Stochastic assessment of calcite dissolution rates from microscale imaging through Atomic Force Microscopy

Department of Hydrology and Atmospheric Sciences
 
* SPECIAL TIME * 10:00 am on Thursday, March 3, 2022
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Alberto Guadagnini
HAS Adjunct Professor & Professor and Director/Dept Head, Department of Civil and Environmental Engineering, Politecnico di Milano

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.

Bio

Alberto Guadagnini has been Full Professor of Hydraulic Engineering at Politecnico di Milano since 2003 and Director of the Department of Civil and Environmental Engineering since 2017. He is also an Adjunct Professor with the Department of Hydrology and Atmospheric Sciences of the University of Arizona (USA). His primary research activities are focused on the qualitative and quantitative aspects of groundwater systems and underground energy resources at diverse scales and under various sources of uncertainty. He has more than 190 ISI publications with an h-index(SCOPUS) = 38. Other professional highlights include key roles in EU framework projects (FP5-FP7, H2020: Coordinator, Deputy Coordinator, Project leader, Supervisory Board member) and PI of numerous research projects funded by the industrial sector. He is Chair of the Communication Committee of the International Society for Porous Media (Interpore), Chair of the Committee on Groundwater Hydraulics and Management of the International Association for Hydro-Environment Engineering and Research (IAHR), Chief Executive Editor of the Journal, Hydrology and Earth System Sciences (EGU) and Associate Editor of the Journals, Water Resources Research (AGU) and Stochastic Environmental Research and Risk Assessment. Guadagnini was the recipient of the Chaire Gutenberg and Prix Gutenberg in 2018, an award by Cercle Gutenberg and Région Grand-Est, France, for research on climate change and the water cycle in the Upper Rhine Basin. He became an elected member of the European Academy of Sciences and Arts in 2021.