Assessment of sunflower (helianthus annuus l) for phytoremediation of heavy metal polluted mine tailings: a case study of Nampundwe mines tailings dam.

Mining is the main source of export income and contributes significantly to the Zambian gross domestic product. Besides its contributions to exports, the mining industry plays a pivot role in the economic and socio-political development of Zambia. It also provides essential mineral based raw materials to the local industry. However, mining activities have led to a generation of heavy metals laden wastes which are released into the environment in an unsustainable way causing the contamination of the ecosystems and posing a risk to human health. Most mining companies have not employed any rehabilitation or remediation program for the heavy metal laden wastes. For this purpose, this study was conducted to assess the potential of sunflower for phytoremediation of heavy metal polluted Pyritic mine tailings. Phytoremediation is an emerging technology in the remediation of mine tailings that uses tolerant plants species to clean up contaminated sites. It uses plants with high biomass and sunflower has been identified as such. These plants can extract, transfer, sequester and stabilize a variety of metals through mechanisms such as phytoextraction, phytostabilization, phytoaccumulation and phytovolatilization. In this study, pot experiment was conducted by growing sunflower (Helianthus annuus L) in pyrite mine tailings and in agricultural soil as a control. The study showed that the concentration of Cu reduced from 40.76mg/kg to 36.59mg/kg, Zn reduced from 3.58mg/kg to 3.49mg/kg andFe reduced 23.70mg/kg to 10mg/kg respectively in the mine tailings after six (6) weeks. Analysis of harvested sunflower (roots, stems, leaves) showed that sunflower could remove heavy metals from the tailings and the highest removal efficiency was 56.16% and the highest translocation factor was 0.25. Based on the results obtained it can be concluded that sunflowers have the potential to remediate contaminated pyritic mine tailings and phytoremediation is a viable and efficient technology to treat soils contaminated with heavy metals.