Table 6. Concentration of TNT, 2ADNT, and 4ADNT in the aqueous and soil phases in incubation
study 2.
Days
0
7
14
21
28
56
TNT in aqueous phase (mg/L)
93.38
81.64
90.72
97.00
95.80
94.34
2ADNT in aqueous phase (mg/L)
0.000
0.095
0.207
0.141
0.119
0.216
4ADNT in aqueous phase (mg/L)
0.00
0.354
0.722
0.417
0.283
0.478
TNT in soil (g/g)
0.00
6.35
24.82
30.40
25.81
24.47
2ADNT in soil (g/g)
0.00
0.236
0.114
0.290
0.091
0.095
4ADNT in soil (g/g)
0.00
1.467
0.814
0.661
0.424
0.428
in these studies ranged from 0.012% for LAAP soil
aqueous and soil phases. The total mass had
to 1.3% for the Charlton, New Hampshire, soil. If
decreased to 90% of the original mass of TNT
TNT were to bind with the soil organic matter at a
(Table 7). By day 21 the percentage of amino-DNTs
level of 0.2% (w/w), the mass of carbon resulting
present increased, but the primary component of
from the TNT would only be 19 g in a 2-g soil
the system was still the TNT in the solution phase.
sample. This represents only 0.074% of the total
The total mass had increased to 105% of the origi-
carbon present in the sample, which is too small a
nal mass and remained unchanged through day
difference to measure.
56 (Table 6). The mass changes and redistribution
of the analytes translated to concentrations of
Incubation study 2: Unlimited contaminant source,
extractable TNT, 2ADNT, and 4ADNT of 25, 0.1,
and 0.4 g/g, respectively, after 14 days. At day
maximum loading of soil
The objective of this experiment was to simu-
14, the concentration of the analytes in the aque-
late a situation where an unlimited amount of con-
ous phase was 95, 0.2, and 0.5 mg/L for TNT,
taminant material is available to the soil. At time
2ADNT, and 4ADNT, respectively. All of these con-
zero, TNT was the only analyte in the system and
centrations remained relatively unchanged
was present solely in the aqueous phase (Table 6).
through 56 days.
By day 7, the analyte composition consisted of both
The data plotted in Figure 9 showed definite
TNT and the amino-DNTs, although it was pri-
trends in the change in concentration of TNT over
marily TNT, and it was distributed between the
time. The isotope data suggest a possible trend;
Table 7. Mass recovered from aqueous and soil phases in incubation study 2.
Mass recovered (moles)
0
7
14
21
28
56
4.36 105
3.81 105
4.39 105
4.63 105
4.59 105
4.54 105
TNT in aqueous phase
5.13 108
1.15 107
7.73 108
6.54 108
1.20 107
2ADNT in aqueous phase
0.00
1.91 107
4.03 107
2.29 107
1.56 107
2.66 107
4ADNT in aqueous phase
0.00
7.74 108
3.72 107
3.87 107
3.51 107
3.97 107
TNT in soil
0.00
3.40 109
1.99 109
4.31 109
1.45 109
1.77 109
2ADNT in soil
0.00
2.11 108
1.43 108
9.84 109
6.76 109
7.93 109
4ADNT in soil
0.00
4.36 105
3.85 105
4.49 105
4.75 105
4.65 105
4.62 105
Total moles recovered
4.47 105
4.33 105
4.55 105
4.53 105
4.44 105
4.36 105
Total moles added
Percent moles recovered
97.50%
88.91%
98.54%
104.76%
104.54%
105.90%
13
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