The oxidation of organic matter coupled to the reduction of Fe(III) or Mn(IV) is one of the most important biogeochemical reactions in aquatic sediments, soils, and groundwater. This process, which may have been the first globally significant mechanism for the oxidation of organic matter to carbon dioxide, plays an important role in the oxidation of natural and contaminant organic compounds in ...

The distribution of the rare earths and yttrium (REY) in co-existing hydrous Mn oxides and Fe oxides that form marine hydrogenetic ferromanganese crusts is used to better describe the partitioning and fractionation of the REY between these (hydr)oxides and seawater in the natural marine system. Four fractions (easily exchangeable, Mn-oxide-bound, Fe-oxidebound, and insoluble-residue-bound REY) ...

The solid solution, sodium [iron(III)/manganese(II)] tris-(orthophosphate), Na₃.₄Mn₀.₄Fe₁.₆(PO₄)₃, was obtained using a flux method. Its crystal structure is related to that of NASICON-type compounds. The [(Mn/Fe)₂(PO₄)₃] framework is built up from an (Mn/Fe)O₆octa-hedron (site symmetry 3.), with a mixed Mn/Fe occupancy, and a PO₄ tetra-hedron (site symmetry .2). The Na⁺ cations are distributed...

Introduction: Composition of chondrites on Fe-MgMn diagram show distinct patterns that result from nebular processes like volatility-controlled Mn-Mg fractionation, metal/silicate fractionation under reducing conditions and subsequent oxidation leading to variations in FeO/MgO ratio [1]. As chondrules are the major constituent of chondrites (except CI) their effect on bulk chemical compositions...

Neurotoxicity due to excessive brain manganese (Mn) accumulation can occur via occupational exposure to aerosols or dusts that contain extremely high levels (>1-5 mg Mn/m(3)) of Mn, or metabolic aberrations (decreased biliary excretion). Given the putative role of astrocytes in regulating the movement of metals across the blood-brain barrier, we sought to examine the relationship between iron (...

This study selected solid wastes, such as rice husk ash (RHA), inactive Saccharomyces cerevisiae powder (ISP), and rice husk (RH), as the potential adsorbents for the removal of Fe(II) and Mn(II) in aqueous solution. The structural characteristics, functional groups, and elemental compositions were determined by scanning electron microscope (SEM) and Fourier translation infrared spectrum (FT-IR...

although micronutrients effect on growth and yield of different plants has been intensively investigated, but there is limited information on its effect on grain yield and seed oil content of pot marigold) calendula officinalis l.). in order to investigate the effects of micronutrients (fe, zn and mn) spraying on yield and yield components and seed oil of pot marigold, a field experiment was co...

In several cases ethylenediaminetetraacetic acid (EDTA) proved to be an efficient mobilising amendment during chemically enhanced phytoextraction of heavy metals. The presence of Fe-(hydr)oxides and their dissolution after the addition of EDTA can limit the phytoextraction of the targeted heavy metals due to the high stability of the formed Fe(III)EDTA complexes. This study has focused on the i...

Metal accumulation in seeds is a prerequisite for germination and establishment of plants but also for micronutrient delivery to humans. To investigate metal transport processes and their interactions in seeds, we focused on METAL TOLERANCE PROTEIN8 (MTP8), a tonoplast transporter of the manganese (Mn) subclade of cation diffusion facilitators, which in Arabidopsis (Arabidopsis thaliana) is exp...