The influence of the Atlantic meridional overturning circulation in the definition of the mean position of the ITCZ north of the equator. A review [A Influência da Circulação de Revolvimento Meridional do Atlântico na Definição da Posição Média da ZCIT ao Norte do Equador. Uma Revisão]
Aimola L.,Vale Institute of Technology |
Moura M.,Federal University of Pará
Revista Brasileira de Meteorologia | Year: 2016
The Intertropical Convergence Zone (ITCZ) is considered the most important atmospheric system in the generation of precipitation in the tropics. Although in the present climate the annual average insolation is symmetrical around the equator, the ITCZ is positioned north of the equator, also having the maximum of precipitation there. In this review article we describe the vision developed in recent studies of the influence of the Atlantic Meridional Overturning Circulation on the Hadley cell in determining of the ZCIT’s position asymmetry. We indicate the importance of strengthening this research topic in face of possible future displacements of the ITCZ with global warming and the consequent tropical rain regime changes. © 2016, Sociedade Brasileira de Meteorologia. All rights reserved.
Menezes C.,Brazilian Agricultural Research Corporation |
Menezes C.,University of Sao Paulo |
Vollet-Neto A.,University of Sao Paulo |
Marsaioli A.J.,University of Campinas |
And 5 more authors.
Current Biology | Year: 2015
The nests of social insects provide suitable microenvironments for many microorganisms as they offer stable environmental conditions and a rich source of food [1-4]. Microorganisms in turn may provide several benefits to their hosts, such as nutrients and protection against pathogens [1, 4-6]. Several examples of symbiosis between social insects and microorganisms have been found in ants and termites. These symbioses have driven the evolution of complex behaviors and nest structures associated with the culturing of the symbiotic microorganisms [5, 7, 8]. However, while much is known about these relationships in many species of ants and termites, symbiotic relationships between microorganisms and social bees have been poorly explored [3, 4, 9, 10]. Here, we report the first case of an obligatory relationship between the Brazilian stingless bee Scaptotrigona depilis and a fungus of the genus Monascus (Ascomycotina). Fungal mycelia growing on the provisioned food inside the brood cell are eaten by the larva. Larvae reared in vitro on sterilized larval food supplemented with fungal mycelia had a much higher survival rate (76%) compared to larvae reared under identical conditions but without fungal mycelia (8% survival). The fungus was found to originate from the material from which the brood cells are made. Since the bees recycle and transport this material between nests, fungus would be transferred to newly built cells and also to newly founded nests. This is the first report of a fungus cultivation mutualism in a social bee. © 2015 Elsevier Ltd. All rights reserved.
Cardoso G.F.,Federal University of Pará |
Souza Jr. C.,Instituto do Homem e Meio Ambiente da Amazonia |
Souza-Filho P.W.M.,Federal University of Pará |
Souza-Filho P.W.M.,Vale Institute of Technology
Wetlands Ecology and Management | Year: 2014
Tropical coastal wetlands form complex and dynamic ecosystems based on a mixture of vegetation, soil, and water components. Optical remotely sensed data have often been used to characterize and monitor these ecosystems, which are among the environments most threatened by climate change and anthropogenic activity worldwide. The present study sought to evaluate the spectral response of Landsat-5 Thematic Mapper (TM) images for the interpretation of different wetlands and associated environments at the mouth of the Amazon River, including mangroves, saltmarshes, beaches, and dunes, as well as secondary vegetation, water with different levels of sediment suspension, and human occupation. A Spectral Angle Mapper (SAM) classifier was applied to the analysis of Landsat-5 TMsatellite imagery to evaluate the potential for the mapping of these coastal wetland land cover classes. The characterization and comparison of the different spectral classes were obtained through the collection of at least 20 polygonal samples (5 × 5 pixels) for each class, with a total of 4,544 points. Spectral separability indices for each pair of classes were based on an Analysis of Variance, with Tukey post-test. The results indicated that most land cover classes could be separated spectrally with Landsat-5 TM. The overall accuracy and Kappa indices for the results of the classification were 86.1 and 0.84 %, respectively. The results of this spectral analysis demonstrated the potential of the SAM classifier for the classification of the different tropical wetlands in a typical Amazon coastal setting from optical remotely sensed data. © 2013 Springer Science+Business Media Dordrecht.
