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The open pit mining development begins with the opening of pits with the rock mass excavation and formation of slopes and berms for ore exploration. Knowledge about the geological conditions represents an important step in this process, since rock masses generally have heterogeneous characteristics and the presence of discon- tinuities can become an aggravating factor in the safety of operations. The characterization and classification of these discontinuities, as well as the identification of the groundwater in the rock mass, has a great importance to ensure the safety of operations during the mine's production process, in addition to ensure the effectiveness of its decommissioning process. The use of DC resistivity geophysical method has been increasing to characterization and identification lithological types and presence of water, since it is a non-invasive research tool with fast ability to obtain data. DC resistivity together with visual investigation methods, such as obtaining the discontinuities orientation and their alteration characteristics, provides important information for the characterization of the rock mass. Given this importance, the present work aimed to use DC resistivity to identify the presence of water and its correlation with lithology and rock mass structure in order to identify how these variables influence the occurrence of ruptures. To this end, two-dimensional resistivity sections were designed and related to visual inspection data and kinematic analyzes obtained from structural data of the rock mass. The integration of these results indicated that the ruptures present in the investigated mine slopes are related to zones whose predominant lithology is volcanic breccia with the presence of water in the subsurface. These ruptures compromise the stability of the slopes and consequently make the decommissioning mine process difficult.

The concentration and mobility of metals in the lithosphere and hydrosphere are led by many physical-chemical parameters and processes from natural and anthropogenic origins, the last one resulting in impacts over many ecosystems around the World, including wetlands. These transitional zones, often characterized by the presence of hydric soils, adapted vegetation, and seasonal or permanent presence of surface water, are commonly under human pressure in terms of land use conversion and contamination, notably in agricultural production areas, where excess of nutrients/organic matter, pesticides, salts, sediments, heavy metals and radionuclides (originated from inorganic fertilizers) can substantially alter the ecological balance of those ecosystems. Thus, this study aimed to evaluate the agricultural impact over a tropical geographically isolated wetland in the Brazilian Cerrado by the analysis of geochemical mobility and interaction between surface and groundwater through in situ gamma-ray spectrometry and hydraulic conductivity measurements. The results demonstrated that the margins of this diabase-derived soil wetland are one of the most important and critical compartments due to its capacity of metal immobilization and surface water infiltration, indicated especially by uranium concentrations. Thorium, in turn, was most related to colluvial transport from slopes to the center of wetland. It was also corroborated by low hydraulic conductivity zones as a result of soil compaction due to heavy agricultural machinery and increase in runoff fluxes. Thus, this methodology could be used as an initial fast screening method in wetlands under other climatic and geological/pedological contexts to evaluate the local hydrogeochemical dynamics and impacts of agricultura.

Este trabajo presenta la caracterización geológica-geofísica de una probable ocurrencia de oro en Santa Catarina Gabro, en la región de São Sepé, estado de Rio Grande do Sul, sur de Brasil. Trabajos anteriores han indicado la presencia de oro en la región en las actuales campañas de prospección geoquímica de sedimentos y sugieren que el área de origen sería Santa Catarina Gabro. Para investigar sobre esta probable ocurrencia de oro, se realizaron estudios geológicos y estructurales, seguidos de la adquisición de información geofísica utilizando los métodos de resistividad DC e IP, con el arreglo dipolo-dipolo. Los datos geofísicos fueron procesados en inversión 2D y luego interpolados para permitir la visualización tridimensional de la posible mineralización. Interpretaciones basadas en la recopilación de datos geológicos y geofísicos, en asociación con el contexto estructural regional, sugieren que la probable mineralización se originó a partir de la intrusión del Granito São Sepé, cuyos fluidos hidrotermales se alojaron en fracturas durante los eventos tectónicos ocurridos en la región. Los resultados obtenidos en este trabajo permiten delinear una arquitectura de yacimiento factible con el contexto geológico de la región y ayudar a una futura estrategia de perforación dirigida a los objetivos probables identificados.

Abstract Slopes are built for the purpose of extracting ore, in the case of mining, or access roads in civil works. The excavation of slopes in tropical countries is facilitated by the thick layer of soil formed from the more intense weathering when compared to other countries. However, the residence time of water in the soil is relatively longer and consequently allows the accumulation and percolation of water through rock fractures even in the dry period. These factors induce a greater probability of occurrence of ruptures. Mines in the decommissioning phase must guarantee slope stability conditions even after closure in order to comply with legislation and environmental safety. In this work, the slopes of a decommissioning mine were investigated using geophysical methods (GPR) and structural analysis of the rock mass. The results were presented in the form of radargrams that correlate distance and depth of investigation. Structural data served as the basis for the execution of kinematic analyzes for planar and wedge ruptures. The analysis of the results allowed the correlation between electromagnetic signal attenuation zones, with the presence of water and the occurrence of ruptures. Thus, the GPR results allowed the recognition of structural discontinuities, accumulation zones and water flow.

