Introduction
Materials and method
Simulation programs
Model site geology and hydrogeology
Model length/width/height (m) | 88/90/1,008 |
---|---|
General properties | |
Number of elements | 5,728 |
Number of layers | 31 |
Simulation period (a) | 1–4 days |
Temperature (°C) | 11.5–50 |
Rock grain density (kg/m3) | 2,700 |
Compressibility (Pa−1) | 0.00 |
Rock grain specific heat (J/kg °C) | 800 |
Formation heat conductivity (W/m °C) | 2.1 |
Salinity (mass fraction NaCl) | 0.00005–0.16 |
Diffusivity of NaCl (m2/s) | 10−9
|
Hydrogeological units | |
Quaternary drift marl [q2] (thickness, m) | 5.2 |
Quaternary sands [q1] (thickness, m) | 34.8 |
Leakage zone (thickness, m) | 968 |
Saturated hydraulic properties | |
q2 permeability (m2) | 1 × 10−14
|
q1 permeability (m2) | 5 × 10−12
|
Leakage zone permeability (m2) | 1 × 10−10–1 × 10−8
|
q2 porosity (−) | 0.15 |
q1 porosity (−) | 0.3 |
Leakage zone porosity (−) | 0.5 |
Unsaturated hydraulic properties | |
Residual liquid saturation (−) | 0.00 |
Residual gas saturation | 0.05 |
Bubbling pressure (Pa) | 1.57 × 104
|
Pore-size distribution index λ (−) | 0.5–6.0 |
Mesh generation
Initialisation of flow and non-reactive transport conditions
Flow and non-reactive transport simulation
Initialisation of reactive-transport conditions
Mineral | Chemical composition | Volume fraction | Reactive surface area (cm2/g) |
---|---|---|---|
Quartz | SiO2
| 0.9 | 9.8 |
Illite IMt-2 | K0.762Na0.044(Si3.387 Al 0.613) (Al1.427Fe
0.292
+3
Mg0.241Fe
0.084
+2
)O10(OH)2
| 0.01 | 151.6 |
Microcline | KAlSi3O8
| 0.01 | 9.8 |
Siderite | FeCO3
| 0.01 | 9.8 |
Calcite | CaCO3
| 0.01 | 9.8 |
Cd-Cr-Ni-goethite | Fe0.999994Cd0.00000001Cr0.000001Ni0.000005O(OH) | 0.01 | 12.9 |
UO2.69
| UO2.69
| 6.4 × 10−7
| 12.9 |
As-Se-pyrite | FeAs0.00001Se0.00001S1.99998
| 0.001 | 12.9 |
Galena | PbS | 4 × 10−6
| 12.9 |
Mineral | Dissolution rate parameters | |||||||||
---|---|---|---|---|---|---|---|---|---|---|
Acid mechanism | Neutral mechanism | Base mechanism | ||||||||
k25 (mol/m2/s) | Ea (KJ//mol) | n(H+) | n(Fe+3) | k25 (mol/m2/s) | Ea (KJ/mol) | n(O2,aq) | k25 (mol/m2/s) | Ea (KJ/mol) | n(H+) | |
Quartz | 1.02 × 10−14
| 87.7 | ||||||||
Illite IMt-2 | 1.05 × 10−11
| 23.6 | 0.34 | 1.66 × 10−13
| 35.0 | 3.02 × 10−17
| 58.9 | −0.4 | ||
Microcline | 8.7 × 10−11
| 51.7 | 0.5 | 3.89 × 10−13
| 38.0 | 6.31 × 10−22
| 94.1 | −0.823 | ||
Siderite | 6.5 × 10−4
| 36.1 | 0.5 | 2.95 × 10−8
| 52.2 | 7.76 × 10−6
| 34.8 | 0.5 | ||
Calcite | 0.5 | 14.4 | 1.0 | 1.55 × 10−6
| 23.5 | 3.31 × 10−4
| 35.4 | 1.0 | ||
Cd-Cr-Ni-goethite | 1.15 × 10−8
| 86.5 | ||||||||
UO2.69
| 1.05 × 10−8
| 32.0 | ||||||||
As-Se-pyrite | 3.02 × 10−8
| 56.9 | −0.5 | 0.5 | 2.82 × 10−5
| 56.9 | 0.5 | |||
Galena | 2.34 × 10−7
| 43.5 | 1.0 |
TOUGHREACT model | AQUA database | |||
---|---|---|---|---|
90 % quantile | Median | 10 % quantile | ||
Temperature (°C) | 11.7 | 12.0 | 10.1 | 8.7 |
pH | 7.4 | 7.6 | 7.2 | 6.4 |
