudia
Fonte: Florianópolis Publicador: Florianópolis
Tipo: Dissertação de Mestrado Formato: 91 p.| il., tabs.
POR
Relevância na Pesquisa
26.08%
Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro Tecnológico. Programa de Pós-Graduação em Engenharia Ambiental; Em casos de derramamentos com misturas de gasolina e etanol, a presença de etanol pode alterar o comportamento de migração dos compostos na zona vadosa, dependendo da umidade do meio solo, características do solo e do volume de etanol e gasolina derramados. Para avaliar a migração de misturas com grandes proporções de etanol em condições reais, foi realizado um experimento de campo com monitoramento em tempo real da liberação controlada de uma mistura contendo 170 L de etanol e 30 L de gasolina na zona não saturada. As concentrações de etanol na zona vadosa foram obtidas com reflectômetros no domínio do tempo. Por ser um método não destrutivo e com resultados em tempo real, foi possível avaliar a influência das condições de campo na migração do combustível. O monitoramento da zona vadosa foi realizado por um período de 30 dias, dos quais nos 12 primeiros dias o nível do lençol manteve-se sem variação significativa. Observou-se que, no primeiro dia após a liberação do combustível, o etanol migrou por 1,5 m da zona vadosa, chegando à franja capilar. No período em que não houve variação do nível do lençol...

Biodegradation of organic compounds in vadose zone and aquifer sediments.

Konopka, A; Turco, R
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /08/1991 EN
Relevância na Pesquisa
26.08%
The microbial processes that occur in the subsurface under a typical Midwest agricultural soil were studied. A 26-m bore was installed in November of 1988 at a site of the Purdue University Agronomy Research Center. Aseptic collections of soil materials were made at 17 different depths. Physical analysis indicated that the site contained up to 14 different strata. The site materials were primarily glacial tills with a high carbonate content. The N, P, and organic C contents of sediments tended to decrease with depth. Ambient water content was generally less than the water content, which corresponds to a -0.3-bar equivalent. No pesticides were detected in the samples, and degradation of added 14C-labeled pesticides (atrazine and metolachlor) was not detected in slurry incubations of up to 128 days. The sorption of atrazine and metolachlor was correlated with the clay content of the sediments. Microbial biomass (determined by direct microscopic count, viable count, and phospholipid assay) in the tills was lower than in either the surface materials or the aquifer located at 25 m. The biodegradation of glucose and phenol occurred rapidly and without a lag in samples from the aquifer capillary fringe, saturated zone, and surface soils. In contrast...

Distribution of Iron-Oxidizing Bacteria in the Nordic Uranium Tailings Deposit, Elliot Lake, Ontario, Canada

Silver, M.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /04/1987 EN
Relevância na Pesquisa
26.48%
Iron-oxidizing bacteria are present within the top 2 m (but not always at the surface) and near the water table-capillary fringe of the vegetated Nordic uranium deposit, Elliot Lake, Ontario, Canada. They are distributed uniformly in the top 0.5 m of unvegetated tailings. The locations of these bacteria correlate with zones of pyrite oxidation as delineated in previous studies by the formation of soluble iron and sulfate. Heterotrophic bacteria are also present in the tailings, with greatest concentrations at the surface and near the water table-capillary fringe. Sulfate-reducing bacteria were detected in the soil and peat at the base of the tailings. The results of this study suggest that the establishment of vegetation directly upon the tailings surface does not arrest bacterial pyrite oxidation.

Modeling Quantification of the Influence of Soil Moisture on Subslab Vapor Concentration

Shen, Rui; Yao, Yijun; Pennell, Kelly G.; Suuberg, Eric M.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /07/2013 EN
Relevância na Pesquisa
26.08%
The U.S. EPA has developed a database of field data obtained from vapor intrusion sites throughout the United States. Large variations in reported subsurface contaminant vapor concentration ratios (e.g. building subslab to groundwater source) present challenges for the analysis of subsurface vapor transport processes. Meanwhile, numerical models have been used by the U.S. EPA and others to describe the transport processes governing vapor intrusion. The influence of the capillary fringe has often been ignored in these models. In this manuscript, the influence of soil moisture content on the subslab vapor concentration is analyzed in the context of mathematical models. Results are compared to those from other modeling methods that do not account for the soil moisture content. The slab capping effect is observed to interact with the effect of soil moisture in determining the subslab contaminant vapor concentration. The slab capping effect is observed to be significant when the building-source separation distance is less than half of the slab size.

