Investigation of Cobalt (Co) Distribution in Some Alfisols Containing Iron and Manganese Concentrations

Cobalt distribution varies by changing soil properties. Fe and Mn concentrations are considered as absorbant agents for heavy metals such as cobalt. In order to study of effective factors on cobalt distribution and the role of Fe and Mn concentrations in Co accumulation in soil seven profiles with same classification and containing Fe and Mn concentrations were investigated. Nitric acid extractable Fe (Fet), Mn (Mnt), non crystalline Fe (Feo), free iron oxides (Fed) and some soil properties (OC, pH, CEC, clay) were measured and their correlation with cobalt (Cot) were studied. Furthermore, both Fe and Mn concentrations and their adjacent soil analyzed for Fet, Mnt, Feo, Fed, and Cot and enrichment coefficients were measured for extracted elements. Mineralogical properties determined by X-ray diffraction (XRD). Scanning Electron Microscopy (SEM) and Energy Dispersive Spectrometry (EDS) were performed for Fe-Mn concentrations. Results showed that cobalt (Cot) positively and significantly correlated with Mnt and Feo while its correlation with clay and Fed as main controling factors of CEC was negative and significant. Cobalt’s correlation with Mnt and Feo demonstrated its occurrence in an unsuitable condition for crystallization.The negative correlation between cobalt with clay and Fed shows that its distribution slightkly affected by clay and crystalline Fe distribution and the resultant CEC. Mean enrichment coefficients of Mnt, Fet, Feo and Fed were 12.3, 1.19, 2.19,1.34 respectively. Cobalt enrichment coefficient was between 4.43-13.4 and in average 7.28. These results prove the ability of Fe-Mn concentrations in heavy metals accumulation and their impacts on distribution of them especially cobalt.