Página Inicial CNEA Laboratorio TANDAR Página Inicial TANDAR Historia del acelerador TANDAR Web interno Web mail
Inicio » Actividades I+D > Publicaciones 2000 > Iron-Oxide Mineralogy of a Mollisol from...
artículo con referato
"Iron-Oxide Mineralogy of a Mollisol from Argentina: A Study by Selective-Dissolution Techniques, X-Ray Diffraction, and Mössbauer Spectroscopy"
S.G. Acebal, A. Mijovilovich, E.H. Rueda, M.E. Aguirre and C. Saragovi
Clay. Clay Miner. 48(3) (2000) 322-330
Selective dissolution techniques by ammonium oxalate (OX), dithionite-citrate-bicarbonate (DCB), and dithionite-ethylenediaminetetraacetic acid (D-EDTA), X-ray diffraction and Mössbauer spectroscopy were used to identify and characterize iron oxides and oxyhydroxides in the <2-mm, <50-µm, and <2-µm size fractions of a Mollisol from Bahía Blanca, Argentina. Iron compounds are present at low concentrations in mixtures with quartz, Na-rich feldspar, illite, interstratified illite-montmorillonite, and traces of kaolinite. Total Fe and Al content increases as soil particle-size decreases, from 4.3 and 13.3 wt. % in the <2-mm size fraction to 8.5 and 22.8 wt. % in the clay fraction (<2µm), respectively. No more than 25-30 % of the total Fe is associated with crystalline and amorphous Fe oxides. Weakly ferromagnetic hematite and goethite were identified in the different fractions. These phases have small particle sizes and/or low crystallinity, and/or Al-substituted sites. Crystalline magnetite or maghemite is scarce. These Fe phases are probably coating coarser particles. In all fractions, the efficiency for Fe removal is highest for the D-EDTA treatment and least efficient for the OX method, regardless of fraction size. The opposite is true for Al removal. Poorly crystallized oxalate-soluble hematite and goethite are only present in coarser fractions. Poorly crystallized and crystalline DCB and D-EDTA-soluble hematite and goethite are present in coarser fractions, but do not exist in the clay fraction. DCB treatment probably dissolves Al in the 2:1 type minerals occurring in this soil, whereas D-EDTA dissolves Fe in hydroxy interlayers or silicate phases.
Av. Gral Paz y Constituyentes, San Martín, Pcia. de Buenos Aires, Argentina
Tel: (54-11) 6772-7007 - Fax: (54-11) 6772-7121