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Registros recuperados: 13
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Clay mineralogy and magnetic susceptibility of Oxisols in geomorphic surfaces Scientia Agricola
Camargo,Livia Arantes; Marques Júnior,José; Pereira,Gener Tadeu; Bahia,Angélica Santos Rabelo de Souza.
Studies analyzing the variability of clay minerals and magnetic susceptibility provide data for the delineation of site-specific management areas since many of their attributes are important to agronomy and the environment. This study aimed to evaluate the spatial variability of clay minerals, magnetic susceptibility, adsorbed phosphorus and physical attributes in Oxisols of sandstones in different geomorphic surfaces. For that purpose, soil samples were collected every 25 m along a transect located within the area where the geomorphic surfaces were identified and mapped. The transect occupied the central portion of 500 ha, where it was also sampled for density purposes with one sample per six hectares. Soil samples were collected at a depth of 0.0-0.2 m....
Tipo: Info:eu-repo/semantics/article Palavras-chave: Goethite; Hematite; Gibbsite; Kaolinite; Soil mapping.
Ano: 2014 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0103-90162014000300010
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Do Aggregate Size Classes of the Subsurface Soil Horizon Have Different Chemical/Mineralogical Properties? Rev. Bras. Ciênc. Solo
Mitton,Rolff Vladimir; Melo,Vander Freitas; Pauletti,Volnei.
ABSTRACT Variations in chemical and mineralogical properties of a soil can occur at short vertical and horizontal distances. The objective of the present study was to evaluate the chemical and mineralogical soil properties of different aggregate classes from young (Ustrochrept) and highly weathered (Acrustox) soils from the state of Paraná, Brazil. Undisturbed blocks (0.20 ×0.20 ×0.20 m) of soils were separated into aggregate classes: Acrustox – 8.0-4.0 mm; 4-2 mm; 2.0-0.5 mm; 0.5-0.2 mm; and <0.2 mm; and Ustrochrept – 8.0-4.0 mm; 4.0-2.0 mm; 2.0-0.5 mm; and 0.5-0.2 mm. The exchangeable K contents showed an opposite behavior for the two soils: higher contents in the Acrustox for the larger aggregate classes and higher contents in the Ustrochrept for the...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Kaolinite; Hematite; Goethite; Gibbsite; K reserve.
Ano: 2019 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-06832019000100401
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Field-scale spatial correlation between contents of iron oxides and CO2 emission in an Oxisol cultivated with sugarcane Scientia Agricola
Bahia,Angélica Santos Rabelo de Souza; Marques Júnior,José; Panosso,Alan Rodrigo; Camargo,Livia Arantes; Siqueira,Diego Silva; Teixeira,Daniel De Bortoli; Scala Júnior,Newton La.
Soil CO2 emission (FCO2) is one of the main sources of carbon release into the atmosphere. Moreover, FCO2 is related to soil attributes governing the transfer of gases from soil to the atmosphere. This study aimed firstly to describe the spatial variability of hematite (Hm), goethite (Gt), iron extracted with sodium dithionite-citrate-bicarbonate (Fed) contents, soil CO2 emission (FCO2) and free-water porosity (FWP) and secondly, to develop statistical models to predict the above mentioned factors in an Oxisol cultivated under manual harvesting of sugarcane (Saccharumspp.) in southeastern Brazil. The study was conducted on an irregular 50 m × 50 m grid containing 89 points, each 0.5-10 m apart. The 0-0.1 m soil layer at each sampling point was used to...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Hematite; Goethite; Soil respiration; Geostatistics; Cross-semivariograms.
Ano: 2015 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0103-90162015000200157
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Iron oxides and organic matter on soil phosphorus availability Ciência e Agrotecnologia
Fink,Jessé Rodrigo; Inda,Alberto Vasconcellos; Tiecher,Tales; Barrón,Vidal.
ABSTRACT Continuous crop expansion has led to a growing demand for phosphate fertilizers. A sound knowledge of the dynamics of phosphorus, and its interaction with iron oxides and organic matter, can be useful to develop effective strategies for sustainable management, especially in a scenario of increasing shortage of mineral phosphate resources. In this paper, we review the relationship of phosphate to iron oxides and organic matter, and its effect on phosphorus availability. Crops typically obtain phosphate from weathered minerals and dissolved fertilizers. However, the amount of phosphorus present in the soil solution depends on the extent to which it is adsorbed or desorbed by iron oxides, which may be influenced by interactions with organic matter....
Tipo: Info:eu-repo/semantics/article Palavras-chave: Goethite; Hematite; Phosphorus adsorption; Phosphorus desorption; Organic carbon.
