Suscetibilidade magnética do horizonte B de solos do Estado do Paraná

Silva, Alceu Rodrigues da; Souza, Ivan Granemann de; Costa, Antônio Carlos Saraiva da

doi:10.1590/s0100-06832010000200006

Cited by 24 publications

(17 citation statements)

References 21 publications

(40 reference statements)

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“…Regarding magnetic susceptibility, [74] found lower values of magnetic susceptibility in soils derived from rocks, such as gneiss, granite, quartzite, marble and dolomite, due to their lower content of Fe when compared to soils derived from mafic rocks. The presence of gneiss, granite, quartzite, marble and dolomite reduces the chances of ferromagnetic minerals to be formed [75], which is in agreement with the lower Fe content and magnetic susceptibility values found for gneiss-derived soils (LA, LVA and LVm) in comparison to the gabbro-derived soil (LVg) found in our study.…”

Section: Soil Classes Mappingmentioning

confidence: 88%

Proximal Sensing and Digital Terrain Models Applied to Digital Soil Mapping and Modeling of Brazilian Latosols (Oxisols)

et al. 2016

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Digital terrain models (DTM) have been used in soil mapping worldwide. When using such models, improved predictions are often attained with the input of extra variables provided by the use of proximal sensors, such as magnetometers and portable X-ray fluorescence scanners (pXRF). This work aimed to evaluate the efficiency of such tools for mapping soil classes and properties in tropical conditions. Soils were classified and sampled at 39 locations in a regular-grid design with a 200-m distance between samples. A pXRF and a magnetometer were used in all samples, and DTM values were obtained for every sampling site. Through visual analysis, boxplots were used to identify the best variables for distinguishing soil classes, which were further mapped using fuzzy logic. The map was then validated in the field. An ordinary least square regression model was used to predict sand and clay contents using DTM, pXRF and the magnetometer as predicting variables. Variables obtained with pXRF showed a greater ability for predicting soil classes (overall accuracy of 78% and 0.67 kappa index), as well as for estimating sand and clay contents than those acquired with DTM and the magnetometer. This study showed that pXRF offers additional variables that are key for mapping soils and predicting soil properties at a detailed scale. This would not be possible using only DTM or magnetic susceptibility.

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Section: Soil Classes Mappingmentioning

confidence: 88%

Proximal Sensing and Digital Terrain Models Applied to Digital Soil Mapping and Modeling of Brazilian Latosols (Oxisols)

et al. 2016

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“…Recently, many studies have investigated natural and synthetic maghemites because of their importance in magnetic soils Silva et al, 2010;Batista et al, 2010;Batista et al, 2011). Maghemite (γ-Fe 2 O 3 or Fe 8/3 1/3 O 4 ) is a cation-deficient spinel with Fe 3+ ions distributed among both tetrahedral (A) and octahedral (B) sites.…”

Section: Introductionmentioning

confidence: 99%

Structural and magnetic characterization of maghemites prepared from Al-substituted magnetites

