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This work shows the construction project of the Geophysical Test Site (Sítio Controlado de Geofísica Rasa, SCGR-I) of the Institute of Astronomy, Geophysics and Atmospheric Sciences (IAG), of the University of São Paulo (USP) and its impact on teaching and research in Geophysics. The IAG/USP test site (SCGR-I) has 1500 m2, being characterized by 7 studies lines with 30 m length in the NS direction. Targets, such as metallic pipes and tanks, plastic pipes and tanks, concrete tubes, ceramic pots, among others, with different geometries and physical properties were buried at depths from 0.5 to 2 m in relation to the surface. A metallic guide pipe of 3.8 cm diameter was buried at the 15 m position along the EW direction, crossing all 7 lines. Targets simulate objects found in archaeological studies, geotechnical and urban planning studies and environmental studies. In this work, comparative analyzes between real and synthetic GPR results on metallic and plastic tanks are shown, as well as EM38 results on metallic tanks. The SCGR-I proved to be an important tool for teaching and research related to the applications of geophysical methods for near surface investigations and could be a motivation to build more test sites.

The moisture content of the municipal solid waste (MSW) is a physical characteristic that plays a fundamental role in the stability and settlement of landfills. However, this physical index is difficult to monitor within the mass of landfilled MSW because it undergoes great variation due, mainly, to the heterogeneity and biodegradation of the waste. Brazilian MSW generally has a large amount of organic matter, that when biodegraded, generates a considerable volume of gases and fluids, aggravated by climatic conditions, such as high rainfall and temperatures. Hence, the importance of obtaining and evaluating the distribution of moisture content in the MSW mass over time. Currently, the electrical resistivity properties have been presented as an interesting approach to obtain the moisture content in landfills indirectly. This study aimed to apply geoelectrical methods as a tool to obtain and evaluate the moisture content distribution in an experimental cell of a sanitary landfill using Archie's law, which correlates the volumetric moisture content and electrical resistivity. Moisture content values were obtained in laboratory tests with MSW samples collected in two vertical holes and electrical resistivity measurements by means of vertical electrical sounding. The moisture content and the resistivity values of the samples were used to calculate the parameters a and m of Archie's law. This allowed to convert the resistivity tomography to moisture content tomography. The good correlation achieved between the moisture content calculated by Archie's law and that obtained from samples indicates that the use of electrical resistivity methods is useful to assess and monitor quantitatively the moisture content in landfills using Archie's law.

The comprehension of groundwater flow depends on the knowledge of hydrogeological features and water cycle, especially the recharge process. Geophysical techniques can provide useful hydrogeological information (e.g., water table and base aquifer) toward improving the water balance in groundwater models. This study, conducted in an outcrop area of the Guarani Aquifer System (GAS) in Sao Paulo state (Brazil), applied Ground-penetrating radar (GPR) and geoelectrical techniques for structuring a conceptual groundwater model. A GPR with 200 MHz antenna, 4 Vertical Electrical Soundings (VES) with Schlumberger array, and 12 Electrical Resistivity Tomographies (ERT) with dipole–dipole array were used. Geophysical techniques, soil samples, and water level from monitoring wells helped the definition of two different hydraulic conductivity regions and a flux boundary condition for the groundwater flow model.

Geophysical methods have been extensively used in fractured rocks water prospection, with varying success levels. The objective of this article is to improve the understanding of the electrical response in 2D surveys for fractures zones mapping in crystalline rocks. 2D resistivity models simulated several types of crystalline rock fractures influenced by fracture dipping, soil coverage, and topography effects. Numerical simulations show that conceptual models are useful in evaluating the expected electrical response and planning the field survey. Field surveys were conducted on areas where fractures and faults are known from geological mapping and groundwater wells: crystalline gneissic bedrock (Louveira), diabase sill from Serra Geral Formation (Tiete), and basalt from Serra Geral formation with sediments coverage (Bebedouro). Fractures and faults were identified by resistivity values lower than 250 Ω m, confirmed by well drilling.

The sanitary landfills in Brazil are, generally, characterized by their high organic material content (around 60%), presence of different types of mixed wastes, and low compaction energy, which differentiates them from the landfills of developed and high-income countries. To prevent environmental and slope stability risks, it is crucial to understand the behavior of such landfills and the changes in their physical properties over time. The compression wave velocity (Vp) and shear wave velocity (Vs) are important parameters to subsidize the mechanical characterization of sanitary landfills, using which can be derived the dynamic elastic properties of municipal solid waste (MSW) for stability analysis. Using the geophysical methods of seismic refraction, active and passive multichannel analysis of surface waves, and crosshole test, it was obtained the values of Vp and Vs by employing an experimental cell and a lysimeter filled with MSW in the City of Campinas, São Paulo State, Brazil. The results obtained from the crosshole test showed that Vp ranged from 217 to 252 m/s and Vs ranged from 86 to 89 m/s. These low values can be attributed to the high content of organic material, low compaction energy, and climatic conditions such as high pluviometry index and high temperatures that together lead to changes in the pore fluid saturation, effective stress, and pore pressure. These values are indicative of the lower limit of the corresponding velocities reported in most literature; however, they are in accordance with the values reported for landfills located in countries with similar socioeconomic and climatic conditions.

