Liu, D;
Xu, Y;
Yu, Q;
Yu, N;
Qiu, X;
Wang, H;
Papineau, D;
(2020)
Catalytic effect of microbially-derived carboxylic acids on the precipitation of Mg-calcite and disordered dolomite: Implications for sedimentary dolomite formation.
Journal of Asian Earth Sciences
, 193
, Article 104301. 10.1016/j.jseaes.2020.104301.
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Abstract
The genesis of dolomite is a contentious issue partly due to the difficulty in its synthesis at ambient temperature. Certain types of microorganisms have been demonstrated to be effective in promoting the precipitation of disordered dolomite, an important precursor of sedimentary ordered dolomite. In contrast to a growing body of research on the catalytic role of microbial exopolymers in the crystallization of disordered dolomite, the role of other microbial exudates (e.g., carboxylic acids) remains unknown. To fill in this knowledge gap, precipitation experiments, mimicking the carbonation process within microbial mats, were conducted in saline solutions containing 0-30 mM succinic acid or citric acid, which are commonly produced by microbes. The starting salinities of experiment solutions were set to 35‰ and 70‰, in order to evaluate the effect of solution salinity on dolomite formation. Our results showed that both succinic acid and citric acid enhanced the incorporation of Mg2+ into growing Ca-Mg carbonates. Solution salinity also played a positive role in enhancing Mg signature in Ca-Mg carbonates. Disordered dolomite with 40.92 mol% MgCO3 was detected under the conditions of 30 mM succinic acid and 70‰ salinity, whereas in other reactors with succinic acid, Mg-calcites formed. Citric acid was more effective in loading Mg2+ into Ca-Mg carbonates compared with succinic acid, as evidenced by the predominant occurrence of disordered dolomite with MgCO3 content ranging from 40.91 mol% to 46.75 mol% in most conditions tested. The results of this study have implications for the formation mechanism of sedimentary dolomite.
| Type: | Article |
|---|---|
| Title: | Catalytic effect of microbially-derived carboxylic acids on the precipitation of Mg-calcite and disordered dolomite: Implications for sedimentary dolomite formation |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.1016/j.jseaes.2020.104301 |
| Publisher version: | https://doi.org/10.1016/j.jseaes.2020.104301 |
| Language: | English |
| Additional information: | This version is the author accepted manuscript. For information on re-use, please refer to the publisher’s terms and conditions. |
| Keywords: | Dolomite problem, disordered dolomite, carboxylic acid, microbial mediation |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Earth Sciences |
| URI: | https://discovery.ucl.ac.uk/id/eprint/10091995 |
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