Failure events in dams can be associated with processes in the dam body and in the foundation of the structure. If they are properly identified in early stages, corrective actions can take place, leading to a reduction in the risk of collapse and/or rupture of the dam. Most studies on dams are carried out on the body of the dam; however, problems associated with the foundation of the structure can also lead to loss of stability and subsequent ruptures. This study presents an analysis of the advantages and limitations of the use of seismic refraction in hydrogeological studies of fractured aquifers under pressure from large loads, specifically a dam in this case. Seismic refraction data were collected on an outcrop of fractured rock near a uranium storage dam foundation in southeastern Brazil. The results and interpretations were supported by a structural analysis performed through manual strike measurements collected with a Clark compass and an uncrewed aerial vehicle digital photogrammetry survey in an outcrop. The digital photogrammetric survey mapped the spatial distribution and orientation of the geological structures of the rock mass. Although the structural measurements performed through digital photogrammetry presented greater variability than the measurements collected from the compass, the maximum density of the fracture measurements obtained from both methods were similar and were corroborated by the regional and local fracture patterning. The integration of seismic refraction data with geotechnical and geological investigations allowed us to identify the positioning of structural lineaments in the rock mass and zones with a higher degree of rock alteration. The identification of highly fractured zones in the rock mass from such non-invasive investigations could be used to assist in decision making for structural reinforcements in the foundation of the dam to avoid the loss of stability at the foot of the dam from possible leaks or water flows from the reservoir.

Abstract Population growth and social and economic development demand increasing volumes of water for public supply, especially in scenarios where surface sources such as rivers may not meet the basic demands for the population. In southeastern Brazil, with emphasis on the Piracicaba region, there is a conflict over water use regarding agricultural and industrial activities, where the sugar-alcohol sector is widely highlighted. The region has thousands of hectares of sugarcane cultivated, which requires intensive use of fertilizers and pesticides, in addition to the need for large volumes of water in the production of sugar and ethanol, where the main effluent produced is represented by vinasse, used as fertilizer complement and soil hydration in sugarcane fields. This work presents the results of a geophysical diagnosis in a closed wetland, located in a sugarcane field region, to evaluate the hydrogeological function of this environment in aquifer recharge and the risks that land use can cause in the quality and availability of surface and underground water resources. The geophysical survey consisted of nine lines of electrical resistivity tomography in Schlumberger arrangement, submitted to 2D processing and inversion followed by interpolation and generation of 3D visualization models. The results indicate a direct connection between water accumulated in the wetland and the aquifer underneath, separated by an aquitard interface about 44 m thickness. The study points out to the high vulnerability to the input of pesticides and vinasse effluent from the surrounding sugarcane fields to the interior of the wetland, given the absence of riparian forest or buffer zone, in addition to the risk of contamination of surface and groundwater. Understanding the local hydrological dynamics should subsidize the sustainable use of the soil providing preservation of water resources, with emphasis on aquifers, a source of increasing importance in the face of the imminent scarcity of surface resources.

La complejidad estructural inherente a los acuíferos fracturados, que controla la acumulación y el flujo de agua subterránea en zonas restringidas, puede dar lugar a un elevado número de pozos tubulares no productivos. El análisis combinado de las características geomorfológicas y las investigaciones indirectas, como los métodos geofísicos, permite identificar objetivos favorables para la explotación de aguas subterráneas. Este trabajo trata de los estudios estructurales regionales y locales acoplados con datos de tomografía de resistividad eléctrica con el fin de identificar objetivos favorables para la explotación de aguas subterráneas para el consumo urbano en un granito fracturado situado en la ciudad de Caçapava do Sul, en el sur de Brasil. El control estructural se manifiesta en las formas del terreno regional y condiciona claramente la orientación de los drenajes principales. Basándose en este control estructural, se realizaron cuatro líneas paralelas de tomografía de resistividad eléctrica en una zona de interés para la explotación de aguas subterráneas, seguidas de la generación de modelos de inversión 2D y de modelos pseudo 3D. El contacto entre el suelo superficial muy fino y el macizo granítico subyacente determina la existencia de un acuífero libre regional y la probable recarga del acuífero fracturado. En los modelos de inversión 2D se producen variaciones bruscas de resistividad relacionadas con las fracturas verticales localmente reconocidas en el yacimiento, aunque no muestran continuidad lateral (fuera del plano). El análisis de los mapas geofísicos a partir de 40metros de profundidad permite reconocer tres alineaciones de baja resistividad (alrededor de 500Ωm) dentro de un contexto granítico donde predominan los valores altos (por encima de 15000Ωm). Estas alineaciones muestran un patrón de triple intersección de fracturas reconocido también en las imágenes de satélite, que son altamente favorables para la acumulación y explotación de aguas subterráneas.

La minería de metales modifica profundamente la dinámica ambiental local y produce grandes volúmenes de roca y residuos, los cuales se espera sean eliminados cuidadosamente para evitar el deterioro del suelo, el agua y el medio ambiente. La mina Osamu Utsumi fue un sitio de explotación de mineral de uranio pionero en Brasil, ubicado en el estado de Minas Gerais. La mina abierta y la alta concentración de sulfuro en las capas de material estéril son hoy en día un tema de preocupación para las Industrias Nucleares de Brasil (INB), debido a la oxidación del sulfuro y el drenaje ácido de la mina resultante (AMD, por sus siglas en inglés). El objetivo de esta investigación es analizar los datos de espectrometría de rayos gamma y la generación de AMD en una capa de material estéril, BF-04, en el sitio. La adquisición de datos radiométricos combinada con estudios previos indica que las altas concentraciones de uranio y torio están asociadas con zonas de alto contenido de sulfuro. El mineral de uranio mineralizado incluye sulfuros que se destruyen rápidamente por las condiciones de hidratación de la superficie y son responsables de generar el drenaje ácido de la mina. En este sentido, las zonas superficiales de la capa de material estéril con altos niveles de eU y eTh son áreas expuestas a la oxidación e hidratación de sulfuros y, por lo tanto, su reconocimiento y neutralización pueden contribuir a disminuir la generación de AMD en el sitio de estudio y áreas con condiciones similares. Los resultados de la espectrometría de rayos gamma pueden ser de interés para una remediación de bajo costo en el entorno local. doi: https://doi.org/10.22201/igeof.00167169p.2022.61.3.2207