Investigations of electromagnetic methods applied to the in-river and near-river environment along the Murray River, Australia.

Hatch, Michael A.
Fonte: Universidade de Adelaide Publicador: Universidade de Adelaide
Tipo: Tese de Doutorado
Publicado em //2011
Relevância na Pesquisa
26.08%
In the last decade more than 2500 km of the Murray River in southeastern Australia and its surrounding floodplains have been surveyed using a variety of geophysical techniques to assess the environmental impact of changing salinity conditions along the river. These have included a combination of ground-based and airborne electromagnetic (EM) techniques. Along the Murray River, particularly in the lower reaches, the near-surface conductivity ranges from being moderately resistive to highly conductive, with groundwater conductivities approaching that of seawater in many areas. Such conditions present challenges for the application of most EM techniques, particularly as the signal attenuates rapidly resulting in little signal penetration. For all EM and DC-resistivity techniques, careful selection of frequency range and/or system geometry is therefore necessary to collect information over depth ranges of interest. An understanding of tradeoffs between frequency range and/or system geometry, resolution, and penetration depth is arguably critical to technique selection at the outset of the survey, and to the application of appropriate data processing and interpretation procedures post-survey. This thesis examines and evaluates a number of geophysical techniques for their suitability in characterising the shallow subsurface beneath and adjacent to the Murray River. Results for three inductively and galvanically based geophysical techniques used to collect data in the in-river setting are compared over the same stretch of river. Two are variations on ground-based systems...

The influence of soil genesis, type and composition on constraints to plant growth in salt-affected soils in upper south east South Australia.

Fraser, Melissa Bronwen
Fonte: Universidade de Adelaide Publicador: Universidade de Adelaide
Tipo: Tese de Doutorado
Publicado em //2011
Relevância na Pesquisa
26.08%
This thesis documents the physicochemical, mineralogical, geochemical and morphological characteristics of two major soil types present on the interdunal Avenue Plain in the Upper South East of South Australia. Their evolution in the landscape is hypothesised. The district has historically been affected by dryland salinity and seasonal flooding; artificial drainage has been adopted in some areas to ameliorate these constraints. The study was instigated in collaboration with members of the Keilira Farm Management Group (KFMG) in response to a perceived decline in pasture growth since the establishment of the Fairview Drain in the Keilira District in 1997. A preliminary study was conducted on three properties at Keilira; two included drains (South and Central sites) and one was un-drained (North), with the aim of investigating the effects of artificial drainage on soil physicochemical condition. Annual rainfall and standing water levels (SWL) in a series of observation wells were assessed. Results showed that groundwater levels have fallen both with a decline in annual rainfall and the implementation of artificial drainage. The lowering of SWL has facilitated the leaching of salts, often resulting in the expression of sodicity. Comparison with 1950 (pre-drainage) data confirmed that a change in soil physicochemical condition has occurred at both drained and un-drained sites. Poor plant growth was prevalent when the soils were both chemically hostile and structurally unstable. Soil type and mineralogy were found to vary both across and within study sites; smectite-dominant soils located at the un-drained North site exhibited the most hostile chemical conditions for plant growth. Subsequent studies at the South site used geophysical tools and soil survey to determine the extent of soil physicochemical variability...

