software release notice i · 04/2002 version 2.4.2) 06. software title: phreeqc, version 2.6: a...

SOFTWARE RELEASE NOTICE

1. SRN Number: & I

2. Project Title: Radionuclide Transport Key Technical Issue Project No. 20.06002.01.141

3. SRN Title: PHREEQC, Version 2.6

4. Originator/Requestor: David R. Turner Date: 02/20/2003

5. Summary of Actions

X Release of new software 0 Change of access software

o Release of modified software: 0 Software Retirement

o Enhancements made

o Corrections made

6. Validation Status

o Validated

o Limited Validation

X Not Validated Explain: Scheduled for Validation in FY2003

7. Persons Authorized Access l

Name [ Read Only/Read-Write | Addition/Change/Delete

David R. Turner Read-WriteF. Paul Bertetti Read-Write

8. Element Manager Approval: V l Date: ZS/

9. Remarks:

NOTE: This acquired code was developed by the U.S. Geological Survey and supersedes/replaces PHREEQC,Version 2.4.2 currently under configuration management.

CNWRA Form TOP-6 (O9/01)

6

0

SOFTWARE SUMMARY FORM

01. Summary Date: 02. Summary prepared by (Name and phone) 03. Summary Action:

01/24/2003 David R. Turner (CNWRA): (201) 522-2139REPLACEMENT

04. Software Date: 05. Short Title: PHREEQC, Version 2.6 (Replaces PHREEQC,

04/2002 Version 2.4.2)

06. Software Title: PHREEQC, Version 2.6: A Computer Program for Speciation, Batch- 07. Internal Software ID:

Reaction, One-Dimensional Transport, and Inverse Geochemical Calculations None

08. Software Type: 09. Processing Mode: 10. Application Area

El Automated Data System E Interactive a. General:X Scientific/Engineering [1 Auxiliary Analyses

X Computer Program l Batch EJ Total System PAEl Subsystem PA E Other

El Subroutine/Module X Combinationb. Specific: Acquired Geochemical Equilibrium SpeciationCode. Developed by U.S. Geological Survey

11. Submitting Organization and Address: 12. Technical Contact(s) and Phone:

CNWRA/SwRI David R. Turner

6220 Culebra Road (210) 522-2139

San Antonio, TX 78228

13. Software Application: PHREEQC, Version 2.6 is a DOS-based geochemical equilibrium speciation model for dilute

aqueous species. Input uses keyword blocks to describe the geochemical system of interest. PHREEQC, Version 2.6 uses a

thermodynamic database with that contains chemical reactions, equilibrium constants, and enthalpies of reaction to solve

mass action and mass balance constraints in geochemical systems. The code is used to investigate geochemical processes suct

as aqueous speciation, precipitation/dissolution, gas partial pressures, redox behavior, sorption, ion exchange, and one-imepndonnl renrtivp trnnqnnrt

14. Computer Platform 15. Computer Operating 16. Programming 17. Number of Source

PC/Pentium running at 100 System: Language(s): Program Statements:

Mhz or faster Windows 9x/Me, Windows ANSI C++ Unknown

NT 4.0, or Windows 2000

18. Computer Memory 19. Tape Drives: 20. Disk Units: 21. Graphics:

Requirements: 8 Mb RAM; N/A N/A N/A

20 Mb free disk space

22. Other Operational Requirements

23. Software Availability: 24. Documentation Availability:

X Available E Limited El In-House ONLY X Available El Preliminary El In-House ONLY

25. Acquired Code ev oped by U.S. Geological Survey

Software Developer K l 1 Date: ___ ___ ___ __NWA For TOPJ-I (05/9S

5

CENTER FOR NUCLEAR WASTE REGULATORY ANALYSESQA VERIFICATION REPORT

FOR-ACQUIRED SOFTWARE NOT TO BE MODIFIED -

Software Title/Name: PcAD G? : QC'

Version: , oDemonstration workstation: ___ H_ __

Operating System: __

User: 9o ^cl v Drevf

NOTE: Acquired software may or may not meet all requirements and will be evaluated on a case-by-case basis.

Installation Testing [TOP-018, Section 5.61

Has installation testing been conducted for each intended computer platform and operating system?Yes: 0-- No:EJ N/A: I

Computer Platforms: •c Operating Systems:j--) O., c Cx NT ( w,

Location of Aeeopwtpm Test Results: QC.. e e C 9Comments:. §:e-c- LSJ U , ( 4

Software Output [TOP-018, Section 5.5.4]

Is software designed so that individual runs are uniquely identified by date, time, name of software and

version?Yes: E No: v N/A: 0

Date and Time Displayed:-Name/Version Displayed:Comments:

NOT . Output identification content and format is typically tan as s.

Medium Documentation [TOP-018, Section 5.5.6]

The physical labeling of software medium (tapes, disks, etc.) contains: Program Name, Module/Name/Title,

Module Revision, File type (ASCII, OBJ, EXE), Recording Date, and Operating SysteyVs)?Yes: 1 No: O N/A: l

Comments:

(04/01) Page 1 of 3


FOR-ACQUIRED SOFTWARE NOT TO BE MODIFIED -

User Documentation [TOP-018, Section 5.5.7]

Is there a Users' Manual for the software and is it up-to-date?Yes: Elz No: O N/A: I

User's Manual Version and Date: {e5; , , 1Comments:

Are there basic instructions for the installation and use of the software?Yes: f/ No:EJ N/A:EJ

Location of Instructions: j',Q God By -rComments:

Configuration Control [TOP-018, Section 5.7, 5.9.3]

Is the Software Summary Form (Form TOP-4-1) completed and signed?Yes: 9' No: J N/A: J

Date of Approval: ozt 2t| i 3

Is the list of files attached to the Software Summary Form complete and accurate?Yes: a_ No: O N/A: O

Comments:

Is the source code available or, is the executable code available in the case of (acquire commercial codes)?Yes: W No: O N/A: J

Location of Source Code: e (L.Comments:

Have all the script/make files and executable files been submitted to the Software Custodian?

Only the executable files are being submitted.

Yes: Eve No: I N/A: O

Location of executable files: < be b c9 c b

Comments:

(04/01) Page 2 of 3


FOR-#ACQUIRED SOFTWARE NOT TO BE MODIFIED 4-

Software Release [TOP-018, Section 5.9]

Upon acceptance of the software as verified above, has a Software Release Notice (SRN), Form TOP-6 beenissued and does the version number of the software match the documentation?

Yes: 1< No: 0 N/A: I

SRN Number: _____

Comments:

Software Validation [TOP-018, Section 5.10]

Has a Software Validation Test Plan (SVTP) been prepared for the range of application of the software?

Yes: J No: GL-1 N/A: IE

Version and Date of SVTP:

Date Reviewed and Approved via QAP-002:

Comments: q { - S c X

Has a Software Validation Test Report (SVTR) been prepared that documents the results of the validationcases, interpretation of the results, and determination if the software has been validated?

Yes: J No: I-V N/A: 1

Version and Date of SVTR:

Date Reviewed and Approved via QAP-002:

Comments.: o &F9 (-l k +% &Yzoztional Comments:

XA& pt/A AAA.^ 1I A / 2v Iire Evaluator/User/Date S stodian/Date

I.

(04/01) Page 3 of 3

Directory PATH listing for volume NEW

Volume serial number is 0FC94

AB16:61E8 W

R:\

I phreeqc.bat

| PHREEQCv26_configuration.wpd

ex7 t

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manual.pdf

NOTICE.txtPhreeqc.txt

README.TXT

RELEASE.TXT

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phrqc26.exe

+---examples asreceived

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I phreeqc.log

| test.bat

+---src

Makefile

| advection.c

| | basic.c

cll.c

| | global.h

integrate.c

inverse.c

I I isotopes.c

| | kinetics.c

I I main.c

| | mainsubs.c

| | model.cp2c.h

p2clib.c

I parse.cI phqalloc.cI phqalloc.h 0I phreeqc.revI prep.c

I print.cread.c

I readtr.cI spread.cI step.cI structures.c

| tidy.cI transportsI utilities.c

I+---Release

phreeqc.exe

-ThermoDatallnl.datminteq.datphreeqc.datphreeqc2-6.datwateq4f.dat

0 0

SOFTWARE VALIDATION REPORT FORPHREEQC, VERSION 2.6

Prepared for

U.S. Nuclear Regulatory CommissionContract NRC-02-02-012

Prepared by

David R. Turner

Center for Nuclear Waste Regulatory AnalysesSan Antonio, Texas

Approved by,

nCeEnglish C. PekhyManager, Geohydrology a\< Geochemnistry

b'/6/Date (

TABLE OF CONTENTS

Section Page

TABLE OF CONTENTS ................ iiFIGURES ....................... iiiTABLES ....................... iv

1 SCOPE OF THE VALIDATION.. 1

2 THERMODYNAMIC DATA USED IN TESTING . . 1

3 TEST CASES. 2

3.1 Installation Check-Results. 2

3.2 Validation Check-Results.. 23.2.1 Aqueous Speciation. 23.2.2 Mineral Solubility. 63.2.3 Aqueous and Gas Phase Carbonate Chemistry. 63.2.4 Sorption-Surface Complexation Modeling. 83.2.5 Redox Equilibria. 93.2.6 Temperature Effects .133.2.7 Modified Database .15

4 SUMMARY AND CONCLUSIONS .23

5 REFERENCES .23

APPENDIX A

ii

FIGURES

Figure Page

3-1 Comparison of Aqueous Speciation of Seawater from PHREEQC, Version 2.6and MINTEQA2, Version 4.02 . ........................................... 5

3-2 Comparison of Zn-ferrihydrite Sorption Results for PHREEQC, Version 2.6(triangles) and MINTEQA2, Version 4.02 (circles) ............................ 10

3-3 Calculated HS- _ SO2- Speciation as a Function of Electron Activity (pe) forExample 8.4 .......................................................... 14

3-4 Comparison of Saturation Indexes (SI) Calculated by PHREEQC, Version 2.6and MINTEQA2, Version 4.02 for Anhydrite and Gypsum as a Function ..... ...... 17

3-5 Aqueous Speciation Predicted by PHREEQC, Version 2.6 (dotted line, opentriangles) and MINTEQA2, Version 4.02 (solid line, filled circles) as a Function ..... 18

iii

TABLES

Table Page

3-1 Comparison of PHREEQC, Version 2.6 and MINTEQA2, Version 4.02 CalculatedConcentrations of Selected Component Species, Carbonate Species, and Redox .... 3

3-2 Comparison of Barite Solubility Results. 73-3 Representative Seawater Composition. 73-4 Seawater in Equilibrium with Calcite at 25 0C, and Open to Atmosphere. 83-5 Fresh Water in Equilibrium with Calcite at 25 0C, and variable PCO2 *.*.. . 83-6 Comparison of PHREEQC, Version 2.6 and MINTEQA2, Version 4.02 Results for

Zn Sorption on Ferrihydrite. 93-7 Calculated Electron Activity (pe) for Example 8.2 ............................. 113-8 Calculated HS- _ So2- Speciation as a Function of Electron Activity (pe) for

Example 8.4 .113-9 Comparison of Saturation Indexes Calculated by (SI) PHREEQC, Version 2.6

and MINTEQA2, Version 4.02 for Anhydrite and Gypsum as a Function .163-10 Comparison of pe Calculated by PHREEQC, Version 2.6 and MINTEQA2,

Version 4.02 Results as a Function of pH ................................... 193-11 Comparison of PHREEQC, Version 2.6 and MINTEQA2, Version 4.02 Results for

Neptunium Speciation as a Function of pH .................................. 203-12 Comparison of PHREEQC, Version 2.6 and MINTEQA2, Version 4.02 Results for

Uranium Speciation as a Function of pH .................................... 22

iv

* 0

1 SCOPE OF THE VALIDATION

The purpose of this document is to report the results of the validation testing for thegeochemical equilibrium speciation code PHREEQC, Version 2.6 (April 2002 release;Parkhurst and Appelo, 1999) performed under the Software Validation Test Plan (Turner, 2003).PHREEQC, Version 2.6 is an acquired code, originally developed by the U.S. GeologicalSurvey. The software is used by staff at the Center for Nuclear Waste Regulatory Analyses(CNWRA) is providing technical assistance to the U.S. Nuclear Regulatory Commission (NRC)in its high-level waste program.

PHREEQC, Version 2.6 includes a number of capabilities that are not planned for use inCNWRA applications and were not tested at this time:

* Ion exchange* Transport modeling* Inverse modeling* Stable isotope modeling* Biodegradation

If a decision is made to use these code capabilities, the software validation test plan will bemodified as necessary and the report supplemented.

2 THERMODYNAMIC DATA USED IN TESTING

The results from geochemical equilibrium speciation codes are dependent on the type andquality of the data used in the simulation. These are typically contained in databases that aresearched and read by the code based on the input provided by the user. While thesedatabases can be modified by the user to incorporate additional species or differentthermodynamic data, they are considered separately from the input file that defines thegeochemical problem, and should not be modified in the context of running the simulation.

Historically, the original PHREEQC databases have been modified to include extensivethermodynamic data for toxic elements such as Cd, Zn, Pb, As, Hg, and Cu as well as organicligands such as EDTA, Citrate, and Acetate. Databases from other codes such as MINTEQA2(Allison, et al., 1991) and WATEQ4F (Ball and Nordstrom, 1991) have been modified for usewith PHREEQC, Version 2.6. Additional modifications at the CNWRA have included theaddition of thermodynamic data (AHro and log K) for almost 600 aqueous species and solidsinvolving 14 potentially important radioelements, including U, Pu, Th, Np, Am, Sr, Cs, Ra, Sn,Zr, Tc, Ru, Eu, and Co (Turner, 1993; Turner, et al., 1993). Thermodynamic data for U, Pu, Np,Am, and Tc are from the Nuclear Energy Agency Thermodynamic Database Project (Grenthe,et al., 1992; Silva, et al., 1995, Rard, et al., 1999, and Lemire, et al., 2001). The source forother data is the EQ3/6 database (Release Gembochs.v2-eq8-data0.alt.r2, 02Aug95). Inaddition, the CNWRA has recently modified the PHREEQC, Version 2.6 database to match thethermodynamic data in MINTEQA2, Version 4.02.

1

3 TEST CASES

The test cases to be used in the validation testing have been identified previously (Turner,2003). The following sections are intended to report the results of the testing. For simplesystems of a few components the same thermodynamic data (e.g., log K at 298K) were usedto ensure consistency between calculational results. For more complicated systems with alarge number of components, the problems were run using the overall databases. ThePHREEQC, Version 2.6 database (Phreeqc2 6.dat) has been modified by CNWRA staff tomatch the MINTEQA2, Version 4.02 database. The PHREEQC, Version 2.6 and MINTEQA2,Version 4.02 input files are included in Appendix A. Key model results are summarized in tablesor figures for each of the test cases. Output files for PHREEQC, Version 2.6 and MINTEQA2,Version 4.02 are quite extensive, and are included in electronic form on the compact discaccompanying this report.

3.1 Installation Check-Results

The installation of PHREEQC, Version 2.6 software was checked as part of bringing the codeinto configuration management under Technical Operating Procedure (TOP)-018 for theCNWRA (2001). The results indicate that the code was installed correctly on the personalcomputer platform and produced the correct results for 18 different example problems providedwith PHREEQC, Version 2.6. The results are documented in the configuration managementpackage for PHREEQC, Version 2.6 stored in the CNWRA Quality Assurance Records Room.

3.2 Validation Check-Results

Benchmarking is the major method that has been used in validating the PHREEQC, Version 2.6geochemical speciation code. PHREEQC, Version 2.6 results are tested against handcalculations for simple systems reported in geochemical textbooks (Richardson and McSween,1989; Stumm and Morgan, 1996; Langmuir, 1997), and against computer simulations of morecomplicated systems using the U.S. Environmental Protection Agency geochemical speciationcode MINTEQA2, Version 4.02 (Allison, et al., 1991; EPA, 1999a,b). The PHREEQC family ofgeochemical codes have been developed by the U.S. Geological Survey separately fromMINTEQA2, Version 4.02, and similar results from the two codes provide confidence thatPHREEQC, Version 2.6 is correctly implementing the thermodynamics for solvinggeochemical problems.

3.2.1 Aqueous Speciation

Parkhurst and Appelo (1999) provide an example to calculate the distribution of aqueousspecies in seawater and the saturation state of seawater at 25 0C relative to a set of minerals.Representative calculated speciation results are reported in Table 3-1. Additional speciationchecks are reported in Section 3.2.7 of this report.

As originally posed in the PHREEQC, Version 2.6 user's manual (Parkhurst and Appelo, 1999),the speciation problem specified thermodynamic equilibrium constants for the uranium aqueousspeciation in the input file. With the update to both PHREEQC, Version 2.6 and MINTEQA2,Version 4.02 to include data from the Nuclear Energy Agency thermodynamic databases(Grenthe, et al., 1992; Silva, et al., 1995; Rard, et al., 1999; Lemire, et al., 2001), we used the

2

0

Table 3-1. Comparison of PHREEQC, Version 2.6 and MINTEQA2, Version 4.02Calculated Concentrations of Selected Component Species, Carbonate Species, and

Redox Sensitive Species T = 25 °C, Po2 = 10-066 atm.

Aqueous Concentration Aqueous Concentration(molal) (molal)

Species MINTEQA2, Version 4.02 PHREEQC, Version 2.6

Non-Redox/Non-Carbonate Species

K+ 1.033 x 10-2 1.043 x 10-2

Na+ 4.766 x 10-1 4.789 x 10-1

Cl- 5.656 x 10-' 5.657 x 10-1

Carbonate Species

Co3 2- 3.024 x 10-5 3.985 x 10-5HCO3- 1.613 x 10-3 1.579 x 10-3

NaHCO3 2.058 x 10-4 1.733 x 10-4

U02CO3 1.242 x 10-12 1.449 x 10-13

Redox-Sensitive Species

U(OV)total 1.419 x 10-37 1.808 x 10-38

U (V)total 5.437 x 10-28 7.171 x 10-29

U(VI)t1 t., 1.267 x 10-8 1.437 x 10-8

UV0 2(CO3)35- 1.071 x 10-21 7.209 x 10-32

UV'02(CO3 )3 4- 1.180 x 1 0-8 1.422 x 1 0-8

Saturation Indices (SI) with respect to solid phases

Anhydrite -0.68 -0.83

Calcite 0.88 0.84

Halite -2.43 -2.54

Schoepite -4.88 -5.82

Uraninite -27.37 -28.34

3

0 0

values from the databases for uranium speciation, rather than specifying thermodynamic data inthe input files. The original formulation of Example 1 in the PHREEQC, Version 2.6 user'smanual (Parkhurst and Appelo, 1999) also used the NO3 /NH4, redox couple to control theoxidation state of uranium, while controlling the distribution of the other redox sensitiveelements (Fe, Mn) by the overall redox equilibrium with atmospheric oxygen. MINTEQA2,Version 4.02 does not allow the user to specify separate redox controls, so the entireproblem was formulated to control all redox reactions, including uranium speciation, only byatmospheric oxygen.

Because of the large number of aqueous species in a multicomponent solution like seawater,only a few representative species concentrations are included in Table 3-1. A graphicalcomparison of the calculated concentration of more than 100 aqueous species (Figure 3-1a)shows a reasonable, although not perfect correlation among the results when plotted on a logmolality scale. Although there are some multiple orders of magnitude differences betweencalculated concentrations of several species (e.g., U02(CO3)35- and U02CO3), most calculatedvalues agree within a factor of two (on a log-log scale). Most of the very large differences seemto be due to differences in the redox state calculated by PHREEQC and MINTEAQ2.Calculated mineral saturations (Table 3-1) show reasonable agreement, and PHREEQC resultsare consistent with MINTEQA2 predictions of saturation and undersaturation.

Because the two databases have been modified to use the same thermodynamic data, a likelycause of the differences in the results from the two computer codes is differences in how activitycoefficients, (y ) are calculated for aqueous species and in how the redox equilibrium of thesystem was controlled. The iterative scheme used by both codes employs mass balance andmass action constraints to adjust y and ionic strength and converge on species concentrations.Comparing results from the two codes (Figure 3-1 b) indicates that there are differences incalculated values for y. The close agreement with the one-to-one correspondence line inFigure 3-1 b indicates that the differences are generally small, but there are a few cases wherethe different formulations result in calculated values for Y that differ by a factor of two or more.It is important to note that Figure 3-1 b is a log-log plot (log y versus log y ), and the differenceare much greater than a factor of two on a linear scale. Typically, MINTEQA2, Version 4.02calculates a higher activity coefficient than PHREEQC, Version 2.6, due in part to slightlydifferent equations for activity coefficients. In PHREEQC, Version 2.6, the b term in the Daviesequation is -0.3*(l.S.), compared with -0.24*(l.S.) in MINTEQA2, Version 4.02 (Parkhurst andAppelo, 1999; Allison, et al., 1991). The differences in calculated)/ are small in dilute solutions,but become significant at the elevated ionic strength of seawater (0.6 to 0.7 molal). Also,because of the Z2 term in the Davies equation, the differences in activity coefficient formulationsbetween the two codes is more pronounced for highly charged aqueous species. For example,for U02(CO3 )34-, the dominant uranium species in the simulation, y = 9.0 X 10-3 for MINTEQA2,Version 4.02 compared to y = 6.0 x 10-4 calculated using PHREEQC, Version 2.6. This effectis also compounded by slight differences in calculated ionic strengths for the two solutions(0.6653 for MINTEQA2, Version 4.02, versus 0.6794 for PHREEQC, Version 2.6).

