ranges. The use of an analytical method that has lower detection limits than the
current standard method for explosives residues, SW-846 Method 8330 (USEPA
1994), detection limit of 250 ug kg-1, allowed delineation of contamination at
training ranges. The GC-ECD method developed recently by Walsh and Ranney
(1999) has detection limits near 1 :g kg-1 for many explosive residues and is
particularly appropriate for use in range characterization studies.
The distribution of explosive residues at all the ranges investigated was
spatially very heterogeneous. Concentrations of explosives-related compounds in
soils collected less than a meter apart differed by over two orders of magnitude at
hand grenade ranges, and by as much as an order of magnitude at artillery firing
points. The spatial heterogeneity at artillery impact areas was large as well,
although difficult to define numerically since many of the concentrations were
below detection limits. Areas that were visibly free of craters, however, often
exhibited explosives concentrations as high as or higher than soils collected from
the rim of a fresh crater. Thus sampling methods, such as compositing in order to
provide representative samples for a given area, may be extremely important for
optimizing impact range characterization.
From preliminary estimates of residues produced from high-order
detonations and the frequency of low-order detonations, low-order detonations
seem to contribute a significant portion of the residues deposited on surface soils
in artillery impact areas. Development of better estimates of the residues
produced from detonations of various military munitions is crucial. Development
of these estimates is proposed under the addition to this project.
Chapter 2 Characterization of Explosives Contamination at Military Firing Ranges