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artículo con referato
"Selective Dissolution Techniques, X-Ray Diffraction and Mössbauer Spectroscopy Studies of Forms of Fe in Particle-Size Fractions of an Entic Haplustoll"
S.G. Acebal, M.E. Aguirre, R.M. Santamaría, A. Mijovilovich, S. Petrick and C. Saragovi
Hyperfine. Interact. 148-149(1-4) (2003) 3-12
Particle-size fractions (O = mean diameter, 5-2 µm, 2-1 µm, and < 1 µm) from the Ap horizon of an Entic Haplustoll from Argentina were treated with the selective-dissolution techniques ammonium oxalate (OX), dithionite-citrate-bicarbonate (DCB), NaOH, and Na-pyrophosphate (PY), and studied by X-ray powder diffraction (XRD) and 57Fe Mössbauer spectroscopy (MS). Quartz, feldspar, smectite, illite and interstratified illite-smectite are the dominant minerals whereas Fe oxides and oxy-hydroxides are present in low concentration but increase as particle size decreases. Poorly crystallized oxides (highly Al-substituted hematite and goethite) amounts are lower, comparable to or slightly higher than the hematite amounts in the O = 5-2 µm, 2-1 µm and < 1 µm fractions respectively. This hematite is well crystallized but presents some degree of Al-substitution. Magnetite/maghemite was identified in the 2-1 µm fraction. Paramagnetic Fe3+ and Fe2+ are associated to the clay minerals and/or hydroxyl-interlayered 2:1 type material present; part of this Fe3+ is located in the hydroxy-interlayers its amount being higher in the smallest fraction. Any possible changes after the PY and NaOH treatments were not detected by MS.
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