except for 2,4,6-TNT, which was enriched com-
tion was minimal or the biological activity was suf-
pared to the vapor. The analyte found at the high-
ficient to microbially transform the analytes as
est concentration was 2,4-DNT. Samples collected
soon as they dissolved in the aqueous layer in the
immediately after removal from the vapor expo-
soil. Neither isomer of amino-DNT was detectable
sure chamber had a mean concentration of 1.41
in the moist soil. However, when we extracted and
0.10 mg/g; samples from the soil air-dried in the
analyzed the moist nylon bag and soil that clung
fume hood overnight had a mean concentration
to the bag, 2,4,6-TNT, 4-Am-DNT, and 2-Am-DNT
of 1.22 0.05 g/g for 2,4-DNT, a decrease of 13%.
were major peaks in the chromatogram. Concen-
trations were 1.9, 2.2, and 1.4 g/g, respectively.
Similarly, all of the other analytes decreased in con-
centration after 24 hours in the fume hood. One-
Based on these results, microbial transformation
tailed t-tests indicated that the means for each
is significant in the Fort Leonard Wood soil. A re-
analyte before and after drying in the fume hood
cent estimation of the half-life of TNT in this Fort
were significantly different at the 95% confidence
Leonard Wood soil confirms this conclusion
level. Except for 1,2-DNB, losses were 20% or less
(Miyares and Jenkins in prep).
for each analyte.
Both the AEC and Fort Leonard Wood soils that
Results were different for the soil that was moist
were not wetted had significant loss of analyte
during exposure to the TNT vapor. Less analyte
when removed from the vapor exposure chamber
sorbed to the moist soil. Again, the analyte found
and air-dried in the fume hood. Because contami-
at the highest concentration was 2,4-DNT (0.65
nation of the soil was by adsorption from the va-
0.09 g/g); however, air-drying did not result in a
por phase, some loss over a 24-hour period was
significant loss (0.60 0.05). Losses were not sig-
expected because analytes will slowly desorb from
nificant for 2,4-6-TNT, 1,3-DNB, 2,5-DNT, and 3,5-
soil exposed to flowing air. However, differences
DNT as well. In addition to those analytes found
between analytes in the amount of loss are not
in the vapor, 4-Am-DNT, the microbial reduction
explained by differences in partition coefficients,
product of TNT, was also found in the moistened
molecular weights, and vapor pressure. Compared
soil.
to the isomers of DNB and DNT, TNT has a higher
To determine whether these results were repeat-
soil/air partition coefficient, a lower vapor pres-
able with a different kind of soil, we set up two
sure, and a higher molecular weight, leading to
more exposure chambers, this time with TNT from
the prediction that desorption from the soil would
an actual land mine (PMA-1A) that was made in
be slower for TNT than the more volatile impuri-
the former Yugoslavia and with soil from Fort
ties. Another mechanism of loss, chemical or bio-
Leonard Wood. The soils were allowed to equili-
logical, may account for this artifact.
brate for 68 days in the chambers and allowed to
The presence of moisture in the soil had a dra-
dry 24 hours and 48 hours prior to analysis.
matic effect on the amount of analyte we found in
The vapor from the Yugoslavian TNT differed
the soil. We expected lower concentrations in the
from the Kodak TNT in that 1,3-DNB was present
moist soil than in the soil that was not wetted be-
at levels similar to 2,4-DNT. When we analyzed
cause of the aqueous boundary layer into which
subsamples from the soil that was not wetted, we
the analytes had to dissolve before partitioning
found 1,3 DNB at 1.43 0.12 g/g, whereas 2,4-
onto the soil. However, the film of water appar-
DNT was 1.10 0.11 g/g and 2,4,6-TNT was 1.14
ently activated the microbial populations within
0.25 g/g. Other TNT impurities were detected
the soils, and was thus not only a barrier to diffu-
in the soil as well (Table 4). When this soil was
sion but also a site of transformation. The biologi-
spread on an aluminum pan and placed in a fume
cal activity of the moist Fort Leonard Wood soil
hood for 24 and 48 hours, concentration decreases
reduced the amount of analyte sorbed to below
were significant for all analytes except for 1,2-
detection limits for analytes other than 2,4-DNT
DNB. For the soil that was moist during exposure
and 2,4,6-TNT. The small concentrations of these
to the TNT vapor, only two analytes were detect-
two analytes that we detected in the moist soil
able in the soil: 2,4-DNT at 0.065 0.005 g/g and
appeared to be unaffected by air-drying. Perhaps
2,4,6-TNT at 0.008 0.003 g/g. Air-drying in the
as the soil dries, the matrix collapses in such a way
fume hood did not result in significant loss for ei-
as to sequester the small amount of sorbed
ther analyte.
analytes.
Initially, we were surprised at the dramatic dif-
This series of experiments failed to answer our
ferences in concentrations between the wetted and
objective of determining the effect of air-drying
non-wetted Fort Leonard Wood soils. Either sorp-
on the more volatile analytes expected in minefield
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