100
2,4,6-TNT
All Soils
PMA-1A
Surface Soils
90
80
70
60
50
40
30
20
10
0
Aug 98
Nov 98
Apr 99
Jul 99
Nov 99
c. 2,4,6-trinitrotoluene.
Figure 12 (cont'd). Detection frequency for ERCs in soil
samples collected near buried PMA-1A land mines.
Remaining surface contamination levels on
detection frequencies are declining with time for soil
buried mines
near the TMA-5 mines.
During the July and November 1999 soil samplings,
The results for the PMA-1A mines appears to be
the mines where soil samples were collected were
even more convincing, particularly for the detection
removed from the ground and the top and bottom sur-
frequency of 2,4-DNT (Fig. 12a) and 2-ADNT (Fig.
faces were sampled to estimate the levels of surface
12b), which shows a consistent increase with time from
contamination that remained after burial. The results,
August 1998 through November 1999. The trend for
along with the estimates of surface contamination
2,4,6-TNT (Fig. 12c) is less compelling, but the
existing before burial (Leggett et al. 2000) for each
median concentrations found for 2,4,6-TNT are much
mine, are presented in Table 21.
lower than for 2,4-DNT and 2-ADNT and, hence, the
For the two metal-cased TMM-1 mines, EX-319 and
detection frequencies may be more influenced by the
detection limit for 2,4,6-TNT than for the other two
324, the surface contamination that was originally
present was almost totally absent after burial for 472
analytes that are often found at higher concentrations.
days (Table 21). Only a very small concentration of
These results suggest that ERCs for the TMA-5 and
2,4,6-TNT (0.368 ng/cm2) remained on the bottom sur-
PMA-1A mines will be long lasting in the soil. This is
important for countermine applications where the mines
face of EX-319. Otherwise, the surface concentrations
may have been in the ground for many years. Because
were all below detection. This result is consistent with
the detection frequencies for the TMM-1 and PMA-2
the results for the soil samples that were collected
mines have been so low, we are unable to speculate on
under the TMM-1 mines, which showed that the con-
the long-term detection probability for these two mines
centrations of ERCs were always less than 10
g/kg, except for three soil samples where 2,4-DNT
based on the results of the soil analyses.
30
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