Undersea Explosive Traces

[Lenny Siegel <lsiegel@cpeo.org>]

UNDERSEA EXPLOSIVE TRACES

Researchers at the Jet Propulsion Laboratory (JPL) in Pasadena,
California have added another piece to the puzzle surround the chemistry
of unexploded ordnance (UXO). In "Trace Explosives Signatures from World
War II Unexploded Undersea Ordnance," (Environmental Science &
Technology, Vol. 32, No. 9, 1998) three JPL researchers describe how
they measured explosives in sediment surrounding UXO found in the
Halifax, Nova Scotia harbor. Shortly after World War II a massive
explosion in the munitions storage area there sent large quantities of
UXO into the harbor.

Most of the article is devoted to a detailed, technical description of
the JPL methodology. Undersea UXO was visually located. Four samples
were taken, in each of the cardinal directions, some six to twelve
inches of each targeted UXO. Samples where shipped to Pasadena, where
researchers used solid-phase microextraction and the reversal electron
attachment detection technique and a gas chromatograph/mass spectrometer
to measure successfully traces of the explosives DNT and TNT. 

The researchers believe they could detect trace explosives even further
from undersea UXO, and they suggest that their methodology would
complement well other approaches to undersea UXO characterization.

The specific results of the study are interesting, as well. Explosive
devices which had been cracked open - but not exploded - during the 1945
accident showed no traces of DNT or TNT in nearby sediment. Apparently,
the explosive chemicals had washed away or degraded. However, those
which remained intact showed trace explosives in adjacent sediment,
demonstrating that undersea UXO slowly leaks chemicals into the
environment.

Lenny Siegel
Director, Center for Public Environmental Oversight
c/o PSC, 222B View St., Mountain View, CA 94041
Voice: 650/961-8918 or 650/969-1545
Fax: 650/968-1126
lsiegel@cpeo.org
http://www.cpeo.org