Hi Brian,
Thank you, this was very helpful.
I want to confirm that the custom rate law equation in GWB calculates a dissolution rate in the units of mol/sec, is that correct?
I think the problem with my siderite rate law was that I was using the "mass" helper function, instead of the "moles" function. I rewrote my rate law in this form:
(9.77e-12) * (moles("Siderite") * mw("Siderite")) * (1 - QoverK)
and it seems to be working...
However, my calcite rate law does not seem to be working
(6.75e-10) * (QoverK - 1)
I am still getting a negative and extremely small precipitation rate. When I check "System Parameters" in xtplot I get low decimals fractions for Q/K, Calcite; but when I check "mineral saturation" for calcite I have Q/K's in the 1000's, which makes more sense since I am running very high Ca and alkalinity waters through the model domain, and siderite is dissolving.
Any idea why this might be? I am attaching my script.
Thanks,
Zeno
siderite_firstorder_customratelaws.x1t