Redox equilibria also contribute to the differences in PHREEQC and MINTEQA2 results. Bothcodes calculate oxidizing conditions for the system (pe > 0), but the MINTEQA2 system is

4

0R

9

awI-z

0o

0)0-J

-20

-40

-60

-80

-100 I"-100 -80 -60 -40 -20

Log Molality (PHREEQC, Ver 2.6)

0

-0CN 2

a)> 0w, -22

0)

00 7 - 6.2!0)o -8-j

-8 -6 -4 -2 0 2

Log Activity Coeff (y) (PHREEQC, Ver 2.6)

Figure 3-1. Comparison of Aqueous Speciation of Seawater from PHREEQC, Version 2.6and MINTEQA2, Version 4.02. (a) Comparison of Concentration (log molality) of Aqueous

Species, (b) Comparison of the Calculated Activity Coefficients ( y ) Used by the TwoComputer Codes. The Solid Line Indicates a One-To-One Perfect Correlation Between

Model Results.5

* S

considerably more oxidizing [pe = 12.4 (MINTEQA2) vs 8.5 (PHREEQC)]. This is also reflectedin the greater differences in concentrations for redox sensitive species such as uranium andiron, as opposed to the excellent agreement between non-redox sensitive species such as Na'and Cl- (Table 3-1). PHREEQC, Version 2.6 and MINTEQA2, Version 4.02 produce results thatare broadly consistent, but may differ significantly for individual aqueous species. For thepurposes of this validation, the differences do not seem to represent errors in the formulation ofeither code, but instead reflect different approaches computational approach. These types ofeffects are amplified in complex multicomponent systems such as natural seawater, particularlywith regard to redox-sensitive species.

3.2.2 Mineral Solubility

Richardson and McSween (1989) present two worked problems to investigate the solubility ofbarite (BaSO4 ) at 298 K in pure water (Worked Problem 3-7), and in a 0.2 m NaCI solution(Worked Problem 3-8). Using an iterative solution of the congruent barite dissolution reaction,Richardson and McSween (1989) demonstrated that barite solubility increases with ionicstrength. In adapting these worked problems to solution by PHREEQC, Version 2.6, someaqueous species such as NaSO4 - were suppressed to match the simple aqueous systemmodeled by Richardson and McSween (1989). The results for barite solubility reported inRichardson and McSween (1989) differ slightly from the results calculated by PHREEQC,Version 2.6 (Table 3-2). The results differ by less than two percent, and are likely due to slightdifferences in the activity coefficient formulation, and a more complete handling of thegeochemical system in PHREEQC, Version 2.6. For example, the extended Debye-Huckel isthe default used in PHREEQC, Version 2.6 (Parkhurst and Appelo, 1999), versus the Debye-Huckel formulation used in Richardson and McSween (1989). PHREEQC, Version 2.6 alsoincludes the dissociation products of water (H+ and OH-) in the geochemical system, resulting insmall changes in calculated ionic strength. Reevaluating the Richardson and McSween (1989)calculations using the activity coefficients calculated by PHREEQC, Version 2.6 shows excellentagreement between the two sets of results (Table 3-2). Both the PHREEQC, Version 2.6 andRichardson and McSween (1989) solubility calculations are in good agreement with theexperimental data of Blount (1977) as reported in Richardson and McSween (1989).

3.2.3 Aqueous and Gas Phase Carbonate Chemistry

Stumm and Morgan (1996) present several hand calculations of aqueous carbonate speciation.Included is Example 7.8, equilibrating calcite (CaCO 3 ) in sea water at 25 0C, and open toatmosphere (fixed Pc02 = 3.55 x 10-4 atm). The seawater composition is not specified in theexample problem, but a representative composition is provided in Table 15.2 of Stumm andMorgan (1996) and reproduced in Table 3-3 of this report.

As indicated in the problem formulation, initial Ca2+, HCO3-, and B were omitted. Results fromStumm and Morgan (1996) and PHREEQC, Version 2.6 are compared in Table 3-4.

The model results agree very well for pH, and H2CO3(aq), and agree within less than 30 percentfor Ca2+, HCO 3;, and Co3

2 - concentrations. The differences in HCO3- and C032 are likely due

to uncertainty in starting composition and slight differences in thermodynamic data for theaqueous carbonate system; Stumm and Morgan (1996) do not indicate the precise startingcomposition of the seawater used in their calculations. As noted previously, there are also likelyto be differences due to the thermodynamic data for aqueous speciation, and different activity

6

0

Table 3-2. Comparison of Barite Solubility Results* and PHREEQC, Version 2.6

| msa2+ (molal) | (mola) 7 B.a2+ (D-H) 7 S042- (D-H)

Problem 3-7 (pure H20)

PHREEQC, Version 2.6 1.055 x 10-5 1.055 x 10-5 0.9697 0.9697

Richardson and McSween (1989)* 1.051 x 10-5 1.051 x 10-5 0.9704 0.9704

Richardson & McSween (1989)* 1.055 x 10-5 1.055 x 10-5 0.9697 0.9697calculations with PHREEQC activitycoefficients

Blount (1977)t 1.06 x 10-5 1.06 x 10-5 N/R N/R

Problem 3-8 (0.2 m NaCPHREEQC, Version 2.6 3.663 x 10-5 3.663 x 10-5 0.29812 0.26173Richardson and McSween (1989)* 3.611 x 10-5 3.611 x 10-5 0.2987 0.2671

Richardson & McSween (1989)* 3.663 x 10-5 3.663 x 10-5 0.29726 0.26082calculations with PHREEQC activitycoefficients

Blount (1977)t 3.7 x 10-5 3.7 x 10-5 N/R N/R

*Richardson, S.M. and H.Y. McSween, Jr. Geochemistry: Pathways and Processes. Englewood Cliffs,New Jersey: Prentice-Hall, Inc. 1989.tBlount, C.W. "Barite solubilities and thermodynamic quantities up to 300 °C and 1400 bars." AmericanMineralogist Vol. 272: pp. 438-475. 1977.N/R not reported

Table 3-3. Representative Seawater Composition*

Constituent Concentration (mg/L)

Na' 10770

Mg2+ 1290

Ca2+ 412.1

K+ 399

Sr2+ 7.9

Cl- 19354

S0 42- 2712

HCO3- 142.4

Br- 67.3

F- 1.3

B 4.5

*Stumm, W. and J.J. Morgan. Aquatic Chemistry: Chemical Equilibria and Rates in Natural Waters. 3r Edition.New York, New York: Wiley-lnterscience. 1996.

7

* 0

Table 3-4. Seawater in Equilibrium with Calcite at 25 0 C, and Open to Atmosphere(fixed Pco2 = 3.55 x 10-4 atm). All Concentrations in Molarity.

1 | HCO3- C032 - H2CO 3(aq)

pH Ca24 (total) (total) (total) (total)

Problem 7.8

PHREEQC, Version 2.6 8.31 1.301 x 10-3 2.03 x 10-3 2.76 x 104 9.91 x 106

Stumm and Morgan 8.34 1.51 x 10-3 2.77 x 10-3 3.80 x 10-4 1.05 x 10-5(1996)*

*Stumm, W. and J.J. Morgan. Aquatic Chemistry: Chemical Equilibria and Rates in Natural Waters. 3' Edition.New York, New York: Wiley-lnterscience. 1996.

Table 3-5. Fresh Water in Equilibrium with Calcite at 25 0C, and Variable Pco2

pH Ca24 (mg/L) HCO3- (mg/L)

PCO2 = 10-35 bar = 10-35' atm

PHREEQC, Version 2.6 8.29 19.6 57.7

Langmuir (1997)*; Table 6.3 8.29 20 58

pCO2 = 10-25 bar = 10-251 atm

PHREEQC, Version 2.6 7.63 43.3 130.5

Langmuir (1997)*; Table 6.3 7.62 44 131

PCO2 = 10-' 5 bar = 1 0-15' atm

PHREEQC, Version 2.6 6.98 99.1 300.6

Langmuir (1997)*; Table 6.3 6.97 100 298

*Langmuir, D. Aqueous Environmental Geochemistry. Englewood Cliffs, New Jersey: Prentice-Hall, Inc. 1997.

coefficient models. Because the details of the model inputs are not presented in Stumm andMorgan (1996), it is not possible to evaluate these differences in more detail.

Alternatively, Langmuir (1997) presents results for calcite solubility in fresh water at 25 °C, andunder variable fixed PCO2 These results are easier to interpret due to the simplergeochemical system.

Again, there are slight differences (Table 3-5) due to thermodynamic data or different activitycoefficient models, [Langmuir (1997) does not provide this information in Table 6.3], but at allthree PCO, values covering two orders of magnitude, the agreement is within one percent(Table 3-5). The overall excellent agreement indicates that PHREEQC, Version 2.6 is correctlyimplementing carbonate equilibria in aqueous speciation calculations.

8

0

Table 3-6. Comparison of PHREEQC, Version 2.6 and MINTEQA2, Version 4.02 Results for ZnSorption on Ferrihydrite (Percent Sorbed). DLM Constants*.

ZnT X 10-4 molal ZnT = 1 x 1O- molal

MINTEQA2 PHREEQC MINTEQA2 PHREEQCpH (% sorbed) (% sorbed) (% sorbed) (% sorbed)

5.00 0.3 0.3 0.3 0.3

5.25 0.8 0.8 0.9 0.9

5.50 1.7 1.7 2.4 2.3

5.75 3.0 3.0 6.2 6.1

6.00 4.5 4.5 15.3 15.1

6.25 6.2 6.2 33.0 32.6

6.50 9.2 9.1 57.3 56.9

6.75 15.1 14.9 78.7 78.4

7.00 24.8 24.6 91.1 91.0

7.25 37.4 37.2 96.6 96.6

7.50 50.4 50.2 98.8 98.8

7.75 62.4 62.3 99.6 99.6

8.00 72.3 72.5 99.8 99.8

*Dzombak, D.A. and Morel, F.M.M. "Surface Complexation Modeling: Hydrous Ferric Oxide." New York:John Wiley and Sons. 1990.

3.2.4 Sorption-Surface Complexation Modeling

Parkhurst and Appelo (1999) provide an example of the use of PHREEQC, Version 2.6 tocalculate Zn2+ sorption on ferrihydrite (HFO) using the diffuse-layer surface complexation modeland parameters described in Dzombak and Morel (1990). Sorption at 25 0C (298 K) isinvestigated for two Zn2+ concentrations (10-4 and 1i0` molal), and the results are presented interms of dissolved and sorbed Zn2+ molality as a function of pH. Model results are given inTable 3-6 (percent sorbed) and shown in Figure 3-2 (surface complex concentration).

The results from PHREEQC, Version 2.6 and MINTEQA2, Version 4.02 show excellentagreement, indicating that the surface complexation modeling subroutines are performing asexpected. The minor variations are likely due to differences in how the two codes sweepthrough a range in pH. In PHREEQC, Version 2.6, pH is fixed based on titration withconcentrated NaOH, in contrast to MINTEQA2, Version 4.02, where pH is fixed externally byadjusting H+ activity. This leads to differences in both Na+ concentrations and ionic strength.

9

0

in-3

, . , . .

EC:0O

Ca)C,C:0U

0EC0

CU

C:

0C-0o

O°

ZnT(aqueous)10-41.

10-5

10o-6>°/ f~On

10-7 / |

1 0-9

10-10

-11 -0- MINTEQA2, Version 4.02

19 (a) n -a-- PHREEQC, Version 2.6I'U-.-

5 6 7 8

pH10-3

5 6 7 8

pH

Figure 3-2. Comparison of Zn-ferrihydrite Sorption Results for PHREEQC, Version 2.6(triangles) and MINTEQA2, Version 4.02 (circles).

10

0

Table 3-7. Calculated Electron Activity (pe) for Example 8.2*

pe calculated

PHREEQC, Hand Calculation Hand CalculationVersion 2.6 (y = 1.0) (y from PHREEQC,

Geochemical System Davies equation)

(Fe2+} = 10-3 M 10.904 11.01 10.904(Fe3+} = 10-5 M

pH = 7.5 13.111 13.111 13.111P0, = 0.21 atm

[Mn2+} = 10-5 M 6.925 6.92 6.925Equilibrium with r -MnO2

*Stumm, W. and J.J. Morgan. Aquatic Chemistry: Chemical Equilibria and Rates in Natural Waters. 3rd Edition. NewYork, New York: Wiley-Interscience. 1996.

Table 3-8. Calculated HS--SO42- Speciation as a Function of Electron Activity (pe) for

Example 8.4*

PHREEQC, Version 2.6 Hand Calculation Hand Calculation(y = 1.0) (y from Davies equation)

pe mHS-(molal) mSO42'(molal) mHS-(molal) mSO4

2,(molal) mHS-(molal) mSO 42'(molal)

-9.00 1.00 x 10-4 9.89 x 10-21 1.00 x 10-4 9.55 x 10-21 1.00 x 10-4 9.89 x 10-21

-8.75 1.00 x 10-4 9.89 x 10-19 1.00 x 10-4 9.55 x 10-'9 1.00 x 10-4 9.89 x 10-19

-8.50 1.00 x 10-4 9.89 x 10-17 1.00 x 10-4 9.55 x 10-17 1.00 x 10-4 9.89 x 10-17

-8.25 1.00 x 10' 9.89 x 10-15 1.00 x 10-4 9.55 x 10-'5 1.00 x 10-4 9.89 x 10-5

-8.00 1.00 x 10-4 9.89 x 10-13 1.00 x 10-4 9.55 x 10-'3 1.00 x 10-4 9.89 x 10-'3

-7.75 1.00 x 10-4 9.89 x 10-11 1.00 x 10-4 9.55 x 10-" 1.00 x 10-4 9.89 x 10-"

-7.50 1.00 x 10-4 9.89 x 10-9 1.00 x 10-4 9.55 x 10-9 1.00 x 10-4 9.89 x 10-9

-7.25 9.90 x 10-5 9.79 x 10-7 9.91 x 10-5 9.46 x 10-7 9.90 X 10-5 9.79 x 10-7

-7.00 5.00 x 10-5 5.00 x 10-5 5.12 x 10-5 4.88 x 10-5 5.00 x 10-5 5.00 x 10-5

-6.75 9.82 x 10-7 9.90 X 10-5 1.04 x 10-6 9.90 x 10-5 9.82 x 10-7 9.90 x 10-5

-6.50 9.91 x 10-9 1.00 x 10-4 1.05 x 10-8 1.00 x 10-4 9.91 x 10-9 1.00 x 10-4

-6.25 9.91 x 10-1 1.00 x 10-4 1.05 x 10-10 1.00 x 10-4 9.92 x 10-" 1.00 x 10-4

-6.00 9.91 x 10-13 1.00 x 10-4 1.05 x 10-12 1.00 x 10-4 9.92 x 10-13 1.00 x 10-4

-5.75 9.91 x 10-'5 1.00 x 10-4 1.05 x 10-14 1.00 x 9.92 x 10-'5 1.00 X 10-4

11

0

Table 3-8. Calculated HS--SO 42 - Speciation as a Function of Electron Activity (pe) forExample 8.4*(continued)

PHREEQC, Version 2.6 Hand Calculation Hand Calculation(Y = 1.0) (y from Davies equation)

pe mHS-(molal) mSO42,(molal) mHS-(molal) mSO 4

21(molal) mHS-(molal) mSO 42'(molal)

-5.50 9.91 x 10-17 1.00 x 10-4

1.05 x 10-16 1.00 x 10'4 9.92 x 10-17 1.00 x 1o-4

-5.25 9.91 x 10-19 1.00 x 10-4 1.05 x 10-18 1.00 x 10-4 9.92 x 10-19 1.00 x 10 4

-5.00 9.91 x 10-21 1.00 x 10-4 1.05 x 10-20 1.00 x 10-4 9.92 x 10-21 1.00 x 10-4

-4.75 9.91 x 10-23 1.00 x 10-4 1.05 x 10-22 1.00 x 10-4 9.92 x 10-23 1.00 x 10-4

-4.50 9.91 x 10-25 1.00 x 10-4 1.05 x 10-24 1.00 x 10-4 9.92 x 10-25 1.00 x 10-4

-4.25 9.91 x 10-27 1.00 x 10-4 1.05 x 10-26 1.00 x 10-4 9.92 x 10-27 1.00 x 10-4

-4.00 9.91 x 10-29 1.00 x 10-4 1.05 x 10-28 1.00 X 10-4 9.92 x 10-29 1.00 x 10-4

*Stumm, W. and J.J. Morgan. Aquatic Chemistry: Chemical Equilibria and Rates in Natural Waters. 3r' Edition.New York, New York: Wiley-Interscience. 1996.

3.2.5 Redox Equilibria

PHREEQC, Version 2.6 uses electron activity (pe) as a master variable to control redoxpotential. Stumm and Morgan (1996) present a number of relatively simple calculations todetermine redox equilibrium. Comparison of PHREEQC, Version 2.6 redox equilibria with handcalculations are provided in Tables 3-7 and 3-8.

Example 8.2 presents three different geochemical problems to calculate electron activity (pe)for Fe and Mn systems open to atmosphere. Simple thermodynamic calculations can be usedto calculate pe.

Example 8.2(a). An acid solution with {Fe3+} = 10-5 M; {Fe2+} = 10-3 M

pe = log K + log {Fe 3} (3-1)

Example 8.2(b). Natural water with pH = 7.5 in equilibrium with atmosphere (PO2 = 0.21 atm)

pe = 1log K + - log P02 - pH2 4

(3-2)

Example 8.2(c). Natural water with pH = 8 in equilibrium with y -MnO2

pe = 2 log K - 2pH - 2 log jMn2+}2 2

(3-3)

12

0 0

Equilibrium constants (log K) were modified in the PHREEQC, Version 2.6 input files to matchthe values provided in Stumm and Morgan (1996). Formation of ferric- and ferrous-hydroxyspecies was suppressed in the PHREEQC, Version 2.6 simulation of Example 8.2(a) to matchthe geochemical equilibrium model used in Stumm and Morgan (1996). Also, a dilute NaCI(10-3 M) solution was added to the natural water in Example 8.2(b) to avoid problems withcreating a singular matrix in the PHREEQC, Version 2.6 simulation. Comparison of modelresults in Table 3-7 show that there are slight differences in calculated pe values. In Stummand Morgan (1996), the assumption is that the activity coefficients for all of the components areunity (y = 1.0), while PHREEQC, Version 2.6 uses the Davies equation to correct for ionicstrength effects. Incorporating activity coefficients calculated with the Davies equation improvesthe agreement significantly (Table 3-7).

Example 8.4 (Stumm and Morgan, 1996) calls for a simple calculation of the speciation of HS-and S04

2 - as a function of pe, with pH = 10, and {HS-} + {SQ42-} = 10-4 M. Aqueous speciationlog K values for the reaction in Equation (3-4) were modified in the PHREEQC, Version 2.6input file to match the values (log K = 34.02) provided in Stumm and Morgan (1996). Based onthe redox equilibrium reaction

SO4 + 9H+ + 8e- = HS- + 4H20 (3-4)

pe can be expressed in terms of pH and component activity (assuming YH20 = 1)

pe = 8 ( log K + log {SO42} - log {HS-} - 9pH) (3-5)

The results from PHREEQC, Version 2.6 are compared with hand calculations usingEquation (3-5).

Comparison of the results in Table 3-8 show that there is very good agreement. PHREEQC,Version 2.6 correctly predicts the crossover point (pe = -7.0) where the concentrations of HS-and SQ42- are equal. There is a slight discrepancy when unity activity coefficients (y = 1) wereassumed for the hand calculations. Performing the hand calculations with the activitycoefficients derived for each pe value by PHREEQC, Version 2.6 using the Davies equationresults in a close match to the HS- and SQ42- concentrations predicted by PHREEQC, Version2.6 (Table 3-8). Concentration-pe plots comparing PHREEQC, Version 2.6 and handcalculation results (Figure 3-3) demonstrate the excellent agreement, indicating that PHREEQC,Version 2.6 correctly implements redox equilibria reactions.

3.2.6 Temperature Effects

Parkhurst and Appelo (1999) provide an example of the use of PHREEQC, Version 2.6 tocalculate the solubility of gypsum and anhydrite in pure water, over a range in temperature from25 0C (298 K) to 75 'C (373 K). Only the pH and temperature are used to define a pure watersolution. Gypsum and anhydrite are allowed to react to equilibrium, and the initial phaseassemblage has 1 mol of each mineral. Each mineral will react either to equilibrium or until it isexhausted in the assemblage. For both PHREEQC, Version 2.6 and MINTEQA2, Version 4.02,

13

10-4 2010-6 - HS- S04210-8-

1o-10

C 10-12 -° 10-14 -

X 10-16C 10-18 so 2- HS4

0 10-22 -

0 10-24 -| PHREEQC, Version 2.6

10-26 -- Hand Calculation (y = 1)1-28 . ..... Hand Calculation (PHREEQC-derived y)

-9 -8 -7 -6 -5

pe

Figure 3-3. Calculated H S -S S 2 Speciation as a Function of4Electron Activity (pe) for Example 8.4 in Stumm and Morgan (1996).The Close Agreement Between Different Calculational Methods Resultsin Overlap of the Symbols and Lines.

the degree of saturation with respect to a given mineral is indicated by the saturation index (SI),such that

SI = log IAP (3-6)

where IAP is the ion activity product, and K is the equilibrium constant. When a solution isundersaturated with respect to a given mineral, SI < 0. Under supersaturated conditions, SI > 0,and SI = 0 at equilibrium.

As a default, both PHREEQC, Version 2.6 and MINTEQA2, Version 4.02 use the Van't Hoffrelationship and enthalpies of reaction (AHro) to correct equilibrium constants for the effects of

14

temperature. If data are available, both PHREEQC, Version 2.6 and MINTEQA2, Version 4.02will employ a polynomial expression to correct equilibrium constants for the effects oftemperature:

Log KT = AT + A2T + ±3 + A 4 Log(T) + A5 T 2 + A6 + A7 (3-7)= A1+ 2T + A T2

where KT is the equilibrium constant at a given temperature T in Kelvin and A, etc.,are constants.

If the same thermodynamic data and polynomial expressions are used, both codes shouldproduce similar results. PHREEQC, Version 2.6 provides a polynomial expression in thephreeqc.dat database for both anhydrite and gypsum. In conducting this validation exercise,the same thermodynamic constants and polynomial expressions were used for anhydrite andgypsum (Appendix A).

