7,402 research outputs found
An integrated investigation of the Rio tailings, Panasqueira mine, Centre Portugal
The risks associated with mine tailings have different nature and, thus, only a multiple approach can investigate and monitor comprehensively the characteristics and evolution of mine tailings impacts on the environment.
Deposition at the Rio tailings (Panasqueira Mine) lasted about ninety years. Over one million cubic metres, of complex very fine to fine material, are deposited on a mountain side overlaying the Zezere river, increasing the risk of contamination of one of the most important hydrographic basins in central Portugal.
Herein, a multidisciplinary study including geophysics, geochemistry and borehole information, organized in a GIS, is used to characterize the Rio tailings.
The geophysical survey comprised ERT (Electrical Resistivity Tomography) and GPR (Ground Penetrating Radar) on the mud impoundment, as well as, on the slope of the tailings. The geochemical survey consisted on collecting water and tailings samples, iron coatings, arsenopyrite stockpile material and ferruginous crust. Samples collected in boreholes, drilled specifically for this project, were also analyzed.
The GIS provided imaging of the geophysical, geochemical and particle size spatial distribution, so that comparisons between the different data sets are easily done. Resistivity and GPR allowed bedrock positioning. GPR was able to give layering results within the tailings.
Finally, comparison and correlation between geophysical and geochemical results are carried out and evaluated on the GIS platform
Desempenho de genótipos de mandioca em um Argissolo eutrófico na região sudoeste da Amazônia.
Objetivou-se com esse trabalho avaliar diferentes genótipos de mandioca quanto ao desempenho agronômico e industrial para a região sudoeste amazônica, em Rondônia
Observation of environment-induced double sudden transitions in geometric quantum correlations
Correlations in quantum systems exhibit a rich phenomenology under the effect
of various sources of noise. We investigate theoretically and experimentally
the dynamics of quantum correlations and their classical counterparts in two
nuclear magnetic resonance setups, as measured by geometric quantifiers based
on trace-norm. We consider two-qubit systems prepared in Bell diagonal states,
and perform the experiments in decohering environments resulting from Bell
diagonal-preserving Markovian local noise. We then report the first observation
of environment-induced double sudden transitions in the geometric quantum
correlations, a genuinely nonclassical effect not observable in classical
correlations. The evolution of classical correlations in our physical
implementation reveals in turn the finite-time relaxation to a pointer basis
under nondissipative decoherence, which we characterize geometrically in full
analogy with predictions based on entropic measures.Comment: 5 pages, 2 figures. v2: Minor corrections. Published versio
Demand and supply of outdoor tourism activities in Northern Portugal: a survey-based approach
This paper focuses on the North of Portugal, as a diversified region with unique natural resources, to create information regarding both resources and equipment and business dynamics; the evolution of tourism supply and demand.This research is a part of a project title “TURNOUT: Desenvolvimento do Turismo Outdoor da Região Norte de
Portugal”, with the reference POCI-01-0145-FEDER-032289; funded by the European Regional Development
Fund (FEDER) (through the Operational Programme ‘Innovation and competitiveness’) and by the Portuguese
Foundation for the Development of Science and Technology (FCT), of the Ministry of Science, Technology and
Higher Education. This work is, also, funded by National Funds through the Foundation for Science and
Technology under the project UIDB/04752/2020. The SABI database was made available by the Applied
Management Research Unit (UNIAG), according to the protocol between UNIAG and COFACE.info:eu-repo/semantics/publishedVersio
Slow pyrolysis of cork granules under nitrogen atmosphere: by-products characterization and their potential valorization
ABSTRACT: Cork granules (Quercus suber L.) were slowly pyrolyzed at temperatures between 400-700 degrees C and under N-2 flow. While preserving its structure, some cells of the cork biochar became interconnected, allowing such carbon residue to be used as templates for manufacturing ceria redox materials. The pyrolytic char morphology was similar to that of the natural precursor. The produced cork biochar belonged to Class 1 (C > 60%) and possessed a high heating value of 32 MJ kg(-1). Other pyrolysis-derived compounds were identified and quantified through GC-FID and GC-MS analyses. The yield of gases released during cork pyrolysis was strongly dependent on the temperature used due to the thermal decomposition reactions involved in the degradation of cork. In particular, rising pyrolysis temperature from 500 to 700 T resulted in reducing the total hydrocarbon gases from 74 to 24 vol%. On the other hand, the yield of H-2 increased from 0 to 58% by increasing the pyrolysis temperature from 400 to 700 T. Due to the presence of suberin in cork, the composition and yield of bio-oil could be regulated by the pyrolysis temperature. Cork bio-oil was found to consist of long-chain hydrocarbons (from C11 to C24). The bio-oil resulting from the slow pyrolysis of cork residues is suitable as an appropriate feedstock for producing aliphatic-rich pyrolytic biofuels or as a source of olefms. Overall, the findings of this study suggest that Quercus suber L. could be a promising feedstock for biochar and biofuel production through the pyrolytic route and could contribute to the environmental and economic sustainability of the cork production industry.info:eu-repo/semantics/publishedVersio
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