THE STRUCTURE OF DANDELION CENOPOPULATIONS AND SPECIFIC FEATURES OF HEAVY-METAL ACCUMULATION

The accumulation of Pb, Cd, Cu, and Zn by two dandelion species Taraxa cum dahlstedtii Lindb. hi. and I: pectinatiforme Lindb. fil. was studi ed. The first, more abundant species was shown to accumulate smaller a mounts of toxicants from slightly polluted soils than the second speci es. The inverse effect was observed on heavily polluted soils. The thr eshold concentrations of heavy metals in the soil, at which they penet rate the root barrier, were determined. The coefficients of Ph and Cd transfer to the aboveground organs were greater in I: pectinatiforme i n the heavily polluted zone; in the background zone, they were greater in T. dahlstedtii. The plants of the latter species in the impact zon e strongly fixed toxicants in the roots, ensuring the protection of ve getative and generative organs. Coefficients of copper and zinc transf er to the aboveground biomass were similar in both species.