Fractionation and mobilization of toxic elements in floodplain soils from Egypt, Germany, and Greece: A comparison study

Abstract

Determining the chemical fractions of toxic elements (TEs) in soils is important to evaluate their mobilization and bioavailability. In this study, samples from three representative floodplain soils located close to the Rivers Nile (Egypt), Elbe (Germany), and Pinios (Greece) were used to link the soil formation and properties to the geochemical fractions and mobilization of cadmium (Cd), copper (Cu), nickel (Ni), lead (Pb), and zinc (Zn) in these soils. The Elbe soil showed the highest total concentration of the elements except for Ni, in which the Pinios soil had the highest amount. A significant amount (55–94%) of the elements was present in the Elbe soil in the potentially mobile (non-residual) fraction, while the amount of this fraction ranged between 9 and 39% in the Pinios soil and between 9 and 34% in the Nile soil. In the Elbe soil, most of the non-residual Ni, Pb, and Zn was associated with the Fe-Mn oxide fraction, while Cd was distributed in the soluble plus exchangeable fraction and Cu in the organic fraction. In the Nile and Pinios soils the Fe-Mn oxide fraction was the abundant pool for Cu, Ni, Pb, and Zn whereas Cd had the highest amount in the soluble plus exchangeable as well as in the carbonate fractions.