Readily-extractable hydroxyaluminium interlayers in clay- and silt-sized vermiculite

Abstract

The dominant source of oxalate-soluble Al in the B horizon of a brown podzolic soil developed on andesite appears to be hydroxyaluminium interlayers in a dioctahedral vermiculite in the clay and silt fractions, of which the latter contributes most to the total extractable Al and fluoride reactivity of the whole soil. Cold sodium carbonate solutions extract as much interlayer Al as does oxalate, indicating that this fraction of the interlayer material is highly reactive, and sharply distinguished from more resistant interlayers which are also present.

Nature and origin of an aluminous vermiculitic weathering product in acid soils from upland catchments in Scotland

“…The increasing amount of interstratified micavermiculite towards the surface of the profiles described indicates that vermiculitization of mica takes place in these soils also, and from the structural formulae, it appears that it is dioctahedral vermiculite that is being formed from dioctahedral mica. Formation of dioctahedral hydroxy-interlayer vermiculite from dioctahedral mica was suggested by Brown (1953) and more recently was confirmed by transmission electron microscopy (from the nature of the electron diffraction patterns) by Farmer et al (1988) in the clay and silt fraction from a brown podzolic soil on andesite. The only structural formulae available for natural hydroxy-interlayered minerals are approximations made by Kirkland & Hajek (1972) for minerals in some Alabama soils.…”

Fracionamento do alumínio por técnicas de dissoluções seletivas em espodossolos da planície costeira do Estado de São Paulo

“…A remoção de conteúdos similares entre os extratores já foi constatada anteriormente, bem como relatado por Gomes et al (2007) 2,90, respectivamente). Esses resultados sugerem falta de especificidade dos extratores para Al: seja do pirofosfato para formas do elemento unicamente associadas à matéria orgânica, as quais podem incluir óxidos (Soon, 1993), tal como relatado por vários autores (Bascomb, 1968;Higashi et al, 1981;McKeague & Schuppli, 1982;Soon, 1993;Kaiser & Zech, 1996;Sauer et al, 2007), seja do oxalato (Iyengar et al, 1981;Shoji & Fujiwara, 1984;Farmer et al, 1988;Skjemstad et al, 1992a) ou ditionito (Farmer et al, 1983;García-Rodeja et al, 2004).…”

“…Considera-se que o Al extraído por oxalato representa a soma do Al presente na alofana (Parfitt & Henmi, 1982;Kodama & Ross, 1991) e em alguma imogolita, em complexos orgânicos (McKeague & Day, 1966;McKeague et al, 1971;Parfitt & Henmi, 1982;Kodama & Ross, 1991;García-Rodeja et al, 2004), e, em menores conteúdos, pode representar o elemento substituído na estrutura de óxidos de Fe de baixa cristalinidade (Parfitt & Henmi, 1982;Parfitt & Childs, 1988), bem como pode extrair uma pequena fração do elemento da gibbsita (Parfitt & Childs, 1988;Kodama & Ross, 1991) e do Al-hidroxi entrecamada de argilas silicatadas 2:1 (Shoji & Fujiwara, 1984;Farmer et al, 1988;Iyengar et al, 1981). Para determinados solos, representa o pool de Al lábil, com potencial para regular a solubilidade do elemento na solução do solo (Takahashi et al, 1995), bem como proporciona razoável estimativa do total de Al translocado no perfil (Childs et al, 1983).…”

High-Charge Smectite in Spanish “Raña” Soils

“…The hydroxy-interlayered 2:1 clay minerals may have been formed from the illite transformation (April et al, 1986;Farmer et al, 1988) and its presence (Table 2) may be restricted to the surface horizons (Barnhisel and Bertsch, 1989). Illite was probably transformed into hydroxy-interlayered 2:1 clays in the surface horizons, whereas high-charge smectite was formed in the deeper horizons.…”