Table 3. Comparison of air and water fluxes at 22C (g/mine per
day).
Mine-Number
Medium
Data period
DNB
DNT
TNT
RDX
PMA2-147
water
5871 days
1.3
0.72 1.27
--
PMA2-151
air
0.24
0.24 0.021 --
PMA2-147
water
04 days
11.6
6.82 8.28
--
PPM2-803
air
0.46
21.1
2.04
--
PPM2-803
water
624 days
1
66.9
4.64
--
PPM2-803
water
06 days
2.49
212
10.8
--
VS-50-573
air
--
--
--
0.008
VS-50-573
water
2752 days
--
--
--
1.46
VS-50-573
water
09 days
--
--
--
6.64
cm2, yields a flux of 5.6 ng DNT/cm2 per day. After 4
SUMMARY AND CONCLUSIONS
months, 670 ng DNT is estimated to have been emitted
Fluxes of ERC from six types of land mine from 4
over each square centimeter of mine surface. A soil core
to 34C in air are presented here. The quality of the sim-
approximately 2 cm in diameter would theoretically
ple exponential relations developed suggest that ERC
contain this mass of DNT in 2 cm3 of soil or in about
fluxes from these mines can be predicted within the lim-
33.5 g of soil. An average soil concentration might
its imposed by the variability of individual mines. Based
therefore be estimated as 670/3.25 or ~200 ng/g. The
on this selection of mines, which is by no means univer-
mean concentration of DNT in 16 soil cores taken
sal, and data reported elsewhere (Leggett et al. 1977),
around this mine after 4 months of burial was actually
2,4-DNT appears to be the predominant contaminant
120 ng/g. Agreement such as this may be fortuitous,
vapor emitted by TNT-filled mines, although 1,3-DNB
however. TNT plus its metabolite concentrations in the
flux was slightly higher for two of the tested mines.
same set of samples averaged 110 ng/g, which consid-
Higher fluxes occurred initially on placement of mines
erably exceeded predicted vapor emission of ~ 20 ng/g
in water, which tended toward steady-state values only
at 20C. The relatively high TNT/DNT ratio in soil
slightly larger than those in air.
compared to the vapor source could be attributable to
removal of excess surface contamination originally pres-
ent on the mine by contact with moisture. TNT concen-
LITERATURE CITED
trations in surface swabs of TMA5 mines prior to burial
at Fort Leonard Wood were as high as 370 ng/cm2 and
Aminabhavi, T.M., S.F. Harlapur, R.H. Balundgi, and
averaged 84 compared to 6 for DNT (Leggett et al.
J.D. Ortego (1996) Sorption kinetics and diffusion of al-
2000). Precipitation events were also noted during this
kanes into tetrefluoroethylene/propylene copolymer
period (Jenkins et al., in press).
membranes. Journal of Applied Polymer Science, 59:
The soil temperature at Fort Leonard Wood in July,
18571870.
when the mines were laid, may have been greater than
Berens, A.R., and H.B. Hopfenberg (1982) Diffusion
30C. According to the vapor flux model developed
of organic vapors at low concentrations in glassy PVC,
here, the emission rate increases about three-fold for
polystyrene, and PMMA. Journal of Membrane Science,
each 10 rise in temperature. Similarly, in cold climates,
10: 283303.
vapor emissions will be much lower. Under snow cover,
Bender, E., A. Hogan, D. Leggett, G. Miskolczy, and
when the ground is about 0C, the vapor fluxes would
be expected to be ~1/9 of their values at 20C. There-
Journal of Forensic Sciences, 37(6): 16731678.
fore, it may be most advantageous to search for buried
George, V., T.F. Jenkins, D.C. Leggett, J.H Cragin,
mines after soil temperatures have reached their maxi-
J. Phelan, J. Oxley, and J. Pennington (1999) Progress
mum for a given location.
on determining the vapor signature of a buried landmine.
The question of soil moisture is still under investi-
In Proceedings, SPIE Conference on Detection and Reme-
gation. Although the lab experiments support higher
diation Technologies for Mines and Minelike Targets IV,
fluxes in an aqueous environment, a recent experiment
April, Orlando, Florida, vol. 3710.
in wet sand (unpublished) did not support the inference
Jenkins, T.F., W.F. O'Reilly, R.P. Murrmann, D.C.
of higher fluxes in wet soil than in dry. In fact they were
Leggett, and C.I. Collins (1973) Analysis of vapors emit-
considerably lower in wet than dry sand at the same tem-
ted from military mines. U.S. Army Cold Regions Re-
perature. This result remains under investigation.
search and Engineering Laboratory, Special Report 193.
9
Previous Page