Comparing the results in Table 3-9 and Figure 3-4(a) shows a slight discrepancy between the SIvalues calculated by PHREEQC, Version 2.6 and MINTEQA2, Version 4.02. This discrepancyis likely due to differences in how the two codes calculate the activity of water. In calculating theconcentrations of individual ionic species to correct the activity of water, MINTEQA2,Version 4.02 includes the concentrations of the two minerals anhydrite and gypsum (1.0 mole ofeach). This gives a larger correction to unit activity (aH 20 = 0.949) , and results in a constantvariation in the calculated SI values. If, however, gypsum or anhydrite is assigned to be presentin an infinite amount in the MINTEQA2, Version 4.02 input file, then the activity correction forwater does not include the minerals, and is much smaller. Runs under this condition show amuch closer agreement with the SI values calculated by PHREEQC, Version 2.6 (Figure 3-4b).

3.2.7 Modified Database

The main code function to be checked in this section of the test plan is to ensure that thePHREEQC, Version 2.6 database modified to include Nuclear Energy Agency radionuclidethermodynamic data is correct and produces reasonable results. If thermodynamic data are thesame, different geochemical equilibrium speciation codes should produce similar results. Themost straightforward way to test this is to compare aqueous speciation results from severaldifferent codes. This approach has been used before (Turner, 1993; Turner, et al., 1993) toexamine the modified MINTEQA2, Version 3.11/3.12 database.

Speciation checks for uranium and neptunium were performed using MINTEQA2, Version 4.02and PHREEQC, Version 2.6. Identical thermodynamic data from the Nuclear Energy Agencythermodynamic database for neptunium and uranium (Grenthe, et al., 1992; Lemire, et al.,2001) were used to examine speciation as a function of pH under atmospheric C02 (10-3 5 atm)and 02 (100-66 atm) conditions. Temperature was fixed at 25 0C (298 K). Low concentrationswere used to avoid the complications of precipitation of pure phases, and the redox coupleswere allowed to establish the distribution among the different oxidation (2, 3+, 4+, 5+, and 6+)states of Np and U. The focus of the check is the CNWRA-modifications to the PHREEQC,Version 2.6 database, and very simple solutions of 0.1 M NaNO3 were used to minimize theeffects of major ions such as Ca2+, Mg2+.

15

Table 3-9. Comparison of Saturation Indexes (SI) Calculated by PHREEQC, Version 2.6and PHREEQC, Version 2.6 for Anhvdrite and GvDsum as a Function of Temrerature.

MINTEQA2, Version 4.02 (1 molsolid) PHREEQC, Version 2.6

T(-C) pH SI(Anhy) SI(Gyp) pH Sl(Anhy) SI(Gyp)

25 7.08 -0.175 0.000 7.06 -0.220 0.000

30 7.01 -0.153 0.000 6.98 -0.198 0.000

35 6.94 -0.126 0.000 6.91 -0.171 0.000

40 6.88 -0.096 0.000 6.85 -0.141 0.000

45 6.82 -0.061 0.000 6.79 -0.106 0.000

50 6.76 -0.023 0.000 6.73 -0.068 0.000

55 6.70 0.000 -0.019 6.68 -0.026 0.000

60 6.65 0.000 -0.064 6.63 0.000 -0.019

65 6.59 0.000 -0.112 6.58 0.000 -0.067

70 6.54 0.000 -0.162 6.53 0.000 -0.117

75 6.49 0.000 -0.216 6.49 0.000 -0.170

Comparison of the predicted speciation indicates good agreement between PHREEQC,Version 2.6 and MINTEQA2, Version 4.02 for Np and U (Figure 3-5). With atmospheric oxygen(PO2 = 10-0°66 atm), both codes calculate similar pe values for the system over the pH range(Table 3-10). Not only is there good agreement for aqueous speciation as a function of pH, butthere is also good agreement between the two codes in simulating the changing dominance ofdifferent oxidation states for redox sensitive elements like Np and U (Tables 3-11 and 3-12).For example, both codes predict a change from Np(V)-dominance at pH < 8 to Np(VI)-dominance of NpO2(CO3)22- and NpO2(CO3)32- at pH > 8. There are minor differences that aremost likely due to activity coefficient calculation, as discussed previously in Section 3.2. Also,there are slight differences in calculated ionic strength due to differences in how pH isdetermined. Finally, there are differences in how the two codes handle the activity of the neutralspecies U0 2(OH)2(aq) and U0 2CO3(aq). While PHREEQC, Version 2.6 assigns unity activitycoefficients (i.e., y = 1) to neutral species, MINTEQA2, Version 4.02 corrects for ionic strengtheffects using the relationship

log y = 0.1(1.S.) (3-9)

where l.S. is the ionic strength of the solution. For the ionic strength used in the simulation (0.1m NaNO3), the activity coefficient for U0 2(OH) 2(aq) and U02CO 3(aq) is 1.02.

16

0

0.10

0.05

xa)*0

C

0

(UC',

0.00

-0.05 1

-0.10

-0.15

-0.20

-0.25

-0.30

(a)

AA

*-_ SI(anhy) - MINTEQA2-0- Sl(gyp) - MINTEQA2... A, SI(anhy) - PHREEQC* A SI(gyp) - PHREEQC

25 30 35 40 45 50 55 60 65 70

Temperature (°C)

75

0.10

0.05:(b)

Xa)

C

Cn

0

(U

C',

0.00

-0.05

-0.10

-0.15

-0.20

-0.25 [-0.30 -

25

--+ SI(anhy) -MINTEQA2--- SI(gyp) - MINTEQA2**. A, SI(anhy) -PHREEQC* A S l(gyp) -PHREEQC

. , I .. . . . . I . . .. . . .. . ............... .......... ........ .. ....................................

30 35 40 45 50 55 60 65 70 75

Temperature (°C)

Figure 3-4. Comparison of Saturation Indexes (SI) Calculated by PHREEQC,Version 2.6 and MINTEQA2, Version 4.02 for Anhydrite and Gypsum as a Function

of Temperature. (a) 1.0 mole anhydrite + 1.0 mole gypsum; (b) AssumingInfinite Gypsum (250 to 550C), Infinite Anhydrite (60° to 75 °C) in MINTEQA2,

Version 4.02 calculations.17

0 0

0.z

0

(FU06

10C

9c

8C

7C

6C

5C

4C

3C

20

10C

0

100

90

80

70

60

50

40

30

20

10

0

I

I

I

I

I

I

I

I4 5 6 7 8 9

pH

PHREEQC, Version 2.6| .- MINTEQA2, Version 4.02

10

II

I

I

I

I

I

I I

4 5 6 7 8 9 10

pH

Figure 3-5. Aqueous Speciation Predicted by PHREEQC, Version 2.6 (dottedline, open triangles) and MINTEQA2, Version 4.02 (solid line, filled circles) as a

Function of pH. T = 25 0C, PCO2 = 10-35 atm PCO2 = 10-066 atm, (a) NeptuniumSpeciation with NPTOTAL = 10-7 m. Neptunium Oxidation States Change with pH

and Both Np(V)-Species and Np(VI)-Species Are Shown; (b) Uranium Speciationwith UTOTAL = 10-7 m. Uranium Speciation is Dominated by U(VI) Over Entire pH

Range, and Only U(VI) Species Are Shown.18

0

Table 3-10. Comparison of pe Calculated by PHREEQC, Version 2.6 and MINTEQA2,Version 4.02 Results as a Function of pH. Background Electrolyte is 0.1 M NaNO 3,

T = 25 0 C, pCO2 = 10-3 5 atm, Po2 = 1 -0.66 atm.

pe pepH PHREEQC, Version 2.6 MINTEQA2, Version 4.02

4.00 16.62 16.61

4.50 16.12 16.11

5.00 15.62 15.61

5.50 15.12 15.11

6.00 14.62 14.61

6.50 14.12 14.11

7.00 13.62 13.61

7.50 13.12 13.11

8.00 12.62 12.61

8.50 12.12 12.11

9.00 11.62 11.61

9.50 11.12 11.11

10.00 10.64 10.61

Despite these small differences, the agreement is excellent for a system open to atmosphereover the range in pH, even for very complicated redox-sensitive aqueous systems such asneptunium and uranium. This indicates that the databases are correctly formatted for bothPHREEQC, Version 2.6 and MINTEQA2, Version 4.02, both codes are correctly reading themodified databases, and both codes are calculating aqueous speciation in a similar fashion.

19

Table 3-11. Comparison of PHREEQC, Version 2.6 and MINTEQA2, Version 4.02 Results for Neptunium Speciation as a Function ofpH. Nptota, = 10-7 M, 0.1 M NaNO3, T = 25 'C, PCO2 = I0-.5 atm, PO, = 10-0.66 atm. Both Np(V) and Np(VI) Are Present, as Indicated.

-

I

Percent (%) of Total Neptunium

pH NpvO2 NpvO2,' NpVO2CO,- NpVO2CO,- Np"O,(CO3 ),'- NpO 2(CO3)22 - Np'O3(CO3)j4-

MINTEQA2 PHREEQC MINTEQA2 PHREEQC MINTEQA2 PHREEQC MINTEQA2 PHREEQC

4.00 99.77 99.77 0.00 0.00 0.00 0.00 0.00 0.00

4.25 99.87 99.87 0.00 0.00 0.00 0.00 0.00 0.00

4.50 99.92 99.92 0.00 0.00 0.00 0.00 0.00 0.00

4.75 99.95 99.95 0.00 0.00 0.00 0.00 0.00 0.00

5.00 99.97 99.97 0.00 0.00 0.00 0.00 0.00 0.00

5.25 99.98 99.98 0.00 0.00 0.00 0.00 0.00 0.00

5.50 99.98 99.98 0.00 0.00 0.00 0.00 0.00 0.00

5.75 99.99 99.99 0.00 0.00 0.00 0.00 0.00 0.00

6.00 99.99 99.99 0.00 0.00 0.00 0.00 0.00 0.00

6.25 99.98 99.98 0.01 0.01 0.00 0.00 0.00 0.00

6.50 99.97 99.97 0.02 0,02 0.00 0.00 0.00 0.00

6.75 99.92 99.92 0.06 0.06 0.00 0.00 0.00 0.00

7.00 99.78 99.78 0.20 0.20 0.00 0.00 0.00 0.00

7.25 99.31 99.33 0.64 0.62 0.02 0.02 0.00 0.00

7.50 97.85 97.91 2.01 1.95 0.11 0.11 0.00 0.00

7.75 93.29 93.46 6.05 5.88 0.61 0.61 0.01 0.01

8.00 80.41 80.78 16.47 16.06 2.95 2.97 0.09 0.11

8.25 53.27 53.70 34.52 33.77 10.99 11.11 1.08 1.27

0

20

Table 3-11. Comparison of PHREEQC, Version 2.6 and MINTEQA2, Version 4.02 Results for Neptunium Speciation as a Functionof pH. Nptota, = 10O` M, 0.1 M NaNO3, T = 25 'C, Pco, = 1O-3 atm, PO2 = 10-066 atm. Both Np(V) and Np(VI) Are Present, as

Indicated. (continued)I

Percent (%) of Total Neptunium

pH NpvO2 Npv0 NpVO2CO, NpVO2CO3 Np O2 (CO%)2 Npv'O2 (CO,)22 - NpVO 2(CO 3)3

4Np 'O(CO)3

4

MINTEQA2 PHREEQC MINTEQA2 PHREEQC MINTEQA2 PHREEQC MINTEQA2 PHREEQC

8.50 21.80 21.75 44.66 43.25 25.31 25.36 7.90 9.29

8.75 4.84 4.58 31.35 28.82 31.66 30.21 31.53 35.75

9.00 0.56 0.48 11.50 9.64 20.74 18.17 66.49 71.02

9.25 0.04 0.03 2.59 1.94 8.38 6.67 88.47 90.88

9.50 0.00 0.00 0.45 0.28 2.63 1.80 96.62 97.65

9.75 0.00 0.00 0.06 0.02 0.68 0.32 99.10 99.44

10.00 0.00 0.00 0.01 0.00 0.15 0.02 99.75 99.16

0

21

Table 3-12. Comparison of PHREEQC, Version 2.6 and MINTEQA2, Version 4.02 Results for Uranium Speciation as a Function of pH.Utota1 = 10-7 M, 0.1 M NaNO3, T = 25 0C, Pco2 = 10-3' atm, PO = 10-0.66 atm. All Uranium Species are U(VI), the Dominant Uranium Species

Over the Entire oH Ranae.Percent (%) of Total Uranium

pH UO 2 U0 22 U0 2 (C0) 2 -2 UO(COh 2

I UO2(CO)j4- U 2(C0.),4 - (U0j 2 C0(OH)3 - (U0 2)2C0,(OH),- U2 OH U0 20H- UO2 (OH)2(aq) UO2 (OH)2(aq)MINTEQA2 PHREEQC MINTEQA2 PHREEQC MINTEQA2 PHREEQC MINTEQA2 PHREEQC MINTEQA2 PHREEQC MINTEQA2 PHREEQC

4.00 90.56 91.13 0.00 0.00 0.00 0.00 0.00 0.00 2.71 2.61 0.01 0.01

4.25 88.67 89.30 0.00 0.00 0.00 0.00 0.00 0.00 4.72 4.55 0.02 0.02

4.50 85.46 86.18 0.00 0.00 0.00 0.00 0.00 0.00 8.09 7.81 0.06 0.06

4.75 80.22 81.08 0.00 0.00 0.00 0.00 0.00 0.00 13.51 13.06 0.18 0.185.00 72.15 73.16 0.00 0.00 0.00 0.00 0.00 0.00 21.60 20.96 0.52 0.515.25 60.78 61,93 0.00 0.00 0.00 0.00 0.01 0,01 32.36 31.55 1.38 1.36

5.50 46.67 47.84 0.00 0.00 0.00 0.00 0.07 0.07 44.19 43.34 3.36 3.325.75 31.72 32.73 0.01 0.01 0.00 0.00 0.62 0.57 53.41 52.74 7.22 7.19

6.00 18.33 19.06 0.08 0.08 0.00 0.00 3.65 3.46 54.89 54.60 13.20 13.24

6.25 8.44 8.85 0.37 0.37 0.00 0.00 13.78 13.25 44.96 45.08 19.23 19.44

6.50 2.99 3.16 1.32 1.31 0.00 0.00 30.76 30.01 28.32 28.61 21.54 21.94

6.75 0.86 0.92 3.80 3.80 0.02 0.03 45.72 45.01 14.56 14.78 19.70 20.15

7.00 0.22 0.23 9.66 9.67 0.19 0.22 52.50 51.88 6.58 6.69 15.83 16.22

7.25 0.05 0.05 21.95 21.95 1.39 1.61 48.18 47.55 2.66 2.70 11.37 11.657.50 0.01 0.01 41.31 40.94 8.26 9.49 30.34 29.38 0.89 0.90 6.77 6.86

7.75 0.00 0.00 50.14 47.86 31.72 35.13 7.95 7.14 0.19 0.19 2.60 2.548.00 0.00 0.00 32.11 29.08 64.31 67.70 0.58 0.47 0.02 0.02 0.53 0.498.25 0.00 0.00 13.52 11.83 85.84 87.60 0.02 0.01 0.00 0.00 0.07 0.06

8.50 0.00 0.00 4.72 4.05 95.17 95.85 0.00 0.00 0.00 0.00 0.01 0.01

8.75 0.00 0.00 1.53 1.29 98.45 98.69 0.00 0.00 0.00 0.00 0.00 0.009.00 0.00 0.00 0.48 0.39 99.52 99.60 0.00 0.00 0.00 0.00 0.00 0.009.25 0.00 0.00 0.15 0.11 99.85 99.88 0.00 0.00 0.00 0.00 0.00 0.009.50 0.00 0.00 0.04 0.03 99.96 99.95 0.00 0.00 0.00 0.00 0.00 0.009.75 0.00 0.00 0.01 0.01 99.99 99.91 0.00 0.00 0.00 0.00 0.00 0.00

10.00 0.00 0.00 0.00 0.00 100.00 99.30 0.00 0.00 0.00 0.00 0.00 0.000

22

* S

4 SUMMARY AND CONCLUSIONS

Comparisons for a variety of geochemical problems (solubility, gas chemistry, redox, sorption)show that PHREEQC, Version 2.6 produces results that are consistent with those produced byother methods such as hand calculations, experiments, and other computer codes. For thesimplest systems, the PHREEQC, Version 2.6 results agree well with those calculated by othermethods. For more complicated systems, however, there are differences in how the problemsare formulated in PHREEQC and MINTEQA2, (especially activity coefficient correction) thatlead to differences in the results. Typically, these differences have a relatively small effecton individual species or components, but some can lead to large variance between thecalculational results produced by the two codes, particularly for highly-chargedaqueous species.

Overall, the agreement of trends and results between PHREEQC, Version 2.6 and the variouscalculational methods used in the model validation exercise indicates that the code is correctlyand consistently applying mass action and mass balance constraints to calculating geochemicalequilibrium. As has been demonstrated for the geochemical systems considered in thisvalidation exercise, the observed differences in calculational results are generally small, but insome cases they can be larger than might otherwise be expected. For the purposes of thisvalidation, the differences in results do not seem to represent errors in the formulation ofPHREEQC, Version 2.6, but instead reflect different approaches to geochemical equilibriumcalculations used by different calculation methods (hand calculations and computer codesimulations), and differences in computational approach. These types of variations are oftenobserved among geochemical speciation codes (Morrey, et al., 1986; Emren, et al., 1999),however, and indicate that the code user should pay careful attention to interpreting the resultsof any geochemical speciation calculations.

5 REFERENCES

Allison, J.D., D.S. Brown, and K.J. Novo-Gradac. "MINTEQA2/PRODEFA2, A GeochemicalAssessment Model for Environmental Systems. Version 3.0 User's Manual."EPA/600/3-91/021. Athens, Georgia: U.S. Environmental Protection Agency. 1991.

Ball, J.W. and D.K. Nordstrom. "User's Manual for WATEQ4F, with Revised ThermodynamicDatabase and Test Cases for Calculating Speciation of Major, Trace, and Redox Elements inNatural Waters." U.S. Geological Survey Open-File Report 90-129. Denver, Colorado:U.S. Geological Survey. 1991.

Blount, C.W. "Barite solubilities and thermodynamic quantities up to 300 0C and 1400 bars."American Mineralogist Vol. 272: pp. 438-475. 1977.

CNWRA. "Technical Operating Procedure (TOP)-18: Development and Control of Scientificand Engineering Software, Revision 8, Change 0 (October 5, 2001)." San Antonio, Texas:Center for Nuclear Waste Regulatory Analyses. 2001.

Dzombak, D.A. and Morel, F.M.M. "Surface Complexation Modeling: Hydrous Ferric Oxide."New York: John Wiley and Sons. 1990.

23

* S

Emren, A.T., R. Arthur, P.D. Glynn, and J. McMurry. "The modeler's influence on calculatedsolubilities for performance assessments at the Aspo hard-rock laboratory. Scientific Basis forNuclear Waste Management-XXII. D. Wronkiewicz and J.H. Lee, eds. SymposiumProceedings. Pittsburgh, Pennsylvania: Material Research Society. pp. 559-566. 1999.

Grenthe, I., J. Fuger, R. Konings, R.J. Lemire, A.B. Muller, C. Nguyen-Trung, and H. Wanner."Chemical Thermodynamics Series, Volume 1: Chemical Thermodynamics of Uranium."Nuclear Energy Agency, Organization for Economic Cooperation and Development. New York:Elsevier. 1992.

Langmuir, D. Aqueous Environmental Geochemistry. Englewood Cliffs, New Jersey:Prentice-Hall, Inc. 1997.

Lemire, R.J., J. Fuger, H. Nitsche, P. Potter, M.H. Rand, J. Rydberg, K. Spahiu, J.C. Sullivan,W.J. Ullman, P. Vitorge, and H. Wanner. "Chemical Thermodynamics Series, Volume 4:Chemical Thermodynamics of Neptunium and Plutonium." Nuclear Energy Agency,Organization for Economic Cooperation and Development. New York: Elsevier. 2001.

Morrey, J.R., C.T. Kincaid, C.J. Hostetler, S.B. Yabusaki, and L.W. Vail. "GeohydrochemicalModels for Solute Migration. Volume 3: Evaluation of Selected Computer Codes."EPRI-EA-3417. Palo Alto, California: Electric Power Research Institute. 1986.

Parkhurst, D.L. and C.A.J. Appelo. "User's Guide to PHREEQC (Version 2)-A ComputerProgram for Speciation, Batch-reaction, One-dimensional Transport, And Inverse GeochemicalCalculations." Water-Resources Investigations Report 99-4259. Denver, Colorado:U.S. Geological Survey. 1999.

Rard, J.A., M.H. Rand, G. Anderegg, and H. Wanner. "Chemical Thermodynamics Series,Volume 3: Chemical Thermodynamics of Technetium." Nuclear Energy Agency, Organizationfor Economic Cooperation and Development. New York: Elsevier. 1999.

Richardson, S.M. and H.Y. McSween, Jr. Geochemistry: Pathways and Processes.Englewood Cliffs, New Jersey: Prentice-Hall, Inc. 1989.

Silva, R.J., G. Bidoglio, M.H. R, P.B. Robouch, H. Wanner, and 1. Puigdomenich. "ChemicalThermodynamics Series, Volume 2: Chemical Thermodynamics of Americium." Nuclear EnergyAgency, Organization for Economic Cooperation and Development. New York: Elsevier. 1995.

Stumm, W. and J.J. Morgan. Aquatic Chemistry: Chemical Equilibria and Rates in NaturalWaters. 3r Edition. New York, New York: Wiley-lnterscience. 1996.

Turner, D.R. "Mechanistic Approaches to Radionuclide Sorption Modeling." CNWRA 93-019.San Antonio, Texas: Center for Nuclear Waste Regulatory Analyses. 1993.

