Formation of Aluminum-Substituted Goethite in Seasonally Waterlogged Rice Soils
1984
Karim, Zahurul
Three soils (Aeric Fluvaquentic Haplaquepts, Fluvaquentic Haplaquepts, and Rhodic Paleudults) were collected from three different typical paddy fields in Bangladesh. Goethite was the only crystalline hydrous iron oxide identified by X-ray diffraction, ranging in amount from approximately 4.78 to 12.05 mg g⁻¹ of soil. Aluminum substitution for iron in the soil goethites ranged from 5.38 to 12.69 mole %, the largest amount being in Fluvaquentic Haplaquepts. A probable process of formation of the soil goethite is discussed. Aluminum-substituted goethite was synthesized in simulated rice paddy conditions by the oxidation of Fe(II) solution in the presence of Si and Al. Synthetic goethites contained 3.8 to 6.4 mole % Al in their structures.
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