Even though attenuation processes in the subsurface are known to reduce the impacts of contaminant plumes, their importance is significantly dependent on geological and climatic characteristics, as well as on the leachate quality. The knowledge of attenuation processes linked to different geological formations is therefore fundamental in predicting the impacts of waste disposal areas. Geophysical methods are useful tools for assessing and delineating contaminant plumes, as well as their changes with time, which enables their lower-cost monitoring and association with geological and environmental properties. This paper shows the results of geophysical surveys conducted in the years of 1996, 2005 and 2018 in a waste disposal area located at a Guarani Aquifer recharge zone in Brazil. The objective of this study was to show the evolution of the contamination plume, as well as discuss some possible transport and attenuation processes that the contaminants may undergo in similar areas. Five geophysical sections surveyed within a time span of 20 years were compared, and the information was integrated with physicochemical data from monitoring wells. The results show a horizontal plume spreading, reaching about 200 m from the deposit and about 60 m of depth, 20 years after the ending of disposal activities. The measured resistivities in 2018 are similar to the ones found in 1996 and 2005 in the same surveyed areas, showing that a significant temporal attenuation did not occur. Moreover, samples collected close to anomaly zones and within a distance of 200 m from the deposit presented concentrations of some heavy metals above the screening values according to the Brazilian legislation, showing a metals mobility higher than previously expected, which can be possibly explained by the aquifer's acidic conditions. The estimated plume velocity was about 7 m/yr, a plume deepening was observed until about 50 m and changes in water flow direction and/or diffusion processes made the plume spread to areas previously regarded as upgradient. Therefore, the present paper shows that the rehabilitation of sites neighboring waste disposal sites (less than 200 m from it) did not seem to be feasible through natural attenuation in sandy soils and that the plume spreading is significant in this geological formation. Thus, abandoned disposal areas, constantly considered to be closed after the ending of disposal activities in developing countries, generate plumes which move silently and may reach areas of concern in the future.

This paper shows the construction of the second Geophysical Test Site of the Institute of Astronomy, Geophysics, and Atmospheric Science at University of Sao Paulo, installed at USP campus in Sao Paulo city, Brazil. It shows too the preliminary GPR results on buried pvc/metal pipes and ceramic tubes in the subsoil in which they simulate the gas/water pipelines and pluvial water canalization gallery underground of the great cities of the world. The targets installed in subsoil are constituted by metal and plastic tanks, concrete tubes, ceramic vases, plastic conduits etc., and its top depths varying from 0.5 to 2.0 m. The targets simulate geotechnical, environmental, and archaeological studies where its location is the goal. GPR profiles of 900 MHz and 270 MHz were acquired along of line 3 constituted by pvc/metal pipes and ceramic tubes. Preliminary GPR results show typical hyperbolic reflections pattern characteristic for each target. The IAG/USP Test Site-II was constructed with teaching and research purposes in Applied Geophysics. These results can help in location of buried utilities in subsoil of the great cities minimizing the risks of dangerous accidents.

In Brazil, the large quantities of solid waste produced are out of step with public policies, technological developments, and government budgets for the division. In small municipalities, the common lack of technological knowledge and financial conditions for suitable waste disposal has resulted in a large number of illegal dumps. Therefore, small sanitary landfill facilities are working with simplified operations focusing on cost reduction and meeting the economic and technological standards of the city without endangering the environment or public health. Currently, this activity is regulated at a federal level although there is some uncertainty regarding the risk of soil and aquifer contamination as theses facilities do not employ liners. Thus, this work evaluates a small landfill to identify changes in soil and groundwater using geotechnical parameters, monitoring wells, and geophysical tests performed by electrical profiling. It is verified that based on current conditions, no contaminants have migrated via underground water aquifers, and overall no significant changes have occurred in the soil. It is concluded that, despite its simplicity, the method investigated is a viable alternative for the final disposal of municipal solid waste from small cities, especially in developing countries.

