Eduardo Antonio Gomes Marques

Avaliação de contaminação por mercúrio em Descoberto, MG

Mercury is a chemical element considered unessential to any metabolic process; however, it is easily accumulated in most organisms. It is naturally found in both organic and inorganic forms in solid, liquid and vapor states. Its biogeochemical cycle involves processes occurring in the soil, water and the atmosphere. In 2002, elementary mercury was found in the city of Descoberto, Minas Gerais, Brazil, where 70 families live, and its origin may be related to gold exploration that happened in this region in the 19th century. In this work, three areas were chosen to identify a possible mercury contamination of water, soil, sediment and fish samples and to establish local reference values and counter-evidence of the data previously obtained. Based on the results, high mercury concentrations in soil (0.26 to 0.55 mg.kg-1), sediments (0.13 to 0.61 mg.kg-1) and water (< 0.2 to 2,10 µg.L-1) were verified.

Multicriteria analysis applied to landslide susceptibility mapping

Current human settlements are characterized by disorganized urbanization and high population densities, which can impact the landscape and the environment. Soil transport leads to erosion and aggradation of water bodies and increases landslide susceptibility in regions with more uneven topographies. Landslides are the most common environmental accidents and have caused the most deaths; one example is the incident that occurred in the mountainous region of the state of Rio de Janeiro (Brazil) in January 2011. Mapping the predisposition or susceptibility of components of the physical environment to landslides provides an integrated view of the characteristics and physical processes that act within a region. Therefore, the objective of this study is to evaluate the urban expansion proposal of Baptista (Avaliação da suscetibilidade aos movimentos de massa, erosão e escoamento superficial em Nova Friburgo, RJ, 2009) and compare it with the areas affected by the mega-disaster of 2011 using hierarchical decision analysis and a GIS toolkit. The results show that landslides did not affect the areas selected for urban expansion, i.e., the method was useful for identifying the areas that were most susceptible to landslides prior to the disaster.

Digital land-use cartography: the example of Viçosa, Brazil

Abstract This work was carried out in Vicosa, MG, Brazil to present a characterization of this towns real geological urban risk. Input data was obtained to develop a digital database that could be useful for future urban planning and provide a more accurate characterization of geological risks. A simple software for storage and graphic visualization of the collected data was also developed. Field work comprised the characterization of 68 selected points in selected places, allow the recovery of several areas in Vicosa and to detect its most common geological risk situations. These points were characterized to standardize their description, and data quality, creating reliable database, and to incorporate the specificity of the area where Vicosa is located. A Geographical Information System (GIS) was then used for information storage and spatial analysis, either graphical or descriptive. Topographic and hydrographic data, street system and location of the points were converted into digital format. This digital topographic information was then used to obtain a digital model of the terrain and slope charts. The database obtained describes the geological processes, field evidences, main geological conditioning, soil or rock type, layer thickness, type of occupation, potential damages, geological risk, other important features observed, photos and sketches.

Spatial variability of the physical attributes of soil under pasture

O objetivo desse trabalho foi avaliar a variabilidade espacial de atributos fisicos do solo para areas de Latossolo, Argissolo e Cambissolo ocupadas por pastagens. O conhecimento dessa variabilidade e importante, pois ela influencia a qualidade das pastagens e a recarga de agua subterrânea. Foram coletadas 154 amostras georreferenciadas para cada area de estudo. Para analisar os dados foi usada a estatistica descritiva e a geoestatistica. A dependencia espacial ocorreu para a maioria dos atributos fisicos: condutividade hidraulica em solo saturado e densidade do solo para as tres classes de solos; microporosidade, macroporosidade e porosidade total para as areas de Cambissolo e Latossolo. Os resultados da estatistica descritiva e o fato do padrao da dependencia espacial nao ter se mantido constante indicam que as classes de solo, juntamente com a declividade e o uso da terra influenciaram a variabilidade espacial dos atributos fisicos do solo analisadas e que a media nao e suficiente para representar a distribuicao espacial das variaveis analisadas. A malha de amostragem usada e adequada, pois permitiu captar a dependencia espacial da maioria das variaveis analisadas.

