Accumulation of Heavy Metals in Vegetables from Agricultural Soils

This study analyzed the heavy metals in vegetables cultivated in private gardens in Bregu i Matit, an important agricultural area in the NW Albania.The plant and soil samples taken from irrigated and non-irrigated fields in this area were analyzed for the concentrations of Cd, Cu, Zn, Pb and Ni using atomic absorption spectroscopy (AAS), after extraction by HNO3 and H2O2.The transfer factors (TF) were used to evaluate the risk of metal transfer from soil to plant and the FAO/WHO safe limits to assess the potential hazards of heavy metals to human health. The ranges of heavy metal concentrations ± standard deviation in vegetable samples were (mg kg-1): Cu 2.98-12.90 (±3.08), Ni 4.82-35.79 (±7.68), Zn <1-81.67 (±24.41), Cd 0.05-0.60 (±0.16) and Pb 0.03-0.44 (±0.11). The maximum contents of Cu, Cd, Zn and Pb were found in salad samples taken from the intensively irrigated fields and Ni in a salad sample from a moderately irrigated field, suggesting that the irrigation with polluted waterled to accumulation of heavy metals in plants. The TF was of the order Cd > Zn > Cu > Ni > Pb. The TF values indicate that only Cd was accumulated in plants.The contents of Cd in three vegetable samples, Pb in four samples, and Cu in one sample were above the safe limits set by the FAO/WHO for heavy metals in foods and vegetables indicating that consumption of vegetables grown in the studied soils could be dangerous to human health.