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Characterization and stability of transition metal complexes of chestnut (Castanea sativa L.) leaf litter
Author(s) -
SENESI N.,
SPOSITO G.
Publication year - 1989
Publication title -
journal of soil science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.244
H-Index - 111
eISSN - 1365-2389
pISSN - 0022-4588
DOI - 10.1111/j.1365-2389.1989.tb01288.x
Subject(s) - chemistry , metal , distilled water , inner sphere electron transfer , infrared spectroscopy , coordination sphere , leaching (pedology) , litter , nuclear chemistry , inorganic chemistry , ion , soil water , organic chemistry , chromatography , agronomy , environmental science , biology , soil science
SUMMARY The water‐ and acid‐insoluble fractions of a chestnut ( Castanea sativa L.) leaf litter sample and their complexes with Cu(II), Fe(III), and Mn(II) prepared in the laboratory were characterized by major elemental analysis, total Cu, Fe, and Mn content, infrared (IR), and electron spin resonance (ESR) spectroscopy. The IR spectra revealed a broad typology of functional groups (particularly carboxyls) in the solid litter, whereas the ESR spectra showed the existence of indigenous organic free radical species, inner‐sphere Fe 3+ complexes, and outer‐sphere Mn 2+ complexes. The litter exhibited a high residual binding capacity for Cu, Fe, and Mn in chemical forms of differing stability against water leaching and proton exchange. The ESR spectra of the metal complexes prepared in the laboratory indicated that Fe 3+ and Cu 2+ formed highly water‐stable, inner‐sphere complexes, whereas Mn 2+ formed water‐labile, outer‐sphere complexes. Oxygen ligands of the litter were involved in metal complexation in all cases. The litter showed the highest affinity for Cu 2+ , followed by Fe 3+ and Mn 2+ , when it was reacted with a single metal, whereas it complexed Fe 3+ preferentially in the presence of both Cu 2+ and Fe 3+ . Only a limited portion of the metal ions retained at the pH of distilled water remained bound in stable forms by the litter when the pH was lowered. Thus, variations of pH in forest soils will significantly affect micronutrient metal content and mobility in leaf litter.