3. Results and discussion
3.1. Levels of heavy metals in soil
The concentrations of heavy metals (lg/g) in agricultural soil
collected from different crop production sites ranged from a minimum
of 9.8 to a maximum of 19.3 for Cu, 83–133 for Zn, 0.6–2.3 for
Cd and 2.9–10.3 for Pb (Table 2). The upper limits of Cu, Zn and Cd
in the soil during the present study were higher than the values reported
for uncontaminated soil (Cu; 15, Zn; 100 and Cd; 1 lg/g),
but were lower for Pb (50 lg/g) (Temmerman et al., 1984). The
crop production sites which were in the vicinity of brick kilns or