Microbially influenced formation of anhydrite at low temperature
<p dir="ltr">Calcium sulfate minerals are abundant in nature – on Earth and on Mars – and important in several fields of material sciences. With respect to gypsum and bassanite, anhydrite represents the anhydrous crystalline phase in the CaSO<sub>4</sub>–H<sub>2<...
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2023
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| Summary: | <p dir="ltr">Calcium sulfate minerals are abundant in nature – on Earth and on Mars – and important in several fields of material sciences. With respect to gypsum and bassanite, anhydrite represents the anhydrous crystalline phase in the CaSO<sub>4</sub>–H<sub>2</sub>O system. Despite years of research, the formation of anhydrite in the laboratory at low temperature remains challenging and, in the geological record, this mineral is mostly interpreted as a secondary phase that form through metamorphic dehydration of gypsum. Here, we present the results of laboratory precipitation experiments showing that anhydrite can form at 35 °C from evaporated seawater through a microbially influenced mineralization process. The experiments were conducted in the presence of extracellular polymeric substances (EPS) produced by bacterial strains isolated from a modern evaporitic environment, the Dohat Faishakh sabkha in Qatar. Without organic molecules, only gypsum formed in parallel control experiments. This finding provides a possible explanation for the origin of several natural occurrences of anhydrite that cannot be satisfactorily explained by existing models and reveals a new precipitation pathway that may have industrial applications.</p><h2>Other Information</h2><p dir="ltr">Published in: Science of The Total Environment<br>License: <a href="http://creativecommons.org/licenses/by/4.0/" target="_blank">http://creativecommons.org/licenses/by/4.0/</a><br>See article on publisher's website: <a href="https://dx.doi.org/10.1016/j.scitotenv.2023.165820" target="_blank">https://dx.doi.org/10.1016/j.scitotenv.2023.165820</a></p> |
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