Investigating biomineralization using synchrotron based X-ray computed microtomography

This work presents the results of a study where synchrotron based x-ray computed microtomography (CMT) was used to investigate changes in pore morphology during calcium carbonate biomineralization. We simultaneously examine changes in pore microstructure and bulk permeability within glass bead columns during biogenic CaCO3 precipitation induced by Sporosarcina pasteurii. We observe a three order of magnitude reduction in permeability over relatively short time-scales (similar to 60 hrs) during the carbonate precipitation process. The resulting precipitates were a microporous composite of spherical and cubic CaCO3 precipitates. CMT images taken during precipitation were analyzed for effective pore radii, effective throat radii, and other pore-scale characteristics using 3DMA-ROCK. The Kozeny-Carman relation provided a poor fit to the raw permeability data, however, once this function was augmented with geometric information extracted from CMT imagery a better fit was provided suggesting that pore geometry should be considered temporally variable when modeling permeability change during biomineralization. Citation: Armstrong, R., and J. Ajo-Franklin (2011), Investigating biomineralization using synchrotron based X-ray computed microtomography, Geophys. Res. Lett., 38, L08406, doi:10.1029/2011GL046916.