Oxygen transfer in a fluctuating capillary fringe

Haberer, Christina M.
Fonte: Universidade de Tubinga Publicador: Universidade de Tubinga
Tipo: Dissertação
EN; DE_DE
Relevância na Pesquisa
26.08%

Oxygen Transfer in a Fluctuating Capillary Fringe

Haberer, Christina M.; Rolle, Massimo; Cirpka, Olaf A.; Grathwohl, Peter
Fonte: Soil Sci Soc Amer Publicador: Soil Sci Soc Amer
Tipo: Artikel
EN
Relevância na Pesquisa
26.08%

Mass Transfer of Oxygen across the Capillary Fringe; Stofftransport von Sauerstoff über den Kapillarsaum

Liu, Sanheng
Fonte: Universidade de Tubinga Publicador: Universidade de Tubinga
Tipo: Dissertação
EN
Relevância na Pesquisa
66.98%
Mass transfer of oxygen from soil air across the capillary fringe affects the fates of many contaminants in groundwater. The processes involved in mass transfer include aqueous and gas phase molecular diffusion, mechanical dispersion, reaction and partitioning between the aqueous and gas phases. The extent to which each of these processes contributes to mass transfer between the saturated and unsaturated zone depends on both the properties of the solute and the conditions within the subsurface. It is generally believed that transversal mixing controls the flux of electron acceptors such as oxygen across the capillary fringe into groundwater. The objective of this work is to investigate the transfer of oxygen between soil gas and groundwater. The thesis consists of three parts: the numerical simulations, derivation of analytical solutions, and high resolution data bench scale tank experiments for the validation of the models. Numerical simulation results show that in both reactive and non-reactive cases the oxygen gradient increases rapidly when the water saturation reaches about 85%. The maximum product concentration does not depend on the concentration of oxygen. Instead, it increases proportionally to the concentration of electron donor. Results from the numerical simulation also show that due to a lower horizontal flow velocity in the not fully saturated capillary fringe...

Oxygen Transfer in a Fluctuating Capillary Fringe; Der Stoffübergang von Sauerstoff im fluktuierenden Kapillarsaum

Haberer, Christina M.
Fonte: Universidade de Tubinga Publicador: Universidade de Tubinga
Tipo: Dissertação
EN
Relevância na Pesquisa
47.03%
Mass transfer processes across and within the capillary fringe affect the transport behavior of volatile compounds and, thus, the natural attenuation of contaminants present in this region. We studied the mass transfer of oxygen in the fluctuating capillary fringe since oxygen is the most relevant electron acceptor for many biogeochemical processes. Cyclic fluctuations in water table elevation are important in the supply of oxygen to oxygen-depleted groundwater and, thus, can significantly affect the groundwater geochemistry, but also the effective hydraulic properties of the porous medium due to gas entrapment. We performed a series of quasi two-dimensional flow-through experiments at the laboratory bench-scale (i) to directly compare oxygen transfer across the capillary fringe with mass transport within the saturated zone at steady state; (ii) to gain an improved understanding of the processes governing oxygen transfer in a fluctuating capillary fringe; (iii) to study the influence of different flow conditions and porous medium properties on oxygen transfer in the capillary fringe following an imbibition event; and (iv) to investigate the effect of a coarse-material inclusion, present in the vicinity of the water table, on flow and oxygen transfer. High-resolution vertical profiles of oxygen concentration were measured at distinct positions along the horizontal groundwater flow direction...

Experimental Sensitivity Analysis of Oxygen Transfer in the Capillary Fringe

Haberer, Christina M.; Cirpka, Olaf A.; Rolle, Massimo; Grathwohl, Peter
Fonte: Wiley - Blackwell Publicador: Wiley - Blackwell
Tipo: Artikel
EN
Relevância na Pesquisa
26.08%

Impact of Heterogeneity on Oxygen Transfer in a Fluctuating Capillary Fringe

Haberer, Christina M.; Rolle, Massimo; Cirpka, Olaf A.; Grathwohl, Peter
Fonte: Wiley - Blackwell Publicador: Wiley - Blackwell
Tipo: Artikel
EN
Relevância na Pesquisa
26.08%

Experimental Sensitivity Analysis of Oxygen Transfer in the Capillary Fringe

Haberer, Christina M.; Cirpka, Olaf A.; Rolle, Massimo; Grathwohl, Peter
Fonte: Wiley - Blackwell Publicador: Wiley - Blackwell
Tipo: Artikel
EN
Relevância na Pesquisa
26.08%

Evaluation of fuel ethanol releases in a pilot-scale aquifer tank: Source dynamics, NAPL migration and microbial community response

