• Tidal-fluvial interplay governs mining contaminant dynamics in the Huelva estuary. • High river flow enhances contaminant fluxes and export potential to the Atlantic Ocean. • Fe and Al precipitate during mixing, scavenging Cu and Pb into particles. • Zn, Cd, Mn, Co and Ni remain largely mobile during estuarine mixing. • As is first adsorbed to particles, then desorbs at pH > 6, becoming fully mobile.
Sánchez-López et al. (2026) studied this question.