Characterization of Heavy Metals Contents in Various Plant Foods from Polluted Sites

Food safety and quality are a major public concern worldwide, regarding the risk associated with consumption of food stuffs contaminated with heavy metals as toxins. Bioavailability of metals occurring in soil is the basic source of its accumulation in plant food. The impact of soil pollution (due to urban and mining areas) on the food chain presents a challenge for many investigations. Bioavailability of metals in a potentially polluted soil and their possible transfer and bioaccumulation in several vegetable species and herbs was examined. Microwave digestion was applied for total digestion of the plant tissues, while on the soil samples open wet digestion with a mixture of acids was applied. Three extraction methods were implemented for determination of bioavailable metals in the soil. Atomic emission spectrometry with inductively coupled plasma was used for determination of the total contents of 21 elements. Significant enrichments in agricultural soil for As, Pb and Zn (in urban area), Cd, Cu and Ni (in a copper mine area), compared with the respective values from European standards were detected. On the basis of three different extraction methods, higher availability was assumed for both lithogenic and anthropogenic elements. Translocation factors higher than 1 were obtained for As, Cd, Cu, Ni, Pb and Zn. Higher root to shoot translocation of these metals indicated that plants species have vital characteristics to be used for phytoextraction of these metals. The obtained data also suggested that S. oleracea and R. acetosa were singled out to have a phytostabilization potential for Cd, Cu, Ni and Pb, while U. dioica only for Cu. Rumex acetosa has a potential for phytoextraction of Cd in urban and copper polluted areas