Batista

Costa²,

Bigham

et al. 2013

Rev. Bras. Ciênc. Solo

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SUMMARYSynthetic aluminum-substituted maghemites were characterized by total chemical analysis, powder X-ray diffraction (XRD), Mössbauer spectroscopy (ME), and vibrating sample magnetometry (VSM). The aim was to determine the structural, magnetic, and hyperfine properties of γ γ γ γ γ-Fe 2-x Al x O 3 as the Al concentration is varied. The XRD results of the synthetic products were indexed exclusively as maghemite. Increasing Al for Fe substitution decreased the mean crystalline dimension and shifted all diffraction peaks to higher o 2θ θ θ θ θ angles. The a 0 dimension of the cubic unit cell decreased with increasing Al according to the equation a o = 0.8385 -3.63 x 10 -5 Al (R 2 = 0.94). Most Mössbauer spectra were composed of one sextet, but at the highest substitution rate of 142.5 mmol mol -1 Al, both a doublet and sextet were obtained at ≈ 300 K. All hyperfine parameters from the sub-spectra were consistent with high-spin Fe 3+ (0.2 a 0.7 mms -1 ) and suggested a strong superparamagnetic component associated with the doublet. The magnetic hyperfine field of the sextets decreased with the amount of Al-substitution [B hf (T) = 49.751 -0.1202Al; R 2 = 0.94] while the linewidth increased linearly. The saturation magnetization also decreased with increasing isomorphous substitution.Index terms: isomorphous substitution, hyperfine parameters, spinel, ferromagnetic.( RESUMO: CARACTERIZAÇÃO ESTRUTURAL E MAGNÉTICA DE MAGHEMITAS PREPARADAS A PARTIR DE MAGNETITAS SUBSTITUÍDAS COM AlMaghemitas sintéticas substituídas com Al foram caracterizadas por meio de análise química total, difratometria de raios-X (DRX), espectroscopia Mössbauer (EM) e magnetometria de amostra vibrante (MAV). Objetivou-se com este trabalho determinar as propriedades estruturais, magnéticas e hiperfinas de γ-Fe 2-x Al x O 3, conforme a variação da concentração de Al.Os resultados de DRX dos produtos sintéticos foram indexados somente para maghemita. Com o aumento da substituição de Fe por Al, o diâmetro médio do cristalito diminuiu e levou todos os picos de difração para maiores ângulos o 2θ. A dimensão a 0 da cela unitária cúbica decresceu com o aumento de Al, de acordo com a equação a o = 0,8385 -3,63 x 10 -5 Al (R 2 = 0,94). A maioria dos espectros Mössbauer foi composta de um sexteto, mas na taxa mais alta de substituição de 142,5 mmol mol -1 Al um doubleto e sexteto foram obtidos a ≈ 300 K. Todos os parâmetros hiperfinos do subespectro foram consistentes com o alto spin Fe 3+ (0,2 a 0,7 mms -1 ) e sugeriram um forte componente superparamagnético associado com o dubleto. O campo magnético hiperfino dos sextetos decresceram com a substituição de Al [B hf (T) = 49,751 -0,1202Al; R 2 = 0,94], enquanto as larguras da linha aumentaram de forma linear. A magnetização de saturação também diminuiu com o aumento da substituição isomórfica.Termos de indexação: substituição isomórfica, parâmetros hiperfinos, espinélio, ferrimagnético.

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“…The level of magnetic susceptibility depends on the concentration and characteristics of the minerals (composition, spatial structure and crystal size) (Verosub & Roberts, 1995;Fontes et al, 2000;Blundell et al, 2009;Silva et al, 2010). This soil property can be a useful tool to gain further insights on soil knowledge, aside from being fast and cheap, applied in a number of areas, e.g., environmental monitoring, paleoclimatology, limnology, archeology, stratigraphy, and in pedology (Chaparro et al, 2008).…”

Section: Introductionmentioning

confidence: 99%

Magnetic susceptibility to identify landscape segments on a detailed scale in the region of Jaboticabal, São Paulo, Brazil

Barrios

Marques

Panosso

et al. 2012

Rev. Bras. Ciênc. Solo

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SUMMARYThe agricultural potential is generally assessed and managed based on a onedimensional vision of the soil profile, however, the increased appreciation of sustainable production has stimulated studies on faster and more accurate evaluation techniques and methods of the agricultural potential on detailed scales. The objective of this study was to investigate the possibility of using soil magnetic susceptibility for the identification of landscape segments on a detailed scale in the region of Jaboticabal, São Paulo State. The studied area has two slope curvatures: linear and concave, subdivided into three landscape segments: upper slope (US, concave), middle slope (MS, linear) and lower slope (LS, linear). In each of these segments, 20 points were randomly sampled from a database with 207 samples forming a regular grid installed in each landscape segment. The soil physical and chemical properties, CO 2 emissions (FCO 2 ) and magnetic susceptibility (MS) of the samples were evaluated represented by: magnetic susceptibility of air-dried fine earth (MS ADFE ), magnetic susceptibility of the total sand fraction (MS TS ) and magnetic susceptibility of the clay fraction (MS Cl ) in the 0.00 0.15 m layer. The principal component analysis showed that MS is an important property that can be used to identify landscape segments, because the correlation of this property within the first principal component was high. The hierarchical cluster analysis method identified two groups based on the variables selected by principal component analysis; of the six selected variables, three were related to magnetic susceptibility. The landscape segments were differentiated similarly by

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Suscetibilidade magnética do horizonte B de solos do Estado do Paraná

Abstract: RESUMO(1) Recebido para publicação em fevereiro de 2009 e aprovado em novembro de 2009.

Cited by 24 publications

References 21 publications

Proximal Sensing and Digital Terrain Models Applied to Digital Soil Mapping and Modeling of Brazilian Latosols (Oxisols)

Proximal Sensing and Digital Terrain Models Applied to Digital Soil Mapping and Modeling of Brazilian Latosols (Oxisols)

Structural and magnetic characterization of maghemites prepared from Al-substituted magnetites

Magnetic susceptibility to identify landscape segments on a detailed scale in the region of Jaboticabal, São Paulo, Brazil

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