The aim of this study was to use the technique of diffusion gradients in thin films (DGT) to evaluate the availability of copper in soil with high presence of this metal treated with biosolids, and to compare this technique, in terms of metal extractability, with simple and sequential extraction procedures. The order of importance of the copper fractions in the soil was: residual > oxidizable > reducible > soluble. Biosolid application decreased of both soluble and reducible fractions and increased the amount of metal attached to the oxidizable fraction. Copper amount extracted by DGT from the soil solution was 13% of total metal in solution. In the case of soil, this amount was less than 0.3% of total metal. Furthermore, it was possible to directly relate the metal extracted by DGT with the available metal with CaCl2 or the metal bound to organic matter.
copper availability; DGT; sequential extraction; biosolid, metallic species
