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Registros recuperados: 34
Primeira ... 12 ... Última
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Impact des émissaires et canalisation sur l'environnement de la baie de Tanger ( Maroc ) : Approche géochimique OceanDocs
Achab, M.; El hatimi, I.; El moumni, B..
Dans le but d’évaluer le degré de contamination chimique et/ou organique des sédiments superficiels le long des émissaires continentaux, des échantillons de sédiments de surface ont été prélevés et analysés le long des oueds Souani et Mghogha et au niveau de la canalisation majeure de la ville de Tanger débouchant sur la baie située sur la marge méditerranéenne marocaine. La dynamique sédimentaire dans les oueds montre exceptionnellement une évolution amont–aval granocroissante en relation avec l’activité anthropique (remblaiement des bassins versants par les matériaux de construction tels que les briques, ciments, verres, etc.). La matière organique est présente à des teneurs relativement élevées en corrélation positive avec la sédimentation fine. L’azote...
Tipo: Journal Contribution Palavras-chave: Sedimentology; Mineralogy; Pollution; Geochemical surveys; Bay dynamics.
Ano: 2002 URL: http://hdl.handle.net/1834/199
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Essai d'interprétation de la dynamique sédimentaire par l'analyse granulométrique et minéralogique au large du golfe de Gabès OceanDocs
Brahim, M.; Ben Amor, R.; Gueddari, M..
The results of the grain size and mineralogical analysis of the surface sediments of the Gulf of Gabes, taken with Various depths between the coast Sfax-Zarzis and the isobaths -100 m, allow to identify the origin of these sediments and to specify the factors and the phenomena, which are involved in their transport and their deposit. The mineralogical study resulted in high lighting a clear relation between the recent sedimentary stock of the gulf of Gabès and the bordering geological formations. The sediments study showed that the detritus materials are of continental origin and the sediments coming from the coastal erosion are subjected to a dynamics, which is controlled, primarily by the action of the currents (current coastal and currents tide and by...
Tipo: Journal Contribution Palavras-chave: Grain size; Sediment analysis; Sediment chemistry; Sediments; Mineralogy.
Ano: 2003 URL: http://hdl.handle.net/1834/1118
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Estudio sedimentológico y mineralógico de la plataforma continental ecuatoriana en el tramo comprendido entre Salinas y Ayampe OceanDocs
Soledispa, B.; Villacres, J..
Esta investigación tiene como principal objetivo conocer como están distribuidos los sedimentos en el área, su origen, procedencia y su comportamiento en relación a los agentes de transporte y sedimentación que allí actúan.
Tipo: Journal Contribution Palavras-chave: Sedimentology; Mineralogy; Distribution; Sediment analysis; Mineralogy; Distribution; Http://aims.fao.org/aos/agrovoc/c_4856; Http://aims.fao.org/aos/agrovoc/c_35773.
Ano: 1989 URL: http://hdl.handle.net/1834/2158
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INTERNAL STRUCTURE OF A VERMICULAR IRONSTONE AS DETERMINED BY X-RAY COMPUTED TOMOGRAPHY SCANNING Rev. Bras. Ciênc. Solo
Zinn,Yuri Lopes; Carducci,Carla Eloize; Araujo,Marla Alessandra.
Ironstones or petroplinthites are common materials in soils under humid tropical climate, generally defined as the result of Fe oxide accumulation in areas where the water table oscillates, and may exhibit considerable morphological variability. The aim of this study was to examine the internal structure and porosity of an ironstone fragment from a Petroferric Acrudox in Minas Gerais, Brazil, by computed tomography (CT) and conventional techniques. The sample analyzed had total porosity of 59.5 %, with large macropores in the form of tubular channels and irregular vughs, the latter with variable degrees of infilling by material released from the ironstone walls or the soil matrix. The CT scan also showed that the ironstone has wide variation in the density...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Laterite; Soils with plinthite; Density; Mineralogy.
Ano: 2015 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-06832015000200345
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Estimation of water retention and availability in soils of Rio Grande do Sul Rev. Bras. Ciênc. Solo
Reichert,José Miguel; Albuquerque,Jackson Adriano; Kaiser,Douglas Rodrigo; Reinert,Dalvan José; Urach,Felipe Lavarda; Carlesso,Reimar.
Dispersed information on water retention and availability in soils may be compiled in databases to generate pedotransfer functions. The objectives of this study were: to generate pedotransfer functions to estimate soil water retention based on easily measurable soil properties; to evaluate the efficiency of existing pedotransfer functions for different geographical regions for the estimation of water retention in soils of Rio Grande do Sul (RS); and to estimate plant-available water capacity based on soil particle-size distribution. Two databases were set up for soil properties, including water retention: one based on literature data (725 entries) and the other with soil data from an irrigation scheduling and management system (239 entries). From the...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Pedotransfer functions; Texture class; Water retention curve; Mineralogy.
