Quantitative speciation of Zn in technosols using chemical fractionation and X-ray absorption spectroscopy

摘要

Human activity, such as mining, is often detrimental to the environment. For risk assessment of polluted soils, it is crucial to establish the speciation of the contaminants such as zinc. The aim of the work was to identify the Zn species in contaminated anthropogenically transformed soils known as 'spolic technosols'. The Zn speciation in technosols was studied using a combined fractionation scheme and a set of X-ray synchrotron methods. Spolic technosols within the Karabashmed Company zone of the southern Urals have a very high level of Zn contamination. The role of soil components in metal fixation in both the loosely and firmly bound states were revealed. Iron oxides actively participate in the immobilization of Zn. The study of the local structure of technosols by X-ray absorption spectroscopy showed that Zn is coordinated to six oxygen atoms forming a distorted octahedron with Zn-O bond lengths close to those in ZnSO4. The presence of short bonds, formed by Zn atoms, has been also revealed. Thus, the application of two independent methods can be helpful in defining Zn speciation in polluted soils.