Agriculture Reference
In-Depth Information
In addition, the corresponding irreversible reactions are
∂
[]
[][]
S
∂
[]
S
irrr
irrm
=
k
Sand
=
[][]
k
S
(9.44)
irrr
kr
irrm
km
∂
t
∂
t
The above formulation was incorporated into the convective-dispersive
equation (CDE) such that:
2
∂
∂
C
t
∂
∂
C
x
−ν
∂
∂
C
X
ρ
θ
∂
[]
S
t
∂
−−
ρ
∂
[]
S
kr
km
R
=
D
−
f
(1
f
)
(9.45)
2
θ
∂
t
and
R
= 1 + ρ λ
(9.46)
The CDE was numerically solved using the implicit-explicit finite-differ-
ence approximation subject to the initial and boundary (third-type) condi-
tions as discussed in previous chapters.
9.7.1 Experimental Evidence
Figures 9.17 and 9.18 are examples of the use of SOTS in a mixed soil system
(Zhu, 2002). In Figure 9.17 atrazine breakthrough results from miscible dis-
placement experiments are presented for a reference sand material mixed
Crop Residue + Sand
Mixed Column
1.0
0.8
0.6
Measured
Predicted - SOTS
0.4
0.2
0.0
0
5
10
15
20
25
Pore Volume (V/V
o
)
FIGURE 9.17
Measured and predicted atrazine breakthrough curves from a mixed-soil column of crop resi-
due plus sand.
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