The phytoextraction potential of selected vegetable plants on Kosovo contaminated soils

Mining activities generate a great deal of particulate emissions and waste slag enriched in heavy metals that contaminate the surrounding, that is soil, water and air. Such effects are particularly serious and pose a severe ecological and human health risk, mainly if smelters are located in the proximity of urban areas. This is the case regarding the Kosovo, where from the 1930s the British company "Seltrust" founded Trepca Mining & Metallurgical Complex, causing a high level of pollution especially in the area of Mitrovicë, northern Kosovo. Two soils, A and B, have been sampled from two different sites in Mitrovicë municipality, showing a total content of Pb and Zn, respectively, of 2153 and 3087 mg kg^-1, and 3214 and 4619 mg kg^-1. A pot experiment was carried out aiming to understand the phytoremediation potential of two selected non-food crops (Sorghum bicolor L. Moench and Brassica napus cv. Westar) chosen for their economic importance and heavy metal accumulation capacities. Sorghum and canola plants were cultivated in polluted soils A and B. For both plant species, the accumulation of heavy metals proved to be higher in the roots. Indeed, in order to obtain an adequate phytoextraction, it is required that the metals be moved to the epigeal part of the plants, and plants with bioconcentration factor (BCF) and translocation factor (TF) values < 1 are not considered suitable for phytoextraction. The results obtained in this study indicate that, although canola was quite effective in translocating metals from roots to aerial parts, both sorghum and canola are not suitable for phytoextraction since their coefficient values were < 1. Anyway, both plants, especially canola ones, grew up in presence of high level of Pb and Zn pollution, thus they could be used for phytostabilisation process. Actually, the Tolerance Index (TI) values of the sorghum and canola clearly suggest, under the experimental conditions used in this study, a better performance of the canola in tolerating the presence of Pb and Zn in the soil, even if in soil B was not found the same efficiency shown by the same plants grown in soil A. Probably, since soil B has an absolute higher content of Pb and Zn and a lower pH, the availability of both metals is slightly higher, which may have induced in the plants that grow there a more intense condition of stress. This study shows that canola, unlike sorghum, can be an ideal choice for phytostabilization, and its breeding can represent an effective alternative to food crop.