Accumulation of Cd, Pb, Cu, Mn, and Zn by Silybum marianum L. grown on polluted soils

摘要

In 1989-93, field and pot experiments were conducted to study the effect of heavy metals on the productivity and quality of S. marianum cv. Silmar. Field experiments were performed in the vicinity of the Non-Ferrous Metals Combine near Plovdiv, Bulgaria, an area subject to severe soil and air pollution. Plants were grown at 3 sites situated at 0.8, 3 and 10 km (control) from the smelter. Pot experiments were performed using soils from the 3 sites, and soil taken at 6 km from the smelter. Plants from the field experiment experienced the effects of heavy metal pollution of both soil and air, while those from the pot experiment experienced the effects only of heavy metals in the soil. The contents of Cd, Pb, Cu, Mn and Zn in the soil, plant parts (roots, stems, leaves and seeds), fatty oil and silymarin were determined on Inductively Coupled Plasma (ICP) apparatus. In field experiments, the degree of heavy metal concentration at 0.8 km from the smelter (with soil Cd, Pb, Cu and Zn contents above orwithin the critical levels for these elements) decreased the seed yield by 16% compared with the control, while yields from the site 3 km from the smelter were 11% lower than in the control; in both cases there were no visible toxicity symptoms. In pot experiments, seed yield from plants grown in soil taken at 0.8 km from the smelter was 13% lower than from the control, while yields from the other soils (taken at 3 and 6 km from the smelter) were not significantly affected by heavy metal pollution. Seedsilymarin and fatty oil contents were not affected by heavy metal pollution, and these products were not contaminated.