http://hdl.handle.net/10174/14412 Sat, 04 Apr 2026 02:44:43 GMT 2026-04-04T02:44:43Z http://hdl.handle.net/10174/41136 Title: Restoration of Water Bodies Impacted by Mine Drainage - the GeoMaTre Project. Findings for Mercury Assessment at Caveira Mine, Portugal Authors: Fonseca, R.; Albuquerque, T.; Araújo, J.; Mota Silva, N. Editors: Battelle Publisher Abstract: Evaluating the effectiveness of geomaterials in retaining potentially toxic elements of mine effluents is a key issue for the environmental remediation of former mining areas. The project GeoMaTre (Institute of Castelo Branco and the University of Évora, Portugal), aims at finding low-cost solutions for water and sediments rehabilitation using raw geomaterials, on abandoned mines from the Iberian Pyritic Belt, a metallogenic province in SW Portugal and Spain, hosting the largest concentration of massive sulphide deposits worldwide. One of the case studies is the Caveira mine in southwestern Portugal. Large piles of mining wastes containing significant quantities of metals, record the long history of its exploitation, which began in Roman times with the extraction of Au and Ag, having focused after the exhaustion of its reserves, on the extraction of the remaining metals (Cu, Pb, Zn) and S, until the date of its abandonment in the 1960s. These waste piles represent the main sources of metals in the streams, some with very high toxicity, such as Hg, resulting from the mixing with the gold-containing ore, widely used in the past in gold exploration. The design of the best remediation technique using the most suitable geomaterials for retaining pollutant metals started with the study and characterization of the spatial distribution of Hg in stream sediments, given its environmental hazardousness and geochemical behaviour. Sun, 01 Jan 2023 00:00:00 GMT http://hdl.handle.net/10174/41136 2023-01-01T00:00:00Z http://hdl.handle.net/10174/41115 Title: Regional background values for metals in Sado sediments. Authors: Freitas, M.C.; Costa, A.M.; Cruces, A.; Fonseca, R. Editors: Lopes, F. C.; Dinis, P. A.; Duarte, L. V.; Cunha, P. P Abstract: This paper presents regional geochemical baselines for cadium (Cd), cobalt (Co), chromium (Cr), copper (Cu), nickel (Ni), lead (Pb), vanadium (V) and zinc (Zn) determined using sediments of the Sado estuary. The baselines were calculated by analyzing 34 sediment samples selected from 3 sediment cores performed in the Sado basin alluvial plain at Arapouco, Laxique and Arez, located between 50 and 65 km upstream the estuary inlet and in the Comporta salt marshes, located in the central estuarine basin. The samples were selected based on their age and only samples older than ca. 3000 cal BP were analyzed to discard anthropic influence. Maximum values of Cd=4 Co=9, Cr=58, Cu=40, Ni=21, Pb=11, V=71 and Zn=56 mgKg-1 were achieved. These values can be applied as geochemical baselines for the Sado estuary in contamination studies or for the determination of the anthropic metal contribution in the area. Fri, 30 Jun 2023 23:00:00 GMT http://hdl.handle.net/10174/41115 2023-06-30T23:00:00Z http://hdl.handle.net/10174/41112 Title: Observation of the level of contamination in the sediments of Canal Caveira (Grândola): A critical case of Acid Mine Drainage Authors: Silva, R.; Fonseca, R.; Araújo, J.; Silva, N.; Albuquerque, T. Editors: Lopes, F. C.; Dinis, P. A.; Duarte, L. V.; Cunha, P. P Abstract: Following the present work inserted in the GeoMatRe Project, an ongoing project funded by Fundação La Caixa, the conditions of the most updated physical and chemical parameters of an Acid Mine Drainage are analysed, a critical situation which occurs in the mining area of Canal Caveira (Grândola, Portugal), abandoned since the 60’s. It is intended, within the scope of the project, to observe the conditions of contamination by heavy metals in the sediments, both dissolved and suspended forms in the water column, in order to carry out a general characterization of the mining system, based on the nature and amounts of the contaminating elements, as well as the conditions of acidification occurring in the environment that surrounds the mining area. The aim is to understand, based on the existing conditions, the best environmental remediation technology to be applied in the region. Fri, 30 Jun 2023 23:00:00 GMT http://hdl.handle.net/10174/41112 2023-06-30T23:00:00Z http://hdl.handle.net/10174/41110 Title: Ordovician-Silurian transition in the Centro-Iberian Zone; Just a stratigraphic boundary or a major element in the evolution of the Iberian Variscides? Authors: Tereso, V.; Dias, R.; Romão, J.; Coke, C.; Fonseca, R.; Ribeiro, A. Editors: Lopes, F.C.; Dinis, P. A.; Duarte, L. V; Cunha, P. P Abstract: Although the Ordovician-Silurian transition in the Central-Iberian Zone is usually considered a normal stratigraphic one, recent studies show that often the black-shales of the Lower Silurian, control the development of shear zones subparallel to the main layers. This behavior has been observed, not only in the Marão-Alvão region, but also in other sectors such as, the synclines of S. Mamede, Mação and Buçaco. This seems to show that the Lower Silurian weak layers have been a major factor in controlling the evolution of the Iberian Variscides. Ongoing studies in the Celorico de Basto region will try to characterize and understand the evolution of these shear zones. Fri, 30 Jun 2023 23:00:00 GMT http://hdl.handle.net/10174/41110 2023-06-30T23:00:00Z