PLANT, ELEMENT AND SOIL PROPERTIES GOVERNING UPTAKE AND AVAILABILITY OF HEAVY-METALS DERIVED FROM SEWAGE-SLUDGE

Coordinated pot experiments were conducted with soils from long-term field trials which had received large and/or frequent treatments with sewage sludge. A comparison of different plant species has confirmed that most dicotyledoneous plants absorb more heavy metals than the monocots do. An exception is ryegrass which absorbs Ni in unusually large amounts. Contrary to Cd, Zn and Ni, the uptake of Cu, Pb and Cr was rather small. The vegetative plant organs contained more Cd and Zn than the generative ones did. Only Cu and Ni were preferentially translocated into fruits and seeds. Compared with the soil contents, the plant roots accumulated Cd, Zn, Ni and Cu, but did not enrich Pb and Cr. Only the Cd, Zn and Ni contents were influenced by soil acidity, but no significant changes in uptake were found for Cu, Pb and Cr.