New parameter files for GWB from THEREDA

[Helge]

I would like to announce that in the mean time two packages of data were released from the Thermodynamic Reference Database project in Germany (THEREDA). Each package comes with ready-to-use parameter files and with benchmark documents which contain representative test cases including scripts and input files for the tested codes. The data are available free of charge at www.thereda.de.

 

The second release of data from the THEREDA database (R-02) was issued just before last christmas (2011-12-23) and came with parameter files for the system Na,Mg,Ca,Cl - Am(III), Nd(III), Cm(III) - H2O.

Valid range of temperature: 298.15 K

Supported codes: CHEMAPP, PHREEQC, Geochemist's Workbench

 

The data have been rigorously tested for simple, ternary subsystems only:

[NaCl or MgCl2 or CaCl2] - [Am(III) or Nd(III) or Cm(III)] - H2O.

This implies that for calculations in higher component systems no quantitative measure for the description quality can be given and no warranty can be accepted for computational results.

As to interactions between Am, Cm, and Nd (R-02) and SO4 or carbonate, data are available but still subject of internal control in the THEREDA-team and can therefore not be released yet.

The responsibility of the data for Am(III), Nd(III), and Cm(III) lies with C. Marquardt from KIT-INE.

 

On the 21st of February new data were released. This release was denoted as third release (R-03). The new release of data from the THEREDA database came with parameter files for the system Na, Mg, Ca, K - Cl, SO4 - HCO3/CO2(g) - H2O.

Valid range of temperature: 298.15 K

Supported codes: CHEMAPP, PHREEQC, Geochemist's Workbench, EQ3/6 (Version 8.0a)

 

The data have been rigorously tested for simple, ternary subsystems only, as described in the respective benchmark document. This implies that for calculations in higher component systems no quantitative measure for the description quality can be given and no warranty can be accepted for computational results.

Although no example is given in the benchmark document which contains MgCl2 or MgSO4, agreement between our results and those obtained with the HMW84 database was verified for the solubility of CO2(g) or Nesquehonite in MgCl2 and MgSO4 solutions.

The responsibility of the data in R-03 lies with W. Voigt from TUBAF.

 

Consistency with earlier releases: the released data are consistent with those for the system of oceanic salts (R-01), calculated for 298.15 K. Thus, with the new parameter files, calculations from the first release (R-01) for 298.15 K can be reproduced.

 

The first release (R-01) covered the system of oceanic salts (excluding carbonate/CO2) for temperatures between 273.15 and 393.15 K, depending on the particular system. However, this release has not been opened for Geochemist's Workbench yet. For the temperature dependence of equilibrium constants THEREDA uses the expression:

log10(K) = A1 + A2T + A3/T + A4log10(T) + A5/T^2 + A6T^2

For the temperature dependence of Pitzer interaction coefficients THEREDA uses the expression

P = A0 + A1*(1/TK - 1/TR) + A2log(TK/TR) + A3*(TK-TR) + A4*(TK*TK - TR*TR) + A5*(1/(TK*TK) - 1/(TR*TR))

 

The terms A6T^2 and A5*(1/(TK*TK) - 1/(TR*TR)) are not available with Geochemist's Workbench. The THEREDA team intends to downgrade the first release for GWB users to calculations for 298.15 K only. However, calculations for other temperatures can only be performed with the other supported codes (PHREEQC, CHEMAPP, EQ3/6). This issue had been discussed with Tom who forwarded our request to the developers of GWB about 2010-06-01.

 

If any questions arise as to the new data, please don't hesitate to initiate a thread in our discussion forum:

http://www.thereda.de > Forum

 

On behalf of the THEREDA management board

Helge C. Moog

[Brian Farrell]

Hi Helge,

 

Regarding the temperature extrapolation issue you mention for the R-1 dataset, can you please send us (support@gwb.com) a copy of the database in GWB format, with the additional parameters entered in? We’ll look into what’s involved in adapting the GWB codes to use the expanded database.

 

Thanks,

 

Brian Farrell

Aqueous Solutions LLC

[Helge]

Hi Brian,

I will be glad to provide you with a polythermal parameter file for GWB, may be next week. Please note that this file will be untested (of course), but you can compare with the results from the benchmark documents when you validate your code for the new temperature function.

Regards,

Helge

[Helge]

In the meantime more data packages were release from THEREDA which are available also for GWB:

 

R-04: System Na, Cl, Np(V) - H2O

R-05: System Cs - Na, Mg, Ca, K - Cl, SO4 - HCO3/CO2(g) - H2O

R-06: System (Si, Al) - Na, Mg, Ca, K - Cl, SO4, CO3, HCO3 - H2O

R-07: System Na, K, Ca, Cl, Th(IV), Np(IV), Pu(IV), HCO3/CO2(g) - H2O

 

All parameter files are valid for 298.15 K only. Please visit www.thereda.de >> THEREDA Data Query >> Tailored Databases. Any feedback is welcome.

 

Enjoy!

 

Helge