Turner, D.R. "Software Validation Test Plan for PHREEQC, Version 2.6." San Antonio, Texas:Center for Nuclear Waste Regulatory Analyses. 2003.

Turner, D.R., T. Griffin, and T.B. Dietrich. Radionuclide sorption modeling using the MINTEQA2speciation code. Scientific Basis for Nuclear Waste Management-XVI. C. Interrante and R.Pabalan, eds. Symposium Proceedings. Pittsburgh, Pennsylvania: Material Research Society.pp. 783-789. 1993.

24

U.S. Environmental Protection Agency. "MINTEQA2/PRODEFA2, A Geochemical AssessmentModel for Environmental Systems: User Manual Supplement for Version 4.0." Athens, Georgia:U.S. Environmental Protection Agency, National Exposure Research Laboratory, EcosystemsResearch Division. 1999a.

U.S. Environmental Protection Agency. "Diffuse-Layer Sorption Reactions for use inMINTEQA2 for HWIR Metals and Metalloids." Athens, Georgia: U.S. Environmental ProtectionAgency, National Exposure Research Laboratory, Ecosystems Research Division. 1999b.

25

0 0

APPENDIX A

0 0

PHREEQC, Version 2.6 and MINTEQA2, Version 4.02 input files

Validation Test Case 1.

The installation of PHREEQC, Version 2.6 software was checked as part of bringing the codeinto configuration management under Technical Operating Procedure (TOP)-018 for theCNWRA. The results indicate that the code was installed correctly on the PC platform andproduced the correct results for 18 different example problems provided with PHREEQC,Version 2.6. The results are documented in the configuration management package forPHREEQC, Version 2.6 stored in the CNWRA QA Records Room.

A-1

* S

INPUT FILES, SECTION 3.2.1

Validation Test Case la-Aqueous Speciation. PHREEQC, Version 2.6 input file forseawater speciation check (from Parkhurst and Appelo, 1999)

TITLE Modified Example 1.--Add uranium and speciate seawater.SOLUTION 1 SEAWATER FROM NORDSTROM ET AL. (1979)

units ppmpH 8.22pe 8.451density 1.000temp 25.0redox O(0)/O(-2)Ca 412.3Mg 1291.8Na 10768.0K 399.1Fe 0.002Mn 0.0002Si 4.28Cl 19353.0C(4) 141.682 as HCO3S(6) 2712.0N(5) 0.29 gfw 62.0N(-3) 0.03 as NH4U 3.3 ppbO(0) 1.0 02(g) -0.66

END

Validation Test Case llb-Aqueous Speciation. MINTEQA2, Version 4.02 input file forseawater speciation check (from Parkhurst and Appelo, 1999)

Add U and speciate seawater (Nordstrom et al., 1979)Modified PHREEQC 2.6 Ex. 1 (Parkhurst and Appelo, 1999)25.00 PPM 0.000 0.OOOOOE+00O 0 1 0 1 0 0 0 1 1 0 0 00 0 0

330 0.000E+00 -8.22 y /H+1150 4.123E+02 -1.99 y /Ca+2460 1.292E+03 -1.27 y /Mg+2500 1.077E+04 -0.33 y /Na+1410 3.991E+02 -1.99 y /K+1280 0.OOOE+00 -11.75 /Fe+2281 2.OOOE-03 -7.45 y /Fe+3470 2.OOOE-04 -8.44 y /Mn+2471 0.OOOE+00 -11.74 y /Mn+3770 4.280E+00 -3.82 y /H4SiO4180 1.935E+04 -0.26 y /Cl-1140 1.393E+02 -2.63 y /C03-2732 2.712E+03 -1.55 y /S04-2492 2.900E-01 -5.33 y /NO3-1490 3.OOOE-02 -5.78 y /NH4+1891 0.OOOE+00 -12.43 y /U+4892 0.OOOE+00 -12.43 y /UO2+1893 3.300E-03 -7.86 y /U02+2

1 0.OOOE+00 -7.00 y /E-1

3 63300021 -82.4318 571.6600 /02 (g)2802810 13.0320 -42.7000 /fe+2/fe+34704710 25.3500 -107.8000 /mn+2/mn+38918930 9.0400 -143.8600 /u+4/uo2+28928930 1.4800 -6.1300 /uo2+/uo2+2

330 8.2200 0.0000 /H+16 1

1 0.0000 0.0000 /E-1

A-2

* 0


Validation Test Case 2a-Mineral Solubility. MINTEQA2, Version 4.02 input file. BariteSolubility in pure H20 comparison to Richardson and McSween (1989) (Worked Problem 3-7):

TITLE Barite (BaSO4) solubilityComparison to Richardson and McSween (1989)

SOLUTION 1 Pure waterpH 7.0temp 25.0

EQUILIBRIUMPHASES 1Barite 0.0 1.0

SELECTEDOUTPUT-file baritel.sel-molalities Ba+2 S04-2

PHASESBarite

BaSO4 = Ba+2 + S04-2logk -9.98deltah 5.50 kcal

END

Validation Test Case 2b-Mineral Solubility. MINTEQA2, Version 4.02 input file.Barite Solubility in 0.2 m NaCI comparison to Richardson and McSween (1989) (WorkedProblem 3-8):

TITLE Barite (BaSO4) solubilityComparison to Richardson and McSween (1989)

SOLUTION 1 Pure waterunits mol/kgwpH 7.0temp 25.0Na 0.2Cl 0.2

EQUILIBRIUM-PHASES 1Barite 0.0 1.0

SOLUTIONSPECIESNa+ + S04-2 = NaSO4-log k 0.00

SELECTED-OUTPUT-file barite2.sel-molalities Ba+2 S04-2

PHASESBarite

BaSO4 = Ba+2 + S04-2logk -9.98delta h 5.50 kcal

END

A-3

* C


Validation Test Case 3a-Gas Chemistry. MINTEQA2, Version 4.02 input file. Aqueousspeciation of seawater in equilibrium with calcite at 25 CC, and open to atmosphere (fixed PC 2 =3.45 x 10- atm) (Stumm and Morgan, 1996; Example 7.8).

TITLE Speciate seawater. Seawater from Stumm&Morgan Table 15.2SOLUTION 1

units mg/Ltemp 25.0pH 7.0Na 10770Mg 1290K 399Sr 7.9Cl 19353.0S(6) 2712.0Br 67.3F 1.3

EQUILIBRIUM PHASESCalcite 0.0 10.0C02(g) -3.45 1.0

SELECTED_OUTPUT-file Stumm96.sel-molalities C03-2 MgCO3 NaCO3- HC03- CaCO3 SrCO3\MgHCO3+ NaHCO3 CaHCO3+ H2C03-totals Ca

END

Validation Test Case 3b-Gas Chemistry. MINTEQA2, Version 4.02 input file. Aqueousspeciation of fresh water in equilibrium with calcite at 25 °C, and variable PCO2 (Langmuir, 1997;Table 6.3).

TITLE Calcite Solubility in Pure Water, PCO2=lE-3.5Langmuir (1997, Table 6.3)


EQUILIBRIUM PHASES 1Calcite 0.0 10.0C02(g) -3.51 1.0

SELECTEDOUTPUT-file langmuir97.sel-molalities Ca+2 CaCO3 CaOH+ CaHC03+ HCO3-

END

TITLE Calcite Solubility in Pure Water, PCO2=1E-2.5Langmuir (1997, Table 6.3)


EQUILIBRIUMPHASES 2Calcite 0.0 10.0C02(g) -2.51 1.0

END

TITLE Calcite Solubility in Pure Water, PCO2=1E-1.5Langmuir (1997, Table 6.3)


EQUILIBRIUM PHASES 3Calcite 0.0 10.0C02(g) -1.51 1.0

END

Note: The partial pressures in Langmuir (1997) are presented in terms of bars, while PHREEQC readspressures in terms of atmospheres. For conversion, 1 bar = 0.98692 atm.

A-4

* 0


Validation Test Case 4a-Surface Complexation (Double Diffuse-Layer Model).PHREEQC, Version 2.6 input files for Zn-sorption on ferrihydrite, using the parameters ofDzombak and Morel (1990). This input file is from Example 8 in the PHREEQC, Version 2.6installation test problems (Parkhurst and Appelo, 1999).

TITLE Example 8.--Sorption of zinciron oxides.

SURFACE-SPECIESHfosOH + H+ = HfosOH2+log.k 7.18

on hydrous

HfosOH = Hfo_sO- + H+logk -8.82

Hfo_sOH + Zn+2 = HfosOZn+ + H+log-k 0.66

Hfo_wOH + H+ = HfowOH2+logk 7.18

Hfo wOH = Hfo wO- + H+log-k -8.82

HfowOH + Zn+2 = Hfo_wOZn+ + H+log-k -2.32

SURFACE 1HfosOHHfowOH

SOLUTION 1-unitspHZnNaN(5)

SOLUTION 2

5e-62e-4

600. 0.09

mmo 1 / kgw8.00. 0001100. charge100.

-units nIpH 8Zn 0Na 1(N(5) 1(

solution none

.nol/kgw

.0

.1

DO.charge

USE

# Model definitions

PHASESFixH+H+ =H+

log-k 0.0END

# Zn = le-7

SELECTEDOUTPUT-file ex8.sel-molalities

USE solution 1USE surface 1EQUILIBRIUMPHASES 1

Fix_H+ -5.0ENDUSE solution 1USE surface 1EQUILIBRIUMPHASES 1

FixH+ -5.25ENDUSE solution 1

Zn+2 Hfo_wOZn+

NaOH 10.0

NaOH 10.0

Hfo_sOZn+

A-5

S 0

USE surface 1EQUILIBRIUMPHASES 1

FixH+ -5.5ENDUSE solution 1USE surface 1EQUILIBRIUMPHASES 1










FixH+ -8.0END

* Zn = le-4

USE solution 2USE surface 1EQUILIBRIUMPHASES 1

Fix_H+ -5.0ENDUSE solution 2USE surface 1EQUILIBRIUMPHASES 1


FixH+ -5.5

NaOH

NaOH

NaOH

NaOH

10. 0

10. 0

10. 0

10. 0

NaOH 10.0

NaOH 10. 0

NaOH 10.0

NaOH 10. 0

NaOH 10.0

NaOH

NaOH

NaOH

NaOH

NaOH

10. 0

10. 0

10. 0

10. 0

10.0

A-6

0

ENDUSE solution 2USE surface 1EQUILIBRIUMPHASES 1


FixH+ -6.0ENDUSE solution 2USE surface 1EQUILIBRIUM_PHASES 1








FixH+ -8.0END

NaOH 10.0

NaOH 10.0

NaOH 10.0

NaOH 10.0

NaOH 10. 0

NaOH 10.0

NaOH 10. 0

NaOH 10.0

NaOH

NaOH

10.0

10.0

Validation Test Case 4b-Surface Complexation (Double Diffuse-Layer Model).MINTEQA2, Version 4.02 input file for Zn-sorption on ferrihydrite, using the parameters ofDzombak and Morel (1990). This input file is constructed to match Example 8 in thePHREEQC, Version 2.6 installation test problems (Parkhurst and Appelo, 1999).

Zn-HFO sorption, Double Diffuse-Layer ModelExample 8; PHREEQC, Version 2.6 installation test files25.00 MOLAL 0.000 0.OOOOOE+000 0 1 0 1 0 0 0 1 1 1 3 313 H+1 ACTIVITY mol/L1 330 1.000

5.00 0.25valid65.123 950 8119500 81295004 1 79.OOOE-02 600.00 0.000 0.000 81

330 0.OOOE+00 -5.00 y /H+1500 1.OOOE-01 -1.00 y /Na+1

A-7

0

492950813811812

2 49503300950330195033029503303

3 1330

6 3813

95049219504922

1. OOOE-011. OOOE-071. OOOE-075. OOE-062. OOOE-04

-8.9600-16.9000-28.4000-41.2000

-1.00 y-7.00 y-7.00 y-5.30 y-3.70 y

/NO3-1/Zn+2/ADSlPSIo/ADSlTYPl/ADSlTYP2

55.81000.00000.00000.0000

/ znoh+/zn(oh)2 (aq)/zn(oh)3-/zn(oh)4-2

/H+1

/ADS1PSIo/znno3+/zn(no3)2 (aq)

5.0000 0.0000

0.0000 0.00000.4000 -4.6000

-0.3000 0.0000

2 68113300 Hfo_sOH2+0.00 3 1.000 8110.000 0 0.000

0 0.000 0 0.0008113301 HfosO-0.00 3 1.000 8110.000 0 0.000

0 0.000 0 0.0008119500 HfOsOZn+0.00 4 1.000 8110.000 0 0.000

0 0.000 0 0.0008123300 Hfo_wOH2+0.00 3 1.000 8120.000 0 0.000

0 0.000 0 0.0008123301 HfOwO-0.00 3 1.000 8120 .000 0 0.000

0 0.000 0 0.0008129500 HfowOZn+0.00 4 1.000 8120.000 0 0.000

0 0.000 0 0.000

0.00001.000 3300 0 .0000 0 .0000.0000

-1.000 3300 0.000

0 0.0000.0000

1.000 9500 0 .000

0 0.0000 .0000

1.000 3300 0. 000

0 0.0000.0000

-1.000 3300 0.000

0 0.0000. 0000

1.000 9500 0. 000

0 0.000

7.1800 0.000 0.0001.000 813 0.000 00 0.000 0 0.0000

-8.8200 0.000 0.000-1.000 813 0.000 00 0.000 0 0.0000

0.6600 0.000 0.000-1.000 330 1.000 8130 0.000 0 0.0000

7.1800 0.000 0.0001.000 813 0.000 00 0.000 0 0.0000

-8.8200 0.000 0.000-1.000 813 0.000 00 0.000 0 0.0000

-2.3200 0.000 0.000-1.000 330 1.000 8130 0.000 0 0.0000

0.00 0.00 0.00 0.00000.000 0 0.000 00 0.000 0

0.00 0.00 0.00 0.00000.000 0 0.000 00 0.000 0

0.00 0.00 0.00 0.00000.000 0 0.000 00 0.000 0

0.00 0.00 0.00 0.00000.000 0 0.000 00 0.000 0

0.00 0.00 0.00 0.00000.000 0 0.000 00 0 .000 0

0.00 0.00 0.00 0.00000.000 0 0.000 00 0.000 0

Zn-HFO sorption, Double Diffuse-Layer ModelExample 8; PHREEQC, Version 2.6 installation25.00 MOLAL 0.000 0.OOOOOE+000 0 1 0 1 0 0 0 1 1 1 3 313 H+1 ACTIVITY mol/L1 330 1.000

5.00 0.25valid65.123 950 8119500 81295004 1 79.OOOE-02 600.00 0.000 0.000 81

330 0.OOOE+00 -5.00 y500 1.OOOE-01 -1.00 y492 1.OOOE-01 -1.00 y950 1.OOOE-04 -4.00 y813 1.OOOE-07 -7.00 y811 5.OOOE-06 -5.30 y812 2.OOOE-04 -3.70 y

test files

/H+1/Na+l/NO3-1/Zn+2/ADSlPSIo/ADSlTYPl/ADSlTYP2

2 49503300950330195033029503303

3 1

-8.9600-16.9000-28.4000-41.2000

55.81000.00000.00000.0000

/znoh+/zn(oh)2 (aq)/zn(oh)3-/zn(oh)4-2

6330 5.0000 0.00003

813 0.0000 0.0000

/H+1

/ADS1PSIo

A-8

0

9504921 0.4000 -4.60009504922 -0.3000 0.0000

/znno3+/zn(no3)2 (aq)

2 68113300 Hfo_sOH2+0.00 3 1.000 8110.000 0 0.000

0 0.000 0 0.0008113301 Hfo_sO-0.00 3 1.000 8110.000 0 0.000

0 0.000 0 0.0008119500 HfOsOZn+0.00 4 1.000 8110.000 0 0.000

0 0.000 0 0.0008123300 HfowOH2+0.00 3 1.000 8120.000 0 0.000

0 0.000 0 0.0008123301 HfOwO-0.00 3 1.000 8120.000 0 0.000

0 0.000 0 0.0008129500 HfowOZn+0.00 4 1.000 8120.000 0 0.000

0 0.000 0 0.000

0.00001.000 3300 0.0000 0 .0000. 0000

-1.000 3300 0. 000

0 0.0000. 0000

1.000 9500 0.000

0 0.0000.0000

1.000 3300 0.0000 0. 0000.0000

-1.000 3300 0.000

0 0.0000.0000

1.000 9500 0.000

0 0.000

7.1800 0.000 0.0001.000 813 0.000 00 0.000 0 0.0000

-8.8200 0.000 0.000-1.000 813 0.000 00 0.000 0 0.0000

0.6600 0.000 0.000-1.000 330 1.000 8130 0.000 0 0.0000

7.1800 0.000 0.0001.000 813 0.000 00 0.000 0 0.0000

-8.8200 0.000 0.000-1.000 813 0.000 00 0.000 0 0.0000

-2.3200 0.000 0.000-1.000 330 1.000 8130 0.000 0 0.0000

0.00 0.00 0.00 0.00000.000 0 0.000 00 0.000 0

0.00 0.00 0.00 0.00000.000 0 0.000 00 0.000 0

0.00 0.00 0.00 0.00000.000 0 0.000 00 0.000 0

0.00 0.00 0.00 0.00000.000 0 0.000 00 0.000 0

0.00 0.00 0.00 0.00000.000 0 0.000 00 0.000 0

0.00 0.00 0.00 0.00000.000 0 0.000 00 0.000 0

A-9


Validation Test Case 5a-Redox Equilibria. MINTEQA2, Version 4.02 input file for redoxExample 8.2 in Stumm and Morgan (1996). The simulation is intended to determine electronactivity (pe).

TITLE Calculate electron activity (pe) for Example 8.2a (Stumm&Morgan96)#Note: For direct comparison, all Fe+2 and Fe+3 hydroloysis species#suppressed in PHREEQC databaseSOLUTION 1 Defined Fe+2/Fe+3

units mol/kgwpH 7.0temp 25.0Fe(2) le-3Fe(3) le-5

SOLUTIONSPECIESFe+3 + e- = Fe+2log k 13.0

SELECTED-OUTPUT-file redoxl.sel-pe

END

TITLE Calculate electron activity (pe) for Example 8.2b (Stumm&Morgan96)SOLUTION 2 Fixed pH = 7.5 and pO

2=0.

21 atm

units mol/kgwpH 7.5temp 25.0

PHASESFix H+H+ -1H+log k 0.0

SOLUTION SPECIES2H20 = 02 + 4H+ + 4e-log k -83.10

EQUILIBRIUM PHASES 202(g) -0.678 1.0FixH+ -7.5

END

TITLE Calculate electron activity (pe) for Example 8.2c (Stumm&Morgan96)SOLUTION 3 Fixed pH = 8 and le-5 M Mn(II)

units mol/kgwpH 8.0temp 25.0Mn(2) le-5

PHASESFixH+

H+ = H+log k 0.0

PyrolusiteMnO2 + 4H+ + 2e- = Mn+2 + 2H20log k 40.84

EQUILIBRIUMPHASES 3Pyrolusite 0.0 10.0FixH+ -8.0

END

A-10

Validation Test Case 5b-Redox Equilibria. MINTEQA2, Version 4.02 input file for redoxExample 8.4 in Stumm and Morgan (1996). The simulation is intended to determine HS--S0 4

2 -speciation as a function of electron activity (pe).

TITLE Calculate electron activity (pe) for Example 8.4 (Stumm&Morgan96)SOLUTION 1 Fixed pH = 10.0, and 1E-4 M S04-2/HS-

units mol/kgwpH 10.0temp 25.0pe -9.0S le-4

SOLUTIONSPECIESS04-2 + 9H+ + 8e- = HS- + 4H20

log k 34.02SELECTEDOUTPUT

-file redox2.sel-pe-molalities HS- S04-2-activities HS- S04-2

END




logk 34.02END


units mol/kgwpH 10.0temp 25.0pe -8.5

S le-4SOLUTION SPECIESS04-2 + 9H+ + 8e- = HS- + 4H20

log-k 34.02END




log k 34.02END



SOLUTION SPECIESS04-2 + 9H+ + 8e- = HS- + 4H20

A-11

logk 34.02END




log k 34.02END




logk 34.02END




log-k 34.02END




log-k 34.02END



SOLUTION SPECIESS04-2 + 9-H+ + 8e- = HS- + 4H20

log k 34.02END


units mol/kgwpH 10.0

A-12

temp 25.0pe -6.50S le-4


log k 34.02END



SOLUTION SPECIESS04-2 +- 9H+ + 8e- = HS- + 4H20

logk 34.02END




logk 34.02END




logk 34.02END




log k 34.02END



SOLUTION SPECIESS04-2 + 9H+ + Be- = HS- + 4H20

logk 34.02END

A-13




log k 34.02END




log_k 34.02END




logk 34.02END




logk 34.02END




log k 34.02END

A-14


Validation Test Case 6a-Temperature Effects. PHREEQC, Version 2.6 input file fortemperature effects on saturation of gypsum and anhydrite. Pure water with 1.0 moles ofanhydrite and 1.0 moles of gypsum. This input file is from Example 2 in the PHREEQC, Version2.6 installation test problems (Parkhurst and Appelo, 1999).

TITLE Example 2.--Temperature dependence of solubilityof gypsum and anhydrite


EQUILIBRIUMPHASES 1Gypsum 0.0 1.0Anhydrite 0.0 1.0

REACTIONTEMPERATURE 125.0 75.0 in 51 steps

SELECTEDOUTPUT-file ex2.sel-Si anhydrite gypsum

END

Validation Test Case 6a1-Temperature Effects. MINTEQA2, Version 4.02 input file fortemperature effects on saturation of gypsum and anhydrite. Pure water with 1.0 moles ofanhydrite and 1.0 moles of gypsum, based on Example 2 in the PHREEQC, Version 2.6installation test problems (Parkhurst and Appelo, 1999). Thermodynamic data modified tomatch PHREEQC, Version 2.6.

