Microscopic structure of soil Fe-Mn nodules: environmental implication

Abstract

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.

Trace elements in ferromanganese concretions, gibbsite spots, and the surrounding terra rossa overlying dolomite: Their mobilization, redistribution and fractionation

“…Distinct iron and Mn negative relationships have been reported in Fe-Mn pans (Birnie and Paterson, 1991), Mn oxide accumulations (Sullivan and Koppi, 1992) and Fe-Mn nodules (Gasparatos et al, 2005;Schwertmann and Fanning, 1976) from various soils. The analysis of …”

Applicability of selective dissolution of manganese oxide by acidified 0.1M NH2OH–HCl in Japanese soils

“…Febdorf et al (1993) showed that Al in solution can form Al(OH) 3 on the surface of synthetic Mn oxides and can suppress the redox reaction between Cr (III)and Mn oxide. Otsuka (1980) showed that Al minerals such as gibbsite exist on the outer edges of volcanogenic Fe-Mn concretions (pisolite-like particles) collected from Andisols, whereas Gasparatos et al (2005) pointed out the homogenous distribution of Al in concretions of Alfisols. Noshiroya (1992) showed a negative relationship between acetic acid (pH 2.8)-soluble Fe and Alo (described in detail by Nanzyo et al, 1993), and the addition of synthetic noncrystalline Al hydroxide to alluvial soils depressed Fe(II)formation during laboratory incubation.…”

Estimation of Phosphorus Status of Soil Fe‐Enriched Concretions with the Acid Ammonium Oxalate Method

“…Nevertheless, in several studies, the main components of concretions are ferrihydrite and goethite or hematite with variable amounts of Al as substitutions, while Mn oxides were found to be fine-grained with relatively diffuse X-ray diffraction (XRD) peaks (Rhoton, Bigham, and Schulze 1993;Gasparatos, Haidouti, and Tarenidis 2004;Zhang and Karathanasis 1997;Singh and Gilkes 1996;Tokashiki, Dixon, and Golden 1986). The nature of Fe and Mn oxides in soil concretions is of great interest from the viewpoints of both pedogenesis and environmental chemistry (Gasparatos et al 2005). Studies on the dynamic role of Fe oxides in the soil system have shown the need for the expansion of current knowledge on the properties and morphology of natural secondary iron oxide accumulations such as concretions (Gasparatos, Haidouti, and Tarenidis 2004;Gasparatos et al 2005).…”

“…The nature of Fe and Mn oxides in soil concretions is of great interest from the viewpoints of both pedogenesis and environmental chemistry (Gasparatos et al 2005). Studies on the dynamic role of Fe oxides in the soil system have shown the need for the expansion of current knowledge on the properties and morphology of natural secondary iron oxide accumulations such as concretions (Gasparatos, Haidouti, and Tarenidis 2004;Gasparatos et al 2005).…”