Ano: 2009 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-06832009000600004
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Contribution of non-exchangeable potassium forms and its accumulation in corn plants AGRIAMBI
Vieira,Montesquieu da S.; Oliveira,Fábio H. T. de; Santos,Hemmannuella C.; Medeiros,Jailma dos S. de.
ABSTRACT The state of Paraíba, Brazil, has soils from well- to poorly-developed, in which potassium (K) is found in different levels, forms and, consequently, with varying availability to plants. The objective of this study was to evaluate the contribution of non-exchangeable K forms to corn plants in 12 soils from Paraíba state, along four successive cycles. The experimental design was completely randomized block with three replicates and the 24 treatments consisted of the combination between two K levels (0 and 100 mg dm-3) ​​and 12 soils. Before and after each cycle, subsamples of 0.2 dm3 were collected in each pot for the determination of non-exchangeable K (Kne), exchangeable K (Ke) and soluble K (Ks). For each cycle, dry matter production, dry matter...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Northeastern soils; Mineralogy; K forms; K availability.
Ano: 2016 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1415-43662016000100009
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Modeling boron adsorption on five soils before and after removal of organic matter Scientia Agricola
Santos,Patricia dos; Goldberg,Sabine; Costa,Antonio Carlos Saraiva da.
ABSTRACT Boron- B concentrations that cause deficiency and those that cause toxicity appear to be very similar, compared to other nutrients, which can complicate successful management of this element in soils. In this study, B adsorption onto two Oxisols from Brazil (Rhodic Eutroperox and Anionic Acroperox), two Alfisols (Natric Palexeralf and Aridic Paleustalf) and an Entisol (Xeric Torrifluvent) from the United States of America were evaluated. The samples were treated with sodium hypochlorite in order to remove soil organic matter. Both treated and untreated samples were used to determine B adsorption isotherms using different B concentrations (0-4.630 mmol L–1) and NaNO3 (0.05 M) as background electrolyte solution at pH 7. Boron adsorption envelopes...
Tipo: Info:eu-repo/semantics/article Palavras-chave: FITEQL; Chemical properties; Mineralogy.
Ano: 2020 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0103-90162020000401401
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Carbon sequestration in clay and silt fractions of Brazilian soils under conventional and no-tillage systems Scientia Agricola
Reis,Cecília Estima Sacramento dos; Dick,Deborah Pinheiro; Caldas,Jennifer da Silva; Bayer,Cimélio.
The capacity of soils to sequestrate carbon (C) is mainly related to the formation of organo-mineral complexes. In this study, we investigated the influence of soil management systems on the C retention capacity of soil with an emphasis on the silt and clay fractions of two subtropical soils with different mineralogy and climate. Samples from a Humic Hapludox and a Rhodic Hapludox, clayey soils cultivated for approximately 30 years under no-tillage (NT) and conventional tillage (CT) were collected from six layers distributed within 100-cm soil depth from each site and from an adjacent native forest. After the removal of particulate organic matter (POM), the suspension (<53 µm) was sonicated, the silt and clay fractions were separated in accordance with...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Carbon saturation; Mineralogy; Physical fractionation; Soil organic matter; Soil profile.
Ano: 2014 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0103-90162014000400006
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Mineralogical and geochemical influences on sediment color of Amazon wetlands analyzed by visible spectrophotometry Acta Amazonica
Guimarães,José Tasso Felix; Cohen,Marcelo Cancela Lisboa; França,Marlon Carlos; Silva,Any Kelly Terra da; Rodrigues,Suyanne Flavia Santos.
Based on sedimentological and geochemical data, this work relates spectrophotometric measurements with sediment composition and its application in palaeoecological studies of Amazon wetlands. The CIELAB values are directly related to mineralogical and chemical composition, mostly involving quartz, iron oxyhydroxides and sulfides (e.g. pyrite), and total organic carbon. Total organic carbon contents between 0.4-1%, 1-2%, 3-5% and 15-40% were related to L* (lightness) data of 27, 26-15, 7-10 and 7 or less, respectively. The CIELAB values of a deposit in Marabá, Pará, were proportional to variations in quartz and total organic carbon contents, but changes in zones of similar color, mainly in the +a* (red) and +b* (yellow) values of deposits in Calçoene, Amapá...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Sedimentology; Amazon region; Munsell color systems; Mineralogy; Chemical composition.
Ano: 2013 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0044-59672013000300009
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The ceramic artifacts in archaeological black earth (terra preta) from lower Amazon region, Brazil: mineralogy Acta Amazonica
Costa,Marcondes Lima da; Kern,Dirse Clara; Pinto,Alice Helena Eleotério; Souza,Jorge Raimundo da Trindade.
Several archaeological black earth (ABE) sites occur in the Amazon region. They contain fragments of ceramic artifacts, which are very important for the archaeological purpose. In order to improve the archaeological study in the region we carried out a detailed mineralogical and chemical study of the fragments of ceramic artifacts found in the two ABE sites of Cachoeira-Porteira, in the Lower Amazon Region. Their ceramics comprise the following tempers: cauixi, cariapé, sand, sand +feldspars, crushed ceramic and so on and are composed of quartz, clay equivalent material (mainly burned kaolinite), feldspars, hematite, goethite, maghemite, phosphates, anatase, and minerals of Mn and Ba. Cauixi and cariapé, siliceous organic compounds, were found too. The...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Terra Preta; Black Earth; Archaeological ceramic fragment; Lower Amazon; Phosphates; Mineralogy.