Anhydrite/Gypsum solubility as function of temperatureTest Example 2 for PHREEQC, Version 2.6, 1 mol Mineral25.00 MOLAL 0.000 0.OOOOOE+000 0 1 0 1 0 0 0 1 1 0 0 00 0 0

330 0.OOOE+00 -7.00 y /H+1150 0.OOOE+00 -7.00 y /Ca+2732 0.OOOE+00 -7.00 y /S04-2

4 260150006015001

4.3600 7.1550 1.000E+004.5800 0.4560 1.OOOE+00

Anhydrite/Gypsum solubility as function ofTest Example 2 for PHREEQC, Version 2.6, 130.00 MOLAL 0.000 0.OOOOOE+00O 0 1 0 1 0 0 0 1 1 0 0 00 0 0

/anhydrite/gypsum

temperaturemol Mineral

/H+1/Ca+2/S04-2

/anhydrite/gypsum

330 0.OOOE+00150 0.OOOE+00732 0.OOOE+00

-7.00 y-7.00 y-7.00 y

4 260150006015001

4.3600 7.1550 1.OOOE+004.5800 0.4560 1.OOOE+00


330 0.OOOE+00 -7.00 y150 0.OOOE+00 -7.00 y732 0.OOOE+00 -7.00 y


/H+1/Ca+2/S04-2

A-15

4 260150006015001

4.3600 7.1550 1.O0OE+004.5800 0.4560 1.OOOE+00



/anhydrite/gypsum


/H+1/Ca+2/S04-2

/anhydrite/gypsum

4 260150006015001

4.3600 7.1550 1.OOOE+004.5800 0.4560 1.OOOE+00


330 O.OOOE+OO -7.00 y150 0.OOOE+00 -7.00 y732 0.OOOE+00 -7.00 y


/H+1/Ca+2/S04-2

/anhydrite/gypsum

4 260150006015001

4.3600 7.1550 1.OOOE+004.5800 0.4560 1.OOOE+00




/H+1/Ca+2/S04-2

/anhydrite/gypsum

4 260150006015001

4.3600 7.1550 1.OOOE+004.5800 0.4560 1.OOOE+00




/H+1/Ca+2/S04-2

/anhydrite/gypsum

4 260150006015001

4.3600 7.1550 1.OOOE+004.5800 0.4560 1.OOOE+00



4 2


/H+1/Ca+2/S04-2

A-16

0

6015000 4.3600 7.1550 1.OOOE+006015001 4.5800 0.4560 1.000E+00



/anhydrite/gypsum


/H+1/Ca+2/S04-2

/anhydrite/gypsum

4 260150006015001

4.3600 7.1550 1.OOOE+004.5800 0.4560 1.OOOE+00

Anhydrite/Gypsum solubility as function ofTest Example 2 for PHREEQC, Version 2.6, 170.00 MOLAL 0.000 0.OOOOE+00O 0 1 0 1 0 0 0 1 1 0 0 00 0 0



/H+1/Ca+2/S04-2

/anhydrite/gypsum

4 260150006015001

4.3600 7.1550 1.OOOE+004.5800 0.4560 1.000E+00

Anhydrite/Gypsum solubility as function ofTest Example 2 for PHREEQC, Version 2.675.00 MOLAL 0.000 0.OOOOE+00O 0 1 0 1 0 0 0 1 1 0 0 00 0 0


temperature

/H+1/Ca+2/S04-2

/anhydrite/gypsum

4 260150006015001

4.3600 7.1550 1.OOOE+004.5800 0.4560 1.OOOE+00

Validation Test Case 6b2-Temperature Effects. MINTEQA2, Version 4.02 input file fortemperature effects on saturation of gypsum and anhydrite. Pure water assuming infinitegypsum (250 to 55 °C) and infinite anhydrite (600 to 75 °C). Thermodynamic data modified tomatch PHREEQC, Version 2.6.

Anhydrite/Gypsum solubility as function of temperatureTest Example 2 for PHREEQC, Version 2.6, Infinite Mineral25.00 MOLAL 0.000 0.OOOOOE+00O 0 1 0 1 0 0 0 1 1 0 0 00 0 0

330 0.OOOE+00 -7.00 y /H+l150 0.OOOE+00 -7.00 y /Ca+2732 0.OOOE+00 -7.00 y /S04-2

3 16015001 4.5800 0.4560 /gypsum


330 0.OOOE+00 -7.00 y /H+1

A-17

0 0

150 0.OOOE+00 -7.00 y /Ca+2732 O.OOOE+00 -7.00 y /S04-2

3 16015001 4.5800 0.4560 /gypsum

Anhydrite/Gypsum solubility as function of temperatureTest Example 2 for PHREEQC, Version 2.6, Infinite Mineral35.00 MOLAL 0.000 0.00000E+00O 0 1 0 1 0 0 0 1 1 0 0 00 0 0


3 16015001 4.5800 0.4560 /gypsum



3 16015001 4.5800 0.4560 /gypsum



3 16015001 4.5800 0.4560 /gypsum



3 16015001 4.5800 0.4560 /gypsum



3 16015001 4.5800 0.4560 /gypsum

A-18

0 0

Anhydrite/Gypsum solubility as function of temperatureTest Example 2 for PHREEQC, Version 2.6, Infinite Mineral60.00 MOLAL 0.000 0.00000E+00O 0 1 0 1 0 0 0 1 1 0 0 00 0 0

330 0.000E+00 -7.00 y /H+1150 0.OOOE+00 -7.00 y /Ca+2732 0.OOOE+00 -7.00 y /S04-2

3 16015000 4.3600 7.1550 /anhydrite



3 16015000 4.3600 7.1550 /anhydrite



3 16015000 4.3600 7.1550 /anhydrite



3 16015000 4.3600 7.1550 /anhydrite

A-19

* 0


Validation Test Case 7a-Np and U speciation. PHREEQC, Version 2.6 input files forneptunium and uranium speciation as a function of pH. T = 25 °C, PCO2 = 10-35 atm, P02 =10-0.66 atm, (a) Neptunium speciation with Nptotai = 10-7 m. Neptunium oxidation states changewith pH and both Np(V)-species and Np(VI)-species are written to the output file npphrq2.123;(b) Uranium speciation with Utotal = 10-7 m. Uranium speciation is dominated by U(VI) overentire pH range, an only U(VI) species are written to u_phrq2.123.

TITLE Test Example: Speciation of Np(V), l.Oe-7 molal NpO2+, \PCO2=le-3.5; Speciation over pH range

SOLUTION 1-units mol/kgwpH 7.00redox 0(0)/O(-2)temp 25.0Na 0.100 chargeN(+5) 0.100 as N03-Np(+5) 0.0000001 as NpO2+0(0) 1.0 02(g) -0.66

PHASES 1FixH+H+ = H+logk = 0.0

END

SELECTED_OUTPUT-file npphrq2.123-molalities NpO2+ NpO2OH NpO2(OH)2- NpO2CO3- NpO2(C03)2-3 NpO2(C03)3-5 \NpO2(C03)2(OH)-4 NpO2(C03)2-2 NpO2(C03)3-4

Use Solution 1EQUILIBRIUMPHASES 1

Fix H+ -4.00 NaOH 10.0C02(g) -3.5 1.0

END


FixH+ -4.25 NaOH 10.0C02(g) -3.5 1.0

END


FixH+ -4.50 NaOH 10.0C02(g) -3.5 1.0

END


Fix_H+ -4.75 NaOH 10.0C02(g) -3.5 1.0

END


FixH+ -5.00 NaOH 10.0C02(g) -3.5 1.0

END


FixH+ -5.25 NaOH 10.0C02(g) -3.5 1.0

A-20

END


Fix_H+ -5.50 NaOH 10.0C02(g) -3.5 1.0

END


FixH+ -5.75 NaOH 10.0C02(g) -3.5 1.0

END


FixH+ -6.00 NaOH 10.0C02(g) -3.5 1.0

END


FixH+ -6.25 NaOH 10.0C02(g) -3.5 1.0

END

Use Solution 1EQUILIBRIUM PHASES 1

Fix H+ -6.50 NaOH 10.0C02(g) -3.5 1.0

END


FixH+ -6.75 NaOH 10.0C02(g) -3.5 1.0

END


FixH+ -7.00 NaOH 10.0C02(g) -3.5 1.0

END


FixH+ -7.25 NaOH 10.0C02(g) -3.5 1.0

END


FixH+ -7.50 NaOH 10.0C02(g) -3.5 1.0

END


FixH+ -7.75 NaOH 10.0C02(g) -3.5 1.0

END


FixH+ -8.00 NaOH 10.0C02(g) -3.5 1.0

END


FixH+ -8.25 NaOH 10.0

A-21

* 0

C02(g) -3.5 1.0END


Fix_H+ -8.50 NaOH 10.0C02(g) -3.5 1.0

END


FixH+ -8.75 NaOH 10.0C02(g) -3.5 1.0

END


FixH+ -9.00 NaOH 10.0C02(g) -3.5 1.0

END


FixH+ -9.25 NaOH 10.0C02(g) -3.5 1.0

END


FixH+ -9.50 NaOH 10.0C02(g) -3.5 1.0

END


FixH+ -9.75 NaOH 10.0C02(g) -3.5 1.0

END


FixH+ -10.00 NaOH 10.0C02(g) -3.5 1.0

END

TITLE Test Example: Speciation of U(VI), 1.Oe-7 molal U02+2, \PC02=le-3.5; Speciation over pH range

SOLUTION 1-units mol/kgwpH 7.00redox 0(0)/O(-2)temp 25.0Na 0.100 chargeN(+5) 0.100 as N03U(+6) 0.0000001 as U020(0) 1.0 02(g) -0.66

SOLUTIONSPECIESU02+2 + 2H20 = U02(OH)2 + 2H+

log k -11.7000deltah 18.095 kcal-gamma 3.0 0

PHASES 1FixH+H+ =H+log-k = 0.0

ENDSELECTEDOUTPUT-file u-phrq2.123

A-22

-molalities U02+2 U02N03+ U02C03 U02(C03)2-2 U02(C03)3-4 \(U02)2C03(OH)3- U020H+ U02(OH)2 U02(OH)3- U02(OH)4-2 \(U02)2(OH)2+2 (U02)3(OH)5+


Fix_H+ -4.00 NaOH 10.0C02(g) -3.5 1.0

END


FixH+ -4.25 NaOH 10.0C02(g) -3.5 1.0

END


FixH+ -4.50 NaOH 10.0C02(g) -3.5 1.0

END


Fix_ H+ -4.75 NaOH 10.0C02(g) -3.5 1.0

END


FixH+ -5.00 NaOH 10.0C02(g) -3.5 1.0

END


FixH+ -5.25 NaOH 10.0C02(g) -3.5 1.0

END


FixH+ -5.50 NaOH 10.0C02(g) -3.5 1.0

END


FixH+ -5.75 NaOH 10.0C02(g) -3.5 1.0

END


FixH+ -6.00 NaOH 10.0C02(g) -3.5 1.0

END


FixH+ -6.25 NaOH 10.0C02(g) -3.5 1.0

END


FixH+ -6.50 NaOH 10.0C02(g) -3.5 1.0

END

Use Solution 1

A-23

EQUILIBRIUMPHASES 1FixH+ -6.75 NaOH 10.0C02(g) -3.5 1.0

END


FixH+ -7.00 NaOH 10.0C02(g) -3.5 1.0

END


FixH+ -7.25 NaOH 10.0C02(g) -3.5 1.0

END

Use Solution 1EQUILIBRIUM_PHASES 1

FixH+ -7.50 NaOH 10.0C02(g) -3.5 1.0

END


Fix_H+ -7.75 NaOH 10.0C02(g) -3.5 1.0

END


Fix H+ -8.00 NaOH 10.0C02(g) -3.5 1.0

END


FixH+ -8.25 NaOH 10.0C02(g) -3.5 1.0

END


FixH+ -8.50 NaOH 10.0C02(g) -3.5 1.0

END


FixH+ -8.75 NaOH 10.0C02(g) -3.5 1.0

END


FixH+ -9.00 NaOH 10.0C02(g) -3.5 1.0

END


FixH+ -9.25 NaOH 10.0C02(g) -3.5 1.0

END


FixH+ -9.50 NaOH 10.0C02(g) -3.5 1.0

END

A-24

0


FixH+ -9.75 NaOH 10.0C02(g) -3.5 1.0

END


FixH+ -10.00 NaOH 10.0C02(g) -3.5 1.0

END

Validation Test Case 7b-Np and U speciation. MINTEQA2, Version 4.02 input files forneptunium and uranium speciation as a function of pH. T = 25 °C, PCO2 = 10-3-5 atm, Po2 =10-0.66 atm, (a) Neptunium speciation with Nptotal = 10-7 m. Neptunium oxidation states changewith pH and both Np(V)-species and Np(VI)-species are written to the output file npmint2.123;(b) Uranium speciation with Utotal =10-7 m. Uranium speciation is dominated by U(VI) overentire pH range, an only U(VI) species are written to umint2.123.

Np(V) speciation, Np = le-7 M, PCO2=le-3.5 atmVariable pH, T = 25C, P02=0.22 atm

25.00 MOLAL 0.000 0.OOOOOE+000 0 1 0 1 0 0 0 1 1 1 6 325 H+1 ACTIVI'1 330 1.000

4.00 0.25npmint2.123 552 5523300 55:0 0 0

330 0.OOOE+00 -4.00 y552 1.OOOE-07 -7.00 y500 1.OOOE-01 -1.00 y492 1.000E-01 -1.00 y140 0.OOE+00 -7.00 y

1 0.OOOE+00 -7.00551 0.OOOE+00 -7.00 y553 0.OOOE+00 -7.00 y

TY mol/L

23301 5521400 5521401 5521402

/H+1/NpO2+/Na+1/NO3-1/C03-2/E-1/Np+4/NpO2+2

3 53301403552551055355103300021

3306 1

1

21.6470-10.2100-29 .8000-82.4318

4. 0000

-4.0600149.5000266.9500571. 6600

0 .0000

/C02 (g)/npo2+1/np+4/npo2+2/np+4/02 (g)/H+1

/E-10.0000 0.0000

Np(V) speciation, Np = le-7 M, PCO2=le-3.5 atmVariable pH, T = 25C, P02=0.22 atm

25.00 MOLAL 0.000 0.OOOOOE+000 0 1 0 1 0 0 0 1 1 1 3 325 H+1 ACTIVITY mol/L1 330 1.000

4.00 0.25npmint2.123 5521403 5531401 55314020 0 0

330 0.OOOE+00 -4.00 y552 1.OOOE-07 -7.00 y500 1.OOOE-01 -1.00 y492 1.OOOE-01 -1.00 y140 0.OOOE+00 -7.00 y

1 0.OOOE+00 -7.00551 0.OOOE+00 -7.00 y553 0.OOOE+00 -7.00 y

/H+1/NpO2+/Na+l/NO3-1/C03-2/E-1/Np+4/NpO2+2

3 5

A-25

3301403552551055355103300021

3306 1

21.6470-10.2100-29 .8000-82.4318

4.0000

-4.0600149.5000266.9500571.6600

0.0000

/C02 (g)/npo2+1/np+4/npo2+2/np+4/02 (g)/H+1

1 0.0000 0.0000 /E-1

U(VI) speciation, U = le-7 M, PCO2=le-3.5 atmVariable pH, T = 25C, P02=0.22 atm25.00 MOLAL 0.000 0.OOOOOE+000 0 1 0 1 0 0 0 1 1 1 6 325 H+1 ACTIVITY mol/L1 330 1.000

4.00 0.25u_mint2.123 893 8934920 8931400 8931401 E0 0 0

330 0.OOOE+00 -4.00 y893 1.OOOE-07 -7.00 y500 1.000E-01 -1.00 y492 1.OOOE-01 -1.00 y140 0.OOOE+00 -7.00 y

1 0.OOOE+00 -7.00891 O.OOOE+00 -7.00 y892 0.OOOE+00 -7.00 y

3931402 8931405

/H+1/U02+2/Na+l/N03-1/C03-2/E-1/U+4/U02+1

/uo2(oh)2(aq)

/C02 (g)/02 (g)/u+4/uo2+2/uo2+/uo2+2/H+1

2 18933301

3 53301403330002189189308928930

3306 1

1

)0 75.7100-11.70C

21.6470-82.4318

9.04001.48004.0000

-4.0600571.6600

-143.8600-6.1300

0.0000

0.0000 0.0000

U(VI) speciation, U = le-7 M, PC02=le-3.5 atm

Variable pH, T = 25C, P02=0.22 atm25.00 MOLAL 0.000 0.OOOOOE+000 0 1 0 1 0 0 0 1 1 1 6 325 H+1 ACTIVITY mol/L1 330 1.000

4.00 0.25u_mint2.123 8933300 8933301 8933302 8933303 8933305 8933307

0 0 0330 0.OOOE+00 -4.00 y /H+1893 1.OOOE-07 -7.00 y /U02+2

500 1.000E-01 -1.00 y /Na+1

492 1.OOOE-01 -1.00 y /NO3-1

140 0.OOOE+00 -7.00 y /C03-2

1 0.OOOE+00 -7.00 /E-1

891 0.OOOE+00 -7.00 y /U+4

892 0.OOOE+00 -7.00 y /U02+1

2 18933301 -11.7000

3 53301403 21.64703300021 -82.43188918930 9.04008928930 1.4800

330 4.00006 1

1 0.0000

75.7100

-4.0600571.6600-143.8600-6.13000.0000

/uo2(oh)2(aq)

/C02 (g)/02 (g)/u+4/uo2+2/uo2+/uo2+2/H+1

/E-10. 0000

A-26

SOFTWARE VALIDATION TEST PLAN FORPHREEQC, VERSION 2.6

Prepared for

U.S. Nuclear Regulatory CommissionContract NRC-02-02-012

Prepared by

David R. Turner


Approvede by:

C- _ Q, lcz)3English C. PearcyManager, Geohydrology and Geochemistry

Date/

CONTENTS

Section Page

1 SCOPE OF THE VALIDATION . 1

2 REFERENCES.

3 ENVIRONMENT.3.1 Software-Introduction .I3.2 Code Description.

3.2.1 Input.3.2.2 Output.

3.3 Hardware Requirements and Installation ...3.3.1 System Requirements .3.3.2 Installing PHREEQC, Version 2.6 ...

4 PREREQUISITES.

5 ASSUMPTIONS AND CONSTRAINTS .

6 TEST CASES .6.1 Installation Check.6.2 Aqueous Speciation.6.3 Mineral Solubility.6.4 Gas Chemistry .6.5 Sorption-Surface Complexation Modeling6.6 Redox Conditions .....................6.7 Temperature Effects ...................6.8 Modified Database .

1

....................

..........

..........

..........

..........

..........

..........

33334444

........

....

....

....

................

.. . . . . . . . . . . . . . . . . . . . . 5

.~~~~~~6

.~~~~~~6

.~~~~~~7

.~~~~~~8

.~~~~~~8

.~~~~~~88

.~~~~~~99

. . . . .. . . ... 9. . . - - - - - - - - -

7 TESTIINPUTS.

8 TEST PROCEDURES .8.1 Installation Check.8.2 Comparison With Hand Calculations .8.3 Comparison with MINTEQA2, Version 4.02 Simulations

..................

.........

.........

. 10

. 12

. 12

. 12

. 12

ii

FIGURES

Figure Page

3-1 Example PHREEQC Input File for PHREEQC, Version 2.6 ........... 11

iii

TABLES

Table Page

3-1 PHREEQC, Version 2.6 Installation Directory Structure ......... ................ 5

4-1 Execution Commands for PHREEQC, Version 2.6 ........... ................. 5

iv

* 0

1 SCOPE OF THE VALIDATION

This document establishes the software validation test plan for validating the installation andfunctionality of the geochemical equilibrium speciation code PHREEQC, Version 2.6 (Parkhurstand Appelo, 1999). PHREEQC, Version 2.6 is an acquired code, originally developed by theU.S. Geological Survey. The software is used by staff at the Center for Nuclear WasteRegulatory Analyses (CNWRA) to provide technical assistance to the U.S. Nuclear RegulatoryCommission (NRC) in its high-level waste program.

This software validation test plan applies to PHREEQC, Version 2.6, and is intended to validatethe software for use in modeling geochemical equilibrium reactions as identified in the testcases described in Section 6. An earlier version, PHREEQC, Version 2.4.2 is currently underconfiguration control in accordance with Technical Operating Procedure (TOP)-018. Asnecessary, this validation plan identifies differences from the earlier PHREEQC, Version 2.4.2.PHREEQC, Version 2.6 will be placed under TOP-018 configuration control prior to performingthe validation activities outlined in Sections 6 and 7.

2 REFERENCES

The following documents are referenced or used as the basis for this software validationtest plan.

Allison, J.D., D.S. Brown, and K.J. Novo-Gradac. "MINTEQA2/PRODEFA2, A GeochemicalAssessment Model for Environmental Systems." Version 3.0 User's Manual.EPA/600/3-91/021. Athens, Georgia: U.S. Environmental Protection Agency. 1991.

Ball, J.W. and D.K. Nordstrom. "WATEQ4F-User's Manual with Revised Thermodynamic DataBase and Test Cases for Calculating Speciation of Major, Trace and Redox Elements in NaturalWaters." U.S. Geological Survey Open-File Report 90-129. Washington, DC: U.S. GeologicalSurvey. 1991.

CNWRA. "Technical Operating Procedure (TOP-18): Development and Control of Scientificand Engineering Software, Revision 8, Change 0 (October 5, 2001)." San Antonio, Texas:CNWRA. 2001.

Charlton, S.R. and D.L. Parkhurst. "PHREEQCI-A Graphical User Interface to theGeochemical Model PHREEQC." U.S. Geological Survey Fact Sheet FS-031-02.Washington, DC: USGS. 2002. Available at:htto://wwwbrr.cr.usgs.aov. librarv.csuhavward.edu/Droiects/GWC courled/ohreeac/fs/FactSheetFS-031-02.html.

