The present disclosure is related to porous media with adjustable fluid permeabilities and related systems and methods. In certain cases, the fluid permeability of a porous medium can be adjusted by applying an electrical potential to the porous medium. In some such cases, the application of the electrical potential to the porous medium results in the deposition of material over or the removal of material from the porous medium. Also disclosed herein are systems and methods for capturing species (e.g., acid gases) in which porous media with adjustable fluid permeabilities are used, for example, to control the flow of fluid into and out of a medium used to capture the species.