18 - Inverse Modeling of the Madison Aquifer
This example corresponds to the “Example 18-Inverse Modeling of the Madison Aquifer” from the Phreeqc manual. It can be retrieved from the Phreeqc Website.
In this example, inverse modeling, including isotope mole-balance modeling, is applied to the evolution of water in the Madison aquifer in Montana. Plummer and others (1990) used mole-balance modeling to quantify the extent of dedolomitization at locations throughout the aquifer.
Studies
This project contains 1 Studies.
PhreeqcStudy: “study_18 - Inverse Modeling of the Madison Aquifer”
Db used: “Phreeqc_dat” database
TITLE Example 18.--Inverse modeling of Madison aquifer
SOLUTION 1 Recharge number 3
units mmol/kgw
temp 9.9
pe 0.
pH 7.55
Ca 1.2
Mg 1.01
Na 0.02
K 0.02
Fe(2) 0.001
Cl 0.02
S(6) 0.16
S(-2) 0
C(4) 4.30
-i 13C -7.0 1.4
-i 34S 9.7 0.9
SOLUTION 2 Mysse
units mmol/kgw
temp 63.
pH 6.61
pe 0.
redox S(6)/S(-2)
Ca 11.28
Mg 4.54
Na 31.89
K 2.54
Fe(2) 0.0004
Cl 17.85
S(6) 19.86
S(-2) 0.26
C(4) 6.87
-i 13C -2.3 0.2
-i 34S(6) 16.3 1.5
-i 34S(-2) -22.1 7
INVERSE_MODELING 1
-solutions 1 2
-uncertainty 0.05
-range
-isotopes
13C
34S
-balances
Fe(2) 1.0
ph 0.1
-phases
Dolomite dis 13C 3.0 2
Calcite pre 13C -1.5 1
Anhydrite dis 34S 13.5 2
CH2O dis 13C -25.0 5
Goethite
Pyrite pre 34S -22. 2
CaX2 pre
Ca.75Mg.25X2 pre
MgX2 pre
NaX
Halite
Sylvite
PHASES
Sylvite
KCl = K+ + Cl-
-log_k 0.0
CH2O
CH2O + H2O = CO2 + 4H+ + 4e-
-log_k 0.0
EXCHANGE_SPECIES
0.75Ca+2 + 0.25Mg+2 + 2X- = Ca.75Mg.25X2
log_k 0.0
END
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