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General form of the ADE:
sink/source term
Chemical sink/source term
t
ccq
x
cv
x
cD
ss
2
2
Simple form of the ADE
Uniform 1D flow; longitudinal dispersion;sink/source term
General form of the ADE:
sink/source term
Chemical sink/source term
We will consider two types of chemical reactions
1. Sorption (adsorption & absorption)
2. 1st order irreversible reactions (radioactive decay,
hydrolysis, some forms of biodegradation)
(Zheng & Bennett)
LEA
sorption 1st order
Zheng & Bennett, Fig. 4.3
= v/vc
Sorption (or retardation)
R > 1
= v/vc
Zheng & Bennett, Fig. 4.3
Zheng & Bennett, Fig. 4.2
Linear Isotherm
LEA (Local Equilibrium Assumption)
Linear Isotherm
from MT3DMS manual
t
cR
cq
x
cv
x
cD
ss
2
2
Simple form of the ADE
Uniform 1D flow; longitudinal dispersion;sink/source term; retardation
Retardation Factor
t
c
R
cq
x
c
R
v
x
c
R
D ss
2
2
Simple form of the ADE
= vc
R = v/vc
Zheng & Bennett, Fig. 4.2
Linear Isotherm
Freundlich Isotherms
Unlimited sorption sites
Freundlich Isotherm
Langmuir Isotherm
Limited sorption sites
= maximum sorption capacity
Langmuir Isotherm
Spitz and Moreno (1996)
fraction of organic carbon
Spitz and Moreno ( 1996)
General form of the ADE:
Chemical sink/source term
Zheng & Bennett
dbKR
1
linear
We will consider two types of chemical reactions
1. Sorption (adsorption & absorption)
2. 1st order irreversible reactions (radioactive decay,
hydrolysis, some forms of biodegradation)
t
cRRc
cq
x
cv
x
cD
ss
2
2
Simple form of the ADE
Uniform 1D flow; longitudinal dispersion;sink/source term; retardation; 1st orderirreversible reaction ( is the same for thedissolved phase and the sorbed phase)
1st order rate constant= ln 2 / half life = 0.693/ t½
Zheng & Bennett