Document Type : Research Paper
Authors
1
Ph. D. Student, Faculty of Agriculture & Natural Resource, University of Tehran, Tehran, Iran
2
Associate Professor, Faculty of Agriculture & Natural Resource, University of Tehran, Tehran, Iran
3
Professors, Faculty of Agriculture & Natural Resource, University of Tehran, Tehran, Iran
Abstract
Soil reduces the hazardous effects of compounds on the components of ecosystem because of self –purification property and the ability for their fixation. Playing such a role in soils under redox conditions is performed by pedogenic Fe-Mn concentrations. In order to investigate cobalt, copper and lead accumulation in iron and manganese concentrations, at first the concentrations were precisely separated from the adjacent soil and nitric acid extractable iron (Fet), manganese (Mnt), Copper (Cut) and lead (Pbt); free iron oxides (Fed) and amorphous iron (Feo) were measured. Mineralogy of Fe-Mn concentrations were determined by x-ray diffraction (XRD) technique, and microscopic investigation and elemental analysis were performed using scanning electron microscopy. Mean of the enrichment coefficients for Fet, Mnt, Cot, Pbt, Cut, Feo and Fed were obtained 1.2, 12.41, 7, 4.47, 2.13, 2.16, 1.33 respectively. Existence of lepidocrosite and goethite were taken as evidence for a combination of alternative oxidation and reduction conditions in concentrations. Mn enrichment coefficient was rather high compared to Fe due to its higher mobility in soil. Distinct difference between Feo amount of soil and concentrations shows the specific conditions dominated in concentrations. High adsorption surface of Fe and Mn oxides with , more amorphous structures, alternative redox condition causing heavy metals trapping, chemical properties of heavy metal such as different valence for cobalt and low pk1 for Pb and Cu were the effective factors in accumulation of these heavy metals in concentrations.
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