Total and extractable forms of Cu, Zn, Ni, Cr, and Fe in vineyard soil (Valandovo valley, Macedonia) determined by a sequential extraction procedure

Abstract

The total and extractable forms of Cu, Zn, Pb, Ni, Cr, and Fe in vineyard soils from Valandovo valley were analyzed in order to understand the existence of metals in soils and their potential availability to the flora and fauna. The metals (Cu, Zn, Ni, Pb, Cr, and Fe) in soil was determined by by ICP-EAS and sequential extraction procedure [5]. Other chemical and physical properties such as pH, CEC (cation exchange capacity), organic matter, carbonate and particle size of soils collected from vineyards plots were also analyzed. The total concentrations of Cu, Zn, Pb, Ni, Cr, and Fe in almost all soil samples does not exceed the maximum permissible concentrations (MPC) of trace elements in agricultural soils proposed by Kabata-Pendias and Pendias (2001). The only exception was the soil sample R (3), where higher concentrations were measured especially for Fe, Ni and Cr, and to a lesser extent Cu and Zn. Sequence extraction shows that the distribution of metals increase in order: oxidisable (e.g., organic substance and sulphides) > fraction bound in the crystal lattice of silicate minerals (residual fraction) > reducible (e.g., iron/manganese oxides) > exchangeable, water and acid soluble (e.g., carbonates). The prevalence of metals in oxidisable fraction in the soil shows that this fraction has a dominant role in controlling the behavior and transport of these metals in soil. The low levels of metals in exchangeable and carbonate bound fraction (Ni (7,5%)>Pb (3,5%)> Cu (2,6%)> Zn (2,2%)> Cr (0,2%)) indicates a low rate of activity and mobility of these metals in soil solution caused by the current physico-chemical conditions in soil.