Redoximorphic features in Albeluvisols from south-western Ukraine

Polarizing microscopy and scanning electron microscopy were used to determine the distribution, size, shape, and chemical composition of Fe-Mn nodules in Albeluvisols (Retisols) from south-western Ukraine and the relationship of these pedological features with redox processes. Intrusive, impregnative, and depletion features were observed. The highest content of hard nodules is present in the upper part of the solum, indicating that cyclic redox processes occur most often above the illuvial horizon. The nodules are enriched in Fe and Mn (4-14 and 7-40 times, respectively). The chemical composition of the surface of the nodule in contact with microorganisms indicates their crucial role in the accumulation of Fe and Mn and nodule formation.