# Retraction of dissolution front in natural porous media **Authors:** Yi Yang (1), Stefan Bruns (1), Melania Rogowska (1), Sepideh S. Hakim, (1), J\"org U. Hammel (2), Susan L. S. Stipp (1), Henning O. S{\o}rensen (1), ((1) Nano-Science Center, Department of Chemistry, University of Copenhagen,, (2) Helmholtz-Zentrum Geesthacht, Germany) arXiv: 1704.01065 ยท 2018-05-09 ## TL;DR This paper reveals a surprising retraction of the dissolution front in natural porous media driven by infiltration instability, supported by real-time imaging and simulations, challenging existing assumptions in water-rock interaction studies. ## Contribution It uncovers the spontaneous migration of the dissolution front against flow pressure and links it to surface generation mechanisms, providing new insights into dissolution dynamics. ## Key findings - Dissolution front can spontaneously retract against flow pressure. - Surface generation significantly influences reactive surface area. - Flow-dependent surface dynamics reconcile field and lab reaction rate discrepancies. ## Abstract The dissolution of porous materials in a flow field shapes the morphologies of many geologic landscapes. Identifying the dissolution front, the interface between the reactive and the unreactive regions in a dissolving medium, is a prerequisite for studying dissolution kinetics. Despite its fundamental importance, the dynamics of a dissolution front in an evolving natural microstructure has never been reported. Here we show an unexpected spontaneous migration of the dissolution front against the pressure gradient of a flow field. This retraction stems from the infiltration instability induced surface generation, which can lead to a reactive surface dramatically greater than the ex situ geometric surface. The results are supported by a very good agreement between observations made with real time X-ray imaging and simulations based on static images of a rock determined by nanoCT. They both show that the in situ specific surface area of natural porous media is dependent on the flow field and reflects a balancing between surface generation and destruction. The reported dynamics challenge many long-held understanding of water-rock interactions and shed light on reconciling the discrepancies between field and laboratory measurements of reaction kinetics. --- Source: https://tomesphere.com/paper/1704.01065