Capiro, Natalie Lara
Fonte: Universidade Rice Publicador: Universidade Rice
ENG
Relevância na Pesquisa
26.25%
Ethanol is playing a key role in current discussions on energy, agriculture, taxes and the environment. This work addresses the potential environmental impacts and behavior of subsurface fuel-ethanol releases. A continuous-flow 8,150-L pilot-aquifer tank packed with sand was used to simulate two spill scenarios: (1) fuel-grade ethanol (E95, 95% v/v ethanol, 5% v/v hydrocarbon mixture as a denaturant) into uncontaminated soil, and (2) neat ethanol (100% v/v) release onto gasoline-contaminated soil. Measurement of ethanol and hydrocarbon concentrations in groundwater and capillary-fringe pore water from over 30-locations over 120+ days provided a quantitative evaluation of the extent of plume migration, longevity, and impacts to groundwater quality. Real-time quantitative PCR (RTQ-PCR) was also used to estimate temporal and spatial trends in concentrations of total bacteria (16s rDNA) and various genotypes that inhabit different electron-accepting zones at sites undergoing natural attenuation. Furthermore, the anaerobic catabolic gene bssA (coding for benzylsuccinate synthase), and the aerobic catabolic genes dmpN (coding for phenol hydroxylase) and todC1 (coding for toluene dioxygenase) were also quantified as biomarkers for BTEX biodegradation. Ethanol...

Multiphase unsaturated zone contaminant transport model for source term definition in ground water

Chang, Chi-Chung
Fonte: Universidade Rice Publicador: Universidade Rice
ENG
Relevância na Pesquisa
26.08%
A multiphase unsaturated zone contaminant transport (MUCT) model has been developed to simulate the simultaneous vertical flow of water and a second immiscible fluid in unsaturated porous media. The model couples multiphase flow equations with a multiphase solute transport equation. The multiphase flow equations are solved semi-analytically by applying finite difference computations. Multiphase solute transport is governed by a simplified three-phase flow advection-dispersion equation. The solute transport equation is solved analytically under the assumptions of a steady flow field and local partition equilibria between phases. The solute transport is assumed to be strictly one dimensional; only longitudinal advection and dispersion are included. The MUCT model is evaluated by applying generic examples, mass balance, and sensitivity analyses to demonstrate the potential application of the model. Results of the generic simulations could be applied in ground water modeling to characterize the hydrocarbon source loading in terms of the release rate and intensity of the pollutant. The OILENS model (Charbeneau and Shultz, 1988) is selected and combined with the MUCT model to study the impact of a hydrocarbon release event on ground water quality. The combination of MUCT and OILENS also defines the interfacial boundary conditions with the existence of a light immiscible hydrocarbon between the unsaturated zone and the saturated zone. The Horizontal Plane Source model (Galya...

Avaliação de investigação ambiental e de tecnologia de intervenção aplicadas em uma área industrial com elevadas concentrações de hidrocarbonetos; Not available.

Ogihara, Sérgio Hiroshi
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 28/07/2000 PT
Relevância na Pesquisa
26.08%
O objetivo deste trabalho foi apresentar e discutir uma metodologia utilizada em um projeto de avaliação ambiental de uma área industrial impactada por hidrocarbonetos monoaromáticos localizada no município de São Paulo, bem como as tecnologias implementadas na intervenção para extração e controle de fase livre sobrenadante. A área de estudo localiza-se na Zona Sudoeste do Município de São Paulo. A geologia caracteriza-se por solo arenoso fino silítico argiloso derivado da intemperização de rocha gnáissica. A metodologia utilizada na avaliação compreendeu a execução de sondagens a trado para amostragem de solo, instalação de poços de monitoramento para amostragem de água subterrânea e caracterização hidrogeológica, medição de fase livre nos poços, levantamento de vapores orgânicos no solo e prospecção geofísica através de geo-radar para delimitar os setores de elevadas concentrações de compostos orgânicos no solo e água subterrânea. Tal metodologia apresentou resultados satisfatórios para delimitar os setores de elevadas concentrações de compostos orgânicos no solo e água subterrânea. O levantamento de vapores orgânicos executado com tubos de difusão apresentou bons resultados, para efeito de delimitação de áreas com presença de fase livre. O georadar apresentou interferências em estruturas enterradas não permitindo a avaliação integral dos dados...

