Today at 18.00 CET live on Zoom the Director of the Civil and Environmental Engineering Department, Alberto Guadagnini, will hold the seminar, organized by the Department di Hydrology & Atmospheric Sciences della University of Arizona, titled “Stochastic assessment of calcite dissolution rates from micro-scale imaging through Atomic Force Microscopy”.

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Abstract:
We investigate the main traits of the spatial heterogeneity of dissolution rates that are directly observed through Atomic Force Microscopy on the surface of a millimeter-scale calcite sample in contact with deionized water. Our analyses are framed within a stochastic approach and are motivated from the observation that detailed characterizations of mineral dissolution/precipitation rates is critical in the context of a variety of applications including, e.g., aquifer contamination assessment, geologic carbon sequestration, or hydraulic fracturing of hydrocarbon reservoirs. Experimental evidences based on instruments such as Atomic Force Microscopy (AFM) and Vertical Scanning Interferometry (VSI) enable direct observations of the mechanisms taking place across the mineral surface during the reaction and constitute a key information basis for interpretive modeling efforts. In this context, the dissolution process is evidenced to be strongly affected by several sources of variability at the local (i.e., micro-scale) mineral-fluid interface and a marked spatial heterogeneity in the dissolution rate is documented. In this general framework, we collect datasets of surface topography at several observation times from which reaction rate maps are evaluated. The study is aimed at (1) characterizing the statistical behavior of dissolution rates and their spatial increments within a unique and consistent theoretical framework; (2) identifying an appropriate interpretive model for such statistics; and (3) evaluating quantitatively, through observed trends of model parameters, the temporal evolution of the spatial heterogeneity of the dissolution reaction.