Grenthe, I., J. Fuger, R Konings, R.J. Lemire, A.B. Muller, C. Nguyen-Trung, and H. Wanner."Chemical Thermodynamics Series, Volume 1: Chemical Thermodynamics of Uranium."Nuclear Energy Agency, Organization for Economic Cooperation and Development. New YorkCity, New York: Elsevier. 1992.

Langmuir, D. Aqueous Environmental Geochemistty. Englewood Cliffs, New Jersey:Prentice-Hall, Inc. 1997.

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Lemire, R.J., J. Fuger, H. Nitsche, P. Potter, M.H. Rand, J. Rydberg, K. Spahiu, J.C. Sullivan,W.J. Ullman, P. Vitorge, and H. Wanner. "Chemical Thermodynamics Series, Volume 4:Chemical Thermodynamics of Neptunium and Plutonium." Nuclear Energy Agency,Organization for Economic Cooperation and Development. New York City, New York:Elsevier. 2001.

Parkhurst, D.L. and C.A.J. Appelo. "User's Guide to PHREEQC (Version 2)-A ComputerProgram for Speciation, Batch-reaction, One-dimensional Transport, and Inverse GeochemicalCalculations." Water-Resources Investigations Report 99-4259. Denver, Colorado:U.S. Geological Survey. 1999.

Rard, J.A., M.H. Rand, G. Anderegg, and H. Wanner. "Chemical Thermodynamics Series,Volume 3: Chemical Thermodynamics of Technetium." Nuclear Energy Agency, Organizationfor Economic Cooperation and Development. New York City, New York: Elsevier. 1999.

Richardson, S.M. and H.Y. McSween, Jr. Geochemistry: Pathways and Processes.Englewood Cliffs, New Jersey: Prentice-Hall, Inc. 1989.

Silva, R.J., G. Bidoglio, M.H. Rand, P.B. Robouch, H. Wanner, and 1. Puigdomenich. "ChemicalThermodynamics Series, Volume 2: Chemical Thermodynamics of Americium." Nuclear EnergyAgency, Organization for Economic Cooperation and Development. New York City, New York:Elsevier. 1995.

Stumm, W. and J.J. Morgan. Aquatic Chemistry: Chemical Equilibria and Rates in NaturalWaters. 3rd Edition. New York City, New York: Wiley-lnterscience. 1996.

Turner, D.R., T. Griffin, and T.B. Dietrich. "Radionuclide Sorption Modeling Using theMINTEQA2 Speciation Code." Scientific Basis for Nuclear Waste Management-XVI.C. Interrante and R. Pabalan, eds. Symposium Proceedings. Pittsburgh, Pennsylvania:Material Research Society. pp. 783-789. 1993.

Turner, D.R. "Mechanistic Approaches to Radionuclide Sorption Modeling." CNWRA 93-019.San Antonio, Texas: CNWRA. 1993.

Turner, D.R. "Software Validation Report for MINTEQA2, Version 4.02." CNWRA LetterReport. San Antonio, Texas: CNWRA. May 2002.

U.S. Environmental Protection Agency. "MINTEQA2/PRODEFA2, A Geochemical AssessmentModel for Environmental Systems: User Manual Supplement for Version 4.0." Athens, Georgia:U.S. Environmental Protection Agency, National Exposure Research Laboratory, EcosystemsResearch Division. 1999a.

U.S. Environmental Protection Agency. "Diffuse-Layer Sorption Reactions for use inMINTEQA2 for HWIR Metals and Metalloids." Athens, Georgia: U.S. Environmental ProtectionAgency, National Exposure Research Laboratory, Ecosystems Research Division. 1999b.

Wolery, T.J. "EQ3/6, A Computer Program for Geochemical Aqueous Speciation-SolubilityCalculations: Theoretical Manual, User's Guide, and Related Documentation (Version 7.0)."UCRL-MA-11066 Pt 1ll. Livermore, California: Lawrence Livermore National Laboratory. 1992.

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3 ENVIRONMENT

3.1 Software-Introduction

PHREEQC, Version 2.6 (released April 22, 2002, Parkhurst and Appelo, 1999) is a geochemicalequilibrium speciation code developed in the C programming language by the U.S. GeologicalSurvey to model dilute aqueous systems. The code has capabilities for aqueous speciationcalculations in multi-phase (gas, liquid, solid) systems, one-dimensional transport calculations,reversible and irreversible reactions, and solid-solution, surface-complexation, andion-exchange equilibria. It can also simulate kinetically controlled geochemical reactions,solution mixing, and perform inverse modeling to find sets of mineral and gas mole transfersthat account for differences in observed composition between waters, within specifiedcompositional uncertainty limits. PHREEQC is written in ANSI C. The code has been used onUNIX-based computers and on IBM-compatible computers with processors running at100 megahertz or faster. This software validation test plan is designed to evaluate installationand performance of PHREEQC, Version 2.6 on a IBM Personal Computer, Windows NTplatform (see Section 3.2).

3.2 Code Description

The following description of PHREEQC is based on the source code and on the user's manual(Parkhurst and Appelo, 1999) provided with the PHREEQC, Version 2.6 file (downloaded fromthe USGS website at httD://wwwbrr.cr.uscs.iov/Droiects/GWC couDled/phreeac/.

3.2.1 Input

A PHREEQC, Version 2.6 user typically has a problem relevant to a natural chemical system.This system is described in terms of the physical conditions such as temperature and theconcentrations of chemical components, species, solids and gases that are present.PHREEQC uses a free-format input file divided into keyword data blocks to identify thecomponents of interest, read the concentrations, construct the chemical equilibrium model andsolve for aqueous speciation and the distribution of species between the solid, gas, and liquidphases. Input flags can be set to determine the level of output. For speciation modeling,analytical data for a solution composition (SOLUTION keyword) are needed. For batch-reactionmodeling, the initial solution composition is required (SOLUTION or MIX data block). Otherequilibrium reactants may be defined with EQUILIBRIUMPHASES, EXCHANGE, SURFACE,GASPHASE, and SOLIDSOLUTION data blocks. Nonequilibrium reactions may be definedwith KINETICS and RATES, REACTION, and REACTIONTEMPERATURE data blocks.During execution of a geochemical problem, the input file is read and the databases searchedfor the relevant component species and aqueous, gas, and solid phases.

For one dimensional transport modeling, the modeled system requires the informationnecessary to establish the geochemistry in each cell. There is also physical information neededfor each cell to describe the cell dimensions, time steps, and the boundary conditions used inthe one dimensional model. For inverse modeling, the solution composition of the final solutionand one or more initial solutions are needed (SOLUTION data block). Uncertainty limits can bedefined explicitly or by default for each element and element redox state in the solutions.

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Thermodynamic data are contained in a separate database that includes definitions of aqueousspecies, exchange species, surface species, and mineral and phases for a set of elements.Additional elements, species, or phases can be added to the database if information onchemical reactions, log K (the equilibrium constant), and data for the temperature dependenceof log K are available for each added species and/or phase.

Preprocessors such as PHREEQCI, Version 2 (Charlton and Parkhurst, 2002) have beendeveloped for PHREEQC, Version 2.6, but if the user is familiar with the input requirements, heor she can construct the input file without a preprocessor, using an ASCII text editor.

3.2.2 Output

The results from the equilibrium geochemical speciation calculation are written to an output filespecified by the user. PHREEQC, Version 2.6 will overwrite previously existing files with thesame name. The output includes an echo of the input to verify that the input file was readcorrectly. PHREEQC, Version 2.6 does not provide a time stamp in the output file to verify thetime of the run. The level of detail provided as output varies and is set by the user in the inputfiles. The equilibrium concentration of the element(s) of interest are reported in molality(moles aqueous component or species/kg H20) as distributed between the dissolved andsorbed phases assuming a one liter batch reactor solid phases are reported as molesprecipitated or dissolved.

3.3 System Requirements and Installation

3.3.1 System Requirements

PHREEQC, Version 2.6 is designed for the IBM personal computer family of microcomputers orcompatible systems. Installing and running PHREEQC, Version 2.6 requires:

* 10 megabytes of free disk space (installation)* 20 megabytes of free disk space (running PHREEQC, Version 2.6)* Windows 9x/Me, Windows NT 4.0, Windows 2000, Windows XP* Processor running at 100 megahertz or faster* 8 megabytes RAM

3.3.2 Installing PHREEQC, Version 2.6

The following instructions are from the README.TXT file provided on the USGS website athttD://wwwbrr.cr.usgs.cov/proiects/GWC coupled/phreegc/.

To install the software, double-click the file phrqc26.exe to execute the self-extractinginstallation program and follow the directions on the screen. The installation program canoptionally modify the PATH environment variable so that the PHREEQC program can beexecuted from any directory, without needing to type the full pathname of the program'slocation.

By default, the software is installed in the directory c:\Program Files\USGS\phreeqc2.6. This isthe recommended installation directory, but you may use other directories or disk drives.Executing the self-extracting installation file phrqc26.exe will create the following PHREEQC,Version 2.6 directory structure:

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Table 3-1. PHREEQC, Version 2.6 Installation Directory Structure

Directory Directory Contents

phreeqc2.6 Files NOTICE.TXT, RELEASE.TXT, andREADME.TXT

phreeqc2.6\doc Documentation files

phreeqc2.6\examples Examples from user's manual to be used in verificationtests

phreeqc2.6\src Makefile and source code

phreeqc2.6\src\release Compiled executable

phreeqc2.6\test Batch files to run verification tests

It is recommended that no user files be kept in the PHREEQC directory structure. If you plan toput files in the PHREEQC directory structure, do so only by creating subdirectories.

4 PREREQUISITES

If the option to modify the PATH environment variable was chosen during installation, then thefollowing commands may be used to run PHREEQC from any directory in an MS-DOSCommand Prompt window

Table 4-1. Execution Commands for PHREEQC, Version 2.6

Command to execute PHREEQC, ExplanationVersion 2.6

phreeqc The program will query the user for each of the needed files

phreeqc input The input file is named input, the default name for the outputfile will be input.out, and the default database will be used

phreeqc input output The input file is named input, the output file is named output,and the default database will be used

phreeqc input output database All files (input, output, and database) are explicitly identifiedby the user

phreeqc input output database screen- All files (input, output, and database) are explicitly identifiedoutput by the user, and screen output is directed to the file

screen-output

If the option to modify the PATH environment variable was not chosen during installation, thentwo options exist:

(1) the full pathname to the script that runs phreeqc can be used in place of "phreeqc" in theabove commands (for example "c:\program files\usgs\phreeqc2.6\phreeqc." Note that

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because of the space present in "program files", quotation marks must be used to enterthe full pathname.), or,

(2) the executable (installed in phreeqc2.6\src\release\phreeqc.exe) may be copied to thecurrent directory; further, the default database file must be in the current directory andnamed "phreeqc.dat." The default database file is installed inphreeqc2.6\database\phreeqc.dat.

The environment variable PHREEQCDATABASE can be used to specify the default databasefor a DOS window session. This environment variable can be set with the command:

set PHREEQCDATABASE=c:\mydirectory\myproject\mydata.dat

This environment variable takes precedence over any default definition of the database file. IfPHREEQC is invoked with at least three arguments, the third argument is the database file andit takes precedence over the environment variable or the default database.

5 ASSUMPTIONS AND CONSTRAINTS

The results from geochemical equilibrium speciation codes are dependent on the type andquality of the data used in the simulation. These are typically contained in databases that aresearched and read by the code based on the input provided by the user. While thesedatabases can be modified by the user to incorporate additional species or differentthermodynamic data, they are considered separately from the input file that defines thegeochemical problem, and should not be modified in the context of running the simulation.

Historically, the original PHREEQC databases have been modified to include extensivethermodynamic data for toxic elements such as Cd, Zn, Pb, As, Hg, and Cu as well as organicligands such as EDTA, Citrate, and Acetate. Databases from other codes such as MINTEQA2(Allison et al., 1991) and WATEQ4F (Ball and Nordstrom, 1991) have been modified for usewith PHREEQC, Version 2.6. Additional modifications at the Center for Nuclear WasteRegulatory Analyses (CNWRA) have included the addition of thermodynamic data (AHr0 and logK) for almost 600 aqueous species and solids involving 14 potentially important radioelements,including U, Pu, Th, Np, Am, Sr, Cs, Ra, Sn, Zr, Tc, Ru, Eu, and Co (Turner, 1993; Turner, etal., 1993). Thermodynamic data for U, Pu, Np, Am, and Tc are from the Nuclear EnergyAgency Thermodynamic Database Project (Grenthe, et al., 1992; Silva, et al., 1995, Rard, et al.,1999, and Lemire, et al., 2001). The source for other data is the EQ3/6 database (Wolery,1992, Release Gembochs.v2-eq8-data0.alt.r2, 02Aug95).

6 TEST CASES

Although geochemical equilibrium modeling can be performed using hand calculations(Richardson and McSween, 1989), the large number of chemical component species present innatural systems can make for extremely complex calculations. Validation of PHREEQC,Version 2.6 model results against hand calculations for simple systems can exercise basic codefunctions, but a more rigorous testing of the code and its databases is beyond a hand check.

In addition to testing basic code functions against simplified problems, one way to address theissue of complexity in code validation and build confidence in model results is to test

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PHREEQC, Version 2.6 against results from another geochemical speciation code such asMINTEQA2, Version 4.02 (EPA, 1999a,b). MINTEQA2, Version 4.02 has previously beenvalidated against hand calculations and the earlier PHREEQC, Version 2.4.2 for use in CNWRAtechnical assistance activities (Turner, 2002). This approach is followed in the test casesoutlined below. Simple worked problems from standard geochemistry textbooks (e.g.,Richardson and McSween, 1989; Stumm and Morgan, 1996; Langmuir, 1997) and testproblems in the user's manual for PHREEQC, Version 2.6 will be selected to test differentgeochemical processes such as speciation and solubility calculations. To test PHREEQC,Version 2.6 against MINTEQA2, Version 4.02, the same intensive properties (temperature,pressure) will be used and all chemical reactions will be written in terms of the appropriatecomponent species appropriate to the two codes. Some differences in how PHREEQC, Version2.6 and MINTEQA2, Version 4.02 compute ionic strength corrections (extended Debye-Huckelversus Davies equation) may lead to differences in speciation that will be examined andresolved as necessary. For simple systems of a few components the same thermodynamicdata (e.g., log K at 298 K) will be used to ensure consistency between calculational results. Formore complicated systems involving seawater, the problems will be run using the overalldatabases. Resulting differences will be evaluated and resolved as necessary. It is anticipatedthat PHREEQC, Version 2.6 test results will agree with hand calculations and MINTEQA2,Version 4.02 calculations within a few percent.

6.1 Installation Check

The first validation test will be to ensure that the PHREEQC, Version 2.6 software is installedcorrectly on the CNWRA PC platform (Pentium-based PC, Windows NT 4.00 operating system).Part of the self-extracting installation package for PHREEQC, Version 2.6 includes input andoutput for a set of 18 example problems developed to demonstrate the different capabilities ofthe code. The test problems are described in the user's manual (Parkhurst and Appelo, 1999).To test the installation, in an MS-DOS Command Prompt window, the user changes to thephreeqc2.6\test directory:

c:

cd "program files"cd usgs\phreeqc2.6\test

Execute the tests by typing the command:

test [start [stop]]

where: start = the number of the first test to perform, default = 1stop = the number of the last test to perform, default = 18

After the tests are completed, the results are compared to the expected results included inPHREEQC examples directory. The file CHECK.LOG is created to contain the comparisonresults. If the installation check matches the example files, there should be no differences.

6.2 Aqueous Speciation

Parkhurst and Appelo (1999) provide an example to calculate the distribution of aqueousspecies in seawater and the saturation state of seawater relative to a set of minerals. To

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demonstrate how to expand the model to new elements, uranium is added to the aqueousmodel defined by the PHREEQC, Version 2.6 database. This example problem was previouslysimulated using MINTEQA2, Version 4.02 (Turner, 2002).

MINTEQA2, Version 4.02 and PHREEQC, Version 2.6 outputs to be compared include, but arenot limited to:

* Concentration of different aqueous species such as C032, Ca(OH)2 (aq), etc.* Solubility indices [log (Ion Activity Product)-log K] for minerals such as halite, calcite,

and SiO2

6.3 Mineral Solubility

Richardson and McSween (1989) present two worked problems to investigate the solubility ofbarite at 298 K in pure water (Worked Problem 3-6), and in a 0.2 m NaCI solution (WorkedProblem 3-8). The results of the problems are expressed in terms of mBa2+.

Output to be compared includes, but is not limited to:

* Molality of Ba2+* Solubility indices [log (Ion Activity Product)log Keq] of barite with respect to Ba2+

6.4 Gas Chemistry

Stumm and Morgan (1996) present several aqueous carbonate speciation problems. Includedis Example 7.8, equilibrating calcite (CaCO 3) in sea water at 25 0C, and open to atmosphere(fixed PCO2 = 3.55 x 10-4 atm). This problem can be used to test the gas chemistry subroutinesof PHREEQC, Version 2.6.


* Total carbonate species (e.g., HCO3-, CO32-)

* pH* alkalinity

6.5 Sorption-Surface Complexation Modeling

Turner (2002) used the diffuse-layer surface complexation model as implemented inMINTEQA2, Version 4.02 to simulate Zn2+ sorption on ferrihydrite (HFO), with the problemdefined in Parkhurst and Appelo (1999). Sorption at 298 K is investigated for two Zn2+concentrations (10-4 and 10-7 molal), and the results are presented in terms of dissolved andsorbed Zn2+ molality as a function of pH.


* Total dissolved Zn2+ as a function of pH* Total sorbed Zn2+ as a function of pH

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6.6 Redox Conditions

Stumm and Morgan (1996) present a number of relatively simple calculations to determineredox equilibrium. These include calculating electron activity (pe) for Fe and Mn systems opento atmosphere (Example 8.2) and equilibrium distribution in the SO4

2-- HS- system(Example 8.4). These calculations will provide a good check of redox equilibrium in PHREEQC,Version 2.6, which uses pe as a master variable to control redox potential.


* Calculated equilibrium pe for the three solutions presented in Example 8.2 (Stumm andMorgan, 1996)

* Equilibrium distributions of sulfur compounds as a function of pe for the conditionspresented in Example 8.4 (Stumm and Morgan, 1996)

6.7 Temperature Effects

Parkhurst and Appelo (1999) provide an example to use PHREEQC, Version 2.6 to calculatethe solubility of gypsum and anhydrite in pure water, over a range in temperature from 298 K to373 K. Turner (2002) used this example to check the ability of MINTEQA2, Version 4.02 to bothcalculate solubility and the correction of equilibrium for the effects of temperature. Only the pHand temperature are used to define a pure water solution. Gypsum and anhydrite are allowedto react to equilibrium (saturation index equal to 0.0), and the initial phase assemblage has1 mol of each mineral. Each mineral will react either to equilibrium or until it is exhausted in theassemblage. Temperature is swept through 10C intervals from 25 0C (298 K) through 75 0C

(373 K).

Both PHREEQC, Version 2.6 and MINTEQA2, Version 4.02 use the Van't Hoff relationship andenthalpies of reaction (AHro) to correct equilibrium constants for the effects of temperature. If thesame thermodynamic data are used, both codes should produce the same results.


* gypsum and anhydrite solubility as a function of temperature from 25 0C (298 K) through75 0C (373 K).

6.8 Modified Database

The main code function to be checked in this section of the test plan is to ensure that thePHREEQC, Version 2.6 database modified to include Nuclear Energy Agency radionuclidethermodynamic data is correct and produces reasonable results. If thermodynamic data are thesame, different geochemical equilibrium speciation codes should produce similar results. Themost straightforward way to test this is to compare aqueous speciation results from severaldifferent codes. This approach has been used before (Turner, 1993; Turner, et al., 1993) toexamine the modified MINTEQA2, Version 3.11/3.12 database.

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Speciation checks for uranium and neptunium will be performed using results from PHREEQC,Version 2.6 and MINTEQA2, Version 4.02. Identical thermodynamic data for neptunium anduranium will be used to examine speciation as a function of pH, both under C0 2-free andatmospheric CO2 conditions. Temperature will be fixed at 25 0C (298 K). Low concentrationswill be used to avoid the complications of precipitation of pure phases. The focus of the checkis the CNWRA-modifications to the PHREEQC, Version 2.6 database MINTEQ.DAT, and verysimple solutions will be used to minimize the effects of major ions such as Ca2+ and Mg2+.Although the MINTEQ.DAT database distributed with PHREEQC, Version 2.6 is based on theMINTEQA2, Version 3.11/3.12 database (Parkhurst and Appelo, 1999), the MINTEQA2database was revised for Version 4.02. Small differences are likely to persist in thermodynamicdata for some of the chemical component systems that are beyond the intended scope of thisvalidation test plan.


* Percent of different uranium and neptunium aqueous species as a function of pH

7 TEST INPUTS

In all test cases, the test inputs will consist of a batch input file created using the instructionscontained in the user's manual for PHREEQC, Version 2.6 (see Figure 7-1). This input file canbe prepared using either the preprocessor PHREEQCI, Version 2 (Charlton and Parkhurst,2002), or with an ASCII text editor. Chemical conditions in the PHREEQC, Version 2.6 input filesuch as temperature, component concentration, and gas pressure will be set at valuesconsistent with the problems described in Section 6 of this software validation test plan. Forsimple test problem systems, identical thermodynamic data will be used to facilitate comparisonof results. For complex test problem systems such as those involving seawater, the problemwill be run using the PHREEQC, Version 2.6 and MINTEQA2, Version 4.02 thermodynamicdatabases. Differences will be evaluated and resolved as necessary.

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Figure 7-1. Example input file for PHREEQC, Version 2.6

TITLE Example l.--Add uranium and speciate seawater.

