PHYTOTOXICITY OF AMD ON HYDROPONIC VETIVER GRASS (CHRYSOPOGON ZIZANIOIDES L.)

The abandoned Tab-Simco mining site near Carbondale, IL is known for producing acid mine drainage (AMD) with a pH of 2.46 (arrhythmic means for n=9) and 2920 mg L^-1 of sulfate. This AMD also has a high conductivity at 3420 µS from metal contaminants, including Fe, Al, Zn, Ni, Cu and Pb. We are investigating the stress effects of Tab-Simco AMD on vetiver grass (Chrysopogon zizanioides L.) for the use of these plants in remediation. The key characteristic that identifies vetiver as a candidate for AMD remediation is an ability to withstand and accumulate heavy metals, along with a tolerance for acidic conditions. Our objectives are to evaluate the toxicological effects of AMD on vetiver grass through physiological and biochemical analyses. The study included a hydroponic setup using plastic bottles filled with 1.0 L of Tab-Simco AMD and hydroponic media for comparison. Plants were examined following short- and long-term exposure periods of 14 and 56 days, respectively. For both study periods the vetiver showed signs of toxicity, including curling and discoloration of the shoots. The 14 day plants showed a significant reduction in fresh biomass of 35.6±3.11% (mean±SD, n=3), whereas the 56 day plants only showed an 11.2±6.23% reduction. Moreover, the 56 day plants began to stabilize between 14–21 days when they started growing fresh root and shoot tissues. This shows that the AMD significantly reduces initial growth, though the Vetiver is able to acclimate and reestablish when given enough time. Effect of AMD treatment on shoot chlorophyll content and oxidative stress enzymes in vetiver tissue will be discussed.