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Publications

2022

Environmental Impact Assessment of the Subsurface in a Former W-Sn Mine: Integration of Geophysical Methodologies

Authors
Almeida, HD; Gomes Marques, MC; Sant’Ovaia, H; Moura, R; Espinha Marques, J;

Publication
Minerals

Abstract
Associated with the exploitation of metallic minerals in Europe during the 20th century, several mining areas were abandoned without adequate environmental intervention. Furthermore, these areas lack studies to characterize the impact of pollution on the hydrogeological system. The area surrounding the tungsten mine of Regoufe, in northern Portugal, is one such area exploited during the Second World War. The accumulation of sulfide-rich tailings may have caused an acid mine drainage (AMD), where the leaching processes caused by seepage water led to soil contamination, evidenced by its acid character and anomalous concentrations of some Potentially Toxic Elements (PTE) reported in previous studies. The present research proposes an innovative approach that seeks the integration of different geophysical techniques to characterize the impact of mining activity on the subsurface. Electrical resistivity (ER) and electromagnetic (EM) were used to measure subsurface electrical properties. In addition, seismic refraction and Multichannel Analysis of Surface Waves (MASW) were performed to characterize the geometry, depth, and geomechanical behavior of the soil and rock bodies. The integration of these techniques allowed the interpretation of hydrogeological sections and a 3D resistivity volume to gain insight into the distribution of potentially contaminating fluids and tailings material present in the mining valley.

2021

Multi-technique detection of buried inert explosive devices in urban context: Metal detection, magnetometer and ground-penetrating radar

Authors
Rodrigues, D; Barraca, N; Costa, A; Borges, J; Almeida, F; Fernandes, L; Moura, R; Madureira-Carvalho, Á;

Publication
Symposium on the Application of Geophysics to Engineering and Environmental Problems 2021

Abstract

2021

Weathering on volcanic edifices under semi-arid climates. Insights from a regional assessment of the composition of Fogo Island regoliths (Cape Verde)

Authors
Cabral Pinto, M; Dinis, PA; Pitta Groz, D; Marques, R; Prudêncio, MI; Moura, R; Rocha, F; Ferreira da Silva, E;

Publication
Geological Society, London, Special Publications

Abstract
AbstractIn this study, the geochemistry and mineralogy of regoliths formed on Fogo Island (Cape Verde), a polygenic stratovolcano built during the Quaternary, are used to assess the geomorphological factors that control the early stages of basalt weathering. Fogo Island soils are mainly derived from relatively homogenous silica-undersaturated basaltic rocks. However, a discernible exotic component is recognised in areas most exposed to prevailing winds by ratios on non-mobile elements that are hosted in different amounts by basaltic rocks (e.g., Th, Sc and Ti). Weathering extent is evidenced by a relative depletion in mobile elements (e.g., Na, Ca, Mg) and an enrichment in non-mobile elements (e.g., Ti, Fe, Sc, Al), the decomposition of the most labile minerals (olivines), and the enrichment in secondary components (phyllosilicates and some Fe-oxides, such as hematite-goethite), along with quartz supplied from non-volcanic areas. It depends on bedrock age and type (pyroclastic deposits vs. lava-flows). In particular, soils covering older volcanic units tend to be more affected by chemical alteration than those overlying younger units. In addition, more intense weathering is observed in locations characterised by a combination of moderate elevation, slopes with low gradient and relatively high rainfall. The present investigation shows that even in low humidity environments recently formed basalt are affected by weathering, with the extent of chemical decomposition being mainly determined by the age of surface exposure and local orographic/climatic features.

2021

Ground Penetrating Radar for Buried Explosive Devices Detection: A Case Studies Review

Authors
Brito da Costa, AM; Martins, D; Rodrigues, D; Fernandes, L; Moura, R; Madureira Carvalho, A;

Publication
AUSTRALIAN JOURNAL OF FORENSIC SCIENCES

Abstract
Geophysical techniques can be successfully applied towards the detection of buried explosive devices, the ground-penetrating radar (GPR) being an example of one such method. This technology works through emission and reception of electromagnetic radio waves being thus able to detect the presence of a subsurface object fundamentally due to reflections from contrasting electromagnetic properties between the object and the surrounding medium (e.g., soil). Many factors can influence the success of a GPR survey (e.g., target type, soil type, environmental conditions, GPR antenna frequency, data processing techniques), being essential to know and understand their likely effects before performing GPR studies, mainly in real cases. In this paper, through the analysis of case studies related to the use of GPR technology towards the detection of buried explosive devices, we intend to arrange and layout the main prior knowledge that a forensic geophysical expert must have when dealing with this type of fieldwork.

2021

High resolution NDT in the characterization of the inner structure and materials of heritage buildings walls and columns

Authors
Matias, M; Almeida, F; Moura, R; Barraca, N;

Publication
CONSTRUCTION AND BUILDING MATERIALS

Abstract
Rehabilitation, restoration and maintenance of monuments, heritage and buildings pose challenging tasks to engineers and architects, as any intervention must respect their architectural and constructive characteristics. Often these are unknown and sources of information have long been lost in time. Thus, there is a need to use methods capable of providing information on a wide range of aspects such as building foundations, construction characteristics and materials, alterations from the original layout, infrastructure mapping, pathologies, etc. These methods must respect the inherent structural delicacy and characteristics of ancient buildings and non-destructive methods, NDT such as geophysical methods, have been proposed to investigate these problems. It is common knowledge that a single geophysical method cannot provide full information on the problems to investigate. Thus, herein the combined use of Seismic Transmission Tomography and Ground Penetrating Radar - GPR - is demonstrated to provide important results in the investigation of the constructive elements (columns and walls) of a 14th century UNESCO monument. As demonstrated, high-resolution geophysical data obtained from both methods provide very good images of the interior of both walls and columns giving information on the quality and spatial distribution of the materials used in the construction of the monument. Finally, the results herein discussed prove the suitability and complementarity of these two methods to investigate, built heritage, monuments and buildings in general.

Supervised
thesis

2017

Predicting the rankings of financial analysts using machine learning methods.

Author
Artur Aleksandrovich Aiguzhinov

Institution
UP-FEUP

2017

Sistema de recolha e tratamento de dados relativos ao OEE de um centro de maquinagem CNC

Author
João Brochado Coelho Poças

Institution
UP-FEUP