STUDY OF THE EFFECT OF HIGHLY HEAVY METAL POLLUTED SOILS ON METAL UPTAKE AND DISTRIBUTION IN PLANTS FROM GENERA ARTEMISIA, DRACCOCEPHALUM, INULA, RUTA, AND SYMPHYTUM

In pot experiments, the uptake and distribution of heavy metals (Cd, Pb, Cu, Mn and Zn) in plants from genera Artemisia, Draccocephalum, Inula, Ruta and Symphytum were studied. Four soils were used in the experiment, taken from the vicinities of the Non-Ferrous Metals Combine near Plovdiv at distances of 0.5, 3, 6 and 9 km. The latter was used as a control.

The content of Cd, Pb, Mn, Cu and Zn in soils, plant parts (roots, stems, leaves and flowers) as well as in tea and infusions prepared from the plants were determined by AAS and GFAAS.

Concentration of Zn, Cd, and Pb in the soil, taken at 0.5 km from the smelter was above the critical level for these elements in the soils, while Cu concentration was within the critical level. In soils at 3 and 6 km from the smelter metal concentration was very close or within the critical levels.

The tested species accumulated different amounts of heavy metals, as a whole. Plant heavy metal concentrations were in accordance with their concentration in the soils.

Plants, grown on soil, taken at 0.5 km from the smelter accumulated high amounts of Cd, Pb, Zn and Cu. In most of the plant parts, their concentration were above the critical concentration for plants. Although no heavy metal toxicity symptoms were seen, the yields were decreased by 12–21% compared to the control. Heavy metal concentration in the soils taken at distance of 3 and 6 km from the smelter did not affect the yields.

Despite high heavy metal concentration in aboveground plant parts, tea and infusions prepared from the five species as well as essential oils from Inula helenium and Ruta graveolens were not contaminated. The tested medicinal species could be grown on highly heavy metal polluted soils (in the absence of atmosphere deposition of metals).

In order to avoid any risk of contamination of edible products, it is recommended that plant parts from the respective species, if grown on contaminated soils, are used only for obtaining essential oils or other biologically active substances. They could be used for teas and infusions only after analysis for heavy metal concentration in these products, particularly for the roots from Inula helenium and Symphytum officinale.