HEAVY METALS IN VEGETABLES FROM SOILS CONTAMINATED BY VARIOUS SOURCES

The present study aimed to assess the levels of heavy metals Pb, Cd, Cr, Cu, Zn and Ni in the leafy vegetables cultivated in soils contaminated by industrial and agricultural activities. The vegetable samples were collected from three sampling sites (industrial, agricultural and reference). The samples were digested by the mixture of HNO3 and H2O2, and the concentration of metals were measured by a Varian model SpectraA-200 Atomic Absorption Spectrometer. The results indicate that the metals analyzed were present in all the samples, except for Pb and Cr in two different samples, and the highest contents were observed for Cd, Pb and Zn at the industrial site, Cr, Cu at the agricultural site, and for Ni at the reference site, suggesting different sources of metals in vegetables. The significant correlation between Cu and Pb indicates that they may have a common source. The Cd and Pb contents respectively in all and in two vegetable samples collected from industrial and agricultural sites, exceed the safe limit set by the Codex Alimentarius Commission for human consumption. While the contents of other metals analyzed are below the safe limits. Therefore, regular monitoring of heavy metals in vegetables cultivated in contaminated soils is indispensable.