Las rocas metamórficas Precámbricas en la región sur del estado de Espírito Santo (sureste de Brasil) están interceptadas por zonas de cizallamiento dúctiles y quebradizas / dúctiles sobre las cuales se establecieron pueblos como Guaçuí, Marechal Floriano y Domingos Martins. En los años de 2014 a 2016, el estado de Espírito Santo enfrentó la peor sequía de los últimos 80 años. En situaciones como esa, la única fuente de agua dulce disponible es subterránea. Por lo tanto, el propósito de este estudio fue integrar datos de fuentes múltiples para la prospección y gestión de aguas subterráneas. El área de estudio comprende los sectores centrales de las zonas de cizallamiento Guaçuí y Batatal. La metodología abarca la interpretación de pares estereoscópicos para la identificación de lineamientos estructurales, prospección geofísica (resistividad eléctrica) y trabajos geológicos de campo. Los resultados se validaron tentativamente con los datos de producción de pozos de agua subterránea disponibles. Se estudiaron seis perfiles de resistividad con una longitud total de 2.400 m y se describieron 15 afloramientos. Los resultados mostraron que el marco estructural de las zonas de cizallamiento está hecho predominantemente de lineamientos de orientación NW a NNW y NE a NNE. La familia de orientación NW-NNW está relacionada con la tectónica frágil y la familia de orientación NE-NNE coincide con la trama dúctil Precámbrica de las rocas cristalinas del basamento. Un acuífero poroso superficial relacionado al regolito y a depósitos sedimentarios no consolidados recientes, con valores de resistividad < 1.372 Ohm.m y profundidades. doi: https://doi.org/10.22201/igeof.00167169p.2021.60.2.2049

Los mapas magnéticos y gravimétricos (aéreos y/o terrestres) suministran información importante sobre la distribución espacial de las fuentes del sustrato geológico, las cuales normalmente tienen propiedades físicas y geometrías diferentes. Estas fuentes también pueden estar localizadas a distintas profundidades, complicando la identificación de las correspondientes estructuras geológicas. Técnicas de filtrado y de realce de anomalías potenciales, pueden ser utilizadas para realzar ciertas características de interés (como el centro y el borde de las fuentes), para remover aquellas características asociadas a ruidos, para separar las anomalías de las fuentes superficiales y profundas, así como estimar sus profundidades. En este trabajo se analizan los resultados de la utilización de técnicas de realce y estimación de profundidad de las fuentes con datos geofísicos aéreos y terrestres potenciales, con el objetivo de delinear una imagen estructural del subsuelo en un área con dos ocurrencias de cobre en el límite noroeste, entre las rocas del Escudo Sul-Riograndense y la Cuenca del Camaquã. Los resultados confirman estructuras que han sido reconocidas previamente y revelan otras estructuras geológicas que integran una malla estructural interconectada, cuya profundidad, estimada por las soluciones de Euler, alcanzan los 170 m. Esta configuración sugiere una probable conexión entre las mineralizaciones de cobre observadas en los afloramientos, separados por un intervalo de 2,300 m. doi: https://doi.org/10.22201/igeof.00167169p.2021.60.2.2085

Abstract The geophysical diagnosis of mineral deposits can be extremely useful in detailing mineralized zones and is a strategy for direct sampling by probing holes for content analysis. This study involves the combined use of Electrical geophysical methods (DC resistivity and Induced Polarization), geological recognition and structural field analysis, with a study of the mineralized occurrence of copper, previously described in a systematic geochemical survey carried out by the Geological Survey of Brazil (CPRM), located in the north of the Camaquã Basin, extreme south of Brazil. The mineral occurrence is partially outcropped and consists of quartz vein shafts with malachite and relic structures of sulfides, contained in schist. Structural data obtained in the field revealed the existence of a system of fracture pairs in the directions N40-50W and N70-80E. Such information is presented in the programming of the geophysical data acquisition scheme, which consisted of 6 lines of electrical tomography with 410m each, in azimuthal disposition and Schlumberger arrangement, where all lines cross a single center and are separated according to an angle of 30°, in an attempt to cover fractures in various orientations. The 2D results reveal the existence of high chargeability zones (>40mV/V) positioned below the 40m depth. These data were interpolated in 3D visualization models and generated resistivity and chargeability maps for several depths, which integrated with previous structural data, and indicate the existence of zones with potential sulfide concentration with strong structural control, in addition to clear target recognition for direct and objective probing evaluation, with rationalization of costs.

In two small and isolated wetlands located at the interface of the Atlantic Forest and Brazilian savanna (Cerrado) in São Paulo State, Brazil, we employed a pixel-based supervised classification approach using a combination of panchromatic and multispectral bands obtained from Landsat 2, 5, 7, and CBERS-04A satellites (ranging from 80 to 2 m/pixel). In addition, we acquired DJI Phantom 4 Pro UAV-RGB images in twelve different periods with a resolution of +5 cm/pixel. Furthermore, we utilized 2D and 3D Electrical Resistivity Tomography (ERT) to obtain data on the surroundings and center of the wetlands. Finally, we conducted a climatological data analysis. The results from the multisource data allowed us to classify the ecosystems as geographically isolated wetlands (GIWs), for which we documented a seasonal month-to-month (12 months) spatial variation of inundated area, vegetation pattern, soil water interaction, and a point of surface and deep-subsurface water interaction. These results are essential for high-accuracy characterization of small wetlands’ hydrodynamics and hydroperiods at the local scale. Our study contributes to optimizing GIWs understanding, monitoring, and reapplication of the methodology in other wetlands or small ecosystems.