Ano: 2016 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1413-70542016000400369
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Iron oxides dynamics in a subtropical Brazilian Paleudult under long-term no-tillage management Scientia Agricola
Inda,Alberto Vasconcellos; Torrent,José; Barrón,Vidal; Bayer,Cimélio; Fink,Jessé Rodrigo.
Replacing conventional tillage (CT) with no-tillage (NT) management alters the pedoenvironment and the rate of topsoil processes, with possible effects on dissolution processes associated with iron oxides and therefore soil mineralogy. This study aimed to determine the effect of NT on the content and distribution of types of iron oxides in a Rhodic Paleudult in southern Brazil. Soil samples were collected at eight depths within the 0.00-0.80 m layer under CT and NT in a long-term experiment (21 years). Mineralogical identification was conducted by X-ray diffraction (XRD), and the Fe content related to specific types of iron oxides determined by selective dissolution and diffuse-reflectance spectroscopy. Kaolinite, quartz, goethite, hematite, and maghemite...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Dissolution; Ferrihydrite; Hematite; Maghemite; Soil management.
Ano: 2013 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0103-90162013000100008
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Iron oxides in plinthic soils on sedimentary deposits in northeastern Brazil Rev. Bras. Ciênc. Solo
Heck,R. J.; Mermut,A. R.; Santos,M. C..
This study was conducted to examine the distribution and nature of Fe oxides in plinthic soils on the sediments of Barreiras Group (in the state of Piauí) and Itapecuru Formation (in the state of Maranhão) in Northeastern Brazil. Four pedons were selected: a "plinthic, dystrophic, epieutrophic Gray Podzolic with low activity clay" and a "dystrophic Plinthosol with low activity clay" (both Plinthic Kandiustalfs) on the Barreiras sediments, as well as an "eutrophic Plinthosol with low activity clay" and an "allic Plinthosol with low activity clay" (both Plinthustalfs) on the Itapecuru sediments. Soil samples were fractionated into > 2 mm (pisoliths), water-stable aggregates (plinthite) and matrices; the aggregates and matrices were further fractionated...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Plinthosol; Ustalf; Barreiras Group; Itapecuru Formation; Citrate; Dithionite; Oxalate; X-ray diffraction; Aluminum; Goethite; Hematite.
Ano: 1999 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-06831999000300019
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Magnetic and spectral signatures of Cerrado soils in the state of Goiás, Brazil PAB
Fernandes,Kathleen Lourenço; Ribon,Adriana Aparecida; Marques Junior,José; Bahia,Angélica Santos Rabelo de Souza; Tavares Filho,João.
Abstract: The objective of this work was to estimate the iron oxide contents (hematite and goethite) and to characterize the color and the spectral and magnetic signatures of Cerrado soils in the state of Goiás, Brazil. Six Oxisols and one Inceptisol were studied. Spectral and magnetic signatures were determined by diffuse reflectance spectroscopy (DRS) and magnetic susceptibility, respectively. Then, the spectral curves and the second derivative calculations were used to determine hematite and goethite contents, as well as soil color after conversion into tristimulus values. Hematite and goethite contents were also obtained by x-ray diffractometry, and soil color was also defined in the field (Munsell color chart). The values for the isomorphic...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Diffuse reflectance spectroscopy; Goethite; Hematite; Magnetic susceptibility; Oxisols.
Ano: 2017 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-204X2017001000923
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Magnetite and its transformation to hematite in a soil derived from steatite. Repositório Alice
SANTANA, G.P.; FABRIS, J.D.; GOULART, A.T.; SANTANA, D. P..
O presente trabalho objetivou caracterizar o mineral magnetico e identificar suas rotas pedogeneticas de transformacao em um solo formado sobre esteatito, de Minas Gerais, Brasil. O oxido de ferro isoestrutural ao espinelio foi identificado e caracterizado por analises quimicas, difracao de raios X, espectroscopia Mossbauer e medidas de magnetizacao de saturacao. Na rocha fresca, foi encontrada magnetita estequiometrica e bem cristalizada, com parametro da rede cubica, ao = 0.8407(5) nm. Nas fracoes areia e silte, foram detectadas magnetita parcialmente alterada e hematita estequiometrica e bem cristalizada, com parametros de rede hexagonal, a = 0.5036(3) nm e c = 1.375(4)nm. A ocorrencia dessas hematitas deveu-se principalmente a oxidacao do Fe2+ a Fe3+,...
Tipo: Artigo em periódico indexado (ALICE) Palavras-chave: Solo magnetico; Oxido de ferro; Pedra sabao; Espectroscopia; Mossbauer; Magnetita; Hematita; Esteatito; Magnetic soil; Spectroscopy; Iron rich; Iron oxide; Magnetite; Hematite; Steatite.
