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10th International Congress of the Brazilian Geophysical Society
- Conference date: 19 Nov 2007 - 23 Nov 2007
- Location: Rio de Janeiro, Brazil
- Published: 19 November 2007
41 - 60 of 484 results
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Métodos elétricos e eletromagnético na avaliação de contaminação no aqüífero cristalino do alto Rio Curaçá por rejeitos de mineração
More LessThis work presents the results obtained with electrical and inductive electromagnetic-EM34 methods applied to outline the aquifer structure and its eventual contamination related to wastes from the copper sulfide mining in the Pilar district, Curaçá valley, Bahia. The interpreted results shows the presence of conductive, elongated bodies, that may be related to acid drainage contamination leaking from the disposal lagoon of the liquid effluents from the mineral treatment process.
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Estudo de Caso- Avaliação de Áreas Impactadas por Hidrocarbonetos em Solo, Utilizando a Integração de Métodos Geofísicos e Geoquímicos
A elaboração do presente trabalho tem como finalidade apresentar a metodologia utilizada pela Brain tecnologia para diagnóstico geoambiental em área impactada por hidrocarboneto decorrente da deposição incorreta de resíduos oleosos. Para tal foram utilizadas as técnicas GPR (Ground Penetrating Radar) e Eletroresistividade (Eletrical Resistivity Imaging Survey-ERIS) juntamente com um plano de sondagem detalhado para a definição do arcabouço geológico da região e execução de análises geoquímicas para a avaliação da área impactada por hidrocarbonetos.
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Caracterização da Eletroresistividade sob Influência da Biodegradação em Áreas Impactadas – Aplicação de SEVME
Authors Rodrigo R. Oliveira, Maria C. Pessoa and Cleide RomãoAnálise da eletroresistividade através da sondagem Elétrica Vertical Multieletrodo (SEVME), tem sido utilizada frequentemente em estudos de áreas impactadas. Arranjos distintos e complementares são utilizados para atingir objetivos específicos. Neste trabalho serão apresentados resultados de aquisições geofísicas realizadas em áreas de depósito de resíduos oleosos, sob efeito da biodegradação e confinamento de gases.
Para cumprir os objetivos propostos os arranjos utilizados foram: Dipolo-dipolo, Wenner e Gradientes Múltiplos que constituíram a campanha de geofísica. Dados diretos foram utilizados para balizar a interpretação, tais como sondagem e geoquímica de solo.
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Interpretação Integrada de dados de GPR 2-D e SEVME 2-D em Áreas Impactadas
Authors Maria C. Pessoa and Rodrigo R. OliveiraO presente trabalho apresenta resultados geofísicos oriundos de um levantamento de GPR 2-D e SEVME 2-D realizado em áreas com risco de 100% de explosividade e confinamento de gases. Os dados foram adquiridos em área de depósito de resíduos oleosos com duração de mais de 30 anos. As aquisições geofísicas foram específicas para atingir profundidades superiores a 20,0m com resolução vertical e horizontal suficientes para interpretação detalhada e consistente.
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Aplicação de Ferramentas Geofísicas no Diagnóstico Geoambiental
More LessThe present work makes reference to the methodology used by Brain Tecnologia (2007) for diagnosis in areas impacted for hidrocarbonets. For the execution geophysical techniques were used (GPR - Ground Penetrating Radar and VESM - Vertical Electric Survey Multielectrod) associated to a consistent survey plan and, consequently the lease of wells. The correct integration of the geophysical tools comes as an efficient for the evaluation of environmental impacts caused by accidents involving hidrocarbonets e/ou chemical products.
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Padrão de salinização de águas subterrâneas na bacia do rio Curaçá: Avaliação química e isotópica
Authors Vicente Amorim Junior and Antonio Expedito G. de AzevedoGroundwater from crystalline aquifers in the Curaçá basin, northern part of Bahia state, display generally very high salinity. To investigate the origin of this salinization the chemical and stable isotope (±D and ±18O) composition of samples from 16 well boreholes and 2 surface reservoirs was measured. The deuterium and oxygen-18 concentration are much higher in surface samples than in groundwaters, while the major ions concentrations are much higher in groundwater than in surface samples. This indicates that the infiltrating waters that reach the aquifers does not suffer high evaporation and the origin of salinity is from dissolution of salts in the water interaction with the soils and the rocks of the reservoir.