Alteração da espessura da fase livre da gasolina sob ação co-solvente do etanol; Not available.

Pereira, Maria Anisia de Castro
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 01/09/2000 PT
Relevância na Pesquisa
26.7%
A busca de soluções para poluição do ar conduziu a adição de álcool na composição da gasolina. Com esta medida além da redução da emissão de monóxido de carbono para atmosfera o uso de etanol diminui a fração de produtos derivados de petróleo no combustível. Entretanto quando estende-se o tema para o efeito desta mistura ao meio ambiente (solo e águas subterrâneas) algumas propriedades ainda são desconhecidas. Na década de 90 a ciência mundial se voltou ao estudo do etanol devido a descoberta, por parte dos cientistas americanos dos danos causados pelo MTBE (methil tert-buthyl ether). Entretanto poucos trabalhos têm o etanol como alvo de pesquisas e formas de detecção no subsolo. O poço de monitoramento (PM) é uma das ferramentas aplicadas na verificação e quantificação da presença de gasolina no aqüífero. No entanto, os dados oriundos dos poços têm limitações, pois as condições de pressão, tensões e forças a que estão sujeitos os fluidos no meio poroso não são rebatidos para o interior do poço. No experimento desenvolvido neste trabalho, há demonstração visual da diferença entre os ambientes de acumulação de gasolina em termos de espessuras entre as lâminas de gasolina no poço e meio contíguo...

Application of reactive transport modelling to growth and transport of microorganisms in the capillary fringe

Hron, Pavel; Jost, Daniel; Bastian, Peter; Gallert, Claudia; Winter, Josef; Ippisch, Olaf
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 23/10/2014
Relevância na Pesquisa
46.48%
A multicomponent multiphase reactive transport simulator has been developed to facilitate the investigation of a large variety of phenomena in porous media including component transport, diffusion, microbiological growth and decay, cell attachment and detachment and phase exchange. The coupled problem is solved using operator splitting. This approach allows a flexible adaptation of the solution strategy to the concrete problem. Moreover, the individual submodels were optimised to be able to describe behaviour of Escherichia coli (HB101 K12 pGLO) in the capillary fringe in the presence or absence of dissolved organic carbon and oxygen under steady-state and flow conditions. Steady-state and flow through experiments in a Hele-Shaw cell, filled with quartz sand, were conducted to study eutrophic bacterial growth and transport in both saturated and unsaturated porous media. As E. coli cells can form the green fluorescent protein (GFP), the cell densities, calculated by evaluation of measured fluorescence intensities (in situ detection) were compared with the cell densities computed by numerical simulation. The comparison showed the laboratory experiments can be well described by our mathematical model.

Assessment of in situ bioremediation of oil contaminated soil and groundwater in a petroleum refinery: a laboratory soil column study

Zargar, M.; Sarrafzadeh, M.H.; Taheri, B.; Keshavarz, A.
Fonte: Taylor & Francis Publicador: Taylor & Francis
Tipo: Artigo de Revista Científica
Publicado em //2014 EN
Relevância na Pesquisa
46.7%
Precipitation and seasonal water level fluctuations mostly add to the problem of soil and groundwater contamination and lead to pollution of capillary fringe layer and exacerbation of groundwater contamination. At the Tehran Oil Refining Company (TORC), with critical problem of soil and groundwater pollution, finding a suitable remediation method has been a big concern. As bioremediation is one of the most economically and technically attractive decontamination methods, it was chosen for preliminary study to solve this problem. For simulation of the region, soil column treatment method by using oil habituated indigenous microorganisms of the area was selected. The main purpose was assessing the suitability of bioremediation method in the target area for treatment of capillary fringe layer. Two columns (one as treatment column and the other as a control) were designed and the variation of different parameters including dissolved oxygen (DO), pH, the number of viable and active microorganisms (CFU/mL), and biodegradation rate during 30 working days were recorded. The experiments showed that a major part of degrading microorganisms were facultative anaerobic. pH was not an inhibiting factor and the number of active microorganisms was increasing during aeration time. The results of solvent extraction method also revealed that during 30 days...