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1.0
f
m
= 0.1
0.8
0.25
0.6
0.50
0.75
0.4
1.0
0.2
0
0
1
2
3
4
5
6
7
8
9 0
V/V
o
FIGURE 8.13
Effluent concentration distributions for different values of the fraction of active sites
f
m
of the
SOMIM model. (From H. M. Selim and M. C. Amacher. 1997.
Reactivity and Transport of Heavy
Metals in Soils
. Boca Raton, FL: CRC Press. With permission.)
where
v
is the pore water velocity (
v
/Θ
m
). Values for the dispersion coefficient
D
e
used in the above equation were averages of those obtained from BTCs of
tritium and chloride-36 tracers. Selim and Amacher (1988) found that attempts
to utilize tracer data sets from tritium and chloride-36 for parameter estimation
of α and
D
were not successful. The values obtained using least squares param-
eter optimization were inconsistent and ill-defined due to large parameter
1.0
A
B
0.8
C
0.6
D
0.4
0.2
0
0
1
2
3
4
5
6
7
8
V/V
o
FIGURE 8.14
Effluent concentration distributions for Cr in Olivier soil. Curves A, B, C, and D are predictions
using the second-order mobile-immobile model with batch rate coefficients for
C
/
C
o
of 25, 10, 5,
and 1 mg/L, respectively. (From H. M. Selim, and M. C. Amacher. 1997.
Reactivity and Transport
of Heavy Metals in Soils
. Boca Raton, FL: CRC Press. With permission.)
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