EFFECT OF LIMING AND SEWAGE SLUDGE ADDITION ON THE DISTRIBUTION OF THE FRACTION OF HEAVY METALS IN SOIL CONTAMINATED WITH NICKEL

The total content of Zn and Cr and its distribution in fractions separated according to the BCR procedure was determined in soil taken after a three-year pot experiment. The following factors were taken into account in the experiment: I - liming (0 Ca and Ca according to 1 Hh of soil as CaCO3); II - addition of sludge (without addition of sludge and addition of sludge from the wastewater treatment in Siedlce, applied at 2 gC . kg(-1) of soil); III - varied level of contamination with nickel (0, 50 and 100 mgNi . kg(-1) of soil as aqueous solution of NiCl2 center dot 6 H2O). Orchard grass (Dactylis Glomerata L.) was used as the test plant. The total content of Zn and Cr in soil was determined by ICP-AES, and the fractions of those metals by the 3-step BCR procedure. The total content of the metals in the analysed soil did not exceed the highest acceptable standards. Liming reduced the metal content in the exchangeable, reducible and organic matter-related fraction and increased their content in the residual fraction. Addition of sludge reduced the Zn and Cr content in the reducible and residual fraction and increased their total content and share in the organic matter-and sulphides-related fraction. No effect of the varied Ni amount on the total content of Zn and Cr or their distribution in the fractions has been found.