Analysis of Explosives-Related
Chemical Signatures in Soil Samples
Collected Near Buried Land Mines
THOMAS F. JENKINS, MARIANNE E. WALSH, PAUL H. MIYARES,
JESSICA A. KOPCZYNSKI, THOMAS A. RANNEY, VIVIAN GEORGE,
JUDITH C. PENNINGTON, AND THOMAS E. BERRY, JR.
INTRODUCTION
explosives) with the electric field gradient of the
crystal's electron cloud in the vicinity of the 14N
Background
Even after many years of research, land mine
detection remains one of the U.S. Army's most intrac-
cally dependent on the axially symmetrical electric field
table problems. The introduction of land mines manu-
gradient and the nuclear charge distribution's deviation
factured using plastic casings, with few or no metal
from spherical symmetry. These two parameters are
parts, has made detecting buried mines using electro-
essentially unique to a substance (TNT, RDX, Tetryl,
magnetic induction (metal detection) very time consum-
etc.), and there are essentially no known interferences
ing, as all small metal debris must be removed during
with the same resonant frequency. Recent tests demon-
demining. Other techniques, such as ground penetrat-
strated the lack of significant false alarms, with argu-
ing radar, can sometimes detect buried mines, but dis-
ably the best performance against RDX-containing land
criminating between mines and other buried objects has
mines, since the inception of countermine programs 50
been difficult, resulting in false positive rates that are
years ago. Results against TNT-containing targets are
unacceptable for countermine operations, particularly
equally optimistic, but it is understood that the TNT
for anti-personnel land mines.
system requires substantial engineering. All of these
The worldwide effect of buried mines continues to
results were obtained from a hand-held prototype. Ef-
be enormous. The United Nations estimates that 120
forts are currently underway to reengineer both a hand-
million mines are buried in 70 countries and the rate of
held version (U.S. Marine Corps.) and a vehicle-
installation of new mines far exceeds the rate of
mounted version (PM-MCD, Fort Belvoir).
removal of old ones (Yinon 1999). It is estimated that
The second chemical detection concept being
about 24,000 people are killed or injured by land mines
investigated is finding explosives vapors evolving from
each year, sometimes by mines buried as far back as
buried land mines at the soil surface. To do this, it is
the Second World War.
important to understand the qualitative nature of the
signatures given off by the explosives used in various
Detection of land mines using chemical
types of land mines, the levels of surface contamina-
signatures
tion present on the mine at the time of burial, the flux
A technique that is currently being investigated is
of the various explosives-related chemical (ERC) sig-
natures into the soil surrounding the mine, the stability
detecting buried land mines by sensing the presence of
of the various ERCs in the soil environment, the rate of
the explosives that are their lethal ingredient. Two pos-
transport through the soil to the surface, the concentra-
sible techniques are being examined. The first is the
detection of the bulk explosives using methods such as
tions of the various ERCs that accumulate at the soil
surface, and the degree of partitioning that occurs
quadrapole resonance (QR). The QR approach exploits
the interaction of the quadrupole moment of 14N (a
between the soil and the overlying air. Research on all
prevalent element of all common military secondary
of these topics is being supported at ERDC (CRREL
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