Table 18
Adsorption Coefficients for 2,4DNT, 2,6DNT, 1,3,5TNB, and 1,3DNB
in Soils
-1
2
Soil
Compound
Kd, L kg
R
1
LAAP-C (Aquifer Soil)
2,4DNT
0.67
0.85
LAAP-D (Aquifer Soil)
2,4DNT
1.67
0.75
Yokena Clay
2,4DNT
12.5
0.95
LAAP-C (Aquifer Soil)
2,6DNT
0.96
0.96
LAAP-D (Aquifer Soil)
2,6DNT
1.83
0.88
Yokena Clay
2,6DNT
5.96
0.99
1
LAAP-C (Aquifer Soil)
1,3,5TNB
0.49
0.99
1
LAAP-D (Aquifer Soil)
1,3,5TNB
0.27
0.88
Yokena Clay
1,3,5TNB
Steady-state concentrations not attained
1
LAAP-C (Aquifer Soil)
1,3DNB
0.32
0.59
1
LAAP-D (Aquifer Soil)
1,3DNB
No significant adsorption
Yokena Clay
1,3DNB
17.7
0.95
1
Data from Pennington et al. (1999).
Dissolution kinetics
Dissolution rates for different explosive surface areas showed good
agreement as illustrated for TNT dissolution at 10 oC (Figure 23). TNT, RDX,
and HMX at other temperatures behaved similarly. These data indicate that the
procedures were reproducible and accurately estimated the surface area of
different amounts of explosives.
Increased temperature resulted in increased dissolution rates for all
explosives (Figures 24 and 25). Both TNT and RDX dissolution rate increased by
a factor of approximately four as water temperature increased from 10 to 30 oC.
Therefore, temperature is a critical factor affecting the dissolution rates of
explosives, and must be considered when evaluating the transport of explosives
on firing ranges. Increasing stir rate also increased the dissolution rate of
explosives (Figure 26). These results imply that the rate at which water flows
past exposed explosives will affect the dissolution rate, because a constant
dissolution rate as a function of stir rate could not be achieved.
Dissolution rates for TNT, RDX, and HMX decreased in the order
TNT>HMX>RDX at 10 oC and 150 rpm (Figure 27). This suggests that TNT will
be dissolved faster than RDX and HMX. However, this does not mean that
higher concentrations of TNT than RDX or HMX will be observed in
groundwater. TNT is less stable in soil than is RDX or HMX (Price, Brannon,
and Hayes 1997; Price, Brannon, and Yost 1998; Price et al. 2001; Miyares and
Jenkins 2000; Grant, Jenkins and Golden 1993).
56
Chapter 3 Transport Parameters for Firing Range Residues
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