Differential dissolution of hematite and goethite in dithionite and its implication on soil yellowing

Jeanroy, E.; Rajot, Jean-Louis; Pillon, Patrick; Herbillon, A. J.

doi:10.1016/0016-7061(91)90027-q

Cited by 69 publications

(59 citation statements)

References 18 publications

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“…Although goethite and hematite differ in their stability towards reductive dissolution (Torrent et al, 1987;Bryant and Macedo, 1990;Jeanroy et al, 1991), the estimated Hm/(Hm+Gt) relationship within the topsoil layer did not indicate changes in the relative proportion of these oxides (Table 1), allowing combined interpretation of the Fe in the form of Hm and Gt (Fe Hm+Gt ).…”

Section: Resultsmentioning

confidence: 94%

“…Assessing these alterations will contribute to increase the knowledge of the physical and chemical behavior of tropical and subtropical NT-managed soils. Considering that different types of pedogenic iron oxides have distinct dissolution stabilities (Torrent et al, 1987;Bryant and Macedo, 1990;Jeanroy et al, 1991), this study aimed to determine the effect of long-term NT management on content and distribution of Fe relative to the types of iron oxides (goethite, hematite, maghemite, and ferrihydrite) in a subtropical Rhodic Paleudult compared to its CT-managed counterpart. In addition, it aimed to assess the effect of mineralogical alterations on the specific surface area of the soil clay fraction.…”

Section: Introductionmentioning

confidence: 99%

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Iron oxides dynamics in a subtropical Brazilian Paleudult under long-term no-tillage management

Inda

Torrent

Barrón

et al. 2013

Sci. agric. (Piracicaba, Braz.)

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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 were identified in the clay fraction. In the NT-managed soil, there was a decrease in the content of crystalline iron oxides and an increase in the content of poorly crystalline iron oxides with increasing proximity to the soil surface. These results suggest that iron oxides are rearranged in this soil by reductive dissolution of the crystalline types and neoformation of metastable ferrihydrite in topsoil layers, which should be assessed further in laboratory studies.

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Section: Resultsmentioning

confidence: 94%

Section: Introductionmentioning

confidence: 99%

Iron oxides dynamics in a subtropical Brazilian Paleudult under long-term no-tillage management

Inda

Torrent

Barrón

et al. 2013

Sci. agric. (Piracicaba, Braz.)

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“…Vertically-oriented thin sections (5.0 × 8.0 cm large and 30 µm thick) were prepared for micromorphological examination (Jongerius and Heintzberger, 1975).…”

Section: Methodsmentioning

confidence: 99%

“…Despite the removal of free iron, the clay fraction diffractograms of the Pedon 1 showed a small goethite peak of 0.418 nm (Figure 4). The citratebicarbonate-dithionite method is not very efficient in the removal of goethite with high isomorphic substitution by aluminum (Jeanroy et at., 1991;Möller & Lourenço, 1994). The mineralogical composition of these soils differs from the soils developed from similar parental material in the South and Southeast of Brazil.…”

Section: Mineralogy and Micromorphologymentioning

confidence: 99%

Characterization and classification of two soils derived from basic rocks in Pernambuco State Coast, Northeast Brazil

Oliveira¹,

Ferreira²,

Marques

2004

Sci. agric. (Piracicaba, Braz.)