Lima N.P.,Vale S.A. |
de Souza Pinto T.C.,Vale Institute of Technology |
Tavares A.C.,Vale S.A. |
Sweet J.,University of Cape Town
Minerals Engineering | Year: 2016
An iron ore mineral processing plant in Brazil treating Itabirite ore was assessed by sampling a circuit consisting of Wemco 144 mechanical cells, as part of the AMIRA P9P collaborative research project. This paper presents and discusses the results of entrainability, water recovery and quartz and hematite grades associated to hydrodynamic parameters. The results indicated strong correlation between water recovery and hematite losses which was intensified by the operating conditions of the circuit. A potential alternative to reduce the hematite losses through entrainment and to increase quartz removal was to modify the traditional circuit design to treat rougher and cleaner/recleaner tails in different stages. In addition, the scavenger residence time must be matched to the quartz floatability. Changes to design and operation of these circuits are needed to sustain concentrate recovery and grade as iron ores become finer. © 2016
Pimentel B.S.,Vale Institute of Technology |
Gonzalez E.S.,University of Talca |
Barbosa G.N.O.,Vale S.A.
Journal of Cleaner Production | Year: 2016
Natural resource endowments have the potential of transforming the prospects of many developing economies. However, a nation's mineral resources can only generate prosperity if specific technology assets are employed in a way as to effectively develop its resource sector, capture value from it, and transform that value into long-term benefits. The roadmap to such an ambitious goal lies in effective management, supported by consistent, formal decision-making methods. Yet, integrating environmental and social goals into strategic, tactical and operational decisions is a complex challenge, often addressed without adequate analytical rigour. We provide a systematic analysis of the literature devoted to the development and application of quantitative decision-support methods with sustainability considerations in the mining industry. By establishing a framework based on the fundamental elements inherent to decision-making processes pertinent to mining operations, we identify several opportunities for advancing research and practice. In particular, we find important gaps in elements such as project portfolio optimization, operations and waste management, and mine closure and rehabilitation, and even more so when social targets and impacts are considered. It is our belief that insights from this discussion could be of significant value to both academics and practitioners interested in promoting sustainable socio-economic development throughout the mining industry. © 2015 Elsevier Ltd. All rights reserved.
PubMed | Vale Institute of Technology and University of Sao Paulo
Type: | Journal: Journal of hazardous materials | Year: 2017
The bacteria isolated from Hymeniacidon heliophila sponge cells showed bioleaching activity. The most active strain, Hyhel-1, identified as Bacillus sp., was selected for bioleaching tests under two different temperatures, 30C and 40C, showing rod-shaped cells and filamentous growth, respectively. At 30C, the bacteria secreted substances which linked to the leached copper, and at 40C metallic nanoparticles were produced inside the cells. In addition, infrared analysis detected COOH groups and linear peptides in the tested bacteria at both temperatures. The Hyhel-1 strain in presence of electronic waste (e-waste) induced the formation of crust, which could be observed due to bacteria growing on the e-waste fragment. SEM-EDS measurements showed that the bacterial net surface was composed mostly of iron (16.1% w/w), while a higher concentration of copper was observed in the supernatant (1.7% w/w) and in the precipitated (49.8% w/w). The substances linked to copper in the supernatant were sequenced by MALDI-TOF-ms/ms and identified as macrocyclic surfactin-like peptides, similar to the basic sequence of Iturin, a lipopeptide from Bacillus subtilis. Finally, the results showed that Hyhel-1 is a bioleaching bacteria and cooper nanoparticles producer and that this bacteria could be used as a copper recovery tool from electronic waste.
