Bársonyvirágfajok (Tagetes spp.) nehézfém fitoremediációs potenciáljának értékelése laboratóriumi tesztmódszerekkelAssessing the phytoremediation potential of marigold species (Tagetes spp.) for various heavy metals using laboratory test methods

Applying phytoremediation techniques for restoration of contaminated sites is a cost-effective and environmental friendly solution. According to some previous research marigolds could be able for phytoremediation of heavy metal contaminated soils, however little information is available on the toxicity of metals on these plants. In our study two different experiments (a preliminary and a pot experiment) were conducted to measure the bioaccumulation and the toxic effects of four heavy metals (Cd, Pb, Cu, Zn) on three different marigold species. According to the results of the preliminary seed germination experiment French marigold (Tagetes patula) was the least sensitive species to the applied heavy metals, therefore this plant was used in the pot experiment. In pot experiment the plants were exposed to heavy metal doses at 0, 1, 2 and 4 times the soil contamination limit values given in Hungarian regulations. After a 120-day period of soil-plant interaction, growth parameters (shoot heights and dry masses, root heights and dry masses) and aesthetical parameters (number of leaves and flowers, and flowers diameter) were measured. Heavy metal concentration of plant shoots and test soil were determined after HNO₃+H₂O₂ digestion by atomic absorption spectrometry. According to our results French marigold is able to bioaccumulate Cd and Zn in its shoots, since 7 to 18 times more metal concentration were measured in plant shoot than in test soil. Cu were also accumulated in shoots, however the rate of bioaccumulation was decreased with increasing dose of Cu. Plant parameters were significantly decreased only at the highest dose of heavy metal treatment (except for Zn treatments) compared with control. Zn significantly decreased shoot heights, root dry masses and flowers diameter at 400 mg kg⁻¹. Our results indicate that French marigold could be able for phytoremediation of Cd, Cu and Zn contaminated soil within the tested concentration. With the advantage that this plant can also beautify the environment, using it in urban areas (e. g. public parks, gardens or green areas along streets) has an important and practical significance.