evaluation was performed at the Oak Ridge National
site from which the soil had been originally obtained.
Laboratory (ORNL), in Oak Ridge, Tennessee, August
However, this information was confounded by the ran-
2427, 2000, as part of the Site Characterization and
dom assignment of site locations to the blank and ma-
Monitoring Technologies (SCMT) program, which is
trix spike samples.
under the supervision of EPA's National Exposure Re-
Samples were prepared on site by extracting 20 to
search Laboratory. This verification test evaluated the
40 g of soil with a 40-mL volume of acetone. To mea-
performance of technologies for on-site analysis of soils
sure the sample weight, the jar's contents were emp-
for explosives.
tied into a disposable weighing dish, weighed, and then
At the ETV test site the GC-TID instrumentation
returned to the jar. Then 40 mL of acetone was added
and a sample preparation station were set up on sepa-
using an adjustable solvent dispenser. Extraction was
rate folding tables under a canopy with mesh netting
performed by manually shaking the soil acetone slurry
on all four sides. During intermittent rainstorms a large
for several short intervals (2 min.) over a 30-minute
tarp was pulled over the top of this canopy. For secu-
period, then allowing the soil to settle. A 1.5-mL ali-
rity reasons, each night the instrument and all supplies
quot of the extract was filtered in preparation for analy-
were returned to their shipping containers and stored
sis. To screen sample extracts for high concentrations
inside a locked building. Auxiliary support consisted
of nitroaromatic compounds (e.g., TNT), a 0.25-mL
of an electrical extension cord run from a nearby build-
volume was transferred to a clear 2-mL vial and 0.01
ing and a nitrogen gas cylinder. The description of the
mL of a 5-mM tetrabutyl-ammonium hydroxide
samples used for the ETV program stated that the pri-
(TBAOH in water, the active reagent in Method 8515
mary explosives of concern would be TNT, 2,6-DNT,
[Aldrich]) solution was added. The formation of a dark
2,4-DNT, RDX, and HMX at concentrations ranging
purple or red solution provided a visual indication that
from 0 to 90,000 mg/kg (ORNL 2000). The calibration
a high concentration of nitroaromatic compounds was
standard used for this field study contained all of the
present. Depending on the color (i.e., the darker the
Method 8330 analytes (Table 1) in concentrations rang-
color the greater the dilution) sample extracts were di-
ing from 0.4 to 40 mg/L, dissolved in acetone, with the
luted anywhere from 1:10 to 1:2000, or not diluted at
exception of HMX, which ranged from 2 to 40 mg/L.
all, prior to analysis. All of the samples analyzed on site
The soil samples used for this ETV verification test
were refrigerated after analysis and returned to CRREL.
were obtained from five different military facilities
(ORNL 2000). Large bulk soil samples were shipped
RESULTS AND DISCUSSION
to ORNL for processing and characterization. These
bulk soil samples were homogenized by kneading the
Fort Leonard Wood
material in the plastic shipping bags, transferring por-
tions onto glass plates, subjectively removing debris,
2,4-DNT, TNT, 4AmDNT, and 2AmDNT were de-
air-drying, passing through a 2-mm mesh sieve, then
tected in a number of surface and subsurface soil
placing into a 1-L widemouth jar and thoroughly mix-
samples collected near buried land mines. Initially four
ing with a metal spatula. Next the sample was removed
surface samples were collected directly above the cor-
from the bottle and quartered. Each quarter was further
ners of buried land mines (Jenkins et al. 2000). For two
mixed, then a fourth of each quarter was recombined
of the mines, where mg/kg levels of explosives resi-
into new 1-L widemouth jars to yield four separate
dues were detected in one or more of these initial
sample replicates, each of approximately 1000 g. Por-
samples, an extensive iterative sampling protocol was
tions (20 to 40 g) were removed from each sample bottle
performed. Surface soil samples were sequentially col-
and placed in a 4-oz glass sample jar for distribution to
lected while moving away from the established hot
ETV participants and to a reference laboratory where
spot(s) in several directions, in increments of 10 cm.
Method 8330 sample preparation and analysis was per-
This sampling scheme and on-site analysis allowed us
formed. In addition, five matrix spike samples were
to delineate the size of the explosives-related chemical
purchased from a commercial reference standard ven-
signature plume present at the ground's surface above
dor for distribution (ORNL 2000). These matrix spike
these two buried land mines (Fig. 3). Before the devel-
samples were also distributed as quadruplicate
opment of this on-site analytical method, sample col-
subsamples. In total, 108 soil samples (27 quadrupli-
lection was performed using a set sampling design,
cates) were extracted and analyzed. The samples were
which often was inefficient (the majority of samples
distributed on site in lots of 12 using a double-blind
collected had nondetectable explosives concentrations),
format, i.e., the sample jars were randomly numbered
and we were unable to delineate the boundaries of the
and the numbering was unique to each participant. The
surface plumes above these mines (Jenkins et al. 2000).
only information provided with the samples was the
However, this earlier work had established that the ex-
6
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