Abstract
Rare Earth Elements (REE) have emerged as contaminants in surface waters, groundwater, and soils due to their widespread use in modern technologies. The distinct patterns arising from subtle chemical differences within the 14-element series, alongside analogous metals (Sc, Y, Th, U), serve as tracers for hydrobiogeochemical processes. This study aims at elucidating the joint role of REE adsorption onto environmental minerals, and flow conditions, on REE pattern variability in porous media. By combining batch and column experiments with mechanistic modeling approaches at molecular and macroscopic scales, it was revealed that the mobility of REE can be strongly affected by environmental minerals under various conditions, with sand as immobile soil phase and/or colloids as the mobile phase. Results showed that REE adsorption patterns can probe surface site heterogeneity and the occurrence of kinetically limited processes in aqueous vs colloidal transport. This work will help in understanding multiscale chemical and physical heterogeneities for accurately predicting the migration and transport of REE in geochemical settings.
