Seminar Alice Pradel

Abstract

The emission of contaminants to the environment is rapidly increasing, both in quantity and diversity. Aquatic systems represent particularly vulnerable compartments that must be protected urgently to reduce the exposure of living organisms. In the hydrosphere, a significant fraction of contaminants occurs in the colloidal size-range (~ 1 nm to 1 um) as nanoparticles or dissolved contaminants associated with natural colloids. Despite being highly mobile and bioaccessible, exposure to colloidal contaminants is poorly constrained since they are seldom quantified in the environment and their environmental fate remains complex to predict. To address this scientific challenge, my work investigates the transport, retention and transformations of colloidal contaminants in porous media. Indeed, porous media control the behavior of colloids due to their characteristic variations in hydrodynamic and physicochemical conditions. First, I will present the mechanism of retention of plastic fragments in a system that mimicks the pore-scale conditions of terrestrial porous media. Second, we will turn to sea ice – a lesser-known porous media whose porosity depends on water temperature and turbulence – to examine the fate of contaminants across the entire size continuum (dissolved, colloidal, and particulate) and to elucidate the size-dependence of their incorporation mechanisms. Finally, the talk will explore how porous media can be used to improve sampling and remediation of colloidal contaminants.