Wednesday, 9 November 2005
7

Fate of 2-4 and 2-6 Dinitrotolune in a Controlled Soil Ecosystem.

Nadia A. Abou-Zeid, Fawzy M. Hashem, Arthur L. Allen, and Salfu Kanu. University of Maryland Eastern Shore, Department of Agriculture, Princess Anne, MD 21853

Trinitrotoluene (TNT) and its derivatives 2, 4 dinitrotoluene (2, 4 DNT) and 2, 6 DNT are toxic organic compounds widespread in the soil and water environments as a result of runoff, industrial wastes sites, and military testing sites. Thus, these compounds are significant environmental pollutants of considerable concern. This study investigated the fate of two of the TNT's metabolites, 2,4 and 2,6 DNT in self-contained undisturbed soil lysimeters on the Eastern Shore of Maryland using Othello soil. This soil is consedered a representative of soils used at military testing sites. The Experiment was arranged in a randomized complete block design with eight treatments at depth of 30 and 60 cm. Soils were thoroughly mixed with 0,25 and 50 µg of each of 2,4 DNT and 2,6 DNT, and transferred to lysimeters. Soil cores samples were collected at 0-10, 10-20, 20-30, 30-40 and 40-60 cm after 0, 30, 90 and 180 days. Soil cores were examined for 2,4 DNT and 2, 6 DNT and their metabolites using a GC-ECD. The highest concentration of 2,4-DNT and 2,6-DNT was found in the top layer of all lysimeters (0-10 cm depth), while, lower concentration were found at further soil depth.The concentration of 2,4 DNT has declined from 17.5 to 4.21 µg/kg after 180 days. However, no significant changes were observed at 20-30cm depth. While, the concentration of 2,6 DNT decreased successively with soil depth in time (36.37, 34.73, 29.68 and 13.72 (µg/kg). The degradation rate of the two TNT metabolites were almost constant in all soil depths. In concordance, the soil bioremediation of the two highly toxic TNT metabolites 2,4 DNT and 2,6 DNT, were evident through the time length of the experiment for all soil treatments as a result of soil microbial activity.

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