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Geomorphic surfaces that present soils derived from basic rocks under warm and humid climate are unique scenarios for studying tropical soils. This paper aimed to characterize and classify two pedons derived from basalt at the Atlantic Forest Zone, Pernambuco State, Northeastern coast of Brazil. Two representative pedons (P1 and P2) were selected on a hillslope at the Cabo de Santo Agostinho municipality. Field macromorphological descriptions were carried out and soil horizon were sampled for physical, chemical, mineralogical and micromorphological characterization. The soils were classified, according to the Brazilian System of Soil Classification (and US Soil Taxonomy) as: "Latossolo Vermelho-Amarelo distroférrico argissólico" (Typic Hapludox) (P1) and "Nitossolo Vermelho distroférrico típico" (Rhodic Paleudult) (P2). Pedon 1 differs from Pedon 2 in some aspects. For instance, P1 presents more yellowish colors, absence of clay illuviation, more friable consistence and the prismatic structure undergoes transformation to angular and subangular blocks. Pedon 2 presents ferri-argilans and leptocutans which indicate that vertical and lateral illuviation of clay is an active process in their formation. These chemically poor and mineralogically uniform soils are a result of the high temperature and rainfall of the studied area.

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“…Como a estabilidade de cristais de goethita e hematita está relacionada principalmente com as características mineralógicas, a saber: a morfologia, tamanho dos cristais, cristalinidade e substituição do Fe 3+ por Al 3+ (Torrent et al, 1987), procedimentos químicos de dissolução seletiva podem ser utilizados para fracionar populações heterogêneas desses óxidos (Jeanroy et al, 1991;Singh & Gilkes, 1992), constituindo uma importante ferramenta para o estudo da (poli)gênese de solos altamente intemperizados.…”

Section: Seção II -Química E Mineralogia Do Solo Introduçãounclassified

Variabilidade de goethita e hematita via dissolução redutiva em solos de região tropical e subtropical

Inda

Kämpf

2005

Rev. Bras. Ciênc. Solo

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RESUMODezenove amostras de horizontes B latossólicos, uma de B plíntico, uma de B incipiente e uma de horizonte Cr foram submetidas a dissoluções seletivas da goethita e da hematita por ditionito-citratro-bicarbonato de sódio a 20 o C em intervalos de tempo entre 5 e 3.840 minutos. O diâmetro médio do cristal (DMC), área superficial específica (ASE) e substituição do ferro por Al (substituição por Al 3+ ) da goethita e da hematita nas amostras foram estimados, por difratometria de raios X (DRX), em subamostras não tratadas e em subamostras tratadas selecionadas ao longo das dissoluções seletivas. O controle das fases de goethita e hematita que persistiram após cada etapa da dissolução seletiva foi realizado pelo método da difratometria diferencial de raios X (DDRX). A cinética dissolutiva dos cristais foi descrita por meio da segmentação das curvas de dissolução do ferro no tempo em intervalos em que o comportamento dissolutivo foi linear. As taxas de dissolução nos diferentes segmentos lineares foram estimadas a partir do coeficiente angular da reta relativa a cada segmento. Em amostras goethíticas latossólicas, a metodologia discriminou diferentes fases de goethita (populações heterogêneas) quanto à substituição por Al 3+ , DMC e ASE e ofereceu condições para classificar o grau de estabilidade da goethita em baixa, média, alta e muito alta estabilidade. Amostras goethíticas oriundas de ambientes pedogênicos jovens e amostras hematíticas latossólicas caracterizaram-se pela maior homogeneidade de seus cristais, classificados como de baixa e média estabilidade. Nas amostras goethíticas, a proporção de cristais com maior estabilidade (alta substituição por Al 3+ e cristalinidade) em cada população mostrou associação positiva com a proporção de gibbsita em relação a caulinita nas amostras. A hematita apresentou menor resistência à dissolução por redução em relação à goethita, exceto quando a última combinou baixa substituição por Al 3+ e alta ASE. A caracterização de populações heterogêneas

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Differential dissolution of hematite and goethite in dithionite and its implication on soil yellowing

Cited by 69 publications

References 18 publications

Iron oxides dynamics in a subtropical Brazilian Paleudult under long-term no-tillage management

Iron oxides dynamics in a subtropical Brazilian Paleudult under long-term no-tillage management

Characterization and classification of two soils derived from basic rocks in Pernambuco State Coast, Northeast Brazil

Variabilidade de goethita e hematita via dissolução redutiva em solos de região tropical e subtropical

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