The electrical resistivity method (ER) with the electrical profiling technique (EP) were applied to landfill Delta A, located next to the highway dos Bandeirantes in Campinas (SP). Within the landfill there is a region of approximately 5,200 m2...Keywords: electrical resistivity, landfill, experimental cell. RESUMO. O método de eletrorresistividade (ER) utilizando a técnica de caminhamento elétrico (CE) foi aplicado no aterro Delta A, localizado ao lado da rodovia dos Bandeirantes nomunicípio de Campinas (SP). Dentro do aterro há uma região de...Palavras-chave: resistividade elétrica, aterro sanitário, célula experimental.

Waste disposal in dumpsites, or even in sanitary landfills, can generate contamination plumes in the subsurface. The detection and delineation of the shape of the contaminant plume can be assessed using monitoring systems or different site investigation methods, including geophysical methods. This paper presents the results of a geophysical survey conducted to map the soil contamination produced by a waste disposal site located at a geological vulnerable area, characterized by a trench that resulted from the collapse of sandy soils due to erosion. This paper aims to show the improvement in mapping a waste deposit and the contamination produced in sandy soils by integrating resistivity and induced polarization methods. The results of three survey lines performed to map the site are presented—two across the deposit and one external to it; and resistivity, chargeability and normalized chargeability sections were generated. The geoelectrical sections interpretation was integrated with information from monitoring wells to help the characterization of the waste area and to evaluate soil and groundwater contamination. The results show that resistivity identifies the wastes, the contaminated soil and the contamination plume, but it does not distinguish these zones. Normalized chargeability, on the other hand, is more effective in distinguishing the areas with wastes from the areas impacted by the contamination plume.

This paper presents the results of the application of geophysical surveys to update the morphological model of a limestone and gneiss deposit of a mining company near the city of Taubaté, Brazil. The research began with a test to verify the accuracy of the geophysical survey method and it was conducted in the same area as a previous drilling campaign with the aim of confirming the possibility of using Vertical Electrical Sounding (VES) and induced polarization (IP) methods, in order to obtain the required information for the deposit morphological modeling. As a result, the application of geophysical methods in the study area reduced up to 75% the data collection time and presented similar accuracy levels as conventional exploration methods used for the same research objectives.

Este trabalho apresenta e discute resultados de aplicações de métodos geofísicos elétricos como ferramenta de auxílio no planejamento e lavra em pedreira de gnaisse para fabricação de brita. Neste trabalho a espessura do capeamento foi investigada, além de identificar zonas da transição solo-rocha e mapear o contato entre diferentes litologias para avaliar a profundidade do corpo rochoso na base da cava da pedreira. Para isso foram adquiridos treze SEVs e quatro CE em duas frentes de trabalho, a primeira em outubro de 2011 onde foram adquiridos uma parte dos dados de SEVs e todos os caminhamentos elétricos e a segunda frente em fevereiro de 2012 onde foi adquirido o restante dos dados de SEVs. A metodologia utilizada foi a eletrorresistividade e a polarização induzida, diante do histórico de sucesso em aplicações semelhantes. As SEVs possibilitaram delimitar o contato com a rocha sã em subsuperfície, bem como mostrar as relações entre o xisto e o gnaisse, além de identificar uma possível intercalação xisto-gnaisse na porção oeste da pedreira. Ademais as SEVs sugerem que o contato no mapa geológico deve ser reavaliado, especialmente a SEV04, que de acordo com o mapa estaria em área de gnaisse, mas a sondagem apresentou resistividades muito baixas para esse tipo de litologia. Através dos caminhamentos foi possível identificar o contato entre a rocha da jazida, o gnaisse e o xisto em todas as seções. Especificamente as linhas CE02 e CE04 mostraram os contatos entre as litologias um pouco discordantes do esperado pelo mapa geológico da área da pedreira. Dessa forma, foi possível definir melhor os contatos geológicos em algumas áreas e corroborar a interpretação estrutural em outras áreas, de forma a auxiliar o planejamento de futuras frentes de lavra. This work presents end discusses the results of applying electrical geophysical methods as a tool to aid in work front planning in gneiss mine for crushed stones application. This mine produces aggregates for civil construction industry and has a gneiss source rock. In this work the topsoil thickness has been investigated, as well the transitional areas between soil and rock. Moreover the contacts between different lithology have mapped in order to assess the source rock´s depth at the mining boundaries. Thereunto thirteen VES and four EP were acquired in two different stages, the first one was performed on October 2011, where a portion of VES and all the EP were acquired. The second stage was on February 2012 to record the rest of VES data. The methodology used was electroresistivity and induced polarization, due the success history of these methodologies in similar applications. VES allowed to define the contact with the bedrock in subsurface and show the relationships between the schist and the gneiss. Moreover those results identified a possible intercalation of schist-gneiss on west portion at the mine. Furthermore the VES suggest a reevaluation in the geological map, mainly where SEV04 took place, because for the map, the contact would be on gneiss environment, but the sounding showed slower resistivity values for this kind of rock. Through the EP was possible to identify the contact between the gneiss and the schist in all the sections. Specifically the lines CE02 and CE04 showed the contact for both lithologies slightly discordant that were expect for the geological map. Thereby was possible to better define the geological contacts in some places and corroborate the interpretation in others, in order to assess the future work front planning for this mine.

An increasing volume of publications has addressed the role of tectonics in inland areas of northern Brazil during the Neogene and Quaternary, despite its location in a passive margin. Hence, northern South America plate in this time interval might have not been as passive as usually regarded. This proposal needs further support, particularly including field data. In this work, we applied an integrated approach to reveal tectonic structures in Miocene and late Quaternary strata in a coastal area of the Amazonas lowland. The investigation, undertaken in Marajo Island, mouth of the Amazonas River, consisted of shallow sub-surface geophysical data including vertical electric sounding and ground penetrating radar. These methods were combined with morphostructural analysis and sedimentological/stratigraphic data from shallow cores and a few outcrops. The results revealed two stratigraphic units, a lower one with Miocene age, and an upper one of Late Pleistocene-Holocene age. An abundance of faults and folds were recorded in the Miocene deposits and, to a minor extent, in overlying Late Pleistocene-Holocene strata. In addition to characterize these structures, we discuss their origin, considering three potential mechanisms: Andean tectonics, gravity tectonics related to sediment loading in the Amazon Fan, and rifting at the continental margin. Amongst these hypotheses, the most likely is that the faults and folds recorded in Marajo Island reflect tectonics associated with the history of continental rifting that gave rise to the South Atlantic Ocean. This study supports sediment deposition influenced by transpression and transtension associated with strike-slip divergence along the northern Equatorial Brazilian margin in the Miocene and Late Pleistocene-Holocene. This work records tectonic evidence only for the uppermost few ten of meters of this sedimentary succession. However, available geological data indicate a thickness of up to 6 km, which is remarkably thick for an area regarded as a passive margin.

We performed laboratory experiments to investigate the sensitivity of the Spectral Induced Polarization (SIP) method to toluene contamination in clayey soils. We used mixtures of quartzitic sand and montmorillonite as soil samples, artificially contaminated with varying amounts of toluene. Care was taken to quantify the experimental uncertainty resulting from packing since such effects must be quantified if variations in SIP signatures between samples are to be reliably interpreted in terms of the effects of hydrocarbon concentration. The SIP response of all samples following addition of toluene was monitored for a period of 40 days following sample preparation. Stepwise regression was used to examine the statistical significance of correlations between (i) clay content and (ii) toluene concentration and SIP parameters. Both single-frequency real and imaginary conductivity measurements, along with the integral chargeability, normalized chargeability, DC conductivity and time constant obtained from a Debye decomposition fitting, were examined in this regression analysis. The SIP measurements show a clear time dependence following sample preparation, indicating that samples containing toluene may take significant time to reach an equilibrium electrical response. SIP measurements are significantly related to toluene content shortly after sample preparation, when the expected dependence of SIP on clay concentration is apparently suppressed. However, for the state of electrical equilibrium after 40 days (interpreted to indicate surface chemistry at equilibrium) there is no significant relation between SIP measurements and toluene content; instead SIP measurements are then significantly correlated with clay concentration. The total chargeability, normalized chargeability and relaxation time obtained from the Debye decomposition show no correlation with toluene content, indicating that this procedure, which likely integrates over multiple mechanisms, may not be suitable for understanding relationships between SIP and hydrocarbon contamination. We find only small low-frequency polarization signals observed in relation to toluene concentration (2 mrad at 0.01 Hz), which initially decreases the interfacial polarization. Unlike earlier works, our results do not support the use of the SIP method as a tool for monitoring toluene contamination in clay soils.

Electrical imaging provides important subsurface information for the construction of hypervelocity impact models. We here provide an overview and evaluation of the current electrical imaging methods used in impact cratering studies. Although apparent resistivity models are commonly used in the geoelectrical imaging of impact structures, the reliability of these models has not hitherto been determined. In order to assess these imaging approaches in impact cratering, we investigate for the first time the discrepancies between the apparent resistivity and true resistivity models of an impact structure. To this end, we present (1) a new true resistivity model of the Araguainha impact structure in central Brazil by applying L2-norm inversion to previously published data, (2) apparent resistivity model of the impact structure, and (3) models obtained from different stages of the iterative tomographic inversions. Our results show that changes in vertical resistivity gradient are significantly better defined in the true resistivity models than in the apparent resistivity model. On the basis of these results, we outline a new approach that true resistivity models can be effectively assessed by applying both L1- and L2-norm inversion schemes together with the monitoring of intermediate models from iterative inversion. The results of our study highlight the importance of tomographic inversion of resistivity data in impact cratering studies, and they provide a data modeling framework and foundation for cost-effective subsurface imaging of impact structures in the future.