SOLUTION 1 SEAWATER FROM NORDSTROM ET AL. (1979)

units ppmpH 8.22pe 8.451density 1.023temp 25.0redox O(0)/O(-2)Ca 412.3Mg 1291.8Na 10768.0K 399.1Fe 0.002Mn 0.0002 peSi 4.28Cl 19353.0Alkalinity 141.682 as HCO3S(6) 2712.0N(5) 0.29 gfw 62.0N(-3) 0.03 as NH4U 3.3 ppb N(5)/N(-3)O(0) 1.0 02(g) -0.7

SOLUTIONMASTERSPECIESU U+4 0.0 238.0290 238.0290U(4) U+4 0.0 238.0290U(5) U02+ 0.0 238.0290U(6) U02+2 0.0 238.0290

SOLUTIONSPECIES#primary master species for U#is also secondary master species for U(4)U+4 = U+4

log-k 0.0U+4 + 4 H20 = U(OH)4 + 4 H+

log-k -8.538deltah 24.760 kcal

U+4 + 5 H20 = U(OH)5- + 5 H+log-k -13.147delta h 27.580 kcal

#secondary master species for U(5)U+4 + 2 H20 = U02+ + 4 H+ + e-

log-k -6.432deltah 31.130 kcal

#secondary master species for U(6)U+4 + 2 H20 = U02+2 + 4 H+ + 2 e-

logk -9.217deltah 34.430 kcal

U02+2 + H20 = U020H+ + H+log-k -5.782deltah 11.015 kcal

2U02+2 + 2H20 = (U02)2(OH)2+2 + 2H+log-k -5.626deltah -36.04 kcal

3U02+2 + 5H20 = (U02)3(OH)5+ + 5H+log-k -15.641deltah -44.27 kcal

U02+2 + C03-2 = U02C03log-k 10.064deltajh 0.84 kcal

U02+2 + 2C03-2 = U02(C03)2-2logk 16.977deltah 3.48 kcal

U02+2 + 3C03-2 = U02(C03)3-4

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log-k 21.397deltah -8.78 kcal

PHASESUraniniteU02 + 4 H+ = U+4 + 2 H20log_k -3.490delta h -18.630 kcal

END

8 TEST PROCEDURES

In all test cases, the input files described in Sections 6 and 7 will be submitted for batch run inPHREEQC, Version 2.6 as described in Section 4 of this software validation test plan. Resultscontained in the output file created by each run will be evaluated as summarized in thefollowing sections.

8.1 Installation Check

The input files test problems provided with the PHREEQC, Version 2.6 installation package willbe run as described in Section 6.1 of this software validation test plan. The results of theinstallation check will be examined and recorded.

8.2 Comparison with Hand Calculations

The test problems described in Sections 6.3 (Mineral Solubility) and 6.4 (Gas Chemistry)involve comparison of PHREEQC, Version 2.6 results against the results of hand calculations.The results, including component concentration and mineral saturation, will be compared intabular form.

8.3 Comparison with MINTEQA2, Version 4.02 Simulations

For test problems involving comparison against MINTEQA2, Version 4.02 simulations, outputfrom the two computer programs will be compared in several ways:

* Comparison of component concentrations-This will be done in tabular form for a limitedsuite of dominant aqueous species.

* Comparison of mineral saturation indices-This will be done in tabular form for a limitedset of dominant minerals.

* Graphic comparison of aqueous speciation-This is an effective means of comparingmodel results for speciation and sorption as a function of independent variables such aspH, pe, and PC0 2.

It is anticipated that results from the two codes will agree within a few percent, although theremay be differences due to disparities between the thermodynamic databases used in the code.Any differences resulting from these comparisons will be documented, evaluated, and resolvedas necessary. Although databases and modifications will be documented as appropriate, it isimportant to remember that it is beyond the scope of this validation test plan to resolve alldifferences in between the PHREEQC, Version 2.6 and MINTEQA2, Version 4.02thermodynamic databases.

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CONFIGURATION MANAGEMENT:PHREEQC, Version 2.6

Prepared by

David R. Turner


1 TECHNICAL DESCRIPTION OF PHREEQC, Version 2.6

PHREEQC, Version 2.6 (April 2002 release) is an acquired geochemical speciation code,originally developed by the U.S. Geological Survey (USGS). The software is used by staff atthe Center for Nuclear Waste Regulatory Analyses (CNWRA) to provide technical assistance tothe U.S. Nuclear Regulatory Commission (NRC) in its high-level waste program. An earlierversion, PHREEQC, Version 1.6 is currently under configuration control in accordance withTechnical Operating Procedure (TOP) 018.

PHREEQC, Version 2.6 (released April 2002) is a geochemical equilibrium speciation codedeveloped in ANSI C++ by the USGS to model dilute aqueous systems. The code as receivedwas compiled using Microsoft Visual C++ 6.0. The code is PC-compatible, and is run in batchmode in the DOS-operating system. Since the original development, PHREEQC has becomeone of the more common codes used to simulate geochemical equilibria.

As described on the USGS website (http://water.usgs.Qov/cqi-bin/man wrdapp?phreegc)PHREEQC, Version 2.6 is:

"designed to perform a wide variety of low-temperature aqueous geochemicalcalculations. 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 (1 D)transport calculations involving reversible reactions, which include aqueous, mineral, gas,solid-solution, surface-complexation, and ion-exchange equilibria, and irreversible reactions,which include specified mole transfers of reactants, kinetically controlled reactions, mixing ofsolutions, and temperature changes; and (3) inverse modeling, which finds sets of mineral andgas mole transfers that account for differences in composition between waters, within specifiedcompositional uncertainty limits."

1.1 Code Description

The documentation provided with the self-extracting PHREEQC, Version 2.6 file (downloadedfrom the USGS website at ftp://brrcrftp.cr.usgs.gov/aeochem/pc/phreeqc/phrgc26.exe) includesa user's manual that describes the features and their implementation of the code (Parkhurstand Appelo, 1999) in the PHREEQC geochemical speciation codes. Electronic and hard copiesof these documents are included in this configuration control package for PHREEQC, Version2.6. In addition, the download from the EPA website includes ASCII files that describe theinstallation and system requirements of the code (README.TXT) and provide a listing ofspecific updates to the PHREEQC, Version 2.6 code (RELEASE.TXT). A hard copy ofREADME.TXT is included in Appendix A. Hard copy of RELEASE.TXT is included in AppendixB.

The entire self-extracting compressed download file as is included in this configurationmanagement file.

1.1.1 Input

A PHREEQC, Version 2.6 user typically has a problem relevant to a natural chemical system.This system is described in terms of the physical conditions such as temperature, and the

1

concentrations of chemical components, species, solids and gases that are present. PHREEQCuses a free-format input file divided into keyword data blocks to identify the components ofinterest, read the concentrations, construct the chemical equilibrium model and solve foraqueous speciation and the distribution of species between the solid, gas, and liquid phases.Input flags can be set to determine the level of output. For speciation modeling, analytical datafor a solution composition (SOLUTION keyword) are needed. For batch-reaction modeling, theinitial solution composition is required (SOLUTION or MIX data block). Other equilibriumreactants may be defined with EQUILIBRIUMPHASES, EXCHANGE, SURFACE,GASPHASE, and SOLIDSOLUTION data blocks. Nonequilibrium reactions may be definedwith KINETICS and RATES, REACTION, and REACTIONTEMPERATURE data blocks. Inputfiles are constructed by the user an ASCII text editor. During execution of a geochemicalproblem, the input file is read and the databases searched for the relevant component speciesand aqueous, gas, solid phases.

For 1 D transport modeling, the modeled system requires the information necessary to establishthe geochemistry in each cell. There is also physical information needed for each cell todescribe the cell dimensions, time steps, and the boundary conditions used in the 1 D model.For inverse modeling, the solution composition of the final solution and one or more initialsolutions are needed (SOLUTION data block). Uncertainty limits can be defined explicitly or bydefault for each element and element redox state in the solutions.

Thermodynamic data are contained in a separate database that includes definition of aqueousspecies, exchange species, surface species, and mineral and phases for a set of elements.Additional elements, species, or phases can be added to the database if information onchemical reactions, log K, and data for the temperature dependence of log K are available foreach added species and/or phase

1.1.2 Output

The results from the equilibrium geochemical speciation calculation are written to an output filespecified by the user. PHREEQC, Version 2.6 will overwrite previously existing files with thesame name. The output includes an echo of the input to verify that the input file was readcorrectly. PHREEQC, Version 2.6 does not provide a time stamp in the output file to verify thetime of the run. The level of output varies and is set by the user in the input files. Theequilibrium concentration of the element(s) of interest are reported in morality (moles aqueouscomponent or species/kg H20) as distributed between the dissolved, sorbed, and precipitatedphases.

1.2 Hardware/Software Requirements and Installation

PHREEQC, Version 2.6 is designed for IBM PC-compatible systems. For installation, 10megabytes of free disk space is needed. Run requirements for PHREEQC, Version 2.6 include:

- Windows 9x/Me, Windows NT 4.0, or Windows 2000- processor running at 100 megahertz or faster- 8 megabytes RAM- 20 megabytes free disk space

2

PHREEQC, Version 2.6 is installed by executing the self-extracting download filePHRQC26.EXE. The installation program included with the download file can optionally modifythe PATH environment variable so that the PHREEQC program can be executed from anydirectory, without needing to type the full pathname of the program's location.

By default, the software is installed in the directory C:\Program Files\USGS\phreeqc2.6, but theauthor can specify an alternate directory. Using a customized installation option, the user canselect only certain parts for the initial installation, but program components not installed initiallycan be installed later. The file PHRQC26.EXE also has a maintenance version of theinstallation program to reinstall any damaged or overwritten program files.

During installation, PHREEQC, Version 2.6 will create a directory structure:

phreeqc2.6 files NOTICE.TXT, RELEASE.TXT, and this README.TXT; abatch file to run PHREEQC, database files

----- doc documentation files----- examples examples from user's guide--used in verification tests----- src Makefile and source code

----- release compiled executable----- test batch files to run verification tests

2 INSTALLATION CHECKS

The PHREEQC, Version 2.6 software has been checked to ensure that it was installed correctlyon the CNWRA PC platform (Pentium-based PC, Windows NT 4.00 operating system). Part ofself-extracting installation package for PHREEQC, Version 2.6 includes input and output for aset of 18 example problems developed to demonstrate the different capabilities of PHREEQC,Version 2.6. The test problems are described in the user's manual (Parkhurst and Appelo,1999). To test the installation, in an MS-DOS Command Prompt window, the user changes tothe phreeqc2.6\test directory:

c:cd "program files"cd usgs\phreeqc2.6\test


test [start [stop]]


After the tests are completed, the results are compared to the expected results included inPHREEQC examples directory. The file CHECK.LOG is created to contain the comparisonresults. If the installation check matches the example files, there should be no differences.

The input files for these example problems were submitted in batch mode to PHREEQC,Version 2.6 as installed, and the output compared against the files provided in the installation

3

* 0

package. Comparison results are included in the file CHECK.LOG. As installed, PHREEQC,Version 2.6 produced results identical to those provided by the code developers. Thecomparison file CHECK.LOG is included in Appendix C. Electronic versions of these installationchecks are provided in this configuration management package.

3 CONTENTS OF THIS CONFIGURATION MANAGEMENT PACKAGE

This configuration management includes the following information

Self-extracting download file (PHRQC26.EXE) from the USGS website atftp://brrcrftp.cr.usas.gov/geochem/pc/phreegc/phrgc26.exe (Electronic)

User's Manual for PHREEQC, Version 2.0 (Parkhurst and Appelo, 1999) (electroniccopy in Acrobat Reader Portable Document Format (*.pdf)). Subsequent modificationsare included in the ASCII file RELEASE.TXT included in Appendix B.

Software Summary Form TOP-4-1

Software Release Notice Form TOP-6

Installation check using 18 test problems with output as received, and output afterinstallation on CNWRA PC platform (Electronic ASCII files)

Original databases as received (Electronic ASCII files)

Source code for PHREEQC, Version 2.6 (Electronic ASCII files)

4 REFERENCES

The following documents are referenced or used in this configuration package for PHREEQC,Version 2.6. Electronic copies of these documents are included in this configuration controlpackage.

Parkhurst, D.L., and Appelo, C.A.J., 1999, User's guide to PHREEQC (Version 2)--a computerprogram for speciation, batch-reaction, one-dimensional transport, and inverse geochemicalcalculations: U.S. Geological Survey Water-Resources Investigations Report 99-4259, 312 p.

4

SOFTWARE SUMMARY FORM

01. Summary Date: 02. Summary prepared by (Name and phone) 03. Summary Action:01/24/2003 David R. Turner (CNWRA): (201) 522-2139

REPLACEMENT04. Software Date: 05. Short Title: PHREEQC, Version 2.6 (Replaces PHREEQC,04/2002 Version 2.4.2)

06. Software Title: PHREEQC, Version 2.6: A Computer Program for Speciation, Batch- 07. Internal Software ID:Reaction, One-Dimensional Transport, and Inverse Geochemical Calculations None

08. Software Type: 09. Processing Mode: 10. Application Area

l Automated Data System El Interactive a. General:X Scientific/Engineering E Auxiliary Analyses

X Computer Program El Batch E Total System PAE Subsystem PA E Other

E Subroutine/Module X Combinationb. Specific: Acquired Geochemical Equilibrium SpeciationCode. Developed by U.S. Geological Survey

11. Submitting Organization and Address: 12. Technical Contact(s) and Phone:

CNWRA/SwRI David R. Turner6220 Culebra Road (210) 522-2139San Antonio, TX 78228

13. Software Application: PHREEQC, Version 2.6 is a DOS-based geochemical equilibrium speciation model for diluteaqueous species. Input uses keyword blocks to describe the geochemical system of interest. PHREEQC, Version 2.6 uses athermodynamic database with that contains chemical reactions, equilibrium constants, and enthalpies of reaction to solvemass action and mass balance constraints in geochemical systems. The code is used to investigate geochemical processessuch as aqueous speciation, precipitation/dissolution, gas partial pressures, redox behavior, sorption, ion exchange, and one-dimensional reactive transport.

14. Computer Platform 15. Computer Operating 16. Programming 17. Number of SourcePC/Pentium running at 100 System: Language(s): Program Statements:Mhz or faster Windows 9x/Me, Windows ANSI C++ Unknown

NT 4.0, or Windows 2000

18. Computer Memory 19. Tape Drives: 20. Disk Units: 21. Graphics:Requirements: 8 Mb RAM; N/A N/A N/A20 Mb free disk space l

22. Other Operational Requirements

23. Software Availability: 24. Documentation Availability:X Available El Limited El In-House ONLY X Available El Preliminary E In-House ONLY

25. Acquired Code developed by U.S. Geological Survey

Software Developer: Date:CNWRA Form TOP-4-1 (05/98)

5

SOFTWARE RELEASE NOTICE

1. SRN Number:

2. Project Title: Radionuclide Transport Key Technical Issue Project No. 20.06002.01.141

3. SRN Title: PHREEQC, Version 2.6

4. Originator/Requestor: David R. Turner Date: 02/20/2003

5. Summary of Actions

X Release of new software E Change of access software

El Release of modified software: Cl Software Retirement

El Enhancements made

El Corrections made

6. Validation Status

El Validated

a Limited Validation

X Not Validated Explain: Scheduled for Validation in FY2003

7. Persons Authorized Access |

Name | Read Only/Read-Write | Addition/Change/Delete

David R. Turner Read-WriteF. Paul Bertetti Read-Write

8. Element Manager Approval: Date:

9. Remarks:

NOTE: This acquired code was developed by the U.S. Geological Survey and supersedes/replaces PHREEQC,

Version 2.4.2 currently under configuration management.

CNWRA Fo.m TOP-6 (09/01)

6

APPENDIX A

7

README.TXT

PHREEQC

A program for speciation, batch-reaction, one-dimensionaltransport, and inverse geochemical calculations

NOTE: This file describes the batch version of PHREEQC. However, agraphical user interface, PhreeqcI, is available that runs under Windowsoperating systems. This interactive program can be downloaded fromhttp://water.usgs.gov/software/geochemical.html. Phreeqcl has internaldocumentation for all PHREEQC data input and is a complete interface toPHREEQC. A brief description of the program has been published as aFact Sheet:

Charlton, S.R., and Parkhurst, D.L., 2002, PhreeqcI--A graphical userinterface to the geochemical model PHREEQC: U.S. Geological SurveyFact Sheet FS-031-02, 2 p.

PHREEQC - Version 2.6 2002/04/22

Instructions for installation, execution, and testing are providedbelow. After installation, see the file doc\phreeqc.txt in the PHREEQCinstallation directory for summary information on PHREEQC.

For assistance, enhancement requests, or to report bugs, contact theHydrologic Analysis Software Support Program by sending e-mail [email protected].

For all versions of Microsoft Windows, this Windows console version ofPHREEQC must be run using an MS-DOS Command Prompt window.

TABLE OF CONTENTS

A. SYSTEM REQUIREMENTSB. DISTRIBUTION FILEC. DOCUMENTATIOND. INSTALLING

o Installing PHREEQCo PHREEQC directory structure

E. COMPILINGF. RUNNING THE SOFTWARE

o Out of environment space errorG. TESTINGH. CONTACTS

A. SYSTEM REQUIREMENTS

For installation of PHREEQC, 10 megabytes of free disk space is needed.

To run PHREEQC, the following are necessary:

- Windows 9x/Me, Windows NT 4.0, Windows 2000, Windows XP- processor running at 100 megahertz or faster- 8 megabytes RAM- 20 megabytes free disk space

B. DISTRIBUTION FILE

The following distribution file (containing the software, test data sets,and information files) is currently available.

phrqc26.exe - Compiled using Microsoft Visual C++ 6.0, includes source code

C. DOCUMENTATION

8

Parkhurst, D.L., and Appelo, C.A.J., 1999, User's guide to PHREEQC(Version 2)--a computer program for speciation, batch-reaction,one-dimensional transport, and inverse geochemical calculations:U.S. Geological Survey Water-Resources Investigations Report 99-4259,312 p.

This document is available in electronic format. PortableDocument Format (PDF) and Postscript files are included in thedoc subdirectory of the PHREEQC program distribution. An onlineHTML version of the User's Guide can also be found athttp://water.usgs.gov/software/phreeqc.html.

See http://water.usgs.gov/software/ordering-documentation.html forinformation on ordering printed copies of USGS publications.

D. INSTALLING

Installing PHREEQC__________________

Note that if the software is to be installed on a server system,the person installing the software generally must have administratorrights.

To install the software, double-click phrqc26.exe to executethe installation program and follow the directions on the screen.The installation program can optionally modify the PATH environmentvariable so that the PHREEQC program can be executed from any directory,without needing to type the full pathname of the program's location.

By default, the software is installed in the directoryC:\Program Files\USGS\phreeqc2.6. This is the recommended installationdirectory, but you may use other directories or disk drives.

Note that program components not installed initially can be installedlater, and that any components damaged by, for example, beinginadvertently overwritten, can be quickly reinstalled by double-clickingphrqc26.exe--a maintenance version of the installation program will beexecuted.

PHREEQC directory structure

The following directory structure will be created (the contents of eachdirectory are shown to the right):

phreeqc2.6 files NOTICE.TXT, RELEASE.TXT, and this README.TXT;batch file to run PHREEQC, database files

-----doc documentation files-----examples examples from user's guide--used in verification tests-----src Makefile and source codeI '-----release compiled executable-----test batch files to run verification tests

Note: It is recommended that no user files be kept in the PHREEQCdirectory structure. If you plan to put files in the PHREEQCdirectory structure, do so only by creating subdirectories.

E. COMPILING

The source code is provided so that users can generate the executablethemselves. Little or no support is provided for users generatingtheir own versions of the software. In general, to compile a newversion of the software, you will need:

(a) a C compiler,

9

(b) familiarity with the compiler and the Windows operating system.

A Makefile used to compile the program under Linux is provided as an examplein the phrqc26.exe distribution,

F. RUNNING THE SOFTWARE

If the option to modify the PATH environment variable was chosenduring installation, then the following commands may be used to runPHREEQC from an MS-DOS Command Prompt window.

command to execute PHREEQC explanation

phreeqc The program will query for each of theneeded files.

phreeqc input The input file is named input, the outputfile will be named input.out and thedefault database file will be used.

phreeqc input output The input file is named input, the outputfile is named output, and the defaultdatabase file will be used.

phreeqc input output database All file names are specified explicitly.

phreeqc input output database screenoutput

All file names are specified explicitly,and screen output is directed to thefile screen-output.

If the option to modify the PATH environment variable was not chosenduring installation, then two options exist: (1) the full pathnameto the script that runs phreeqc can be used in place of "phreeqc" inthe above commands (for example "c:\programfiles\usgs\phreeqc2.6\phreeqc". Note that because of the space presentin "program files", quotation marks must be used to enter the fullpathname.), or, (2) the executable (installed inphreeqc2.6\src\release\phreeqc.exe) may be copied to the currentdirectory; further, the default database file must be in the currentdirectory and named "phreeqc.dat". The default databasefile is installed in phreeqc2.6\database\phreeqc.dat.

The environment variable PHREEQCDATABASE can be used to specify thedefault database for a DOS window session. This environment variablecan be set with the command:

set PHREEQC-DATABASE=c:\mydirectory\myproject\mydata.dat

This environment variable takes precedence over any default definitionof the database file. If PHREEQC is invoked with at least threearguments, the third argument is the database file and it takesprecedence over the environment variable or the default database.

Out of environment space error______________________________

This error can occur in earlier Windows operating systems when assigninga value to the PHREEQC DATABASE environment variable or running PHREEQC,including when running the verification tests. The error occurs whenthere is insufficient space to hold a new environment variable definition.

You can avoid this error by initiating a new command shell and specifyinghow much environment space you need. For example, in an MS-DOS CommandPrompt window, typing

10

command /e:1024

will initiate a new command shell with 1024 bytes of environment space.Environment space can be between 256 and 32768 bytes.