Rock Mass Classification Applied to Volta Grande Underground Mine Site in Brazil

Rock mass classification is a key procedure for evaluation of rock mass behavior under underground excavation. This paper presents part of the results of a rock mass classification applied to the Volta Grande mine, located at Nazareno city, Minas Gerais State, Brazil, in order to evaluate its implantation feasibility and to define the most favorable design. Currently, Volta Grande operates an open pit mine in an intrusive pegmatitic body with amphibolite and graphite-rich schist as surrounding rock. All data to be used on RMR and Q classification schemes were collected on twenty-nine boreholes, selected according to their position and to provide an adequate knowledge of both geology and geomechanical characteristics of the project area. However, this paper presents only the results for three boreholes in only one geological cross-section (NS06), considered representative of Volta Grande mine rock mass, as the volume of data from all boreholes is too large. Samples were collected on these boreholes for all rock types and weathering grades, in quantities sufficient to allow physical and mechanical tests and to represent variations in depth and in area. Results show that despite Q system is more sensible to rock type and weathering grade changes when compared to the RMR system, dividing the rock mass in more different compartments, this division did not show good agreement to field and borehole samples observations, as the rock mass do not show such fragmentation and, so, these compartments do not control the overall behavior of the rock mass. As a general result, the rock mass classification results point out that underground mining is feasible for the studied area.

Identificação de áreas adequadas para a construção de aterros sanitários e usinas de triagem e compostagem na mesorregião da Zona da Mata, Minas Gerais

A disposicao final inadequada dos residuos solidos urbanos (RSU) em lixoes e realizada em 60% dos municipios brasileiros. Ademais, a escolha das areas para a implantacao desses depositos, comumente, nao leva em consideracao as restricoes legais vigentes. Na Zona da Mata mineira, esse fator e agravado pela existencia de extensas areas de preservacao permanente, que implica em reduzido numero de areas disponiveis para tratamento de residuos. O consorcio intermunicipal, como forma de gestao compartilhada, e considerado uma alternativa prevista em lei para regularizar essa situacao. Para nortear o consorciamento, a Fundacao Estadual do Meio Ambiente (FEAM), por meio do Sistema Estadual de Meio Ambiente e Recursos Hidricos (SISEMA), subdividiu o estado em arranjos territoriais otimos (ATOs). Considerando que as formas adequadas de tratamento de RSU mais adotadas no Brasil sao aterros sanitarios e usinas de triagem e compostagem, este trabalho teve como objetivo identificar areas para a implantacao de aterros sanitarios e usinas de triagem e compostagem na Zona da Mata. Ademais, foi realizado o calculo estimado das areas requeridas para atender aos ATOs atraves de consorcios e o numero de areas existentes que atendessem a extensao minima calculada. Para tanto, foi construida uma extensa base de dados para a identificacao das areas restritas legalmente e realizacao de analises espaciais multicriterio utilizando os softwares de geoprocessamento ArcGIS e IDRISI Taiga. As analises resultaram em numero reduzido de areas passiveis de serem utilizadas para o tratamento de residuos dificultando, assim, a utilizacao dos ATOs como referencia para a gestao de RSU.

Caracterização Hidrogeológica de um Sistema de Filtração em Margem de Lago

Riverbank filtration (RBF) is a technique that has been successfully used in many countries, as a pre-treatment for water supply purposes, especially in regions under high demand. The technique comprises the construction of well(s) located at river/lake margins, and the water collected in the well is a mixture of surface water and groundwater. Hydrogeological approach is important in this context because it provides a better knowledge of the interaction between surface water and groundwater, and an evaluation of how physical environmental characteristics influence on water quality and quantity. Vicosa city, Minas Gerais State, Brazil, has an increasing demand of water resources and a shortage of drinking water sources. In this context, the proposed pilot bank-filtration design under study was constructed in 2013 in the margins of a dam at Universidade Federal de Vicosa campus, with the main purpose of generating hydrogeological data for the complete characterization of the designed system. This paper presents the results of a detailed characterization based mainly on pumping and recovering hydrogeological aquifer tests and potentiometric monitoring. Results show that the hydrogeological characteristics of the study area favor the efficiency of the RBF system and can supply considerable amounts of water at low cost, especially during dry seasons.