A contaminated site from a downstream municipal solid waste disposal site in Brazil was investigated by using a 3D resistivity and induced polarization (IP) imaging technique. This investigation purpose was to detect and delineate contamination plume produced by wastes. The area was selected based on previous geophysical investigations, and chemical analyses carried out in the site, indicating the presence of a contamination plume in the area. Resistivity model has successfully imaged waste presence (ρ 31 mV/V), water table depth, and groundwater flow direction. A higher chargeability zone (m > 31 mV/V) outside wastes placement and following conductive anomaly was interpreted as a contamination plume. Normalized chargeability (MN = m/ρ) confirmed polarizable zone, which could be an effect of a salinity increase (contamination plume), and the clay presence in the environment.

Three soil profiles in Ilha Solteira, Brazil were investigated to establish their potential for collapsible behavior. The soil profiles were identified using terrain evaluation techniques and simple laboratory tests. Geophysical surveys were undertaken as they are quick and relatively cheap. The results were correlated with trial pit descriptions and cone and standard penetration tests. The study has shown that electrical resistivity is a useful tool for the preliminary identification of horizons of collapsible soils, before more expensive intrusive and laboratory work is undertaken.

We present five profiles from electrical resistivity tomography (ERT), with surface constraints and gravity data, in the central uplift of the Araguainha impact structure in central Brazil. The central uplift, the overlying polymict breccias, and decameter-scale impact melt rocks are characterized by contrasting ranges of electrical resistivity. Our resistivity model provides empirical evidence that supports the existing model in which impact melt and breccias resurged toward the crater center in the final stages of the cratering process. On the basis of our results from the first use of ERT in impact cratering studies, we conclude that the deposition and flow of impact melt and breccias over the central uplift were influenced by the geometry of the lithologic boundaries in the central uplift.

Geophysics has been shown to be effective in identifying areas contaminated by waste disposal, contributing to the greater efficiency of soundings programs and the installation of monitoring wells. In the study area, four trenches were constructed with a total volume of about 25,000 m3. They were almost totally filled with re-refined lubricating oil waste for approximately 25 years. No protection liners were used in the bottoms and laterals of the disposal trenches. The purpose of this work is to evaluate the potential of the resistivity and ground penetrating radar (GPR) methods in characterizing the contamination of this lubricant oil waste disposal area in Ribeirao Preto, SP, situated on the geological domain of the basalt spills of the Serra Geral Formation and the sandstones of the Botucatu Formation. Geophysical results were shown in 2D profiles. The geophysical methods used enabled the identification of geophysical anomalies, which characterized the contamination produced by the trenches filled with lubricant oil waste. Conductive anomalies (smaller than 185 Ωm) immediately below the trenches suggest the action of bacteria in the hydrocarbons, as has been observed in several sites contaminated by hydrocarbons in previously reported cases in the literature. It was also possible to define the geometry of the trenches, as evidenced by the GPR method. Direct sampling (chemical analysis of the soil and the water in the monitoring well) confirmed the contamination. In the soil analysis, low concentrations of several polycyclic aromatic hydrocarbons (PAHs) were found, mainly naphthalene and phenanthrene. In the water samples, an analysis verified contamination of the groundwater by lead (Pb). The geophysical methods used in the investigation provided an excellent tool for environmental characterization in this study of a lubricant oil waste disposal area, and could be applied in the study of similar areas.

Different geoenvironmental site investigation techniques to assess contamination from a municipal solid waste disposal site in Brazil are presented here. Superficial geophysical investigation (geoelectrical survey), resistivity piezocone penetration tests (RCPTU), soil samples collected with direct-push samplers and water samples collected from monitoring wells were applied in this study. The application of the geoelectrical method was indispensable to identify the presence and flow direction of contamination plumes (leachate) as well as to indicate the most suitable locations for RCPTU tests and soil and water sampling. Chemical analyses of groundwater samples contributed to a better understanding of the flow of the contaminated plume. The piezocone presented some limitations for tropical soils, since the groundwater level is sometimes deeper than the layer which is impenetrable to the cone, and the soil genesis and unsaturated conditions affect soil behavior. The combined interpretation of geoelectrical measurements and soil and water samplings underpinned the interpretation of RCPTU tests. The interpretation of all the test results indicates that the contamination plume has already overreached the landfill’s west-northwest borders. Geoenvironmental laboratory test results suggest that contamination from the solid waste disposal site has been developing gradually, indicating the need for continuous monitoring of the groundwater.

