The effect of sewage sludges and composts on the extractability of heavy metals from soil

Abstract

In a field experiment heavy metals extractability from soil treated for two years with high rates of sewage sludges and composts was determined by a sequential extraction with H₂O, KNO₃ and DTPA. The extractable amounts of heavy metals showed a typical pattern over the two years with a maximum value 30 days after each addition of sludges. Increases in the KNO₃ and DTPA extractable fractions were observed for Zn, Cd and partially for Pb.