Phytoremediation of Pb and Cd contaminated soils by using sunflower (Helianthus annuus) plant

Phytoextraction is an emerging cost effective remediation technology that uses plants to remove metals from contaminated soils. Pot experiments were conducted to compare the biomass of Helianthus annuus L. plant grown on Pb and Cd contaminated soils, and to evaluate its efficacy for the removal of Pb and Cd. The obtained results showed that as the concentration of heavy metals increased in soil, the fresh and dry weights of the growing plants gradually decreased. The application of 200 mg kg(-1) soil of Pb and Cd reduced the fresh weights of shoot and root (up to 76.6% and 64.3%; 88.5% and 80.80%, respectively), shoot and root length (up to 71.6% and 94.1%; 83.2% and 95.1%, respectively). The maximum concentration of Pb and Cd in shoot (40.1 and 65.7 mg kg(-1) Dwt) and roots (107.7 and 71.3 mg kg(-1), respectively) were recorded in the plant cultivated in soil amended with 200 mg kg (-1) metal concentration. The highest bioaccumulation (BAF) was recorded for Cd in the root grown on soil amended with 20 mg kg(-1) with an average value of 1.67. In addition, the value of the translocation factor (TF) of Cd increased by increasing the levels of Cd in soil; however, Pb translocation factor decreased by increasing the levels of Pb in soil. The study concludes that H. annuus plant was more favorable for Cd uptake compared to Pb, and we suggest its ability for the remediation of Pb and Cd contaminated soils.