This paper presents the results of integrated geophysical investigations to characterize aquifers in fractured rocks in the Granite complex of Itu, SE Brasil, to help locate sites for tubular wells for groundwater exploration. Ground penetrating radar (GPR) profiles, dipole–dipole electric survey, gamma spectrometry, and radon gas emanometry were applied on a same line for a comparative study of these methodologies. The results allowed us to characterize structural discontinuities up to 30 m in depth, such as, dipped, or vertical fractures. The dipped fractures appear as strong GPR reflectors, probably due to the presence of water. Besides, two anomalous regions were identified, one at 50 m and other at 75 m, both showing high attenuation of the GPR signals, and they correspond to the vertical fracture zones. 2D modeling of the dipolar electric survey shows that the two anomalous areas correspond to high electric conductivity zones, and that in the position of 75 m, a vertical fracture zone is clearly identified. In the gamma rays profiles, the values of K and Th concentrations observed in the position of 50 m indicate the presence of vertical fractures filled with clay minerals. On the other hand, in the position of 70 m of the Rn gas emanometry profile, the peak of Rn emanation is five times higher than the regional level, indicating the presence of a vertical fracture zone, clearly filled with fresh water in circulation. The geophysical characterization of the vertical fracture zones with fresh water subsidized the drilling of a well for groundwater exploration in fractured aquifers, which was an important contribution for the local community because the main sources of surface water are contaminated.

Este trabalho sintetiza os resultados de investigações geofísicas de superfície e de poço realizadas no Sítio Controlado de Geofísica Rasa do IAG-USP, visando caracterizar os sedimentos e o topo do embasamento. A área é constituída por sedimentos areno-argilosos da Bacia de São Paulo (Formações São Paulo e Resende) sobrepostos ao embasamento granito-gnáissico com diferentes graus de intemperização. Na área de estudos, também denominada de campo de provas do IAG, foram perfurados três poços para pesquisas geológicas e geofísicas (pioneiros no Brasil), visando verificar a litoestratigrafia, coleta de amostras de calha, calibrar os resultados e realizar as perfilagens geofísicas. Foram utilizados os seguintes métodos: sísmica rasa (reflexão e refração), eletrorresistividade (caminhamento elétrico e sondagem elétrica vertical) e GPR-Ground Penetrating Radar. A integração dos resultados mostrou uma excelente concordância e permitiu elaborar um modelo geológico-geofísico para este ponto da Bacia Sedimentar de São Paulo, bem como testar, em condições controladas de campo, os diversos métodos geofísicos usados rotineiramente em estudos geológicos, geotécnicos e ambientais. This paper presents the results obtained from surface and borehole geophysical investigations carried out at the Shallow Geophysical Test Site of IAG-USP. The main objective was to characterize the sediments and the top of basement. The area is constituted by sandy-clay sediments of São Paulo Basin (São Paulo and Resend Formations) on the granite-gneiss basement with different degrees of weathering. In the area of studies, three boreholes were drilled for geological and geophysical research purposes (pioneer in Brazil). These boreholes were used to verify the stratigraphy, to collect the sample for laboratory measurements, to calibrate the results of surface geophysics and to carry out well logging. The surface methods used were: seismic (reflection and refraction), electric-resistivity (profiling and vertical electric sounding) and GPR-Ground Penetrating Radar. The integration of results show excellent agreement and allow constructing a geological-geophysical model for the site which is at the border of São Paulo sedimentary basin. Moreover, the various geophysics methods, commonly used in geological, geotechnical and environmental researches, have been tested under controlled conditions.

