The role of pedogenic processes and soil characteristics on nickel distribution in some Oxiaquic Paleudalfs

Abstract:Soil properties and pedogenic processes can significantly affect heavy metals accumulation and distribution in soils. In order to study the effective factors on nickel distribution, seven soil profiles containing Fe-Mn concentrations with Oxiaquic Paleudalfs classification were investigated. Nitric acid extractable iron (Fet), manganese (Mnt), free iron oxides (Fed), amorphous iron (Feo) and some soil properties (OC, CEC, Clay, and pH) were measured and their correlations with nitric acid extractable Nickel (Nit) were investigated. In addition, Fe and Mn concentrations and their adjacent soils were separated and then Fet, Mnt, Nit, Feo and Fed were measured in them. Mineralogical study showed that vermiculite, smectite, mica and kaolinite were dominant clay minerals in the studied soils. Lepidocrocite, goethite, ferrihydrite and birnessite were the minerals existed in the Fe-Mn concentrations. The results showed that Nit had a significant and positive correlation with Fe d and clay as well as significantly and negatively correlated with OC, Mnt and Feo. The mean accumulation coefficient (K) of Ni in the Fe-Mn concentrations was 1.5, indicating the ability and role of pedogenic microzones in Ni accumulation. With regard to the results, the co-migration of clay and crystalline iron oxides (Lessivage) and Fe-Mn concentrations genesis can be considered as two main processes in the Ni distribution in the studied soil profiles.