Iron Oxide Removal From Soils and Clays by a Dithionite–citrate System Buffered With Sodium Bicarbonate

Mehra, O. P.; Jackson, M. L.

doi:10.1016/b978-0-08-009235-5.50026-7

Cited by 1,055 publications

(767 citation statements)

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“…As formas de ferro livre (Fed) foram extraídas com ditionito-citrato-bicarbonato de sódio, pelo método de Mehra & Jackson (1960). Na extração dos óxidos de ferro mal cristalizados (Feo), foi utilizado o oxalato ácido de amônio (Camargo et al, 1986).…”

Section: Métodos De Campo E Amostragemunclassified

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Gênese de solos coesos do leste maranhense: relação solo-paisagem

Dantas

Júnior

Filho

et al. 2014

Rev. Bras. Ciênc. Solo

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RESUMOA ocorrência dos solos coesos no Brasil está relacionada dominantemente com os sedimentos argiloarenosos da Formação Barreiras, os quais estão geologicamente relacionados com os depósitos sedimentares do período Terciário, que constituem a unidade geomorfológica dos Tabuleiros Costeiros. Os objetivos deste trabalho foram identificar a ocorrência de solos coesos e estudar suas relações com a paisagem na região leste do Estado do Maranhão. A área do estudo localiza-se na Fazenda Typuana, região leste maranhense, no município de Brejo, MA, nas coordenadas geográficas de 03 o 36' S e 42 o 52' W. A vegetação predominante da área de estudo é do tipo Cerrado, com uma composição florística diversificada. Foram abertas três trincheiras, uma em cada área do estudo, com distintas formações vegetais para as caracterizações morfológica, física, química, mineralógica e a classificação taxonômica dos solos. A caulinita foi o mineral predominante nos horizontes coesos, porém seu grau de cristalinidade não influenciou na variação da densidade do solo (1,40 a 1,56 kg dm -3 ) e na resistência à penetração (1,24 a 2,18 MPa). Constatou-se que a posição da paisagem foi determinante para a distinção dos solos coesos, de modo que os desenvolvidos em pedoforma côncava apresentaram a maior expressão do caráter coeso e com maior status de fertilidade e matéria orgânica, refletindo na vegetação mais exuberante, caracterizada pelo Cerradão.Termos de indexação: pedogênese, Argissolos, Formação Barreiras.

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Section: Métodos De Campo E Amostragemunclassified

“…O mineral da fração argila caulinita (Ct) foi caracterizado por DRX, pelo método do pó. Na caracterização da Ct, a fração argila foi submetida à eliminação dos óxidos de Fe pelo método ditionito-citrato-bicarbonato, segundo Mehra & Jackson (1960), e peneirada em malha de 0,10 mm.…”

Section: Análise Mineralógicaunclassified

Gênese de solos coesos do leste maranhense: relação solo-paisagem

Dantas

Júnior

Filho

et al. 2014

Rev. Bras. Ciênc. Solo

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“…Total sulfur (S t ) was determined by combustion using a Leco total C, N, S analyzer (Leco Corp. St. Joseph MI). Sodium citrate bicarbonate dithionite (CBD) solution extracts both the crystalline and poorly crystalline (amorphous) Al oxides [16], while the ammonium oxalate (AO) solution extracts the poorly crystalline (amorphous)…”

Section: Core Materials Geochemical Analysismentioning

confidence: 99%

“…Free Al oxides (Al d ) were extracted by shaking over-night ~2.0 gr of core material in 24 ml of 0.3M CBD solution until the material changed to a gray color (generally 3 times) [16]. Uranium was also extracted with the AO solution (U o ) and CBD solution (U d ).…”