This paper presents the results of the application of the Ground Penetrating Radar (GPR) method, or Georadar, in outlining a zone of contamination due to solid residues at the waste burial site of Rio Claro in the state of Sao Paulo, SE Brazil. A total of eight GPR profiles with 50- and 100-MHz antennae were surveyed. Six profiles were located within the landfill site and the remaining two were outside. The main objective of the GPR survey was to evaluate the side extension of contamination. A Vertical Electric Sounding (VES) survey was performed at four points within the site in order to investigate the vertical extent of the contamination plume and to define the bottom of the landfill. Two additional VESs were done outside the landfill with the purpose of determining the top of the ground water table and the geoelectric stratigraphy of the background. From the interpretation of the GPR profiles, it was possible to locate the top of the contamination plume and to infer that it was migrating laterally beyond the limits of the waste disposal site. This was observed along the profile situated close to the highway SP-127, which was about 20 m from the limit of the site. The signature of the contaminant appears as a discontinuous reflector that is believed to be a shallow ground water table. The discontinuity is marked by a shadow zone, which is characteristic of conductive contaminant residues. The contamination did not move far enough to reach a sugar cane plantation located at approximately 100 m from the border of the site. In the regions free from contamination, the ground water table was mapped at approximately 10 m of depth, and it was characterized by a strong and continuous reflector. The radar signal penetrated deep enough and enabled the identification of a second reflector at approximately 14 m deep, interpreted as the contact between the Rio Claro and the Corumbatai formations. The contact is marked by the presence of gravel characterized by ferruginous concretes, which cause the strong amplitude reflection in the GPR profile. Within the landfill site, the quantitative interpretation of the VES results showed the contamination zone. The base of the landfill varies between 11 and 15 m deep. Outside the landfill site, the VES results showed no indication of contamination and allowed the determination of the top of the ground water table and the contact between the Rio Claro and the Corumbatai formations. The results of GPR and VES showed a good agreement and the integrated interpretations were supported by local geology and information from several boreholes, about 17 m depth, on average. The bottom of the landfill reaches a maximum of 14.5 m depth.

Atualmente existem várias técnicas geofísicas de mapeamento de fraturas como GPR, e caminhamentos eletromagnético e geoelétrico dipolo-dipolo. Esses métodos não fornecem informações acerca do conteúdo da zona de fratura, que pode estar preenchida de argila. Usando métodos nucleares, tais como, espectrometria gama e emanomeria de radônio, torna-se possível identificar a natureza da composição mineral do material da fratura e estudar a circulação de água usando o transporte de radônio pela água de percolação. Neste trabalho, a integração das técnicas nuclear, GPR e geoelétrica nas rochas intrusivas graníticas de Itu mostrou-se muito interessante porque torna possível encontrar e identificar fraturas em rocha granítica preenchidas com argila ou contendo água doce. Nowadays there are many geophysical techniques of rock fractures mapping as GPR, electromagnetic and dipole-dipole geoectrical sounding. These methods don't give information about the content of fracture zone, that can be fullfilled of clay. Using nuclear methods as gamma spectrometry and radon emanometry become possible to identify the nature of mineral composition of fracture material and to study the freshwater circulation using the radon transport by water. In this work the integration of nuclear, GPR and geoelectric techniques in Itu granitic intrusives became very interesting because it was possible to find and identify fracture in granitic rock with clay and freshwater content.

This paper present the preliminaries resistivity surveys taken at a paint industry located in city of Sao Paulo. This area suffered three major contamination and to prevent the spread of the was installed a pump-and-treat system. system and the evolution of the plume comparing previous data with our fresh data. Introduction The water supply is a critical concern in many cities of the world. In the city of Sao Paulo it’s not different; industrialization process has contaminated a large portion of the underground water and as result our major supply it’s from dams. In this paper we are evaluating the pump-and-treat system applied at a contaminated site by hydrocarbon, this site is located in a paint industry; this system is designed to stop the spreading of the contamination plume by pumping the contaminated water through wells. This water is treated and returned to the dam. The main episode of contamination was which was caused by a fire 30 years ago were the incorrect storage, and accidental spills of solvents. The area is close to a major the Guarapiranga dam it’s waters supplies a large part of the population of Sao Paulo city. Figure 1: Location of the site (adapted from Minozzo 2009) al Congress of the Brazilian Geophysical Society IAG/USP the August 26-29, 2013. the 13 th

A hydrocarbon contaminated area and an urban sanitary landfill were investigated using DC-resistivity method. Soil samples were collected from both areas, based on the geophysical survey. Electrical resistivity of each sample was measured in laboratory. Microbial population was also measured in the hydrocarbon contaminated area’s samples, with the objective to correlate the geophysical signature with the occurrence of biodegradation. The results show that biodegradation could be occurring and therefore, contributing to the recorded conductive anomaly. Moisture content could also be impacting the resistivity measurements. An experiment with varying contaminant concentration flow was conducted with the samples collected at the landfill, aiming to study the contaminant effect on the electrical response. The results show that changes in the electrical model could be due to variations in clay content. However, resistivity tends to be insensitive to lithology variations on highly contaminated areas.