The above command will increase the environment space for only thecurrent Command Prompt window. To permanently increase your environmentspace, on Windows 9x/Me machines, click the MS-DOS icon in the upper-leftcorner of the Command Prompt window and select Properties. Select theMemory tab and increase the value in the Initial environment field.

G. TESTING

Test data sets are provided to verify that the program is correctly installedand running on the system. The tests execute the examples presented inthe user's guide, which demonstrate most of the program's capabilities.The tests are run in the phreeqc2.6\test directory. The directoryphreeqc2.6\examples contains the PHREEQC input data and expected resultsfor each test.

To test the installation, in an MS-DOS Command Prompt window change tothe phreeqc2.6\test directory:

c:cd "program files"cd usgs\phreeqc2.6\test


test [start [stop]]


For example:

command what happens

test runs all of the teststest 1 1 runs the first testtest 2 3 runs tests 2 and 3test 4 runs test 4 through the last test

After the tests are completed, the results are compared to theexpected results (found in the PHREEQC examples directory). See thefile check.log; if all goes well, there should be no differences.

Note: Sometimes different processors, or different compilers causeminor numerical differences in the results or differences inrepresentation of exponents. In general, concentrations shoulddiffer by less than about le-14 (mol/kg water) between two setsof results. The pe may vary several units in some systemswithout redox buffering, however, all concentrations shouldstill differ by only small amounts.

Problem 9 generates a warning message that indicates negativeconcentrations were generated in a kinetic run. The numericalmethod automatically reduces the step size until negativeconcentrations are eliminated and an accurate kinetic integrationis obtained.

Problems 11, 12, 13, and 15 generate warning messages. Themessages simply indicate a shorthand method for defining celllengths and cell dispersivities was used in a transportcalculation.

1 1

To clean up after the tests, type the command:

clean

The tests are described in the table below. Test is the test number andthe usage column indicates how a file is used, with i for input and o foroutput.

test description of test and files file name & usage

1 Add uranium and speciate seawater

PHREEQC input file exl iPrinted results of calculation exl.out 0

2 Temperature dependence of solubilityof gypsum and anhydrite

PHREEQC input file ex2 iPrinted results of calculation ex2.out 0

Results written to the selected-output file ex2.sel o

3 A. Calcite equilibrium at log Pco2 = -2.0 and 25CB. Definition of seawaterC. Mix 70% ground water, 30% seawaterD. Equilibrate mixture with calcite and dolomiteE. Equilibrate mixture with calcite only

PHREEQC input file ex3 iPrinted results of calculation ex3.out o

4 A. Rain water evaporationB. Factor of 20 more solution


5 Add oxygen, equilibrate with pyrite, calcite, and goethite.

PHREEQC input file ex5 iPrinted results of calculation ex5.out oResults written to the selected-output file ex5.sel o

6 6A. React to phase boundaries6Al.--Find amount of k-feldspar dissolved to

reach gibbsite saturation6A2.--Find amount of k-feldspar dissolved to

reach kaolinite saturation6A3.--Find amount of k-feldspar dissolved to

reach K-mica saturation6A4.--Find amount of k-feldspar dissolved to

reach k-feldspar saturation6A5.--Find point with kaolinite present,

but no gibbsite6A6.--Find point with K-mica present,

but no kaolinite6B. Path between phase boundaries6C. Kinetic calculation

PHREEQC input file ex6 iPrinted results of calculation ex6.out oResults written to the selected-output file ex6A-B.sel oResults written to the selected-output file ex6C.sel o

7 organic decomposition with fixed-pressure andfixed-volume gas phases


12

Results written to the selected-output file ex7. sel 0

8 Sorption of zinc on hydrous iron oxides

PHREEQC input file ex8 iPrinted results of calculation ex8.out oResults written to the selected-output file ex8.sel 0

9 Kinetically controlled oxidation of ferrous iron.Decoupled valence states of iron.

PHREEQC input file ex9 iPrinted results of calculation ex9.out oResults written to the selected-output file ex9.sel 0

10 Solid solution of strontianite and aragonite.

PHREEQC input file exlO iPrinted results of calculation exlO.out 0Results written to the selected-output file exlO.sel o

11 Transport and ion exchange.

PHREEQC input file exll iPrinted results of calculation exll.out oResults written to the selected-output file exlladv.sel oResults written to the selected-output file exlltrn.sel o

12 Advective and diffusive transport of heat and solutes. Constantboundary condition at one end, closed at other. The problem isdesigned so that temperature should equal Na-conc (in mmol/kgw)after diffusion.

PHREEQC input file exl2 iPrinted results of calculation exl2.out oResults written to the selected-output file exl2.sel o

13 A. 1 mmol/l NaCl/N03 enters column with stagnant zones. Implicitdefinition of first-order exchange model.

B. 1 mmol/l NaCl/N03 enters column with stagnant zones. Explicitdefinition of first-order exchange factors.

C. 1 mmol/l NaCl/N03 enters column with stagnant zones. 5 layerstagnant zone with finite differences.

PHREEQC input file exl3a iPrinted results of calculation exl3a.out oResults written to the selected-output file exl3a.sel oPHREEQC input file exl3b iPrinted results of calculation exl3b.out oResults written to the selected-output file exl3b.sel oPHREEQC input file exl3c iPrinted results of calculation exl3c.out oResults written to the selected-output file exl3c.sel o

14 Transport with equilibrium_phases, exchange, and surface reactions

PHREEQC input file exl4 iPrinted results of calculation exl4.out oResults written to the selected-output file exl4.sel o

15 1D Transport: Kinetic Biodegradation, Cell Growth, and Sorption

PHREEQC input file exl5 idatabase file exl5.dat iPrinted results of calculation exl5.out aResults written to the selected-output file exl5.sel a

16 Inverse modeling of Sierra springs

13

.

PHREEQC

Printed

17 Inverse

PHREEQC

Printed

18 Inverse

PHREEQC

Printed

input file eresults of calculation e

modeling of Black Sea water evaporation

input file Eresults of calculation

modeling of Madison aquifer

input file Eresults of calculation E

exl6exl6.out

i0

exl7exl7.out

1

0

exl8exl8. out

i0

H. CONTACTS

Inquiries about this software distribution should be directed to:

U.S. Geological SurveyHydrologic Analysis Software Support Program437 National CenterReston, VA 20192e-mail: [email protected]

14

APPENDIX B

15

RELEASE.TXT

Features not documented in WRIR 99-4259.

Version 2.6:____________________________________________________________

No new features are documented.

____________________________________________________________

Version 2.5:

Added the capability to use square brackets to define an"element" name. The brackets act like quotation marksin that any character string can be used within thebrackets as an element name. For example, [Fe3], [13C],and [N5] are now legal "element" names. All elementnames without brackets must begin with a capital letter,followed by zero or more lower case letters and underscores.

Added identifier -activitywater for a species in SOLUTIONSPECIESdata block. This identifier has been added for future updatesthat will allow isotopic calculations. It is intended to beused only for isotopic variations of H20, like D20 orH2[018]. It forces the activity coefficient for thespecies to be activity(water)/55.5. This effectively setsthe activity of the species to the mole fraction insolution.

Added identifier -badstepmax to KINETICS data block.An integer following -bad step-max gives the maximum numberof times a rate integration may fail before execution of theprogram is terminated. Default is 500.

____________________________________________________________

Version 2.4:

____________________________________________________________

Added identifier -warnings to PRINT keyword.

An integer following -warnings gives the maximum numberof warnings to print into the output file. A negativenumber allows all warnings to be printed.

Example: -warnings 20

Changed the results of the function CELLNO in Basic programs.

Function cellno in Basic now prints a number equivalentto -solution in SELECTEDOUTPUT data block. It gives thesolution number for initial solution calculations and thesolution being used in batch reaction calculations.Result is the same as previous versions for ADVECTION orTRANSPORT calculations.

Version 2.3:

DATABASE--New keyword data block

It must be the first keyword in the input file.The character string following the keyword isthe pathname for the database file to be usedin the calculation. The file that is specifiedtakes precedence over any default databasename, including environmental variablePHREEQCDATABASE and command line arguments.

16

LLNLAQUEOUS MODELPARAMETERS--New keyword data block

Added new keyword to make aqueous model similar toEQ3/6 and Geochemists Workbench when usingllnl.dat as the database file. Valuesof Debye-Huckel a and b and bdot (ionic strengthcoefficient) are read at fixed temperatures.Linear interpolation occurs between temperatures.

New options for SOLUTIONSPECIES are-llnl-gamma a where a is the ion-size parameter.-co2_11nlgamma , indicates the temperature dependent

function for the bdot term given in-co2_coefs of LLNL.AQUEOUSMODELPARAMETERSwill be used. Applies to unchargedspecies only.

LLNLAQUEOUS MODELPARAMETERS-temperatures

0.0100 25.0000 60.0000 100.0000150.0000 200.0000 250.0000 300.0000

#debye huckel a (adh)-dh_a

0.4939 0.5114 0.5465 0.59950.6855 0.7994 0.9593 1.2180

#debye huckel b (bdh)-dh_b

0.3253 0.3288 0.3346 0.34210.3525 0.3639 0.3766 0.3925

-bdot0.0394 0.0410 0.0438 0.04600.0470 0.0470 0.0340 0.0000

#cco2 (coefficients for the Drummond (1981) polynomial)-co2_coefs

-1.0312 0.0012806255.9 0.4445

-0.001606

____________________________________________________________

Added function SURF to Basic.

SURF("element", "surface") gives the amount of elementsorbed on "surface". "surface" should be the surfacename, not the surface-site name (that is, no underscore).

Allow decimals in definition of secondary master species.

Some redox states do not average to integers,for convenience in identifying them, decimal numbersmay be used within the parentheses that define theredox state, example S(0.3) could be used in theMASTERSPECIES data block for the valence state ofaqueous species S6-2.

Eliminate echo of input file in PRINT data block.

-echoinput T/F turns echoing on and off.Default is true, initial value is true.

Added option for an equilibrium-phase to dissolve only."dis" is added at the end of a line defining an equilibrium-

phase. No data fields may be omitted. Should notbe used when adding an alternative reaction.

Example:EQUILIBRIUMPHASESDolomite 0.0 0.001 dis

17

Version 2.2:____________________________________________________________

Added function EDL to Basic.EDL("element", "surface") gives the amount ofelement in the diffuse layer for "surface", notincluding sorbed species. "surface" should bethe surface name, not the surface-site name(that is, no underscore).

Special values for "element" include:"charge" - gives surface charge, equivalents."sigma" - surface charge density, C/m**2."psi" - potential at the surface, Volts."water" - mass of water in the diffuse layer, kg.

____________________________________________________________

End of Features not documented in WRIR 99-4259.

Revisions and bug fixes

Version 2.6 Date: Mon April 22, 2002

PhreeqcI released.

All selected-output is routed through a single routine.

Allow "_" inside square brackets, [A-bcd].

Fixed bug match-eltsinspecies, check for "e-" was wrong.

Modified minteq.dat to put CuS4S5-3, Cu(S4)2-3 inin Cu(l) mole balance equations instead ofCu(2). Before the change, the program wouldnot converge if Cu(2) were defined in aninitial solution.

Made revisions hopefully to improve SOLIDSOLUTIONSconvergence with small numbers of moles ofsolids.

Made changes related to dump file and PhreeqcI.

Iterations now sums iterations in all kinetics calculations

Fixed bug with LA("H20"), which was returning natural logof activity of water.

Version 2.5 Date: Mon October 1, 2001In llnl.dat, fixed sign errors in RRE (rare earth elements)

for some redox reactions and removed some redundantspecies, generally ReeO2- was retained and Ree(OH)4-was removed.

Added the capability to use square brackets to define an"element" name. The brackets act like quotation marksin that any character string can be used within thebrackets as an element name. This was introduced tosimplify expansion of the model to isotopic species.[13C], [14C], and [180] are legal element names.

Added identifier -activitywater for a species inSOLUTIONSPECIES data block. This identifier has beenadded for future updates that will allow isotopic

18

calculations. It is intended to be used only forisotopic variations of H20, like D20 or H2[018]. Itforces the activity coefficient for the species to beactivity(water)/55.5. This effectively sets the activityof the species to the mole fraction in solution.

Fixed bug in checking solid solutions for presence orabsence of elements in the system. Programmingerror caused segmentation fault if an errorwas detected under certain conditions.

Changed return value of MOL to be molality of waterif argument is "H20'. Also changed return valueof LA to be activity of water if argument is"H20".

Diffuse layer calculation was incorrect if aqueous phase did nothave 1 kilogram of water. Eq. 74 of manual has molality,but code used moles. The code was corrected by addingthe mass of water to the formulation.

Stagnant zones with first-order exchange approximation (1 stagnantcell, exchange factor, and porosities defined) did not workcorrectly if mobile and immobile cells did not have equalvolumes of water. The mixing factors were revised to accountfor the masses of water in the stagnant and mobile zones.

A fatal error was erroneously detected if the database filehad a DATABASE data block. DATABASE data block isnow ignored while reading the database file.

Added identifier -bad stepmax to KINETICS data block.An integer following -bad step-max gives the maximum numberof times a rate integration may fail before execution of theprogram is terminated. Default is 500.

Version 2.4.2: Date: Fri June 15, 2001Fixed spreadsheet bug. Program was not ignoring columns

that could not be identified as either elementnames or allowed data (ph, pe, number, description,etc). Also, the program failed if a spreadsheet solutionnumber was negative.

Version 2.4.1: Date: Mon June 4, 2001Fixed spreadsheet bugs with isotopes.

Version 2.4: Date: Fri June 1, 2001

Added structure for spreadsheet for use by PhreeqcI.

Isotope value initialized incorrectly if only an -uncertainty wasdefined in SOLUTION_SPREAD.

Fixed segmentation violation when primary and secondary masterspecies were defined improperly.

Corrected enthalpies of reaction in llnl.dat. Previous release haderroneously had enthalpies of formation in -delta_Hparameter; the values should be enthalpies of reaction.Enthalpies of reaction were calculated from theenthalpies of formation and these values are now includedin the -deltaH parameter. This change will have verylittle impact on calculations because the analyticalexpression has precedence over -delta H in calculatingtemperature dependence of log K, and nearly all speciesand minerals have an analytical expression or lack bothan analytical expression and an enthalpy of reaction.

Corrected bugs in punch of solid solution components that caused

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both selected output and output file errors: moleswere incorrect in selected output, and total moles andmole fraction were incorrect in output file.

Added surface complexation constants for Fe+2; two complexes forweak sites and one complex for strong sites. phreeqc.datand wateq4f.dat modified.

Comment for units of parameters for calcite rate equation waswrong. Rate equation now uses cm^2/L for area parameter.Previously the correct units would have been 1/decimeter.phreeqc.dat and wateq4f.dat modified.

Fixed a bug when rates were equal within tolerance, but negativeconcentrations occurred because of small initialconcentrations.

Added -warnings to PRINT keyword for specification of maximumnumber of warnings to print. Negative number allowsall warnings to be printed.

Function CELL NO in Basic now prints a number equivalent to-solution in SELECTEDOUTPUT data block. This does notchange printing for ADVECTION or TRANSPORT calculations.

Kinetics time is halved for advective part of reaction intransport; time incorrectly accounted for before.

-punch_ identifiers printed -1 instead of the correct solutionnumber for batch-reaction calculations.

-high-precision is no longer reset to false with everySELECTEDOUTPUT data block.

SELECTED_OUTPUT file name stored for use by PhreeqcI.

Alkalinity for NH3 corrected to 1.0 in llnl.dat.

Fixed bug with USERPRINT of kinetics. Did not find correctkinetics information in some cases.

Fixed bug in default values for SOLUTION-SPREAD. Cannot use phasename and SI for pH or pe, and bug did not allow PHREEQCto run. Now PHREEQC runs, but warns that this is notallowed.

Version 2.3: Date: Tue January 2, 2001

Added new keyword DATABASE. It must be the first keyword inthe input file. The character string following thekeyword is the pathname for the database file tobe used in the calculation. The file that isspecified takes precedence over any defaultdatabase name, including environmental variablePHREEQCDATABASE and command line arguments.

Fixed bug in SOLUTIONSPREAD. If first heading inthe spread-sheet input was an identifier--pH,pe, units, etc--then the headings were interpretedas an identifier and bad things happened.

Added new keyword to make aqueous model similar toLLNL and Geochemists Workbench when usingllnl.dat as the database file. Valuesof Debye-Huckel a and b and bdot (ionic strengthcoefficient) are read at fixed temperatures.Linear interpolation occurs between temperatures.

New options for SOLUTION-SPECIES are

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-llnlgamma a where a is the ion-size parameter.-co2_11nlgamma indicates the temperature dependent

function for the bdot term given in-co2_coefs of LLNLAQUEOUSMODELPARAMETERSwill be used. Applies to unchargedspecies only.

LLNLAQUEOUSMODELPARAMETERS-temperatures

0.0100 25.0000 60.0000 100.0000150.0000 200.0000 250.0000 300.0000

#debye huckel a (adh)-dh_a

0.4939 0.5114 0.5465 0.59950.6855 0.7994 0.9593 1.2180

#debye huckel b (bdh)-dh_b

0.3253 0.3288 0.3346 0.34210.3525 0.3639 0.3766 0.3925

-bdot0.0394 0.0410 0.0438 0.04600.0470 0.0470 0.0340 0.0000

#cco2 (coefficients for the Drummond (1981) polynomial)-co2_coefs

-1.0312 0.0012806255.9 0.4445

-0.001606

Fixed bug in basic interpreter. A number like "..524" wouldcause an infinite loop.

Added function SURF to Basic.SURF("element", "surface") gives the amount of

element sorbed on "surface". "surface"should be the surface name, not thesurface-site name (that is, no underscore).

Fixed option to "runge-kutta" from "runge-kutta" to matchdocumentation for KINETICS.

Fixed U02+2 and Mn+2 reaction stoichiometry for Hfo surface complexationin wateq4f.dat.

Added option for an equilibrium-phase to dissolve only."dis" is added at the end of a line defining an equilibrium-

phase. No data fields may be omitted. Should notbe used when adding an alternative reaction.

Example:EQUILIBRIUMPHASES

Dolomite 0.0 0.001 disR-K integration failed when only the final rate generated

negative concentrations.Allow decimals in definition of secondary master species, for

example S(0.3).Fixed bug if description was more than about 85 characters;

now allows about 400 characters.Fixed bug for surface/exchange sites related to phases. Was

checking internal copies of surfaces/exchange with negativenumbers.

Fixed bug in quick prep that did not set the correct pointerfor gas phases.

Fixed segmentation fault that occurred if all elements forphase-boundary mineral were not in the solution.Only applied to a phase used to define concentrationin an initial solution calculation.

Added option to eliminate echo of input file in PRINTdata block. -echoinput T/F turns echoing onand off. Default is on.

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Release 2.2: Date: Wed March 1, 2000

Fixed bug in MIX if no solutions are defined.Changed printout for surface.

Only gives net surface charge for diffuse layercalculation.

Prints correct value for the surface charge andsurface charge density for diffuse-layercalculation.

Added function EDL to Basic.EDL("element", "surface") gives the amount of

element in the diffuse layer for "surface".not including sorbed species. "surface" shouldbe the surface name, not the surface-site name(that is, no underscore).

Special values for "element" include:"charge" - gives surface charge, equivalents."sigma" - surface charge density, C/m**2."psi" - potential at the surface, Volts."water" - mass of water in the diffuse layer, kg.

Changed distribution to be more consistent with other USGSwater-resources applications.

Release 2.1: Date: Wed January 19, 2000

Added additional #ifdef's for PhreeqcI.Fixed problem with formats for USERPUNCH and

others with Microsoft C++ 3 digitexponents.

Initial Release 2.0: Date: Wed December 15, 1999

Version: C_54 = Version 2.0

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APPENDIX C

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CHECK.LOG (Dated 1/27/2003)

Comparing files ..\EXAMPLES\exl.out and EX1.OUTFC: no differences encountered

Comparing files ..\EXAMPLES\ex2.out and EX2.OUTFC: no differences encountered

Comparing files ..\EXAMPLES\ex2.sel and EX2.SELFC: no differences encountered






Comparing files ..\EXAMPLES\ex6A-B.sel and EX6A-B.SELFC: no differences encountered

Comparing files ..\EXAMPLES\ex6C.sel and EX6C.SELFC: no differences encountered







Comparing files ..\EXAMPLES\exlO.out and EX1O.OUTFC: no differences encountered

Comparing files ..\EXAMPLES\exlO.sel and EX1O.SELFC: no differences encountered

Comparing files ..\EXAMPLES\exll.out and EXll.OUTFC: no differences encountered

Comparing files ..\EXAMPLES\exlladv.sel and EX11ADV.SELFC: no differences encountered

Comparing files ..\EXAMPLES\exlltrn.sel and EX11TRN.SELFC: no differences encountered

Comparing files ..\EXAMPLES\exl2.out and EX12.OUTFC: no differences encountered

Comparing files ..\EXAMPLES\exl2.sel and EX12.SEL

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FC: no differences encountered

Comparing files ..\EXAMPLES\exl3a.out and EX13A.OUTFC: no differences encountered

Comparing files ..\EXAMPLES\exl3b.out and EX13B.OUTFC: no differences encountered

Comparing files ..\EXAMPLES\exl3c.out and EX13C.OUTFC: no differences encountered

Comparing files ..\EXAMPLES\exl3a.sel and EX13A.SELFC: no differences encountered

Comparing files ..\EXAMPLES\exl3b.sel and EX13B.SELFC: no differences encountered

Comparing files ..\EXAMPLES\exl3c.sel and EX13C.SELFC: no differences encountered


Comparing files ..\EXAMPLES\exl4.sel and EX14.SELFC: no differences encountered


Comparing files ..\EXAMPLES\exl5.sel and EX15.SELFC: no differences encountered



Comparing files ..\EXAMPLES\exlB.out and EX18.OUTFC: no differences encountered

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software release notice i · 04/2002 version 2.4.2) 06. software title: phreeqc, version 2.6: a...

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