Table 4. Rate of loss equations for primary TNT signature analytes in Fort Leonard Wood soil.

Figure 5. Plots of ln(C/C0) versus time (days) at the two lower temperatures.

Table 6. Half-lives of explosives determined for a variety of soils.

TR00-17
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Table 4. Rate of loss equations for primary TNT signature analytes in

Fort Leonard Wood soil.

Key

ln C/C0 = 0.573t 0.046

ln C/C0 = 0.068t 0.618

22 (1 to 20 days)

ln C/C0 = 0.035t 0.102

*C is the concentration at time (t) and C0 is the concentration at time zero.

CONCLUSIONS

A12). These studies examined the degradation rates of

TNT, 2,4-DNT, 1,3,5-trinitrobenzene (TNB), and me-

The nitroaromatic compounds that compose the va-

thyl-2,4,6-trinitrophenylnitramine (tetryl) in three soils,

por signature of military grade explosive in land mines

a Windsor silt, a Charlton sandy loam, and a Fort

Edwards clay at three temperatures, 22, 4, and 15C.

have been shown to degrade in soils. Studies investi-

gating the holding times for explosives-contaminated

Data showing the degradation rate of TNT in a deep

samples have shown rapid to moderate loss of the dif-

aquifer soil from the Louisiana Army Ammunition Plant

(LAAP) at 22C were also used (Table A13) (Miyares

et al. 1999). Using the same plotting and curve fitting

software, we established rate of loss equations for each

compound in each soil at each temperature. From the

Table 5. Half-lives of the primary TNT signa-

equations, the half-lives were estimated (Table 6).

ture analytes in Fort Leonard Wood soil.

These data show similar trends with respect to tem-

perature and between analytes as the data for the Fort

Key

Temperature

Half-life

(C)

components

(days)

Leonard Wood soil. The half-lives at lower tempera-

tures are much longer than at room temperature and

TNT

1.1

the half-life of TNT in most cases is significantly shorter

than that of 2,4-DNT for each soil type. These data also

illustrate the variation in the half-lives of the compounds

1,3-DNB

9.9

in the different soils. The half-life of TNT in the Fort

Edwards, Windsor, and Charlton soils was less than 1

day, 1.9 days, and 3.5 days, respectively, whereas the

half-life for TNT in the LAAP soil was 140 days. This

2,4-DNT

suggests that there are soils in which TNT does not

degrade at any appreciable rate. Similar variations are

seen for other components as well. Half-lives for all of

2,6-DNT

the analytes in the Fort Edwards soil were shorter by

an order of magnitude over the Charlton and Windsor

104

soils, even at the extreme low temperature.

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