C (mol/L) | 4.7 × 10−3
| 6.1 × 10−3
| 4.3 × 10−3
| 1.4 × 10−3
|
Cl (mol/L) | 7.9 × 10−4
| 2.4 × 10−3
| 7.9 × 10−4
| 2.8 × 10−4
|
S (mol/L) | 7.5 × 10−4
| 1.4 × 10−3
| 6.9 × 10−4
| 2.3 × 10−4
|
K (mol/L) | 4.8 × 10−5
| 1.8 × 10−4
| 5.2 × 10−5
| 2.8 × 10−5
|
Na (mol(L) | 7.4 × 10−4
| 1.9 × 10−3
| 7.0 × 10−4
| 2.4 × 10−4
|
Ca (mol/L) | 1.8 × 10−3
| 3.5 × 10−3
| 2.4 × 10−3
| 9.5 × 10−4
|
Mg (mol/L) | 1.3 × 10−3
| 1.3 × 10−3
| 5.5 × 10−4
| 2.4 × 10−4
|
Fe (mol/L) | 3.2 × 10−5
| 1.2 × 10−4
| 5.7 × 10−7
| 1.8 × 10−7
|
Si (mol/L) | 1.2 × 10−4
| 3.0 × 10−4
| 2.0 × 10−4
| 1.2 × 10−4
|
Al (mol/L) | 2.5 × 10−8
| 8.7 × 10−7
| 7.8 × 10−8
| 1.5 × 10−8
|
As (mol/L) | 3.5 × 10−9
| 9.2 × 10−8
| 2.9 × 10−9
| 6.8 × 10−10
|
Cd (mol/L) | 3.1 × 10−10
| 1.3 × 10−9
| 2.8 × 10−10
| <1.0 × 10−10
|
Cr (mol/L) | 1.8 × 10−8
| 2.5 × 10−8
| 1.3 × 10−8
| <1.0 × 10−9
|
Ni (mol/L) | 2.4 × 10−8
| 9.0 × 10−8
| 2.3 × 10−8
| 6.9 × 10−9
|
Pb (mol/L) | 8.2 × 10−10
| 2.8 × 10−9
| 7.2 × 10−10
| 2.4 × 10−10
|
Se (mol/L) | 3.9 × 10−9
| 1.2 × 10−8
| 4.4 × 10−9
| 1.5 × 10−9
|
U (mol/L) | 1.9 × 10−9
| 9.8 × 10−9
| 2.1 × 10−9
| 9.2 × 10−11
|
Reaction | Equilibrium constant | ||
---|---|---|---|
0.01 °C | 25 °C | 60 °C | |
As-Se-bearing pyrite | |||
FeAs0.00001Se0.00001S1.99998 + 3.4999725 O2,aq + 1.000005 H2O = Fe+2 + 1.99997 H+ + 1.99998 SO
4
−2
+ 0.00001 HSe− + 0.00001 As(OH)3,aq
| 239.447 | 217.193 | 190.827 |
Galena | |||
PbS + 2 O2,aq = Pb+2 + SO
4
−2
| 137.795 | 125.231 | 110.342 |
Cd-Cr-Ni-bearing goethite | |||
Fe0.999994Cd0.00000001Cr0.000001Ni0.000005O(OH) + 2.000001 H+ = 0.24999975 O2,aq + 1.5000005 H2O + 0.999994 Fe+2 + 0.00000001 Cd+2 + 0.000001 Cr+3 + 0.000005 Ni+2
| −8.727 | −8.128 | −7.404 |
Uraniumoxide | |||
UO2.69 + 2H+ + 0.155 O2,aq = H2O + UO2+2
| 13.591 | 11.840 | 9.830 |
Reaction | Equilibrium constant | Source |
---|---|---|
(I)SiH2AsO3 + H2O = (I)SiOH + As(OH)3,aq
| −4.490 | Schwartz (2014) |
(I)SiHAsO
3
−
+ H2O + H+ = (I)SiOH + As(OH)3,aq
| 1.850 | Schwartz (2014) |
(I)SiAsO
3
−2
+ H2O + 2H+ = (I)SiOH + As(OH)3,aq
| 11.200 | Schwartz (2014) |
((I)SiO)2Ni + 2 H+ = 2(I)SiOH + Ni+2
| −0.34 | Schwartz (2014) |
((I)SiO)2Pb + 2H+ = 2(I)SiOH + Pb+2
| −1.10 | Schwartz (2014) |
((I)SiO)2Cd + 2H+ = 2(I)SiOH + Cd+2
| 0.05 | Gu and Evans (2007) |
(I)SiHSe + H2O = (I)SiOH + HSe− + H+
| −17.50 | Schwartz (2014) |
(I)SiOUO2
+ + H+ = (I)SiOH + UO
2
+2
| 1.360 | Schwartz (2014) |
(I)SiOUO2OH + 2H+ = (I)SiOH + UO
2
+2
+ H2O | 5.320 | Schwartz (2014) |
(I)SiOCrOH+ + 2H+ = (I)SiOH + Cr+3 + H2O | −2.06 | See text |
-
The solid-phase FeAs0.00001Se0.00001S1.99998 (As-Se-bearing pyrite) is added. This is a calibrated phase with respect to As and Se. The dissociation constants are identical with those of pyrite.
-
The solid-phase Cd0.00000001Cr0.000001 Ni0.000005Fe0.999994OOH (Cd-Cr-Ni-bearing goethite) is added. This is a calibrated phase with respect to Cd, Cr and Ni. The dissociation constants are identical with those of goethite.