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Análise do fluxo subsuperficial por eletrorresistividade
More LessThis paper proposes a comparative analysis of data obtained through electrical imaging. The methodology applied to observe the underground water flow paths and infiltration distribution is here presented. The base flow was traced by saline water applied in a rectangular area and measured in different times by surface measurements of apparent resistivity with a pseudo-depth section perpendicularly to a slope. The obtained data were compared and the results represent the differences along time.
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Avaliação de áreas impactadas através de Eletroresistividade associada à geoquímica
More LessA elaboração do presente trabalho tem como principal finalidade apresentar a metodologia utilizada para diagnóstico ambiental em área impactada por hidrocarboneto decorrente da disposição de resíduos oleosos em um corpo de água superficial. Para cumprir
os objetivos propostos foram utilizados métodos diretos (geoquímica) e indiretos de investigação da qual destaca - se a eletroresistividade (Eletrical Resistivity Imaging Survey-ERIS). Esta resistividade é obtida injetando-se corrente elétrica no solo e medindo-se simultaneamente a diferença de potencial gerada em diferentes pontos da superfície. A aquisição dos dados é formada ao se repetir esse procedimento diversas vezes em vários pontos da superfície. Agregado a um plano de sondagem bem detalhado, orientado pelo ERIS, com análises químicas de amostras de solo e sedimento de fundo a eletroresistividade é uma importante ferramenta de imageamento subterrâneo principalmente para o caso específico desse trabalho, uma vez que distingue materiais, que possuam resistividade elétrica contrastante, como é o caso de hidrocarbonetos no solo. A integração das ferramentas geofísicas e geoquímicas apresenta-se como uma metodologia precisa para a avaliação de impacto ambiental causado por acidentes envolvendo hidrocarbonetos e/ou produtos químicos. A profundidade atingida pelo imageamento está intrinsecamente ligada ao comprimento da seção. A resolução é diretamente proporcional ao espaçamento mínimo entre eletrodos, e diminui gradativamente com a profundidade. A parte mais rasa do terreno é a que mais influencia na medida, portanto uma boa modelagem superficial é importante mesmo quando o que se deseja visualizar está bem profundo.
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Aplicação de Métodos Geoelétricos na Caracterização de Áreas Contaminadas
As contaminações por hidrocarbonetos em solo e água subterrânea têm sido alvo de inúmeras pesquisas, principalmente devido à complexidade dos fenômenos químicos e bioquímicos que ocorrem a partir do momento que o contaminante é absorvido pelo solo. Técnicas diretas tradicionais como sondagens mecânicas e coleta de amostras para análise são comumente utilizadas no mapeamento de plumas de contaminação, mas limitadas devido ao seu custo e morosidade. Levando em consideração este fato, as investigações geofísicas estão sendo comumente aplicadas na caracterização geológica de subsuperfície e na identificação de áreas contaminadas por hidrocarbonetos do tipo LNAPLs (light non-aqueous phase liquids). Buscando diagnóstico de menor custo e maior agilidade, utilizou-se os métodos de eletrorresistividade e potencial espontâneo, aplicando as técnicas de sondagem elétrica vertical (SEV) e imageamento elétrico 3D na identificação de possíveis plumas de contaminação, em área onde ocorreram vazamentos de hidrocarbonetos.
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Composição isotópica do carbono combinado com os íons (Ca+2, Mg+2, SO4 =) para avaliar a interação água-rocha no sistema aqüífero Salitre-Ba
Analysis of stable isotope composition (δC13) of carbon dissolved inorganic of carbonates and major ion concentration in groundwater from the Salitre basin in Bahia was carried out to investigate the water-rock interaction in the aquifers of that region. The important aquifers of the Salitre basin are the fractured metasedimentary rocks of Chapada Diamantina Group and the Karsts of the carbonates rocks of the Una Group and Caatinga Formation. The chemical data show a dear distinction between the two groups with a much lower concentration of dissolved salts in waters from the metasedimetary aquifers. The δC13 of carbon dissolved inorganic ranged from -4,3 to -13,2‰ with the water samples from the karst aquifers enriched in C13 indicating a higher interaction with the carbonate rocks. One sample very rich in sulfates from one well in metasedimentary rock rich in C13 shows that in some points the pyrite oxidation can be an important source for dissolution.
