4161 research outputs found
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Influência dos rejeitos de uma mina de sulfuretos na qualidade da água de drenagem, 60 anos após o seu abandono: Caso de estudo no SW de Portugal
No full textABSTRACT: The GeoMatRe project aims to find low-cost solutions for water and sediment rehabilitation using raw geomaterials, in abandoned mines of the Iberian Pyritic Belt. One of our case studies is the Caveira mine in southwestern Portugal, where large piles of mining waste, containing significant amounts of metals, record the long history of its exploitation for gold (Au) and silver (Ag). After the exhaustion of its reserves, the extraction of the remaining metals (cooper (Cu), lead (Pb) and zinc (Zn)) and sulphur (S) continued, until its abandonment during the 60s of 20th century. This work has two objectives: (i) to study the influence of mine and mine tailings drainage on water quality by analysing the dissolved and particulate material in drainage waters, and (ii) to determine whether there are differences in the contamination level of these waters according to the different weather conditions of the last two winters.RESUMO: O projeto GeoMatRe tem como objetivo encontrar soluções de baixo custo para a remediação de águas e sedimentos utilizando geomateriais, em minas abandonadas da Faixa Piritosa Ibérica. Um dos nossos casos de estudo é a mina de Caveira, no sudoeste de Portugal, onde grandes quantidades de resíduos mineiros acumulados, contendo quantidades significativas de metais, registam a longa história da sua exploração de ouro (Au) e prata (Ag). Após o fim das suas reservas, a extração dos restantes metais (cobre (Cu), chumbo (Pb) e zinco (Zn)) e enxofre (S) continuou, até ao seu abandono durante os anos 60 do século XX. Este trabalho tem dois objetivos: (i) estudar a influência da drenagem da mina e dos rejeitos mineiros deixados ao abandono, sobre a qualidade da água, através da análise do material dissolvido e particulado nas águas de drenagem, e (ii) determinar se existem diferenças nos sues níveis de contaminação em função das diferentes condições meteorológicas dos dois últimos Invernos
Geotechnical characterisation of the Vale da Anta North Slope Cabo Mondego
No full textRESUMO: A ocorrência de roturas em taludes (por exemplo, taludes de estradas, frentes de pedreiras e de antigas explorações mineiras), pode causar graves prejuízos económicos e/ou colocar vidas em risco. Assim, é necessária uma intervenção rigorosa e integrada para recuperar taludes abandonados ou instáveis e locais de exploração. Foi estudado um talude rodoviário localizado na zona norte do Cabo Mondego (Vale de Anta) de modo a avaliar possíveis situações de instabilidade e apresentar soluções baseadas na engenharia natural e na restauração geomorfológica. Foi realizada a caracterização geotécnica do talude considerado, que envolveu a realização de ensaios laboratoriais e in situ de determinação das propriedades índice, das propriedades mecânicas e da durabilidade. Também foram utilizados o sistema classificativo Rock Mass Rating (RMR) e o Geological Strength Index (GSI). Na avaliação da estabilidade de taludes utilizaram-se as classificações geomecânicas Slope Mass Rating (SMR) e Q-Slope. A partir da identificação e definição das situações das instabilidades, as quais têm uma maior propensão de ocorrerem na parte do talude mais fragmentado/alterado, apresentaram-se soluções sustentáveis e duradouras.ABSTRACT: The occurrence of slope failures (e.g., roadway slopes, quarry fronts and abandoned old mining operation), can cause severe economic damage and/or put lives at risk. Thus, a conscious intervention is required the recover abandoned or unstable slopes and exploitation sites. A road slope located in the northern area of Cabo Mondego (Vale de Anta) was studied to evaluate possible instabilities and present solutions based on natural engineering and geomorphological restoration. Geotechnical characterization of the slope considered was carried out, which involved carrying out laboratorial and situ tests of the index values, mechanical properties, and durability. The Rock Mass Rating (RMR) system classification and Geological Strength Index (GSI) were also used. The assessment of slope stability was defined using the Slope Mass Rating (SMR) and Q-Slope geomechanical classifications. From the identification of instabilities, which are more likely to occur in the most fragmented/weathered part of the studied slope, sustainable and long-last solutions were able to be presented
Palinoestratigrafia do Jurássico Inferior e Médio da Bacia Lusitânica (Portugal) no contexto proto-Atlântico
No full textABSTRACT: Palynomorphs, especially dinoflagellate cysts, are important biostratigraphical and palaeoenvironmental tools and their study can be applied to the Lusitanian Basin of Portugal. A palynostratigraphical high-resolution survey was undertaken in eight Lower and Middle Jurassic (upper Sinemurian to lowermost Bathonian) sections from the Lusitanian Basin. We present the resulting biostratigraphical scheme comprising the most significant palynomorph bioevents for this interval.RESUMO: Os palinomorfos, em especial os quistos de dinoflagelados (dinoquistos), são uma ferramenta muito útil nos trabalhos de bioestratigrafia e interpretações paleoambientais, a qual pode ser aplicada no conhecimento da geologia da Bacia Lusitânica. Foi desenvolvido um estudo palinoestratigráfico de alta-resolução em oito perfis do Jurássico Inferior e Médio (Sinemuriano superior até à base do Bathoniano) da Bacia Lusitânica. Neste trabalho apresentamos o esquema bioestratigáfico final, com os principais bioeventos dos palinomorfos identificados neste intervalo
