Rate expression for pyrite oxidation

[ACSchubert]

Dear all,

I looked into the paper of Williamson and Rimstidt form 1994, on which the rates expression for the pyrite weathering in the PhreeqC database is based. I'll attach the link to the paper below. Now my question is: The rates-expression used in the database is
R(Pyrite) = 10^-10.19 (O2(aq))^0.5 (H+)^-0.11.
Nowhere in the paper can I find this expression. What I do find though, is the following:
R(Pyrite) = 10^-8.19 (O2(aq))^0.5 (H+)^-0.11
Can someone explain this to me? Am I missing something?

Best wishes,
Agnes Schubert

Link to the paper: https://www.sciencedirect.com/science/article/pii/0016703794902410

[John Mahoney]

Yes, there are two different rate constants that are used.  One is in moles per square meters per gram, and that uses the 10^-8.19 rate constant (that is provided in the original W&R reference and also in Appelo and Postma page 451 equation 9.69)  and the the other in square the 10^-10.19 rate constant is in mole per square decimeters per gram.  I would stick to the square meters units it is simpler;  at this time I cannot recall the reason for the other units. 

I might have more on this topic in a day or two. 

[ACSchubert]

Thank you a lot for the quick answer!