Microscopic structure of soil Fe-Mn nodules: environmental implication

The internal structure, iron and manganese distributions of Fe-Mn nodules from imperfectly drained soils of central Greece were studied by scanning electron microscopy (SEM) and elemental analysis. Nodules exhibited a differentiated structure with discontinuous concentric rings as expression of their redox history. Fe and Mn have shown distinct repartition and were distributed mainly in concentric bands. The microstructure and the arrangement of iron—manganese compounds reflect the periodical development and the relative slow accretion rates of the studied nodules. These properties provide ample opportunity for adsorption and isolation of heavy metals from the soil system.