Vapors were sampled by solid phase microextraction (SPME) and determined by gas
chromatography with an electron capture detector. (From George et al. 1999.)
Source
1,3-DNB
2,4-DNT
1,3,5-TNB
2,4,6-TNT
3.46 1010
5.51 1010
6.72 1012
6.97 1011
U.S. 1966
4.59 109
1.43 109
8.05 1012
7.76 1011
PMA-1A
9.74 1010
2.75 1010
8.57 1013
7.65 1011
PMA-2
9.61 1011
1.84 109
4.30 1012
6.95 1011
TMA-5
and the Environmental Laboratory) and Sandia National
are presented in Table 2. The level of 2,4,6-TNT is much
Laboratories by the Defense Applied Research Agency
greater on these mine surfaces than what is observed in
(DARPA). While uptake of these signature chemicals
the headspace vapor above military TNT. This is con-
by vegetation is known to occur, detection of these
sistent with the analysis of the solid composition of TNT
imbibed signatures in near real-time is thought to be
as compared to the vapor composition. The 2,4,6-TNT
much more difficult to engineer and, hence, we have
remains on the surface of the land mine, while the 2,4-
devoted less effort toward characterizing this.
DNT and 1,3-DNB are more volatile and do not persist
Our analysis of the current demining literature, dis-
in solid form on the surface of the mine to the same
tributed by the National Ground Intelligence Center,
degree.
tells us that 85% of all land mines contain TNT. While
George et al. (1999) reported on the flux of 1,3-DNB,
military grade TNT generally contains about 99% of
2,4-DNT, and 2,4,6-TNT into air from PMA-1A, PMA-
2,4,6-trinitrotoluene (Murrmann et al. 1971), research
2, TMA-5, and TMM-1 land mines (Table 3). For the
has demonstrated that the most abundant ERC evolv-
three plastic-cased mines (PMA-1A, TMA-5, and PMA-
ing from these military grade TNTs is often 2,4-
2), the flux of 2,4-DNT and 1,3-DNB is always much
dinitrotoluene (2,4-DNT) (Murrmann et al. 1971,
greater than that for 2,4,6-TNT. For the metal-cased
Leggett et al. 1977). Other important components of
TMM-1, the flux of 2,4,6-TNT is greater than that for
the ERC are 1,3-dinitrobenzene (1,3-DNB), 1,3,5-
1,3-DNB and similar in magnitude, but less than, that
trinitrobenzene (TNB), other geometric isomers of DNT
for 2,4-DNT. As expected, increasing temperature
and DNB, and 2,4,6-trinitrotoluene (2,4,6-TNT)
causes a large increase in the flux for all four mine types
(Jenkins et al. 1999). Ranney determined equilibrium
(Leggett et al., in prep.).
concentrations of ERCs for three samples of military-
The soil near buried mines probably becomes con-
grade TNT (Table 1).
taminated with ERCs by vapor flux (Table 3) into soil
These same components of military TNT have been
pore spaces and dissolution of contamination from mine
detected on the exterior of a variety of U.S. and foreign
surfaces into soil moisture. The former should be domi-
land mines (Leggett et al. 2000). Mean surface concen-
nated by the air flux, such as shown in Table 3, while
trations of these chemicals on eight types of land mines
the later should be controlled more by the levels of sur-
Table 2. Concentrations of ERC components on land mine surfaces. (From
Leggett et al. 2000.)
Mean surface concentration (ng/cm2)
relative standard deviation
Area
(cm2)
Mine
1,3-DNB
2,4-DNT
2,4,6-TNT
RDX
3.1 1.4
6.1 3.9
83.9 87.5
TMA-5
2720
--
7.3 6.2
11.0 6.5
13.2 19.7
TMM-1
2240
--
9.0 3.8
4.8 2.6
5.0 3.5
PMA-1A
345
--
1.3 0.9
0.95 0.43
1.3 0.5
1.2 0.4
PMA-2
118
1.4 1.0
73.7 159
Type 72
1990
nd
>17
0.81 0.5
118 237
VS-50
254
nd
nd
0.20 0.1
273 96
TS-50
254
nd
nd
1.3 0.8
7.3 3.9
3610 2400
VS-2.2
1480
nd
2
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