Abstract The Guacuí and Batatal lineaments in the southern region of the state of Espírito Santo (southeastern Brazil) can be traced from satellite images for tens of kilometers. They are considered shear zones associated to the final tectonic stages of the Araçuaí-West Congo (A-WC) Orogen during the Ediacaran-Cambrian period. In order to understand their nature and tectonic implications for the development of the orogeny, we integrated geological and structural data based on fieldwork and detailed microstructural analysis. Data was collected along two profiles located at the central segments of both structures. The results demonstrated that the Guaçuí shear zone (GSZ) is a typical ductile transpressive shear zone with approximately 9 km width that shows numerous dextral kinematic indicators and records metamorphism of upper amphibolite facies. The GSZ shows different levels of intensity of dynamic deformation. The Batatal shear zone (BSZ) is a narrow brittle shear zone that shows essentially brittle microstructures (intercrystalline microfractures) revealing deformation at low-grade conditions (frictional regime). Based on their characteristics and the level of erosion of the rocks exposed in the region, we interpret that GSZ developed prior to BSZ.

In some Brazilian states, after the long period of drought in the years 2014 to 2015, the issue of water crises became the focus of several studies. Some of these studies propose the use of groundwater to avoid water crises. However, many of these do not understand or ignore the hydrological processes of aquifer recharge and discharge. Understanding the recharge and discharge processes is essential to prevent problems related to aquifers and better understand the exchange relationships between surface and underground reservoirs. Geophysical applications are used to study these hydrological processes of recharge and discharge, however there is a deficit regarding the use of the Electrorestivity method in this type of study. The present work delimited an area close to the escarpment of the Basaltic Cuesta front in the municipality of Ipeúna (SP). The objectives were to understand the recharge and discharge processes using the Electrical Resistivity Tomography (ERT) and a stratigraphic survey. The chosen area is in an outcrop area of the Guarani Aquifer System (GAS), a place known to be important in the recharge of this transboundary aquifer. The stratigraphic survey was carried out by walking along the access road to the study area. In the geophysical survey, 10 parallel lines of electrical resistivity tomography (ERT) were performed in Schlumberger array. The measured resistivity values ranged between 5000 Ω m and 20 Ω m. Data collected in the field were processed and represented in two-dimensional and three-dimensional logarithmic models. Through the correlation between stratigraphy and 2D models, it was possible to locate the porous and fractured aquifers, as well as to relate the resistivity values with the rocks present in the area. The 3D model provided a better visualization of the electrical resistivity values at different depths in the study area. In this way, it was possible to delimit the presence of water in the geological framework. The presence of water inside a large sandstone lens flowing towards the Cuesta front was identified. The geophysical and stratigraphy surveys provided information for the generation of a geological framework model, its relationship with groundwater flow and hydrological processes. The work also reduces the gap of geophysical studies in Guarani Aquifer System and the use of electrical resistivity tomography to understand the hydrological processes of aquifers.

In Brazil, since 2013 the Southeast region has been dealing with recurrent hydric stress resulted from the prolongation of the dry season, whose tendency is to be more dramatic in the function of climate change. The situation is more critical in some areas, including Cordeirópolis, projecting a reduction of 50%–100% in water availability in the next 15 years, demanding urgency in water availability-use balance. Considering the significant presence of small Geographic Isolated Wetlands (GIW) in the region, it is crucial the recognition of the link between wetlands and hydrology in the catchment since these ecosystems store rainwater and can act as aquifer recharger zones. The objective of this study is to evaluate the effectiveness of non-invasive methods, such as UAV-mapping and DC resistivity, and low-invasive (in situ hydraulic conductivity) to unveil the hydrological ecosystem services of a GIW in terms of surface and groundwater. From the high-resolution orthomosaic and digital elevation model, three compartments were qualified and quantified; (i) current wetland, (ii) Flooding area and, (iii) Potential wetland expansion. From the DC resistivity, the interaction between surface water and groundwater was identified, indicating the presence of a shallow saturated only beyond the perimeter of the current wetland as a possible result of land-use conversion or climate change. In addition, the local igneous intrusion comprises the connection between shallow/surface waters and deep aquifers made by fractures. Thus, the association of both methods showed high applicability concerning the identification of GIW superficial hydrological functions (UAV) and the system's subsurface dynamic (DC resistivity).

The inland wetlands can perform the storage of water on the surface and the recharge of aquifers. Even a small wetland can work as a local point of water infiltration, influencing and sustaining the hydrodynamics in the hydrology landscape. These zones have complex mechanisms, as they integrate soil chemical and physical characteristics, and relate both surface and groundwater systems. The study area is an inland wetland located in the Ecological Station of Itirapina, São Paulo State (Brazil). The present work aims to unveil the relationship between hydrodynamics and pedological architecture through a detailed study that combines hydraulic conductivity tests in situ, geophysical method of electrical resistivity (Electrical Resistivity Tomography technique, ERT), and morphological soil descriptions aiming the validation of the ERT and hydraulic conductivity surveys. Two-dimensional (2D) and pseudo-three-dimensional (3D) ERT have been used to investigate the water flow in the subsurface, the pedological architecture that keeps the wetland hydroperiods, and the link between surface water and groundwater that can set a recharge capacity. The results showed areas with distinct surface patterns related to the density of vegetation cover and water infiltration. The lower infiltration areas are characterized by the presence of a perched water table in grassy areas while higher infiltration is associated with exposed topsoil. ERT 2D and pseudo-3D identified these areas as zones with a connection between soil-water and groundwater systems. Hydrodynamics in the flat plateau is associated with the geochemical evolution of soil cover due to the structural complexity acquired by the iron crust dissolution (laterite) which has sustained the relief. Future studies concerning inland wetlands need to be carried out to certify the role of soil-landscape in the water cycle in the Savanna biome.

