The role of microbial sulfate reduction in calcium carbonate polymorph selection

Authors
Lin, Chin Yik 
Turchyn, AV 
Bots, P 
Lampronti, GI 

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Abstract

Microbial sulfate reduction is a dominant metabolism in many marine sedimentary environments. The influence of this metabolism on the kinetics of CaCO3 growth, as well as the dominant polymorphs precipitated, is poorly understood. To investigate the role of microbial metabolism on CaCO3 precipitation and polymorph selection, we conducted growth experiments with the sulfate reducing bacteria (D. bizertensis) in media with varying Mg/Ca and different seeding materials (calcite and kaolinite). Our results suggest that sulfate reducing bacteria both induce carbonate mineral precipitation through an increase in alkalinity and serve as a nucleation sites for the growing carbonate mineral; the majority of the carbonate minerals produced were on cell material rather than mineral seeds. We also find the Mg/Ca and presence of phosphate in the media play a key role in controlling the rates of carbonate mineral precipitation and calcium carbonate polymorph selection. In media where the Mg/Ca is greater than 2, crystalline monohydrocalcite (MHC) is the primary carbonate mineral produced. Although phosphate concentrations have a lesser effect on which polymorph initially precipitates, a series of transformation experiments suggests that the presence of phosphate stabilizes MHC crystals and prevents its transformation to more stable calcium carbonate polymorphs. Collectively, these results suggest that the polymorph of microbially-mediated calcium carbonate cements is determined by the solution chemistry upon nucleation.

Publication Date
2018-09-15
Online Publication Date
2018-06-30
Acceptance Date
2018-06-17
Keywords
Monohydrocalcite, Mg/Ca, Seeding material, Phosphate, Transformation, Sulfate reducing bacteria, Incubation, Inhibitors, Nucleation
Journal Title
Geochimica et Cosmochimica Acta
Journal ISSN
0046-564X
1872-9533
Volume Title
237
Publisher
Elsevier
Sponsorship
European Research Council (307582)
Natural Environment Research Council (NE/J017930/1)
Natural Environment Research Council (NE/S001344/1)
Ministry of Education Malaysia, SLAI (Skim Latihan Akademik IPTA) scholarship to CYL