A Comparison of Suitability of Mild Extraction Procedures for Determination of Available Portion of As, Cd and Zn in Soil

Abstract

Five extraction procedures were tested for the determination of extractable contents of As, Cd and Zn in thirty-five soils differing in their physicochemical properties and in element contents. The extractability from soils varied depending on the individual elements and the extraction agents used. The extractability of arsenic using various extractants decreased in the order NaHCO₃ &gt H₂O &gt CaCl₂ &gt NaNO₃ &gt NH₄NO₃. For cadmium and zinc, the order was: NaHCO₃ &gt CaCl₂ &gt NH₄NO₃ &gt H₂O > NaNO₃. Solutions of the neutral salts released approximately the amounts of the soil elements available to plants. For this reason, the extraction agents proved to be suitable for studying plant - soil relations. Of the solutions tested, 0.01 mol.l^-1 CaCl₂ seems to be the most appropriate for the purpose.