Cemeteries can be considered as potential sources of soil and groundwater contamination in burial sites where there is no collection and treatment system for necroleachate, an effluent rich in organic matter and inorganic elements produced during the decomposition of corpses. Brazilian cemeteries are mostly located in the interior of cities, where collective or family deposits with the absence of necroleachate collection devices predominates. The tropical climate, the recurrence, and the distribution of corpses, combined with soil permeability, are decisive elements in the percolation and distribution of necroleachate in the subsurface. An important tool for the diagnosis and evaluation of organic and inorganic contamination in soil and shallow aquifers is geophysics, through research methods related to the contrast of physical properties in the presence of this type of contaminant. This research consists of a geophysical investigation in a medium-sized cemetery in the southeastern Brazil, using the DC resistivity method using three different electrodes arrays: Wenner, Schlumberger and Dipole-Dipole. Additionally, results were combined with the history of burials in the 5 years prior to the geophysical study. The 2D inversion models confirm the presence of low resistivity anomalies related to the presence of ionic compounds. 3D visualization models with results of the three acquisition arrays are compared to the amount of burial by compartmentalized areas of the cemetery, which clearly reveals a relationship of areas with high and recent recurrence of burials and areas of low resistivity in depth. The results do not present significant differences between arrays, with similarities in terms of location and dimension of the most significant areas of low resistivity.

The main biofuel produced in Brazil is ethanol representing 16% of energy production in the national energy matrix, that is why sugarcane is one of the most important crops for Brazilian agriculture. The land conversion associated with the advancement of agriculture is often carried out inappropriately advancing over areas of high environmental sensitivity, such as natural small wetlands. The level of detail required to monitor subtle changes in their dynamics and landscape makes very high-resolution images (+ 10 cm/pixel resolution) acquired by unmanned aerial vehicles (UAVs) an excellent data. The objective of this research was to use UAV orthomosaics and digital elevation models to carry out seasonal monitoring, simulate the water flow in the areas of hydric-contribution and inland flooding, and validate the flooding simulations. The studied wetland located in the State of São Paulo (Paulista Peripheral Depression), showed a seasonal surface water storage capacity (28,067 m³) and a loss of approximately 12.27% of its total area between October 2019 and February 2020. The flooding simulations were validated with data observed by the imagery (variation of ± 3.27%.), being possible to be reapplied in several small ecosystems.

Los basureros son zonas de depósito final de desechos sólidos directamente en el suelo, en ausencia de criterios técnicos o sistemas de recolección de gases o líquidos. Una gran parte de los municipios brasileños han utilizado esta alternativa extremadamente perjudicial para el ambiente hasta el año 2010, cuando una ley federal hizo obligatoria la instalación de rellenos sanitarios. Sin embargo, una gran parte de los basureros fueron simplemente abandonados, aunque algunos finalmente tuvieron algún tratamiento después de las evaluaciones de los organismos ambientales. Este trabajo presenta los resultados de la investigación geofísica en un basurero cerrado en 2004 en una pequeña ciudad del sur de Brasil, donde las investigaciones anteriores revelaron contaminaciones del suelo y de las aguas subterráneas por lixiviación. Los análisis estructurales en la región de estudios vinculados a datos geológicos de pozos de monitoreo indican la presencia de contaminantes en la fractura de granito, con amplias variaciones en el espesor del suelo, saprolita y el nivel del agua subterránea. La integración del análisis químico de las aguas subterráneas con los datos de la tomografía eléctrica (ERT) en el procesamiento de imágenes 2D y 3D, reveló la existencia de grandes áreas contaminadas dentro de los límites del basurero y el flujo en el acuífero parcialmente libre hasta 5m de profundidad. Estas zonas pueden disminuir gradualmente con el aumento de la profundidad y entre 9m y 19m predominan zonas contaminadas claramente orientadas, asociada con el flujo en el acuífero fracturado. La indicación de zonas restringidas y dirigidos sugiere la focalización y la acumulación de contaminantes en los dos sistemas de fracturas preferenciales. El descubrimiento de estas áreas es esencial para la planificación y la instalación de sistemas de bombeo y de descontaminación de aguas subterráneas, en vista de la disminución de la producción de lixiviado desde la clausura del basurero. doi: https://doi.org/10.22201/igeof.00167169p.2017.56.4.1827

