CONCENTRATION AND SPECIATION OF Cu, Ni, Pb and Zn IN CULTIVATED AND UNCULTIVATED SOILS

This research was carried out to determine the concentration and speciation of some heavy metals in cultivated and uncultivated soils of northwestern Turkey. The total of 50 cultivated soil samples (25 Ultisols and 25 Inceptisols) were collected from some major vegetable growing areas developed over granite (Ultisols) and riverine alluvium (Inceptisols) from Bursa province, Turkey. The Cu, Ni, Pb and Zn were determined by the aqua regia method. The mean values of total heavy metals for the cultivated Ultisols are Cu (21.2 mg kg(-1)), Ni (15.1 mg kg(-1)), Pb (19.2 mg kg(-1)) and Zn (59.7 mg kg(-1)) while those of the cultivated Inceptisols show higher values of Cu (43.6 mg kg(-1)), Zn (79.9 mg kg(-1)) while Pb (13.0 mg kg(-1)) and Ni (7.7 mg kg(-1)) in Inceptisols are lower. The general trend in the Ultisols for Pb and Ni is residual > oxalate >exchangeable>organic. The oxalate extractable phase is highest followed by the residual phase for Zn and Cu. However, all the metals are highest in the residual phase for the Inceptisols. Zinc and lead contents in the Ultisols are also positively correlated to pH of the soil.