BaCO3 saturation index

[jemiddle]

Hello,

I am very new to phreeqc and therefore am at the stage where I have a very simple problem: I am trying to output the saturation index of witherite (BaCO3) in my solution, but am struggling to find the correct commands to do so.

Could someone clarify how to specify which minerals to define saturation state for, or point me towards a thread that discusses this?

Thank you for your time!
Cheers,
Julia

[dlparkhurst]

All you need is a SOLUTION definition.

[jemiddle]

Hmmm, is there a certain command within SOLUTION that would change which saturation indices are output?

Currently my input is very simple:
SOLUTION 1   300nM Ba

units   mol/kgw
pH   8.0
density   1.029
temp    5.00
Ba   300.00000E-09
Ca   8.08743E-03
Cl   3.65935E-01
K   5.94173E-03
Mg   6.67943E-02
Na   2.80575E-01
S   3.44657E-02
O(0)   5.00000E-04
BaCO3 0.00000
BaSO4 0.00000

and the Saturation indices output are:

-----------------------------Saturation indices-------------------------------

  Phase               SI** log IAP   log K(278 K,   1 atm)

  Anhydrite        -1.03     -5.10   -4.07  CaSO4
  Barite            0.35     -9.71  -10.06  BaSO4
  Gypsum           -0.51     -5.11   -4.60  CaSO4:2H2O
  H2(g)           -24.24    -27.28   -3.03  H2
  H2O(g)           -2.06     -0.01    2.06  H2O
  H2S(g)          -70.59    -78.64   -8.05  H2S
  Halite           -2.87     -1.32    1.55  NaCl
  O2(g)            -0.84     -3.55   -2.71  O2
  Sulfur          -52.55    -47.17    5.38  S
  Sylvite          -3.83     -3.04    0.79  KCl



I had tried to force calculation of witherite by adding it to the solution initial list, but it doesn't seem to have done what I wanted

[dlparkhurst]

You can only include individual elements that are in the database. BaCO3 and BaSO4 are not allowed, nor are CO3 or SO4. SO4 can be defined as S(6) (as opposed to total sulfur (S) and carbon can be defined by Alkalinity, C, or C(4).

To get a witherite saturation index, you need to have some carbon in your solution.

[jemiddle]

Excellent! Thank you so much for your help and quick responses!

Cheers,
Julia