Ano: 2001 URL: http://www.alice.cnptia.embrapa.br/handle/doc/484715
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Mineralogy of the clay fraction of Alfisols in two slope curvatures: III - spatial variability Rev. Bras. Ciênc. Solo
Camargo,Livia Arantes; Marques Júnior,José; Pereira,Gener Tadeu.
A good knowledge of the spatial distribution of clay minerals in the landscape facilitates the understanding of the influence of relief on the content and crystallographic attributes of soil minerals such as goethite, hematite, kaolinite and gibbsite. This study aimed at describing the relationships between the mineral properties of the clay fraction and landscape shapes by determining the mineral properties of goethite, hematite, kaolinite and gibbsite, and assessing their dependence and spatial variability, in two slope curvatures. To this end, two 100 × 100 m grids were used to establish a total of 121 regularly spaced georeferenced sampling nodes 10 m apart. Samples were collected from the layer 0.0-0.2 m and analysed for iron oxides, and kaolinite and...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Iron oxides; Kaolinite; Gibbsite; Goethite; Hematite; Relief.
Ano: 2013 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-06832013000200001
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Óxidos de ferro de solos formados sobre gnaisse do Complexo Bação, Quadrilátero Ferrífero, Minas Gerais. Repositório Alice
FIGUEIREDO, M. do A.; FABRIS, J.D.; VARAJÃO, A.F.D.C.; COUCEIRO, P.R. da C.; LOUTFI, I.S.; AZEVEDO, I. de S.; GARG, V.K..
O objetivo deste trabalho foi efetuar a caracterização mineralógica dos óxidos de ferro de horizontes B de três perfis de solos desenvolvidos sobre gnaisse do geodomínio do Complexo Bação, no Quadrilátero Ferrífero, em Minas Gerais. As amostras foram coletadas ao longo dos segmentos de alta, média e baixa vertente. As frações de terra fina (diâmetro médio, f = 2 mm) foram separadas, em todas as amostras. A composição química dos elementos maiores foi determinada por meio da técnica de fluorescência de raios X; a análise mineralógica foi realizada com difratometria de raios X e espectroscopia Mössbauer. Todas as amostras têm composição mineralógica similar, cuja ocorrência geral corresponde à seqüência quartzo >> gibbsita > caulinita > goethita....
Tipo: Artigo em periódico indexado (ALICE) Palavras-chave: Hematita; Goethita; Espectroscopia Mössbauer; Substituição de alumínio; Hematite; Goethite; Mössbauer spectroscopy; Aluminium substitution.
Ano: 2006 URL: http://www.alice.cnptia.embrapa.br/handle/doc/118453
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Pedogenic Iron Oxides in Iron-Rich Oxisols Developed from Mafic Rocks Rev. Bras. Ciênc. Solo
Camêlo,Danilo de Lima; Ker,João Carlos; Fontes,Maurício Paulo Ferreira; Corrêa,Marcelo Metri; Costa,Antonio Carlos Saraiva da; Melo,Vander Freitas.
ABSTRACT Despite the considerable amount of information on the mineralogical characteristics of pedogenic Fe oxides in Brazilian soils, there are few studies on Fe-rich soils developed from mafic rocks with taxonomic identities at lower categorical levels. This study evaluated the mineralogical characteristics of pedogenic Fe oxides in B horizons (Bw) of Fe-rich Oxisols developed from several mafic rocks in the state of Minas Gerais, Brazil. The Bw horizons were sampled at a 0.8-1.0 m depth in 13 Ferric and Perferric Rhodic Oxisols along with a Mesoferric Typic Oxisol originating from basalt, gabbro, tuffite, amphibolite and itabirite in Minas Gerais. The selected soils have taxonomic identities up to the fourth categorical level of the Brazilian System of...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Hematite; Maghemite; Crystallographic characteristics; Al-substitution; Selective dissolution.
Ano: 2017 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-06832017000100413
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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
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Sunlight-driven water splitting using hematite nanorod photoelectrodes Anais da ABC (AABC)
SOUZA,FLAVIO L..
ABSTRACT The efficiency of nanostructures for photoelectrochemical water-splitting is fundamentally governed by the capability of the surface to sustain the reaction without electron trapping or recombination by photogenerated holes. This brief review will summarize the latest progress on hematite, designed with columnar morphology via chemical synthesis, for photoelectrochemical cell application. The columnar morphology efficiently minimizes the number of defects, grain boundaries, and surface traps normally present on the planar morphology. The major drawback related to hole diffusion through the solid/liquid interface was addressed by using high annealing temperature combined with dopant addition. A critical view and depth of understanding of these two...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Sunlight irradiation; Water oxidation reaction; Photoanode; Hematite; Columnar morphology.
Ano: 2018 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0001-37652018000200745
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