Transcript Minerals and water ーPHREEQC programsー

Minerals and water
ーPHREEQC programsー
Groundwater and Geochemistry Rinko
Koichi MATSUBARA
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What is PHREEQC?
• “PHREEQC is used for simulating a variety of
reactions and processes in natural waters or
laboratory experiments.”
• PHREEQC is based on an ion-association
aqueous model and has capabilities for
(1) speciation and saturation-index calculations
(2) batch-reaction and one-dimensional (1D)
transport calculations …
(3) inverse modeling
From abstract of PHREEQC2
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What can we do by PHREEQC?
• Equilibrium Reactions
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What can we do by PHREEQC?
• Ion exchange
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What can we do by PHREEQC?
• Kinetic reaction
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What can we do by PHREEQC?
• Surface complexation
Sorption on charged surfaces is calculated with surface complexation models.
For example, the sorption of Zn2+ on ferrihydrite (hydrous ferric oxide, or 2line FeOOH) follows the reaction:
Zn2+ + Hfo_sOH ↔ Hfo_sOZn+ + H+
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Getting started
1.
Download the software from…
PHREEQC for Windows version 2.13.05, April 6, 2007 (1.8M)
http://www.geo.vu.nl/users/posv/phreeqc/download.html
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3.
Install the software
Click on the PHREEQC icon to start
4.
Run example files
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Example file 1
• Graphs Ca vs F
concentration in
equilibrium with
fluorite
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Keywords
• SOLUTION_MASTER_SPECIES
defines elements and, among other things, their formula
weights.
• SOLUTION
The aqueous concentrations in a solution are defined
with SOLUTION. The symbols for the elements are listed
in the first column of SOLUTION_MASTER_SPECIES in
the database.
Solution 1 Analysis A
-units ppm
Ca 10
F 5.5
end
Prepare “solution”
Mixing the solutions…
Make equilibrium adding reactants..
Make reaction adding reactants…
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Keywords
• Mineral Equilibration
A solution can be equilibrated with minerals assembled
together in EQUILIBRIUM_PHASES, or the initial
concentration of a component can be adapted when
defining the SOLUTION.
equilibrium_phases 1
fluorite 0 gypsum
Mineral attained equilibrium
Saturation index
Reactant (defined as PHASES)
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Keywords
• REACTION
The keyword REACTION is used to stepwise
add reactants or amounts of minerals to the
solution.
REACTION
H -1 Na 1
25 mmol in 25 steps
Reactant relative amount
(relative molal)
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Keywords
• USER_GRAPH
USER_GRAPH
-headings Ca F pH
-chart_title "Fluorite Equilibrium"
-axis_titles "Ca (mg/L)" "F (mg/L)" "pH"
-initial_solutions false
-start
10 graph_x tot("Ca")*40.08e3
20 graph_y tot("F")*19e3
30 graph_sy -la("H+")
-end
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Keywords
• MIX
The effects of mixing of two or more groundwaters on the
speciation and saturation state with respect to minerals
can be calculated with keyword MIX. This keyword is
also useful for simulating laboratory batch experiments.
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Keywords
• EXCHANGE
The keyword EXCHANGE is used to define exchange
properties and to calculate the composition of the
exchanger.
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Keywords
• Surface Complexation
The keyword SURFACE is used to define the surface
complexation properties of sediments in much the same
way as EXCHANGE.
OECD/NEA:Using Thermodynamic Sorption Models for Guiding Radioelement
distribution Coefficient (Kd) Investigations, A Status Report , 2001
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Keywords
• KINETICS
For kinetic calculations a rate equation must be
programmed in BASIC using keyword RATES. The rate
is called with keyword KINETICS which can also pass
parameters to the rate. The BASIC functions are
explained under keyword RATES in the PHREEQC
manual.
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More options…
We can see various options from
http://www.xs4all.nl/~appt/exmpls/index.html
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