APPLICATION OF SOIL FRACTIONATION METHODS TO THE STUDY OF THE DISTRIBUTION OF POLLUTANT METALS

Three agricultural Fluvisols polluted by sewage sludge were dispersed by shaking in water or in organic solvent for particle size and density separations. The perturbations caused by the ultrasonic treatment were discussed. Only the carbonate particles were disrupted to very fine particles. The pollutant metals were not displaced by the treatments, except perhaps Cd that is partly soluble in water and in other solvents. We discussed the relationship between soil constitution and major element chemical analyses. We obtained enough different fractions by using the ultrasonic and other dispersion treatments and by fractionating versus two physical parameters (i.e. particle size and density), for a correlation study between the contents of major and trace elements. We found that Cu was the only element to be more concentrated in the “free” organic matter. Other metals were more concentrated within an organo‐mineral compartment, containing evoluted organic matter, fine clay and hydrous oxides. No pollutant metals were associated with carbonates, feldspars, and quartz. Other less general features were discussed. Copyright © 1990 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim