Surface chemistry allows for abiotic precipitation of dolomite at low temperature
| Autor: | Jennifer A. Roberts, David S. Moore, David A. Fowle, Robert H. Goldstein, Paul A. Kenward, Luis A. González |
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| Rok vydání: | 2013 |
| Předmět: |
Salinity
Biogeochemical cycle Surface Properties Dolomite Mineralogy engineering.material Calcium Carbonate chemistry.chemical_compound Bioreactors X-Ray Diffraction Environmental Microbiology Chemical Precipitation Magnesium Seawater Organic matter chemistry.chemical_classification Calcite Multidisciplinary Mineral Bacteria Precipitation (chemistry) Aragonite Temperature Spectrometry X-Ray Emission Carbon Dioxide Hydrogen-Ion Concentration Models Chemical chemistry Chemical engineering Physical Sciences Microscopy Electron Scanning engineering Biomineralization |
| Zdroj: | Proceedings of the National Academy of Sciences. 110:14540-14545 |
| ISSN: | 1091-6490 0027-8424 |
| DOI: | 10.1073/pnas.1305403110 |
| Popis: | Although the mineral dolomite is abundant in ancient low-temperature sedimentary systems, it is scarce in modern systems below 50 °C. Chemical mechanism(s) enhancing its formation remain an enigma because abiotic dolomite has been challenging to synthesize at low temperature in laboratory settings. Microbial enhancement of dolomite precipitation at low temperature has been reported; however, it is still unclear exactly how microorganisms influence reaction kinetics. Here we document the abiotic synthesis of low-temperature dolomite in laboratory experiments and constrain possible mechanisms for dolomite formation. Ancient and modern seawater solution compositions, with identical pH and pCO2, were used to precipitate an ordered, stoichiometric dolomite phase at 30 °C in as few as 20 d. Mg-rich phases nucleate exclusively on carboxylated polystyrene spheres along with calcite, whereas aragonite forms in solution via homogeneous nucleation. We infer that Mg ions are complexed and dewatered by surface-bound carboxyl groups, thus decreasing the energy required for carbonation. These results indicate that natural surfaces, including organic matter and microbial biomass, possessing a high density of carboxyl groups may be a mechanism by which ordered dolomite nuclei form. Although environments rich in organic matter may be of interest, our data suggest that sharp biogeochemical interfaces that promote microbial death, as well as those with high salinity may, in part, control carboxyl-group density on organic carbon surfaces, consistent with origin of dolomites from microbial biofilms, as well as hypersaline and mixing zone environments. |
| Databáze: | OpenAIRE |
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