A Mina Osamu Utsumi, localizada no município de Caldas – MG, foi durante muito tempo alvo de exploração de minério de urânio e hoje está em fase descomissionamento. A implantação do empreendimento mineiro promoveu profundas modificações no padrão natural dos fluxos hidrológicos tanto superficiais quanto subsuperficiais (Holmes et al. 1992). O avanço das escavações causou o desconfinamento dos maciços rochosos, o que gerou um alívio de tensões e contribuiu para o aumento das descontinuidades (Zea Huallanca, 2004). No caso de exploração de insumos minerais associados a sulfetos, como é o caso do urânio, a percolação de água em fraturas dos maciços rochosos contribui para a formação de drenagem ácida. Esta é resultado da oxidação dos minerais sulfetados, principalmente a pirita (FeS2), na presença de água e oxigênio. A redução do pH das águas provoca a solubilização de metais pesados encontrados tanto nos maciços rochosos quanto nas pilhas de estéril, como Cu, Ni, Cd, U, Mn e Zn, com incremento da mobilidade e risco de carreamento para as drenagens da região, com imapctos diretos nos mananciais superficiais e subterrâneos (Carvalho et al. 2000). O tratamento das águas ácidas na mina representa uma grande parcela dos gastos com a manutenção do empreendimento, em função do grande volume de água que interage com os sulfetos dos maciços e escoa até à cava. Com o intuito de compreender a dinâmica hidrológica próxima à cava da mina e contribuir para a adoção de medidas remediadoras que contenham a formação de drenagem ácida, o presente trabalho traz uma análise conjunta entre o levantamento de medidas estruturais dos planos de fraturas dos maciços e o método de eletrorresistividade a partir do arranjo Schlumberger e técnica do imageamento elétrico, com o intuito de identificar os caminhos preferenciais para a percolação dos fluxos subterrâneos e possíveis zonas saturadas.

A drenagem ácida de mina é um problema pertinente na indústria mineradora e seus efeitos são observados na mina de urânio Osamu Utsumi, operada pelas Indústrias Nucleares do Brasil – INB. Foram aplicados os métodos geoelétricos da Eletrorressitividade (EM) e Polarização Induzida (PI) com o intuito de se avaliar o fluxo subterrâneo local e a delimitação de áreas de interação dessas águas com zonas ricas em pirita presentes em blocos rochosos dispostos em um bota-fora de estéril. Os resultados preliminares apontam para a existência de anomalias de baixa resistividade (< 70 Ohm.m) nas seções geofísicas, provavelmente em decorrência da elevada salinidade ocasionada pelos processos de drenagem ácida. Porções de elevada resistividade e cargabilidade, por outro lado, podem ser entendidas como sulfetos disseminados inseridos em redes venulares de quartzo, prováveis zonas de reação. Um fluxo preferencial de direção NW foi observado através do centro do bota-fora, condicionada pela topografia original do terreno onde foi instalada a BF-04.

O trabalho consiste da aplicação do método geofísico da eletrorresistividade no monitoramento da atenuação natural do chorume em um de aterro sanitário instalado em área de vulnerabilidade ambiental e que apresenta falha no sistema de impermeabilização por geomembrana.

En este trabajo se hace un análisis comparati-vo entre los arreglos Dipolo-dipolo, Wenner e Schlumberger por medio de pruebas de Tomo-grafía de Resistividad Eléctrica (TRE), como la sensibilidad y la resolución en la caracterización espacial de la infiltración de contaminantes en un tanque séptico y cono de depresión en el pozo de captación de agua; ambos contenidos en acuífero libre. La adquisición de datos consistió en lecturas de resistividad utilizando cinco líneas paralelas con 105 m de largo espaciado, 5 m entre los electrodos y líneas. Los datos de cada línea se sometieron a la inversión 2D, posteriormente interpolado para la generación de bloques 3D, de la cual se extrajo una isosuperficie de resistividad fija (620 W.m), lo que permitió el modelado de las estructuras de volúmenes de flujo relacionados. Los resultados para el arreglo Dipolo-dipolo permite el modelado de la estructura asociada con el eje cilíndrico, y un isosurface de la cavidad asociada con la deformación, pero que no permitirá que el modelado de la pluma. Los datos para la disposición Schlumberger no pueden ser reconocidos cono, pero dieron lugar a un modelo de forma de lágrima asociado con el tanque séptico, como una pluma de contaminación. El arreglo Wenner resultó en un modelo con estructura en formato de quilla alargado asociado con el cono de depresión, y uno en formato caída similar también asociado con el tanque séptico. El análisis comparativo muestra que la disposición Dipolo-dipolo se recomienda en las obras de modelado de estructuras tridimensionales de alta resistividad verticales en la zona saturada. La disposición Wenner y Schlumberger se recomiendan en estructuras de modelado en tres dimensiones verticales de baja resistividad en zona no saturada, con énfasis en la disposición Schlumberger doi: https://doi.org/10.22201/igeof.00167169p.2016.55.2.1716

El biogas producido en rellenos sanitarios puede ser una fuente importante de energía en el futuro. Este gas, constituido por CH4, CO2 y vapor de agua, se forma por la descomposición de materia orgánica. Una de las limitaciones técnicas en la planeación de sistemas colectores de este gas es la forma de estimar la producción de metano en un relleno dado. En este trabajo se evalúa la relación entre el flujo de biogas medido en drenes de un relleno sanitario en Brasil con la resistividad eléctrica del material de relleno. La medición en perfiles con el método de Tomografía de Resistividad Eléctrica (TRE) y su inversion a modelos 2D de resistividad muestra una clara correlación entre zonas de alta producción de biogás con áreas de alta resistividad en profundidad. Estos resultados sugieren la posibilidad de usar el método de TRE como una herramienta diagnostica en la colocación de drenes de extracción de biogas en rellenos sanitarios. doi: https://doi.org/10.22201/igeof.00167169p.2015.54.4.1701

Impactos relacionados ao aporte de hidrocarbonetos em subsuperfície são particularmente preocupantes ao ambiente e a saúde humana, devido a aspectos degradativos e separação em fases dissolvida e residual, que resultam num tempo frequentemente prolongado de residência. Os métodos geofísicos são ferramentas consagradas no estudo de contaminações em solo, tanto na fase de confirmação, como na fase de monitoramento, devido á possibilidade de investigações indiretas e não invasivas em solos e rochas. Neste sentido, este trabalho apresenta o diagnóstico geofísico numa área impactada pelo vazamento de hidrocarbonetos, devido a acidente ferroviário. A área investigada é um trecho de ferrovia localizado no município de Cerquilho (SP), onde ocorreu em 2002 um acidente com vagões que transportavam óleo diesel e está em processo de recuperação desde então. Foi medido o parâmetro físico cargabilidade a partir do método geofísico Polarização Induzida, por meio da técnica de imageamento elétrico. Também foram compilados dados de análises químicas realizadas na área de estudos disponibilizados pela CETESB. Os resultados dos ensaios geofísicos foram comparados com as análises químicas, com o intuito de estabelecer as fases residual e dissolvida e avaliar a evolução da pluma de contaminação.

