ature in degrees Celsius, and a and b are constants. This
mine type. Note that the pre-exponential factor a also
represents the flux at 0C.
form is analogous to both the Arrhenius equation for
the dependence of chemical reaction rate constants on
Interestingly, the slopes, b, for the nitroaromatic
temperature and the van't Hoff equation for the tem-
compounds are nearly constant, irrespective of analyte
perature dependence of chemical equilibrium constants
or mine (casing) type, tending toward a value of 0.11.
(ratio of two rate constants), except that t replaces 1/T
To further elucidate this observation, an experiment was
(K) in these equations. A flux resulting from vaporiza-
conducted with two of the PMA2 mines. The fuze plug
tion bears the same relationship to vapor pressure as
on one of them was removed. Each mine was placed in
reaction rate constants do to equilibrium constants, so
a Tedlar bag and the flux determined as before, at 4,
13, and 22C (Fig. 2). We decontaminated the plugged
its temperature dependence is logically the same as that
given by a van't Hoff (Clapeyron-Clausius) equation.
mine by immersing it in water before each test. Though
The modified version appears to be justified empirically
the fluxes for the two mines were different, owing to
over the limited temperature range reported here. The sta-
direct transport through the fuze hole, their tempera-
tistical fit parameter, R, was greater than 0.96 in all cases.
ture dependence was similar. It may be noted that the
Mean flux data are presented graphically in Figure
slopes are around 0.17 for this experiment, however, as
1. The best-fit parameters and calculated flux at 20C
compared to 0.11 before. This may be ascribable to our
for each analyte are shown in Table 2 as a function of
removing surface contamination prior to the later flux
5
10
y = 261 e0.0943x
DNT:
(R = 0.972)
y = 797 e0.0866x
DNB:
(R = 0.962)
y = 25.2 e0.105x
TNT
(R = 0.984)
4
10
3
10
2
10
a. PMA1A.
1
10
5
0
5
10
15
20
25
30
35
Temperature (C)
4
10
y = 28.8 e0.114x (R = 0.995)
DNT:
y = 35.3 e0.112x (R = 0.996)
DNB:
y = 2.61 e0.110x (R = 0.971)
TNT
3
10
2
10
1
10
b. PMA2.
0
10
5
0
5
10
15
20
25
30
35
Temperature (C)
Figure 1. Mean flux of ERC from the test mines.
3
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