Mo Transport With Powellite Precipitation

[davidblevy]

This input file attempts to simulate inflow of Solution 0 containing elevated Mo through an aquifer containing calcite/clean groundwater and allowing powellite to precipitate. The influent is then switched to the clean groundwater to evaluate Mo concentrations as powellite dissolves. I have two questions:(1) Is there a more efficient or correct way to set up USER_GRAPH for two influent solutions? I have looked at some other examples but this is the only way I can get it to plot (correctly?), and more importantly (2) I don't understand why the Mo exiting the last cell does not return to the influent concentration (0.004 mg/L), when the simulation seems to indicate all of the powellite has dissolved...using Cl as a tracer, it seems to be plotting correctly, but I don't understand what is controlling Mo. Any information would be appreciated, thank you. David

Code: [Select]

PRINT
-reset false

USER_GRAPH 1
-chart_title "Mo Transport With Powellite"
-headings Mo Cl Powellite
-axis_titles "Pore Volume" "Mo and Cl (mg/L)" "Powellite (moles)"
-axis_scale x_axis 0 20
-axis_scale y_axis 0.010 1000 auto auto log
-axis_scale sy_axis 0 5e-6
10 PLOT_XY (STEP_NO+0.5)/20, TOT("Mo")*95.94*1000, color = red, symbol = circle, y-axis = 1
20 PLOT_XY (STEP_NO+0.5)/20, TOT("Cl")*35.45*1000, color = green, symbol = square, y-axis = 1
30 PLOT_XY (STEP_NO+0.5)/20, EQUI("CaMoO4"), color = blue, symbol = circle, y-axis = 2
END

SELECTED_OUTPUT
-file c:\output\Transport_With_Powellite.dat

USER_PUNCH
-headings PV Mo Calcite CaMoO4 delta_CaMoO4 Hfo_sMoO4- Hfo_wMoO4- Hfo_sOHMoO4-2 Hfo_wOHMoO4-2
10 PUNCH STEP_NO/20
20 PUNCH TOT("Mo")*95.94*1000
30 PUNCH EQUI("Calcite")
40 PUNCH EQUI("CaMoO4")
45 PUNCH EQUI_Delta("CaMoO4")
50 PUNCH MOL("Hfo_sMoO4-")
60 PUNCH MOL("Hfo_wMoO4-")
70 PUNCH MOL("Hfo_sOHMoO4-2")
80 PUNCH MOL("Hfo_wOHMoO4-2")
-end

SOLUTION 0 #Average of T27, T32, and T36
-units mg/L
-temp 15#est
-redox O(-2)/O(0)
pH 10.1
Alkalinity 1017 as HCO3
O(0) 0.5#est.
Cl 463
S(6) 3580
Ca 524
Mg 129
Na 1430
K 7.7
Fe 0.10#est.
Mo 9.75
Si 6.8#est.
U 11.4
Se 0.16

SOLUTION 1-20 # SMC Alluvial Groundwater (Wells DD, R, Q: Quarters 1 through 3, 2018)
-units mg/L
-temp 16.2
-redox O(-2)/O(0)
pH 7.4
Alkalinity 192.4 as Ca0.5(CO3)0.5
O(0) 1.2
Ca 411
Mg 77.8
Na 314
K 5.9
Cl 66.1
S(6) 1704 charge
Si 17.9
U 0.063
Mo 0.004
Se 0.377
END

EQUILIBRIUM_PHASES 1-20
Calcite 1.5 8.05 # Average SI; 8.7% from XRD (mean)
Quartz 0.72 10 # Average SI; 60% from XRD (mean)
K-feldspar -0.1 2.5 # Average SI; 7.6% from XRD (mean)
Kaolinite 3.4 0.61 # Average SI; 1.7% from XRD (mean)
Ferrihydrite 1.4 0.084 # Average SI; 0.05% from extractable Fe (mean)
CO2(g) -1.2
CaMoO4 0.0 0.0

SURFACE 1-20
-equilibrate 1
Hfo_wOH Ferrihydrite equilibrium_phases 0.2 53300
Hfo_sOH Ferrihydrite equilibrium_phases 0.005

EXCHANGE 1-20
-equilibrate 1
X 0.46 # 4.9 meq/100g from CEC

TRANSPORT
-cells 20
-shifts 200
-lengths 20*15.24
#-dispersivity 20*6.1 #Dispersivity = 20 ft.
-punch_cells 20

END

USER_GRAPH 1
-chart_title "Mo Transport With Powellite"
#-headings "Mo (mg/L)", "Cl (mg/L)", "Powellite (moles"
-axis_titles "Pore Volume" "Mo and Cl (mg/L)" "Powellite (moles)"
-axis_scale x_axis 0 20
-axis_scale y_axis 0.01 1000 auto auto log
-axis_scale sy_axis 0 5e-6
10 PLOT_XY 10+(STEP_NO+0.5)/20, TOT("Mo")*95.94*1000, color = red, symbol = circle, y-axis = 1
20 PLOT_XY 10+(STEP_NO+0.5)/20, TOT("Cl")*35.45*1000, color = green, symbol = square, y-axis = 1
30 PLOT_XY 10+(STEP_NO+0.5)/20, EQUI("CaMoO4"), color = blue, symbol = circle, y-axis = 2