Deactivated dump sites and inadequate sanitary landfills can be a serious potential source of contamination. Due to the large number of these sites, contaminants can be generated and migrate into the ground. For this reason, site investigation programs which consider different types of soils and contaminants are needed. In many countries, sanitary landfills have been recently built according to the engineering standards with satisfactory procedures and following the requirements imposed by the local environmental agencies, including monitoring and proper operations. There is a great concern with the operation of sanitary landfills and with the future of deactivated dump sites located in small and medium-size cities, since many of them were inappropriately constructed and operated. Consequently, the main surficial streams and groundwater aquifers, subsoil and air become vulnerable to contamination and pollution. A continuous site investigation program, including in-situ and laboratory tests are necessary to identify the typical soil profile, hydrogeological characteristics and background chemical values. The site surroundings and the subsoil contamination plume can be characterized based on geotechnical, geochemical and mineralogical techniques.

Integrated geophysical methods in the hydrogeological characterization of the Microbasin Andes, Bebedouro, Sao Paulo State. This paper presents the results of a geophysical survey integrated to well data for studying hydrogeological characteristics of Adamantina and Serra Geral Formations in a microbasin in the Andes District, in Bebedouro, state of Sao Paulo, Brazil. This area was the focus of studies due to the intense exploitation of groundwater for agricultural use and its relation with the increase of local seismic activity. In this paper, geophysical methods and well information were used, in an integrated way, to get more detailed knowledge of the aquifers and their physical properties. The results show that the approach was effective in imaging geological formations and their geometry study, as well as in the identification of geological structures. An estimation of hydrodynamic properties of granular aquifers can be done by the parameters of Dar Zarrouk and their correlation with data obtained from pumping tests. In this study, it was possible to establish a linear correlation between the transmissivity and transverse resistance, however with some limitations, because the majority of wells were drilled also in volcanic rocks. This procedure can be used to assist the aquifer management, under the aspects of exploration and preservation.

Uma area contaminada por hidrocarbonetos com conhecida atividade bacteriologica foi investigada pelos metodosEletrorresistividade e Polarizacao Induzida (IP). O objetivo desse estudo e relacionar a distribuicao da resposta IP observada em uma area contaminada por derivados de hidrocarbonetos a presenca de contaminantes e ocorrencia de biodegradacao natural. A area de estudos e uma industria quimica que desenvolve atividades relacionadas a fabricacao de tintas destinadas ao mercado automotivo. O levantamento de resistividade e IP foi realizado em uma area com conhecida contaminacao por BTEX (Benzeno, Tolueno, Etilbenzeno e Xileno) onde foram coletadas amostras de solo para contagem de bacterias. O levantamento geofisico consistiu na aquisicao de uma malha retangular, composta por seis linhas paralelas de caminhamento eletrico, com o arranjo dipolo-dipolo. O espacamento entre as linhas foi de 3 m, mesma distância entre os eletrodos de corrente e potencial. Os dados das seis linhas foram concatenados em um unico conjunto de dados que foi submetido a rotina de inversao 3D. Baixas resistividades e cargabilidades e altas cargabilidades normalizadas foram interpretadas como resultantes do processo de biodegradacao intrinseca e atenuacao natural da contaminacao local.

The present work presents results of geophysical investigations in a lubricant oil waste area located in the municipality of Ribeirao Preto, Sao Paulo State, Brazil. In the study area the waste was disposed of in four trenches with a total volume of about 25.000 m, in an area of sandstone outcroppings of the Botucatu Formation and in basalts of the Serra Geral Formation. The trenches were totally filled with waste over approximately 25 years and no protection liners were used in the bottom or laterals of the trenches. The goal of the study was the acquisition and modeling of 3D data with the electroresistivity method for the environmental characterization of the study area. The acquisition of 3D data, from a series of 2D electrical surveys, was effective in mapping variations of resistivity in three dimensions, showing in the subsurface the behavior of contaminants. The conductive anomalies in the saturated zone and unsaturated zone were related to contamination generated by the biodegradation process. A direct analysis of the soil and groundwater samples confirmed the contamination. In the soil analysis, low concentrations of several polycyclic aromatic hydrocarbons were found, mainly naphthalene and phenanthrene. In the water samples, there was confirmed contamination of the groundwater by lead (Pb). The biodegradation process was confirmed by the presence of microorganisms (bacteria), as evidenced in a biological analysis of soil samples collected at a specific point, where geophysical signatures suggested contamination.

Este trabalho expoe resultados do emprego do metodo geoeletrico para sondagens em mineracao de calcario, como teste dessa metodologia no contexto do planejamento de lavra.

The use of VES in E Marajo Island had discriminated the presence of an interval with anomalous high resistivity, attributed to the presence of the concretionary horizon, this was crucial to define the top of the Barreiras Formation. The lateral occurrence of the Barreiras Fm and the Quaternary deposits and the abrupt passage between these units are consistent with the presence of a tectonic fault. This information supports previous studies that have claimed reactivation along tectonic faults as the responsible for renewing sediment deposition during the Quaternary in island.