Extraction with EDTA to assess the global risk presented by heavy metals (Cd, Ni, Pb) in soils and sediments

Only part of the heavy metal load of pristine and polluted soils and sediments poses a risk for Man and the Environment. This fraction is usually estimated using either single or sequential chemical extraction procedures. Here we compare, for six solids collected in oxidizing environments, the sequential chemical extraction protocol of Tessier et al. (1979) and single extractions with HNO3 (at pH 2) or 0.01 M EDTA. The latter, a simple technique that is, moreover, independent of pH, provides results similar to the sum of all of the extractable metals in the sequential chemical scheme (total content minus the load associated with the residual phase) and is therefore proposed as a simple, easily implemented technique for evaluating the total potentially soluble fraction of metals in solids.