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Composição Isotópica do carbono em n-alcanos de sedimentos da Baía de Todos os Santos e suas possíveis aplicações na diferenciação da matéria orgânica e como traçador de fluxo de material orgânico de origem terrestre
More LessSix sediment cores from Todos os Santos Bay collected in the area between Landulpho Alves Refinery and São Francisco do Conde city have been analyzed in order to evaluate the sources of organic matter in that region. In this work, the stable isotope composition of carbon (δ13C) of the n-alkanes with carbon number between C22 and C30 along the sediment cores, measured by gas chromatography coupled with mass spectrometer, are utilized to differentiate organic matter of terrestrial sources from marine and petrogenic sources. The values of δ13C of the n-alkanes have shown, in average, an impoverishment in 13C of the sediment cores closer to the Subaé estuary. This difference is more evident in the values of δ13C of the n-alkanes between C27 and C30,
mainly in the C29, evidencing one more time the contribution of terrestrial organic matter in these sediment cores. In the three cores collected closer to Subaé estuary was observed that the averaged δ13C values from C29 are less negatives with increasing distance from Subaé estuary indicating that this parameter can be utilized as a runoff tracer.
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Levantamento, processamento e interpretação de dados de gamaespectrometria terrestre realizado em área utilizada para cultivo agrícola
The present work shows the use of gamma-ray spectrometry applied to precision agriculture in the sub-tropical area. Our dataset comprises measurements both in rock and residual soil. The soil data shows a reduction of 20% on U and Th and 10% on K, when compared to rock samples. This difference could be related to K supplementation associated to chemical fertilization.
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Application of the electrical resistivity method in studies of contamination in cemetery - case of Vila Rezende - Piracicaba/SP – Brazil
This paper shows the results obtained in the application of the electrical resistivity method, using the technique of the vertical electric survey (VES) and electric profiling (EP) (Schlumberger and dipole – dipole arrays), in the investigation underground contamination for - necrochorume in Vila Rezende’s cemetery, Piracicaba - São Paulo, Brazil. The results indicated a depth of the water table between 2 and 6m, with two directions of underground flow, SW and SE. The areas with low resistivity, presented in the geoelectrics sections, demonstrated that the contamination has connection with the depth of the water table and with the time of burial. The applied methods in this work demonstrated as an important instrument for evaluation of the environmental quality in cemeteries.
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Geoelectrical investigation to select an area to install a sanitary landfill over the Guarani aquifer
Authors José Domingos Faraco Gallas, Fabio Taioli and Flávio Luiz VieiraLocated mainly in Brazil, the Guarani Aquifer covers around 1.2 million square kilometers (463,323 square miles) and is characterized by sandstones (named, in Brazil, the Pirambóia and Botucatu Sandstones) covered by lava flows of the Serra Geral Formation of the Paraná Basin. It is considered one of the most important fresh water supplies in the world. The municipality of Timburi is located in the São Paulo State, Brazil, on the border of the basin where there are outcrops of basaltic rocks of the Serra Geral Formation and of the Botucatu Sandstone. The municipality has a population of about 3000 inhabitants and plans to become an important tourist attraction mainly due to its beautiful landscapes and the occurrence of several freshwater springs. One of the problems to be faced is that the domestic waste is taken to a landfill located over the Botucatu Sandstone, in the recharge zone of the aquifer. A geophysical survey was carried out to select an area over basaltic rocks for the installation of a new sanitary landfill. Several vertical electrical soundings were carried out to measure the thickness of the basaltic rock and the weathered basalt soil, which is relatively impermeable and considered an appropriate material for the foundation of the landfill. Profiles of resistivity imaging were carried out to verify the presence of vertical fractures in the basaltic rocks which could provide a hydraulic connection, allowing the percolation of the leachate in the event of leakage in the landfill. In addition, self potential measurements were taken to evaluate the groundwater flow direction. The results facilitated the rejection of areas with thin basalt and weathering thickness and areas where the basaltic rock contained vertical fractures and enabled the selection of an appropriate area to install a new sanitary landfill.
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Mapeamento tridimensional de pluma de contaminação através de resistividade elétrica
This work aims at the detection of the contamination caused by a waste disposal area, by the electrical geophysic method of resistivity. Field measurements had been carried out in Mococa, São Paulo, Brazil, in a deactivated waste disposal area. The obtained data had been dealt with appropriate softwares that enabled the distinction of the anomalies which help the characterization of the environmental pollution problem.