Construction raw materials in Timor Leste and sustainable development
No full textABSTRACT: Timor Leste is the newest and one of the poorer nations in the world. One of its main challenges that could lead to poverty reduction is the reconstruction and maintenance of the infrastructures that were almost completely destroyed after its independence referendum. To achieve this, there is an imperative need for construction raw materials in a country where the extractive industry is scarce and artisanal. Available geological studies deal with the island’s geology and tectonic evolution or its oil and gas potentialities. Very few broach other geological resources. A general study of the country’s territory demonstrates that Timor Leste possesses large resources in clays, limestones and sand and gravel, which can support small- to large-scale raw material extractive industries. Some selected areas have been the target of more detailed study: Venilale and Aileu, with resources for structural ceramics and whiteware respectively, and Beheda, where a crinoid-rich limestone crops out, with potential for usage as ornamental stone. These resources are suitable for non-sophisticated small-scale mining operations that should be able to accomplish environmental and social liabilities. No public policy exists for the management of these mineral resources, which is essential for the sustainable development of Timor Leste.info:eu-repo/semantics/publishedVersio
Optimizing Chlorella vulgaris production and exploring its impact on germination through microalga-N2-fixing bacteria consortia
No full textABSTRACT: Microalgal biomass is increasingly valued in industrial and agricultural sectors due to its bioactive compounds. However, large-scale production remains costly, mainly due to nitrogen fertilizer expenses. A promising sustainable alternative is co-cultivation with N2-fixing bacteria, capable of supplying biologically available nitrogen. In this study, Chlorella vulgaris was grown in synthetic medium with and without nitrogen, as well as in co-culture with three different N2-fixing bacteria in nitrogen-free medium. Microalgal growth was assessed by dry weight, Fv/Fm ratio, and flow cytometry, which also allowed evaluation of population dynamics and cell viability. Biomass composition (proteins, carbohydrates, lipids, chlorophyll, and carotenoids) was analyzed under all conditions. Co-cultures in nitrogen-free medium showed comparable biomass productivity to nitrogen-supplemented controls, although Fv/Fm values indicated physiological stress in some cases. Moreover, the agricultural potential of the resulting biomass and supernatants was evaluated through germination bioassays using lettuce seeds. All cultures tested at 0.2 g & sdot;L-1 significantly improved the germination index. Also, applying the culture supernatant (biomass removed) also yielded positive effects, with GI increases exceeding 40 %. These results suggest that co-cultivation with N2-fixing bacteria can support efficient microalgal production while generating biomass and supernatants with biostimulant potential, contributing to sustainable agriculture and circular bioeconomy strategies
Proposal of a methodology for geoheritage degradation risk assessment
No full textRESUMO: É apresentada uma metodologia para avaliar o risco de degradação do património geológico. A metodologia baseia-se em três critérios: vulnerabilidade natural, vulnerabilidade antrópica e uso público. Cada critério é avaliado com base em parâmetros específicos. A vulnerabilidade natural considera a possibilidade de danos causados por processos naturais não envolvidos na formação do geossítio, enquanto a vulnerabilidade antrópica tem em conta as atividades humanas relacionadas com o valor económico do geossítio. O uso público considera a possibilidade de danos causados pela localização e pela utilização atual e potencial do geossítio. Esta metodologia tem vindo a ser aplicada a geossítios em diferentes contextos e propõe uma abordagem quantitativa para contribuir para a clarificação de conceitos e procedimentos na avaliação da degradação do património geológico e para apoiar procedimentos de gestão adequados.ABSTRACT: A methodology for assessing the risk of degradation of geoheritage is presented. The methodology is based on three criteria: natural vulnerability, anthropogenic vulnerability and public use. Each criterion is assessed based on specific parameters. Natural vulnerability considers the possibility of damage caused by natural processes not involved in the formation of the geosite, while anthropic vulnerability takes into account human activities related to the economic value of the geosite. Public use considers the possibility of damage caused by the current and potential location and use of the geosite. This methodology has been applied in geosites in different contexts and offers a quantitative approach to contribute to a clarification of concepts and procedures in geoheritage degradation assessment and to support adequate management procedures