Relação qualidade da água e fragilidade ambiental da Bacia do Rio Almada, Bahia

Esta pesquisa teve como objetivo a criacao do Indice de Qualidade da Agua em Resposta a Fragilidade Ambiental (IQAFA) e a determinacao dos niveis de fragilidade ambiental da Bacia do Rio Almada, Bahia. O mapa de fragilidade ambiental foi obtido a partir da integracao das caracteristicas: precipitacao pluviometrica, substrato rochoso, declividade, solo e seu uso e ocupacao, por meio de algebra de mapas em ambiente de Sistema de Informacao Geografica na escala de 1:100.000. Foi classificado em cinco graus de fragilidade: Muito baixo, Baixo, Medio, Alto e Muito alto. As maiores fragilidades incluem as areas urbanas, os sedimentos arenosos expostos na zona de praia, manguezais e bolsoes degradados da planicie costeira localizados na porcao Leste e as areas de pastagem e solo exposto nas porcoes Oeste da bacia. Nas classes que apresentaram fragilidade baixa estao incluidas as rochas do embasamento cristalino, recobertas pela floresta de mata atlântica e da cabruca. Os parâmetros utilizados (temperatura, condutividade eletrica, pH, solidos totais e turbidez) para o calculo do IQAFA mostraram-se adequados, uma vez que as alteracoes da qualidade das aguas refletiram a presenca de areas com menor ou maior valor de fragilidade ambiental, tornando-se uma ferramenta importante na compreensao da situacao da qualidade da agua frente a essa fragilidade. Ressalta-se que os resultados obtidos para o IQAFA foram validados por meio de correlacoes estatisticas com a fragilidade baixa e alta.

Effects of weathering on characteristics of rocks in a subtropical climate: weathering morphology, in situ, laboratory and mineralogical characterization

This paper presents the results of a comprehensive study on the morphology of weathering profiles developed on metamorphic and sedimentary rocks under subtropical climate, focusing on its influence on geotechnical parameters of weathering materials. Several cut and natural slopes were selected for more detailed descriptions of their physical, mineralogic, geologic, structural and geotechnical parameters, focusing on weathered rock materials, including characteristics of matrix (e.g., fabric, mineralogy and degree of weathering) and rock mass (e.g., rock:soil ratio, discontinuity characteristics, JRC—joint roughness coefficient, and JCS—joint compressive strength). Samples from the upper portions of the profiles and down into the transition zone between rock and soil were collected to determine their physical and geotechnical parameters, to prepare and describe thin sections and to perform X-ray diffraction (XRD) analyses and point load tests. Results indicate that weathering profiles are thin, contacts between material layers are sharp and there is a strong structural control on weathering, mainly by stress-relief joints. Soil-like material is present only in portions of the rock mass near the ground surface or along structural discontinuities (foliation and fractures). Thin-section description can provide important indexes and information that can be related to chemical and physical weathering of those rocks and so be used to differentiate materials present along profiles. Also, physical parameters have proved to be useful for the distinction of different weathered materials. Finally, XRD and thin-section description have allowed the identification of important mineralogical changes due to weathering.

Weathering of metapelites from the Quadrilátero Ferrífero mineral province, southeastern Brazil

Abstract Low-grade metamorphic rocks are known for their low mechanical strength and high weatherability. In the Quadrilátero Ferrífero, an important mineral province located in southeastern Brazil, this set of features results in frequent issues with mining and road slope instability, mainly associated with phyllites. Despite the significant iron ore production that occurs in this province, little is known about the geotechnical properties of the materials constituting the weathering front. Here, we report work aimed at investigating the changes in the basic properties of phyllites at four weathering grades. The methodology used included the field classification and mapping of four weathering grades in order to assess their spatial distribution on a road slope, as well as sampling for geological characterization by petrography and X-ray diffraction (XRD). In addition, the authors performed a physical characterization of all weathering grades, including index properties, mercury porosimetry, and strength data obtained with a Schmidt hammer both in the field and in the laboratory as well as using the point load test (PLT). Results showed the relevance of structural features such as discontinuities and metamorphic foliation observed in the weathering morphology in situ, with different weathering intensities occurring along the slope. Changes in the porosity and pore size distribution in the weathering front were nonlinear, as were resistance variations. The difficulty involved in performing the macroscopic identification of weathering grades due to the very fine texture of the rock as well as microstructural heterogeneities are likely causes of the observed variability in phyllite properties. This fundamental knowledge may aid the prediction of short-term and long-term scenarios for slope stability based on rock weatherability.