University of Nebraska, Lincoln, NE, 68583-0724, 402-472-1143
Incineration has been widely used to remediate munitions-contaminated soil; however, rising costs and public concern mandate less expensive, more environmentally acceptable alternatives such as phytoremediation. Grasses can be effective remediators because of their high water use, adventitious root systems and rapid establishment. We determined the effects of TNT (2,4,6-trinitrotoluene) and its reduction product, 4-amino-2,6-dinitrotoluene (4ADNT), on germination and early seedling development of tall fescue (Festuca arundinacea Schreb, cv. Rebel Jr.). Tall fescue seeds were germinated in nutrient-free agar containing 0, 1.9, 3.75, 7.5, 15, 30, 45 and 60 mg TNT L-1 or 0, 1.9, 3.75, 7.5 and 15 mg 4ADNT L-1. Radicle emergence was observed within 4 d. Number germinated, radicle length, secondary root length, shoot length, seedling dry weight and respiration were measured for a 14-day period. Germination, radicle emergence and seedling development were not significantly different from the controls at 1.9 and 3.75 mg TNT L-1. At low TNT concentrations, respiration rates tended to be greater than those of the controls. With increasing TNT concentration, germination decreased, seedling development was delayed, meristematic regions of the radicle were more disorganized, and secondary root and shoot development was reduced. Respiration rate decreased exponentially at 7.5 mg TNT L-1 and greater. Germination decreased to 53 and 38% at 45 and 60 mg TNT L-1, respectively. At these high TNT concentrations radicles emerged without root hairs. Cell proliferation occurred in the meristematic region; cells were circular and disorganized. No secondary root development was observed and shoot growth was reduced. Tall fescue germination was not greatly affected by 4ADNT. Radicle emergence, root and shoot development were similar to the controls at 1.9 to 7.5 mg 4ADNT L-1. However, root and shoot development was reduced, and respiration was depressed at 15 mg 4ADNT L-1. Our observations indicate a potential use of tall fescue in remediation of soil marginally contaminated with munitions residues.
TNT, 4ADNT, phytoremediation, tall fescue, Festuca arundinacea
This paper is from the Proceedings of the 10th Annual Conference on Hazardous Waste Research 1995, published in hard copy and on the Web by the Great Plains/Rocky Mountain Hazardous Substance Research Center.