25
almost always under 2 mg/kg. An
RDX value of 7 mg/kg was found for
y = 0.69x + 1.24
subgrid C4D, where the HMX concen-
r = 0.906
20
n = 40
tration was 2070 mg/kg and an RDX
concentration of 11 mg/kg was ob-
served for one replicate of the com-
15
posite sample for grid D7. The RDX
concentrations were never sufficiently
high to interfere in the colorimetric de-
10
termination of HMX.
5
Water analysis
We also found high concentrations
of HMX in the few water samples col-
0
lected at CFB-Valcartier (Table 10). The
22
0
2
4
6
8
10
12
14
16
18
20
TNT (mg/kg) Using Acetone HPLC Method
highest HMX concentrations were in
the well water (295 g/L). TNT con-
Figure 16. Correlation analysis of TNT concentration estimates from
centrations were about 100 times lower
the EIA on-site method with those from HPLC analysis of the same
than HMX, a similar ratio to what we
acetone extracts.
observed in soil. These water samples
were not chemically preserved, and
when separate subsamples were subsequently
tributes to the much lower concentrations of TNT
analyzed at CRREL, HMX concentrations were
compared to HMX. The highest concentrations of
similar to those found at CFB-Valcartier, but TNT
the amino-DNTs were about 10 mg/kg behind
was not detected in the well water samples. How-
tank D (grid D7) where the soil was moist and
ever, the amino-DNTs were detected, which adds
appeared to have a higher organic content. Else-
more evidence that microorganisms capable of
where the amino-DNTs were generally in the 12
transforming TNT are present at this site.
mg/kg range. Formation and further transforma-
The concentration ratio of HMX to RDX in the
tion and conjugation of the amino-DNTs is prob-
well water was approximately six; however, we
ably a major reason that TNT levels are much
only sporadically detected RDX in soil. When RDX
lower than HMX in the soils at CFB-Valcartier.
was detected in soil, the concentrations were gen-
The lab analysis sporadically detected 2,4-DNT,
sometimes at higher concentrations than TNT
erally near detection limits and were always at
(higher then would be expected if the source of
much lower concentrations than HMX. In the
the 2,4-DNT was as an impurity in TNT). We
sandy soils encountered at CFB Valcartier, RDX
previously observed high concentrations of 2,4-
may be more susceptible to leaching then HMX,
DNT at open burning/open detonation sites
perhaps due to a greater rate of dissolution. Al-
where excess propellant was burned (2,4-DNT is
though RDX is about 10 times more water soluble
an ingredient in some propellant compositions).
then HMX, the kinetics of dissolution under envi-
The disagreement was extreme in the DNT con-
ronmental conditions are not well defined. The
eight-membered ring of HMX has been reported
centration estimates for some subsamples of the
to be less susceptible to biotransformation than
same sample. For example, in the composite of
the six-membered ring of RDX (Spanggord et al.
grid D2, the estimates were <0.3 and 24 mg/kg
for the two lab subsamples. Such large heteroge-
neity implies that the contaminant is particulate.
The manufacturing by-product DNB was not de-
Table 10. Concentrations of HMX, RDX, and TNT
tected, nor was TNB.
detected in groundwater and surface water
samples at CFB-Valcartier.
RDX is not a major contaminant in military
grade HMX. However, RDX is the major compo-
Concentration (g/L)
nent in Composition A5, the booster used for the
HMX
RDX
TNT
66-mm M72 rocket. Soil analysis, however, re-
295 (2.0)
46 (2.0)
3.1 (1.1)
vealed only traces of RDX compared to the levels
Well water
of HMX on site. Often the concentrations of RDX
Surface water 1
125
<d
<d
Surface water 2
31.7
1.8
<d
were less than method detection limits and were
23
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