SOLUTION 0 # SMC Alluvial Groundwater (Wells DD, R, Q: Quarters 1 through 3, 2018)
-units mg/L
-temp 16.2
-redox O(-2)/O(0)
pH 7.4
Alkalinity 192.4 as Ca0.5(CO3)0.5
O(0) 1.2
Ca 411
Mg 77.8
Na 314
K 5.9
Cl 66.1
S(6) 1704 charge
Si 17.9
U 0.063
Mo 0.004
Se 0.377

TRANSPORT
-cells 20
-shifts 200
-lengths 20*15.24
#-dispersivity 20*6.1 #Dispersivity = 20 ft.
-punch_cells 20

END









[dlparkhurst]

I need the database you are using, or the additions to one of the standard databases.

[davidblevy]

I am using a modified Minteqv4.dat. I tried to attach but got an error message. What is the best way to send it? thank you.

[dlparkhurst]

I guess just enter as you would a script with the # button.

[dlparkhurst]

I guess the file is too long.

I'll send you a message for how to get the file to me.

[dlparkhurst]

You have loaded up the first cell with Mo. After you switch solutions, you are releasing only a small amount per pore volume. SYS gives the total amount of Mo in a cell, including the SURFACEs, EQUILIBRIUM_PHASES, and others. The amount released sets up a quasi-steady state for the rest of the column at a concentration of about 0.4 mg/L. In the graph you can see a small decrease in sys and the aqueous concentrations over the second 200 pore volumes.

Code: [Select]

PRINT
#-reset false
USER_PRINT
10 PRINT "Mo, ug/kgw: ", TOT("Mo")*GFW("Mo")*1e6
SOLUTION 0 #Average of T27, T32, and T36
-units mg/L
-temp 15#est
-redox O(-2)/O(0)
pH 10.1
Alkalinity 1017 as HCO3
O(0) 0.5#est.
Cl 463
S(6) 3580
Ca 524
Mg 129
Na 1430
K 7.7
Fe 0.10#est.
Mo 9.75
Si 6.8#est.
U 11.4
Se 0.16

SOLUTION 1-20 # SMC Alluvial Groundwater (Wells DD, R, Q: Quarters 1 through 3, 2018)
-units mg/L
-temp 16.2
-redox O(-2)/O(0)
pH 7.4
Alkalinity 192.4 as Ca0.5(CO3)0.5
O(0) 1.2
Ca 411
Mg 77.8
Na 314
K 5.9
Cl 66.1
S(6) 1704 charge
Si 17.9
U 0.063
Mo 0.004
Se 0.377
END

EQUILIBRIUM_PHASES 1-20
Calcite 1.5 8.05 # Average SI; 8.7% from XRD (mean)
Quartz 0.72 10 # Average SI; 60% from XRD (mean)
K-feldspar -0.1 2.5 # Average SI; 7.6% from XRD (mean)
Kaolinite 3.4 0.61 # Average SI; 1.7% from XRD (mean)
Ferrihydrite 1.4 0.084 # Average SI; 0.05% from extractable Fe (mean)
CO2(g) -1.2
CaMoO4 0.0 0.0

SURFACE 1-20
-equilibrate 1
Hfo_wOH Ferrihydrite equilibrium_phases 0.2 53300
Hfo_sOH Ferrihydrite equilibrium_phases 0.005

EXCHANGE 1-20
-equilibrate 1
X 0.46 # 4.9 meq/100g from CEC
END

USER_GRAPH 2
-chart_title "Mo Transport With Powellite"
-headings dist Mo(200) SYS(Mo)(200)
-axis_titles "Distance, m" "Mo, mg/L or Mole"
-axis_scale y_axis auto auto auto auto log
-connect          false

5 pv = total_time / 20
10 GRAPH_X dist
20 GRAPH_Y TOT("Mo")*GFW("Mo")*1000
30 GRAPH_Y       SYS("Mo")*GFW("Mo")*1000

END
TRANSPORT
-cells 20
-shifts 200
-lengths 20*15.24
-time_step  1
#-dispersivity 20*6.1 #Dispersivity = 20 ft.
-punch_cells 0-20
-print_cells      0-20
-print_frequency 200
-punch_frequency 200
END
USER_GRAPH 2
-chart_title "Mo Transport With Powellite"
-headings dist Mo(400) SYS(Mo)(400)


SOLUTION 0 # SMC Alluvial Groundwater (Wells DD, R, Q: Quarters 1 through 3, 2018)
-units mg/L
-temp 16.2
-redox O(-2)/O(0)
pH 7.4
Alkalinity 192.4 as Ca0.5(CO3)0.5
O(0) 1.2
Ca 411
Mg 77.8
Na 314
K 5.9
Cl 66.1
S(6) 1704 charge
Si 17.9
U 0.063
Mo 0.004
Se 0.377

TRANSPORT
#-cells 20
-shifts 200
#-lengths 20*15.24
#-dispersivity 20*6.1 #Dispersivity = 20 ft.
#-punch_cells 1-20
#-print_cells      20
#-punch_frequency 200
#-print_frequency 200

END


[davidblevy]

Thank you David! I really appreciate your time on this.