Nancucheo I.,Bangor University |
Nancucheo I.,Arturo Prat University |
Nancucheo I.,Vale Institute of Technology |
Grail B.M.,Bangor University |
And 3 more authors.
Applied Microbiology and Biotechnology | Year: 2014
An oxidized lateritic ore which contained 0.8 % (by weight) copper was bioleached in pH- and temperature-controlled stirred reactors under acidic reducing conditions using pure and mixed cultures of the acidophilic chemolithotrophic bacterium Acidithiobacillus ferrooxidans. Sulfur was provided as the electron donor for the bacteria, and ferric iron present in goethite (the major ferric iron mineral present in the ore) acted as electron acceptor. Significantly more copper was leached by bacterially catalysed reductive dissolution of the laterite than in aerobic cultures or in sterile anoxic reactors, with up to 78 % of the copper present in the ore being extracted. This included copper that was leached from acid-labile minerals (chiefly copper silicates) and that which was associated with ferric iron minerals in the lateritic ore. In the anaerobic bioreactors, soluble iron in the leach liquors was present as iron (II) and copper as copper (I), but both metals were rapidly oxidized (to iron (III) and copper (II)) when the reactors were aerated. The number of bacteria added to the reactors had a critical role in dictating the rate and yield of copper solubilised from the ore. This work has provided further evidence that reductive bioprocessing, a recently described approach for extracting base metals from oxidized deposits, has the potential to greatly extend the range of metal ores that can be biomined. © 2014 Springer-Verlag.
Tenorio G.S.,Federal University of Pará |
Souza-Filho P.W.M.,Vale Institute of Technology |
Souza-Filho P.W.M.,Federal University of Pará |
Ramos E.M.L.S.,Federal University of Pará |
Alves P.J.O.,Federal University of Pará
Ocean and Coastal Management | Year: 2015
The present study evaluates the role of marine aquaculture in the conversion of mangrove forests into shrimp (Litopenaeus vannamei, Boone, 1931) farms using remote sensing and geographic information system techniques and analyzes the productivity of the installed farms in the mangroves and adjacent coastal plateau. The extension of the shrimp ponds was quantified using satellite image analysis, and the water quality of the shrimp farms was analyzed based on measurements of dissolved oxygen concentration, temperature, pH, and salinity. The productivity of the farms was measured using biometric data. The data were analyzed using ANOVA with Tukey's post-test. The results indicated that shrimp farms cover an area of ~0.8km2 (approximately 0.4% of Brazilian ponds), of which 29.4% are located within areas of mangroves, and 70.6% are located in the coastal plateau. Saltwater aquaculture contributed to the conversion of 0.53km2 of the mangroves into rearing ponds, which represents only 0.007% of the total area of the Amazonian mangroves. The installations in the mangrove presented significantly higher pH, temperature, transparency, and salinity compared with the ponds installed in the coastal plateau, although coastal plateau ponds had higher dissolved oxygen concentrations. Based on these differences, the mean sizes of the shrimp raised in the mangrove and coastal plateau ponds were 5.7g and 4.3g, respectively. However, the estimated value of one hectare of mangrove is much higher than its potential value in the production of shrimp. The considerable value of the ecosystem services provided by the mangroves indicates that the production of shrimp in the coastal plateau is relatively less damaging in ecological and economic terms. Thus, we can consider that the production of shrimp in the coastal plateau instead of in mangrove areas is less damaging to the long-term conservation of mangrove forests, which follows the management best practices established by international organizations. The coastal zone is considered a common resource that belongs to all citizens in Iberoamerican countries, and it is defined as a zone of non-building. Therefore, we conclude that mangroves are more valuable intact than converted into aquaculture ponds. Hence, aquaculture activities in the Amazon coastal plain are not sustainable from environmental and socioeconomic perspectives. © 2014 Elsevier Ltd.