Ano: 2004 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0044-59672004000200004
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Petrology of Gameleira potassic lamprophyres, São Francisco Craton Anais da ABC (AABC)
Plá Cid,Jorge; Campos,Cristiani S.; Nardi,Lauro V.S.; Florisbal,Luana.
Gameleira lamprophyres are dykes and mafic microgranular enclaves associated with the shoshonitic Gameleira monzonite. This association belongs to the Paleoproterozoic alkaline magmatism from Serrinha nucleus, northeast Brazil. The liquidus paragenesis is diopside, pargasite, apatite and mica. Reverse zoning was identified in the groundmass alkali feldspar and was related to the undercooling of lamprophyric magma during the emplacement, with high growth rate of pargasite/edenite inducing disequilibrium between feldspars and liquid. Chemical data indicate that the lamprophyres are basic rocks (SiO2 < 48 wt%), with alkaline character (Na2O + K2O &gt; 3 wt%) and potassic signature (K2O/Na2O ≈ 2). High contents of MgO and Cr are consistent with a...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Potassic lamprophyres; Gameleira lamprophyres; São Francisco Craton; Mantle metasomatism; Petrology; Mineralogy.
Ano: 2012 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0001-37652012000200010
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Geology, petrography and geochemistry of the A-type granites from the Morro Redondo Complex (PR-SC), southern Brazil, Graciosa Province Anais da ABC (AABC)
VILALVA,FREDERICO C.J.; VLACH,SILVIO R.F..
The Morro Redondo Complex is one of the most important occurrences of the Graciosa A-type Province, southern Brazil. It consists of the Papanduva and Quiriri granitic plutons and a contemporaneous bimodal volcanic association. The Papanduva Pluton includes massive and deformed peralkaline alkali-feldspar granites with Na-Ca and Na-amphiboles and clinopyroxenes. The deformed types are the most evolved rocks in the province and carry rare ‘agpaitic’ minerals, some being described for the first time in granites from Brazil. The larger Quiriri Pluton comprises massive, slightly peraluminous, biotite syeno- and monzogranites with rare Ca-amphibole. Biotite compositions are relatively homogeneous, whereas sodic amphiboles and clinopyroxenes show increasing Na...
Tipo: Info:eu-repo/semantics/article Palavras-chave: A-type granites; Geochemistry; Petrography; Graciosa Province; Mineralogy; Morro Redondo Complex.
Ano: 2014 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0001-37652014000100085
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Physical attributes of kaolinitic and oxidic oxisols resulting from different usage systems BABT
Centurion,José Frederico; Beutler,Amauri Nelson; Souza,Zigomar Menezes de.
The objective of this study was to assess the physical attributes of a kaolinitic oxisol, medium texture (Haplustox) and an oxidic oxisol, clayey (Eutrustox) under different usage systems, localized in the region of Jaboticabal, SP, Brazil. The usage systems were sugarcane, cotton and forest. Parameters such as soil bulk density, total porosity, macro and microporosity at the depths of 0.0-0.1; 0.1-0.2; 0.2-0.3, and 0.3-0.4 m were evaluated. Haplustox showed greater bulk density and smaller total porosity, macro and microporosity. The usage increased the bulk density in 0.0-0.3 m depth, with greater effects on the kaolinitic oxisol, mainly in 0.1-0.2 m depth in the areas cultivated with sugarcane.
Tipo: Info:eu-repo/semantics/article Palavras-chave: Sugarcane; Cotton; Forest; Mineralogy; Porosity; Bulk density.
Ano: 2004 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1516-89132004000500007
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Pedogenic iron oxides in soils of the Acre State, Brazil Ciência Rural
Inda,Alberto Vasconcellos; Fink,Jessé Rodrigo; Santos,Tatiele Fruett dos.
ABSTRACT: Iron oxides are environmental indicators and influence on physical and chemical behavior of soils. This research aimed to identify and characterize pedogenic iron oxides in soils of the Acre state, Brazil. The soils developed from sedimentary rocks of the Solimões Formation. Twenty one samples of subsurface horizons were collected from ten soil profiles. Soil samples were analyzed by x-ray diffractometry associated to selective chemical dissolutions. Fe contents in the clay minerals (Fes), in the pedogenic iron oxides (Fed) and in the poorly crystalline oxides (Feo) were determined. The Al3+-substitution and the mean crystal diameter of goethite and hematite were estimated. Soils presented low contents of Fes and Fed. The Fed/Fes ratio indicated...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Mineralogy; X ray diffraction; Hematite; Goethite..
Ano: 2018 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0103-84782018000800251
Registros recuperados: 34
Primeira ... 12 ... Última
 

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