Strontium (Sr) is ubiquitous in groundwater, surface water, and in some soils and is often incorporated into the crystal structure of minerals, such as calcite (CaCO<sub>3</sub>), through ion substitution of strontium for calcium in the crystal structure. Understanding the mechanisms of impurity incorporation is necessary to predict the long term stability of calcite in the environment, such as for contaminant sequestration, and could help refine crystal growth and dissolution models. Strontium is known to act as an inhibitor of calcite growth and the growth rate of calcite correlates with the strontium to calcium ratio of the solution in which growth occurs. This finding implies that growth inhibition by strontium arises from the presence of strontium prohibiting calcium ions from attaching, either through a kinetic kink site blocking process or a thermodynamic process that affects solubility. Here, we grew samples with strontium incorporated in calcite overgrowths and reacted them in undersaturated solutions to examine the stability of strontium-rich calcite as compared to pure calcite. Dissolution rates for strontium rich calcite in deionized water are an order of magnitude slower than the dissolution rates observed for pure calcite in deionized water. In addition, the shape of the etch pits that form on calcite during dissolution are triangular shaped and elongated perpendicular to the c-glide plane, rather than the typical rhombohedral shape observed on pure calcite. These results can be attributed to the presence of strontium affecting the net detachment rate at kink sites. Together, these observations suggest that the incorporated strontium ions may either have a slower detachment rate than calcium ions or their presence affects detachment of calcium and carbonate ions. The gradual dissolution of strontium rich calcite is crucial to remediation efforts. When metals like strontium are locked into a mineral structure, they are immobilized and cannot be transported, thereby limiting exposure.

Effect of strontium (Sr) on calcite (CaCO<sub>3</sub>) dissolution

Macromolecular Chemistry: The Second Century

[Author Benefits](https://scimeetings.acs.org/?utm_source=pubs_content_marketing&utm_medium=website&utm_campaign=0320_MCF_NPI_Launch_Spring_Homepage&ref=pubs_content_marketing)

[How to use SciMeetings](https://storage.googleapis.com/dl.morressier.com/acs/SciMeetings-ACSSpring2020-HowToGuide_M3020-Final.pdf)

[Frequently Asked Questions](https://storage.googleapis.com/dl.morressier.com/acs/SciMtng_ACSNMSp2020_FAQ_M3120_Final.pdf)

ACS Spring 2020 National Meeting & Expo

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.

Effect of strontium (Sr) on calcite (CaCO3) dissolution

Effect of strontium (Sr) on calcite (CaCO₃) dissolution