Efficiency of Seven Different Cultivated Plant Species for Phytoextraction of Toxic Metals from Tannery Effluent Contaminated Soil Using EDTA

Phytoextraction of two toxic metals, namely sodium and chromium, was studied using seven cultivated plants-Brassica campestris L. (mustard), Brassica juncea (L.) Czan. (Indian mustard), Triticum aestivum L. (wheat), Sorghum bicolor (L.) Moench. (millet), Trifolium alexandrianum L. (Egyptian clover), Helianthus annuus L. (sunflower), and Spinacea oleracea L. (spinach)-in greenhouse trials. Soil used was untreated (control), or contaminated with tannery effluents with and without application of EDTA. Maximum dry weights of plants were observed in control soil, followed by contaminated soil without EDTA while in EDTA treated soil, biomass of plants showed a reduction with increasing amount of EDTA in soil. The greatest dry weights were observed in Sorghum bicolor followed by Helianthus annuus and Spinacea oleracea. In almost all plants, sodium uptake in both shoots and roots was reduced with EDTA application. The highest amounts of metals were observed in Spinacea oleracea followed by Brassica spp. Only the seeds of Spinacea oleracea accumulated significant amounts of sodium. Chromium bioaccumulation was greater in all plants and the coefficients of extraction were higher than sodium. The application of EDTA significantly enhanced chromium uptake in all plants, but increasing the amount of EDTA did not show a significant effect. Like sodium, maximum uptake was observed in Spinacea oleracea followed by Brassica spp. A greater bioaccumulation of chromium was observed in seeds of Spinacea oleracea followed by Trifolium alexandrianum and Brassica spp. The uptake and bioconcentration of chromium was significantly enhanced under the influence of EDTA treatment and a good root to shoot translocation was also observed. It is suggested that lower doses of EDTA are suitable for phytoextraction of chromium in high biomass producing plants like Spinacea oleracea and Brassica spp. Later on, the proper disposal of these plants along with seeds is required.