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Structure of short-range ordered aluminosilicates in andic horizons of volcanic soils

Basile-Doelsch Isabelle, Levard Clément, Doelsch Emmanuel, Abidin Z., Miche Hélène, Masion Armand, Rose Jérôme, Borschneck Daniel, Bottero Jean Yves. 2012. Structure of short-range ordered aluminosilicates in andic horizons of volcanic soils. In : 5 th International Workshop on Soil and Sedimentary Organic Matter Stabilization and Destabilization " Unifying concepts of organic matter dynamics in terrestrial and aquatic systems", Ascona, Swi tzerland, 7-11 October, 2012. Swiss Federal Institute of. s.l. : s.n., Résumé, 1 p. International Workshop on Soil and Sedimentary Organic Matter Stabilization and Destabilization " Unifying concepts of organic matter dynamics in terrestrial and aquatic systems". 5, Ascona, Suisse, 7 October 2012/11 October 2012.

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Abstract : Very high levels of C content characterize Andic horizons of volcanic soils. Stabilization of organic matter is due to the presence of short-range ordered aluminosilicates (imogolites, allophanes or proto-imogolites). These phases are often characterized through selective chemical extractions from which the "allophane" content is calculated. However, chemical dissolutions preclude the characterization of the structure of the short-range ordered aluminosilicates. Imogolite is easily distinguishable because of its tubular structure, whereas allophane compounds-usually described as spheres-are harder to identify, especially because of their variable structure and occurrence patterns. In addition, the local structure of allophanes can be very similar to that of proto-imogolite (imogolite precursor). Strangely, this similarity is seldom considered in most characterization studies. In this context, our study focuses on the structure of two short range-ordered aluminosilicates of two different origins, from: (i) an Andosol B horizon (Andosol sample); and (ii) a weathered pumice grain (pumice sample). These natural samples were compared to a synthetic proto-imogolite. The three samples were analyzed using experimental tools that are commonly used for the identification of these nanophases (chemical composition, X-ray diffraction, nuclear magnetic resonance, Fourier transform infrared spectroscopy and transmission electron microscopy). The three samples exhibited the same local structure, but significant differences were observed at a larger scale. The pumice sample clearly showed ring-shaped particles, while the Andosol sample and the synthetic proto-imogolite were amorphous. Our results suggest that poorly ordered proto-imogolite, rather than allophanes, is present in Andosol horizons. (Résumé d'auteur)

Classification Agris : P33 - Soil chemistry and physics
P32 - Soil classification and genesis

Auteurs et affiliations

  • Basile-Doelsch Isabelle, Université d'Aix-Marseille (FRA)
  • Levard Clément, Université d'Aix-Marseille (FRA)
  • Doelsch Emmanuel, CIRAD-PERSYST-UPR Recyclage et risque (FRA) ORCID: 0000-0002-7478-4296
  • Abidin Z., Ehime University (JPN)
  • Miche Hélène, Université d'Aix-Marseille (FRA)
  • Masion Armand, Université d'Aix-Marseille (FRA)
  • Rose Jérôme, Université d'Aix-Marseille (FRA)
  • Borschneck Daniel, Université d'Aix-Marseille (FRA)
  • Bottero Jean Yves, Université d'Aix-Marseille (FRA)

Source : Cirad - Agritrop (https://agritrop.cirad.fr/569240/)

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