Los métodos geofísicos constituyen una herramienta ampliamente utilizada en exploración mineral. Este trabajo presenta y discute los resultados de estudios geológicos y geofísicos desarrollados en un yacimiento de manganeso de origen supergénico, localizado en la región sudeste de Brasil. La zona mineralizada descrita en levantamientos geológicos fue caracterizada por bajos valores de resistividad (20Ω.m) y altos valores de cargabilidad (30ms), en un patrón similar al descrito en diversos trabajos en depósitos minerales de óxidos y sulfuros en rocas. Modelos geofísicos pseudo-3D permita la generación de mapas para diversas profundidades. Las áreas de alta cargabilidad y baja resistividad definen un patrón de mineralización gonditica con altos niveles de Mn. Áreas considerables con elevados valores de cargabilidad y baja resistividad probablemente resulten de la acumulación de hidróxido de manganeso y hierro, originados del intemperismo en cuerpos de mineral gonditico, disolución, percolación y precipitación. doi: https://doi.org/10.1016/S0016-7169(14)71500-4

Los métodos geofísicos constituyen una herramienta efectiva para determinar alteraciones en las propiedades físicas de los ambientes geológicos, como son los suelos y aguas subterraneas influenciados por contaminantes. Este trabajo consistió en el análisis del potencial eléctrico natural obtenido en zanjas que contienedesechos sólidos con tiempo de confinamiento controlado. La interpretación de los resultados indica una correlación entre el tiempo de confinamiento de los residuos y el aumento de las variaciones de voltaje. Los datos sugieren que el potencial eléctrico resulta predominantemente de el fenómeno de potencial de oxidación/reducción, siendo el potencial del flujo insignificante. A través del análisis estadístico de los datos se estimó ocho años para volver a las características de una zona ausente de residuo, tiempo estimado para la descomposición de la mayor parte de la materia orgánica contenida en los residuos enterrados. doi: https://doi.org/10.1016/S0016-7169(13)71484-3

Uberaba municipality, Western Minas Gerais State, has a great geotouristic potential, regarding itsgeological heritage. The igneous rocks from Serra Geral Formation are found in 12 points, highlightingPonte Alta (40 meters) and Peirópolis III (7 meters) waterfalls. The sedimentary rocks from UberabaFormation were described in 11 points, especially Giovane Cave and Waterfall (12 meters). In MariliaFormation sedimentary rocks, the Caieira outcrop (three-meter cave with stalactites and stalagmites)and Vale Encantado Waterfall (8 meters) can be pointed out, among other 8 spots. After the geodiversityassessment, an environmental diagnosis was conducted throughout the potential geotourism attractions,by using the Visitor Impact Management Method. The results indicate that only Vale Encantado Waterfallpresents a moderate impact, the least when compared to 22 other sites, exhibiting high or worrisomeimpact, and 7 with very high impact. In addition to setting the management strategies, and monitoring theenvironmental impact indicators, this work provides the basis so that activities in the potential Geoparkof Uberaba (MG) can be conducted with environmental responsibility and / or geoconservation.

The disposal of solid waste can create environmental problems, in addition to the potential risk of instability even in planned geotechnical works, such as provisions in stacks or high ends of the landfill, because they represent mere adjustments in civil engineering works. The Leme city, SP, generates about 35 t/day of municipal waste, that are deposited in a landfill located in the Barro Preto neighborhood. This work conducted a geophysical survey, based on geotechnical instability evidence in area, for analysis of the conditioners that cause on the sides leachate resurgence landfill and its relationship to mass movements and ravines installation in cover soil, with consequent waste exposure. The results indicate horizons of low resistivity connected with resurgence points generated by the organic matter decomposition contained in the waste. Such horizons result in leachate concentration in some places, which, in turn, may lead to loss of cohesion of the materials constituting the residues mass. The results are areas with mass flow by rotational movements, which, together with the surface flow of rainwater, evolves into ravines and exposed residues, preferably at the resurgence point. The leachate flow on the surface affects areas beyond the limits at landfill with direct impact on local agriculture and risk to pedestrians using the highway bordered by the landfill beyond the soil and the local aquifer.

Geophysical survey is an important method for investigation of contaminated areas used in the characterization of contrasting physical properties in the presence of pollutants. This work applied the geophysical methods of Electrical Resistivity and Self Potential in waste landfill, located in Caçapava do Sul city, RS. The landfill is located over fractured metamorphic rocks. Eight lines of electrical profiling with 288 measures of self potential were done. In addition, 83 measurements of direction and dip of fractures were taken. The application of spontaneous potential method permitted to detect the direction of groundwater flow. The electrical resistivity measurements allowed the identification of low-intensity anomalies associated with the presence of leachate. There is a relationship between anomalous zones and the directions of fractures.