Age dependent variation of the magnetic fabric of dike swarms and implications for the volcanic structure of ocean islands: the example of the Maio Island, Cabo Verde archipelago
No full textABSTRACT: Magnetic fabric analysis of dikes is a powerful technique when assessing magma transfer processes. This study presents an integrated analysis combining magnetic susceptibility and anisotropy of magnetic susceptibility, magnetic mineralogy, geochemistry and new 40Ar/39 Ar dating of dikes intruding formations ranging from the Lower Cretaceous to the Miocene on the island of Maio, in the Cabo Verde archipelago. We show that the dikes, dated at ≈9.2 Ma, intruding the younger Miocene Casas Velhas formation, display a Ti-rich titanomagnetite composition, higher whole-rock TiO2 content and very high magnetic anisotropy. They are clearly distinguished from the dikes, ranging in age from ≈9.3 to 11.3 Ma, intruding older formations, which show a predominantly Ti-poor titanomagnetite composition with multiple magnetic phases, lower whole-rock TiO2 concentration, higher range of magnetic susceptibilities and very low anisotropy. Magnetic fabric is predominantly normal with no significant imbrication relative to the dike margins. Numerical analysis of fabric shows a dominant coaxiality between the magnetic lineation and the preferred orientation of opaques and phenocrystals suggesting that magnetic lineation is, therefore, the proxy of the magmatic flow axis orientation. Based on the orientation of the magnetic fabric, we infer that magmatic flow within the studied dikes is predominantly vertical. The differences observed between the younger dikes and all other dikes may be related to magma sourced from distinct magma chambers. One, probably shallow, underneath the Casas Velhas fm in the southwest of the island, which would explain the very high values of magnetic anisotropy and the inferred vertical flow, and another located in a central position in the island, responsible for the dikes intruding the older formations. The location of such magma reservoirs and the dikes ages suggest a hypothetical migration with age of the magmatic sources that fed the dikes from the central part of the island to the southwest region. The magnetic and mineralogical heterogeneities of the dikes intruding older Lower Cretaceous formations may also be a result of a wider age range of the intrusions
Geoheritage valorisation at the Passadiços do Paiva (Arouca UNESCO Global Geopark)
No full textRESUMO: Os Passadiços do Paiva, localizados no território do Arouca Geoparque Mundial da UNESCO (AGMU), foram inaugurados em 2015 e são uma das principais atrações turísticas da região. O projeto foi reconhecido internacionalmente com vários prémios como melhor iniciativa de desenvolvimento turístico. Ao longo dos passadiços, os visitantes têm a oportunidade de observar 5 dos 41 geossítios do geoparque: Garganta do Paiva, Cascata das Aguieiras, Vau, Gola do Salto e Falha de Espiunca. De forma a potenciar a interpretação do património geológico ao longo dos passadiços e beneficiar das condições de acessibilidade, segurança e visibilidade e da elevada atratividade turística, um conjunto de ferramentas de valorização foi desenvolvido, incluindo estruturas de apoio à observação e interpretação dos geossítios e informação expositiva, textual e cartográfica com linguagem acessível para integração em atividades educativas e turísticas. Para além dos dados sobre as características da geodiversidade, são também exploradas a biodiversidade e a cultura local.ABSTRACT: The Paiva Walkways, situated within the Arouca UNESCO Global Geopark, were inaugurated in 2015 and have since become a prominent tourist destination in the region. This project has garnered international recognition, receiving numerous awards for its excellence in tourism development. Along the walkways, visitors can explore five of the geosites out of the 41 within the geopark: the Paiva Gorge, Aguieiras Waterfall, Vau, Gola do Salto, and Espiunca Fault. To enrich the interpretation of the geological heritage along the walkways, and to take full advantage of the accessible, safe, and visually appealing conditions, a range of enhancement tools has been devised. These include support structures for observing and interpreting geosites, as well as informative displays featuring accessible language for use in educational and tourism activities. Furthermore, in addition to providing information about geodiversity features, the walkways also offer insights into biodiversity and local culture
Systemic complementarities and transformative change: A tentative methodology to examine bidirectionality effects across connected systems [Resumo]
No full textABSTRACT: Achieving energy-sustainable goals involves large-scale production and social changes necessary to fulfil societal functions (Geels, 2004; Markard, 2011). These long-term goals imply a transformative change requiring multiple transitions involving multiple socio-technical systems and their interplay (Raven and Verbong, 2007; Geels, 2007; Papachristos, 2013; Rosenbloom, 2020). To fully address system change, it is necessary to consider that changes in one system affect the other (Geels, 2007; Papachristos, 2013), i.e., the presence of bidirectionality in system interactions. However, bidirectionality has only recently started being tackled and remains under-conceptualized