defining SURFACE_SPECIES

[eeftekhari]

I had a discussion with a friend of mine regarding the definition of surface species. We have defined a surface Chalk as:

SURFACE_MASTER_SPECIES
   Chalk    ChalkOH
SURFACE_SPECIES
   ChalkOH = ChalkOH
   log_k   0.0

In the manual, I have read that "The defined species must be the first species to the right of the equal sign". What happens if I define the following reaction:

        ChalkOH2+ + SO4-2 = ChalkSO4- + H2O
        log_k 11.2
Does Phreeqc recognizes ChalkOH2+ as a new surface species? Or should it be defined before it is used in the above reaction?
   

[dlparkhurst]

You must define the species ChalkOH2+ in a separate reaction (and log K) within SURFACE_SPECIES. It can be before or after the definiton of ChalkSO4-.

[eeftekhari]

Thank you very much.