Siravenha A.C.Q.,Federal University of Pará |
Carvalho S.R.,Vale Institute of Technology
Brazilian Symposium of Computer Graphic and Image Processing | Year: 2015
Plant identification and classification play an important role in ecology, but the manual process is cumbersome even for experimented taxonomists. Technological advances allows the development of strategies to make these tasks easily and faster. In this context, this paper describes a methodology for plant identification and classification based on leaf shapes, that explores the discriminative power of the contour-centroid distance in the Fourier frequency domain in which some invariance (e.g. Rotation and scale) are guaranteed. In addition, it is also investigated the influence of feature selection techniques regarding classification accuracy. Our results show that by combining a set of features vectors - in the principal components space - and a feed forward neural network, an accuracy of 97.45% was achieved. © 2015 IEEE.
Breiter K.,Academy of Sciences of the Czech Republic |
Lamarao C.N.,Federal University of Pará |
Borges R.M.K.,Federal University of Pará |
Dall'Agnol R.,Federal University of Pará |
Dall'Agnol R.,Vale Institute of Technology
Lithos | Year: 2014
The trace element content in zircons from A-type granites and rhyolites was investigated by using back-scattered electron images and electron microprobe analyses. The studied Proterozoic (Wiborg batholith, Finland and Pará, Amazonas and Goiás states, Brazil) and Variscan (Krušné Hory/Erzgebirge, Czech Republic and Germany) plutons cover a wide range of rocks, from large rapakivi-textured geochemically primitive plutons to small intrusions of F-, Li-, Sn-, Nb-, Ta-, and U-enriched rare-metal granites. While zircon is one of the first crystallized minerals in less fractionated metaluminous and peraluminous granites, it is a late-crystallized phase in peralkaline granites and in evolved granites that may crystallize during the whole process of magma solidification. The early crystals are included in mica, quartz, and feldspar the late grains are included in fluorite or cryolite or are interstitial. The zircon in hornblende-biotite and biotite granites from the non-mineralized plutons is poor in minor and trace elements; the zircon in moderately fractionated granite varieties is slightly enriched in Hf, Th, U, Y, and HREEs; whereas the zircon in highly fractionated ore-bearing granites may be strongly enriched in Hf (up to 10wt.% HfO2), Th (up to 10wt.% ThO2), U (up to 10wt.% UO2), Y (up to 12wt.% Y2O3), Sc (up to 3wt.% Sc2O3), Nb (up to 5wt.% Nb2O5), Ta (up to 1wt.% Ta2O5), W (up to 3wt.% WO3), F (up to 2.5wt.%F), P (up to 11wt.% P2O5), and As (up to 1wt.% As2O5). Metamictized zircons may also be enriched in Bi, Ca, Fe, and Al. The increase in the Hf content coupled with the decrease in the Zr/Hf value in zircon is one of the most reliable indicators of granitic magma evolution. In the zircon of A-type granites, the Zr/Hf value decreases from 41-67 (porphyritic granite) to 16-19 (equigranular granite) in the Kymi stock, Finland, and from 49-52 (biotite granite) to 18-36 (leucogranite) in the Pedra Branca pluton, Brazil. In the in situ strongly fractionated Cínovec cupola (Erzgebirge), the Zr/Hf value decreases from 33-51 in the protolithionite granite at a depth of 1255m to 7.5-25 in the zinnwaldite granite at a depth of 40m. At the scale of individual crystals, the Zr/Hf value decreases from 86 to 68 from the cores to the rims of the zircons from the Teplice rhyolite and from 64 to 33 in the zircons from the biotite granite at Krupka, Erzgebirge. The contents of Hf and U in zircon are dependent mainly on the degree of granite fractionation and the nature and volume of the volatile phases and are independent of the A- or S-character of the parental melt. The zircon Zr/Hf ratios 55 and 25 are proposed to approximately distinguish common, moderately evolved and highly evolved granites. Zircons from the moderately and highly evolved granites of A- and S-type can be discriminated on the basis of their HREE content and the U/Th ratios. Nb, Ta, and W are present in zircon from the highly evolved granites from all studied areas, while high As, Bi, and Sc contents are typical only for the Erzgebirge. © 2014 Elsevier B.V.