Phytoremediation of metals using lemongrass (Cymbopogon citratus (D.C.) Stapf.) grown under different levels of red mud in soil amended with biowastes

ABSTRACT

Due to hostile condition of red mud (RM), its utilization for vegetation is restricted. Therefore, RM with biowastes as soil amendment may offer suitable combination to support plant growth with reduced risk of metal toxicity. To evaluate the effects of RM on soil properties, plant growth performance, and metal accumulation in lemongrass, a study was conducted using different RM concentrations (0, 5, 10, and 15% w/w) in soil amended with biowastes [cow dung manure (CD) or sewage-sludge (SS)]. Application of RM in soil with biowastes improved organic matter and nutrient contents and caused reduction in phytoavailable metal contents. Total plant biomass was increased under all treatments, maximally at 5% RM in soil with SS (91.4%) and CD (51.7%) compared to that in control (no RM and biowastes). Lemongrass acted as a potential metal-tolerant plant as its metal tolerance index is >100%. Based on translocation and bioconcentration factors, lemongrass acted as a potential phytostabilizer of Fe, Mn, and Cu in roots and was found efficient in translocation of Al, Zn, Cd, Pb, Cr, As, and Ni from roots to shoot. The study suggests that 5% RM with biowastes preferably SS may be used to enhance phytoremediation potential of lemongrass.

KEYWORDS:

• Cymbopogon citratus
• phytoremediation
• red mud

Acknowledgments

The authors are thankful to the Head, Department of Botany, Institute of Science, B.H.U., Varanasi and HINDALCO Industries Ltd., Renukoot, U.P., for providing all the necessary facilities during the research work. They are also grateful to anonymous reviewers for their critical comments and helpful suggestions, which helped them in improving the manuscript.

Funding

The authors are thankful to Council of Scientific and Industrial Research (CSIR), New Delhi, India, for financial assistance provided in the form of Research Associateship (Divya Pandey) and Senior Research Fellowship (Meenu Gautam), respectively.