Phytoextraction and accumulation of lead from contaminated soil by vetiver grass: Laboratory and simulated field study

Abstract

A soil-culture study was conducted to investigate the phytoextraction of lead (Pb) in two species of vetiver grass (Vetiveria zizanioides and V. nemoralis) irrigated with an increasing level of Pb(NO3)2(5, 7, 9 and 11 g L-1) for 12 weeks. In a laboratory study, the removal of lead from soil was correlated with lead accumulation by roots and shoots of both species of vetiver grass. High concentration of lead (9-11 g L-1) resulted in decrease of growth, total chlorophyll content and biomass of V. zizanioides, while V. nemoralis died after one week of application. Toxicity symptoms (e.g., burning leaf margins, shoot die back) occurred in vetiver grass at a high concentration of lead. Based on the data V. zizanioides tolerated and accumulated the greatest amount of lead most effectively. A simulated field experiment was conducted to examine the efficiency of vetiver grass in removing lead from contaminated soil. The vetiver grasses, V. zizanioides and V. nemoralis, were grown in soil contaminated with Pb(NO3)2(5, 7, 9, and 11 g L-1) for 3 months. The removal of lead from soil was correlated with lead accumulation by roots and shoots of both grass species. The grass roots took up more lead than the shoots. V. zizanioides could uptake more lead from soil than V. nemoralis. The effects of lead on the biomass of V. zizanioides and V. nemoralis showed that in both species, the biomass was decreased when the lead concentration was increased. In comparison, V. zizanioides showed greater biomass than V. nemoralis.