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Desenvolvimento de mini sonda para avaliações ambientais a pequenas profundidades
The evaluation of soil and groundwater contamination has been an important task in the geosciences field and pushing on the methodological improvement. The contamination extension is normally investigated using geophysical methods or boreholes and chemical analysis. Otherwise, several contamination problems are at low depths (less than 0.5m) allowing the easy access to the contaminated region. Therefore, a low-cost and simple system (mini-probe Wenner) was developed and tested and it is aimed at low depth resistivity measurements. The system is formed by a current source (AC) and a PVC probe which contains a Wenner array with a electrode spacing of 1 cm. Laboratory tests show that the current source works adequately in the resistance range normally associated with contaminated materials while the system tests (including the current source and probe) indicated apparent resistivity values very similar to the resistivity values calculated using the equation proposed by Archie, in the 1.5 to 57 Ω.m interval. Preliminary field tests showed that the mini-probe is easily applicable in sandy and sand-silty soils while in clayey or hard soils is difficult its introduction. Therefore, interesting applications to the proposed system are the study of agricultural areas or the study of contamination in predominantly sandy litologies.
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Estudos geofísicos para mapeamento de contaminaçãoe utilização como instrumento de conscientização sócio-ambiental
Authors Juliano das Flores Bahia and Roberto ElisThe high populational density in urban areas, had caused environmental problems related to the genesis and, mainly, the deposal of residuals generated by these inhabitants, which in many situations, the final destiny is the ground.
The present work has the propose of evaluating the contamination caused by the “in situ” deposition of domestic residuals and sewerage, using geophysics methods to build an efficient methodology on evaluation and characterization of environmental problems with these characteristics. Subsequently the research is applied in environmental education in schools near the investigated area and the guests that comes to the park.
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Avaliação da representatividade isotópica da bacia Experimental do rio do Cedro para estudos da evaporação na bacia do rio Jacuípe – região semi-árida baiana
The Jacuípe river is the greater tributary of the Paraguaçu river and its basin has great importance for the State of Bahia, involving a extensive area in the semi-arid region. Experimental Basin of the Cedro river (BHEC), monitored by the Federal University of
Bahia, is inserted in this basin. In order to evaluate the representation of the BHEC, related to the isotopic behavior, isotopic analyzes were carried out in superficial waters of these basins in samples developed among of June and December of 2006. The
local lines of the studied regions showed lesser inclination than global meteoric water line (GMWL), with similar inclination for BHEC and Jacuípe basin, with slope 5.2 0.2 and 5.0 0.1, respectively. This result corroborates with high evaporations rates from
semi-arid region. It was verified that BHEC can be used as laboratory for study of the evaporation effect in reservoirs in the Jacuípe river basin, applying isotopic franctionation methodology, in order to subsidize management action to minimize losses in water amount and quality at semi-arid region due to this phenomenon.
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Evapotranspiração da cana-de-açúcar na região do Recôncavo Bahiano
Authors A.T. Vidal, A.B. Novaes and L.C. PereiraRadiation fluxes over a surface close to a farm in Jaguaripe-BA were measured on clear day. The Bowen ratio method for calculating latent heat e sensible heat fluxes density was used by measuring temperature and water vapour at two heights. Each of energy fluxes density was computed from the Bowen ratio and net radiation minus soil heat fluxes density. The site of interest, under drought conditions, the Bowen ratio was in the range 0 – 1, and the latent heat flux accounted the range 70 – 80% of the net radiation.
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Evolução Isotópica de Oxigênio-18 e Deutério das águas meteóricas da cidade de Salvador no período 2003-2005
Meteoric water samples collected between 2003, october and 2005, july in the Applied Nuclear Physics Laboratory from UFBA. The obtained results indicated that, the δ18O and δD values follow the same trend. These values show also that exist a inverse relationship between precipitation intensity and δ18O and δD values in the majority of the studied moths. The seasonal dependence was observed with deuterium excess parameter d. These values are higher in the cold months and low in the hot months. The
equation parameters values without 2004/jan rain, shows a good agreement with global line of meteoric precipitation and send us to conclusion that this value is out of normal precipitation from this region. The weighted average of δ18O, δD and d values in this work, shows a good agreement with International Atomic Energy Agency values when calculated without anomalous value. This value is probably due to quantity effect united to clouds from intertropical convergence zone.
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