This paper presents the results of the Electrical Resistivity geophysical method applied to determine the area of leaching migration originated from solids waste decomposition, disposed in ditch type landfill. When the monitoring of wells or other direct techniques of the environmental investigation is not possible, the geological characterization, supported by geophysics techniques is an alternative for the assessment and monitoring leached materials. The absence of values below 100 ?.m in the reference line at 4 m of depth and the occurrence of these values in the residues ditches and its surroundings indicate the presence of leachate. This relation is a result of the high content of total dissolved solids that characterize the studied contaminant that reduces the electric resistivity.

A disposição de resíduos sólidos pode gerar problemas ao ambiente, além do risco potencial de instabilidades geotécnicas mesmo em obras planejadas, como disposições em pilhas elevadas ou pontas de aterro, por representarem meras adaptações em obras de engenharia civil. A cidade de Leme, SP, produz aproximadamente 35 t/dia de resíduos sólidos urbanos, depositados em um aterro localizado no distrito de Barro Preto. Este trabalho é um diagnóstico ambiental de um aterro de resíduos sólidos, a partir da análise hidrogeológica e levantamento geofísico, com indícios de instabilidade geotécnica verificados na área, para análise dos condicionantes que provocam a surgência de chorume nas laterais do aterro e sua relação com movimentos de massa e instalação de ravinas no solo de cobertura, com consequente exposição dos resíduos. Os resultados indicam horizontes de baixa resistividade conectados com pontos de surgência, gerados pela decomposição de matéria orgânica. Tais horizontes resultam da concentração de chorume em alguns locais, que, por sua vez, devem provocar a perda de coesão dos materiais que constituem a pilha. Os resultados são áreas com fluxo de massa por movimentos rotacionais, que, aliado ao fluxo superficial de águas pluviais, evolui para ravinas e exposição de resíduos, preferencialmente nos pontos de surgência. O fluxo de chorume em superfície atinge áreas além dos limites do aterro, com impacto direto na agricultura local e risco aos transeuntes que utilizam a rodovia margeada pelo aterro.

Resumo: Aterro é uma obra de engenharia que objetiva acomodar resíduos no menor es paço possível no solo, com danos mínimos ao ambiente e à saúde pública. Uma das formas construtivas de um aterro controlado é a escavação de valas com dimensões apropriadas, para disposição de resíduos sólidos sem compactação ou impermeabilização. Efluentes líquidos gerados por volumes de resíduos semelhantes, dispostos em valas com idades distintas de fechamento, devem resultar em alterações físicas e químicas correlacionáveis ao tempo de residência dos materiais. Com base nesta hipótese, foram realizadas medidas de resistividade elétrica por meio do método geofísico da Eletrorresistividade, sobre valas de resíduos fechadas anualmente entre 12/2001 e 12/2007, localizadas no aterro controlado do município de Cordeirópolis (SP). O chorume é um efluente líquido gerado pela decomposição de matéria orgânica e caracterizado pelo elevado conteúdo de sais dissolvidos, cuja interação com ambiente geológico resulta em alterações em termos de resistividade elétrica passíveis de detecção pelo instrumental geofísico. Os resultados sugerem uma redução da resistividade por percolação de chorume produzido em valas recentes e aumento progressivo da resistividade para valas mais antigas. A análise estatística comparativa com valores de referência para a área sugere idades de término da produção e percolação de chorume para solo e rocha abaixo das valas.

Abstract Ore mining fundamentally depends on the definition of its tenor and volume, something extremely complex in disseminated mineralization, as in the case of certain types of deposits of gold and sulfites. This article proposes the use of electrical tomography for definition of a geophysical signature in terms of electrical resistivity and chargeability, in an outcrop of mineralized quartz lode at the end of an inactive gold mine. One of the targets was to analyze the continuity of the mineralized body, the occurrence of new outcrops and the applicability of the method as an auxiliary tool in mineral extraction. Three parallel lines of electrical tomography in a dipole-dipole arrangement, being orthogonal to the orientation of the gold lode, were installed in an area outside the mine. The results allowed the geophysical characterization of the mineralized zone by high resistivity (above 1000Ω.m) and high chargeability (above 30mV/V). The results of the 2D inversion models were interpolated in 3D visualization models, which allowed definition of the contour surfaces for the physical parameters measured, and the morphological pattern modeling of the mineralization. The data reveal the existence of a new lode in subsurface, localized 30m to the south of the lode outcrop. The versatility of the acquisition and data processing indicate the application potential of electrical tomography as a criterion for sampling and tenor definition in ore extraction activities, since it is objective and low cost.

Abstract Usually, stability conditions of excavation slopes are evaluated by means of kinematic analysis and geomechanical classification systems. However, field surveys are concentrated at the slope toe and information about the upper and internal portions of rock masses are not taken into account. In order to tackle with these issues multisources data were integrated. The studies were carried out in a marble quarry located in one of the largest Brazilian poles of dimension stones. Results have shown that drone images actually help in the structural characterization of rock masses because they allow to classify variable degrees of fracturing and to identify structural domains in the entire slope face. In addition, the number of discontinuities interpreted from drone images was much larger than that determined by scanline survey methods. This demonstrates that the subsampling of classical survey methods may significantly affect slope stability assessment. Results have also shown that the intensive use of explosives as a method for rock dismantling was an important mechanism of fracture generation. The electrical resistivity tomography method coupled with the other survey methods employed in this work, proved an important tool for rock mass characterization and quarry exploitation, since it allowed identifying and assessing subsurface fractured zone.