Dear Seyed,

to derive the 13C fractionation factor between FeCO3 and dissolved
carbonate species you will have to combine the theoretical FeCO3-CO3
factors of Golyshev et al. (1981) with the experimental works
for
the equilibrium fractionation factors between gaseous CO2 and the
individual dissolved carbonate species (probably you may have to
consider if you are dealing with a diluted aqueous solution or
seawater-like solutions; see the work of Zhang et al. (1995; GCA)).
You may also wish to look on
the experimental study of Carothers and co-workers published in GCA.

Good luck
Michael

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Dr. Michael E. Boettcher
Biogeochemistry Department
Max-Planck-Institute for Marine Microbiology
Celsiusstr.1
D-28359 Bremen
FRG
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