Section: Core Materials Geochemical Analysismentioning

confidence: 99%

Distribution of uranium and thorium in dolomitic gravel fill and shale saprolite

Phillips¹,

Watson

2015

Journal of Hazardous Materials

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The objectives of this study were to examine 1) the distribution of U and Th in dolomitic gravel fill and shale saprolite, and 2) the removal of uranium from acidic groundwater by dolomitic gravel through precipitation with amorphous basaluminite at the U.S. DOE Oak Ridge Integrated Field Research Challenge (ORIFRC) field site west of the Oak Ridge Y-12 National Security Complex in East Tennessee. Media reactivity and sustainability are a technical concern with the deployment of any subsurface reactive media. Because the gravel was placed in the subsurface and exposed to contaminated groundwater for over 20 years, it provided a unique opportunity to study the solid and water phase geochemical conditions within the media after this length of exposure. This study illustrates that dolomite gravel can remove U from acidic contaminated groundwater with high levels of Al 3+ , Ca 2+ , NO 3-, and SO 4 2-over the long term. As the groundwater flows through high pH carbonate gravel, U containing amorphous basaluminite precipitates as the pH increases. This is due to an increase in groundwater pH from 3.2 to ~6.5 as it comes in contact with the gravel. Therefore, carbonate gravel could be considered as a possible treatment medium for removal and sequestration of U and other pH sensitive metals from acidic contaminated groundwater. Thorium concentrations are also high in the carbonate gravel. Thorium generally shows an inverse relationship with U from the surface down into the deeper saprolite. Barite precipitated in the shallow saprolite directly below the dolomitic gravel from barium present in the acidic contaminated groundwater. the distribution of U and Th in dolomitic gravel, and 2) the removal of uranium from acidic groundwater by dolomitic gravel through precipitation with amorphous basaluminite on a large-scale under field conditions 20 years after placement. This study 5 provided a unique opportunity to examine the solid and water phase geochemical conditions within the media after this long-term exposure. MATERIALS AND METHODS Study Area and Geological MaterialsThe cores were recovered from Area 4 at the ORIFRC site on the Y-12 National Security Complex on the ORR in Oak Ridge, Tennessee (Fig. 1). The cores were composed of a weakly developed soil (with Ap and Bw horizon) at the surface that formed over a 20-30 year period in soil material that was deposited over a gravel fill which covered the native highly weathered shale saprolite. The gravel fill is composed of dolomite fragments (2mm to 3cm) and fine material (<2mm), and probably excavated Sample Collection, Preparation and Descriptions 6The sections of the two undisturbed continuous cores (2.5" diameter) (6.35 cm)that are used in this study were sampled at the depths of 0-800 cm (FWB 408) and 269cm(top of water table) to 847cm (FWB410), by a pneumatic hammer-drive coring devise by driving the corer containing a polyurethane tube through a hollow barrel into the geological material. Core material was described according to Soil Survey Division Staff...

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“…The soil samples were also subjected to extraction of Fe with H 2 SO 4 concentrate in the ratio 1:1 (Donagema et al, 2011), with tribasic sodium dithionite, sodium citrate dihydrate, and sodium bicarbonate (DCB) (Mehra and Jackson, 1960), and with a 0.2 mol L -1 ammonium oxalate (AO) solution in acid medium (pH 3.0) in the dark (McKeague and Day, 1966). The Fe concentration in the H 2 SO 4 , the DCB, and the AO extracts were determined by AAS.…”

Section: Methodsmentioning

confidence: 99%

Boundary between Soil and Saprolite in Alisols in the South of Brazil

Pedron

Oliveira

Dalmolin

et al. 2015

Rev. Bras. Ciênc. Solo

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Despite numerous studies conducted on the lower limit of soil and its contact with saprolite layers, a great deal of work is left to standardize identification and annotation of these variables in the field. In shallow soils, the appropriately noting these limits or contacts is essential for determining their behavior and potential use. The aims of this study were to identify and define the field contact and/or transition zone between soil and saprolite in profiles of an Alisol derived from fine sandstone and siltstone/claystone in subtropical southern Brazil and to subsequently validate the field observations through a multivariate analysis of laboratory analytical data. In the six Alisol profiles evaluated, the sequence of horizons found was A, Bt, C, and Cr, where C was considered part of the soil due to its pedogenetic structure, and Cr was considered saprolite due to its rock structure. The morphological properties that were determined in the field and that were different between the B and C horizons and the Cr layer were color, structure, texture, and fragments of saprolite. According to the test of means, the properties that support the inclusion of the C horizon as part of the soil are sand, clay, water-dispersible clay, silt/clay ratio, macroporosity, total porosity, resistance to penetration, cation exchange capacity, fe extracted by DCB, Al, h+Al, and cation exchange capacity of clay. The properties that support the C horizon as a transition zone are silt, Ca, total organic C, and fe extracted by ammonium oxalate. Discriminant analysis indicated differences among the three horizons evaluated.

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Iron Oxide Removal From Soils and Clays by a Dithionite–citrate System Buffered With Sodium Bicarbonate

Cited by 1,055 publications

References 11 publications

Gênese de solos coesos do leste maranhense: relação solo-paisagem

Gênese de solos coesos do leste maranhense: relação solo-paisagem

Distribution of uranium and thorium in dolomitic gravel fill and shale saprolite

Boundary between Soil and Saprolite in Alisols in the South of Brazil

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