How to calculate pCO2 and CaCo3 precipitation in a lake

[lsprech1]

Hi,

I'm writing my master thesis about the carbon cycle in lake Geneva and I need to calculate the pCO2 and the saturation index of CaCO3 (pH, temperature, and DIC, Ca2+ and CO32- concentrations are known). What is the easiest way to calculate this?

I know this should be easy with PHREEQC but I never learned how to use it, I'm a total beginner... Therefore any help with explanations and/or codes are very welcome!

Thank youu :)

[dlparkhurst]

Perhaps you should look at the manual. Example 1 calculates pCO2 and calcite saturation indices; you can ignore the parts about adding uranium to the database.