Strategic Elements in Holocene Sediments of the Tinto River Estuary (SW Spain)

Abstract

River mouths act as containers for pollution episodes that have occurred in their drainage basins over time. The estuary of the Tinto River is currently one of the most polluted areas in the world, due to past and recent mining and industrial activities. This communication studies the concentrations of seven strategic minerals in a sediment core obtained in the middle estuary of this river. The Holocene geochemical record has allowed us to distinguish four episodes of contamination: an initial one due to acid rock drainage during the MIS-1 transgression and three anthropogenic ones due to the first mining activities, the Roman period, and the industrial mining stages of the 19th and 20th centuries. The concentrations of these strategic minerals increase from the first episode to the fourth. A first evaluation of the concentrations obtained in this core and adjacent pre-Holocene formations reveals that they are too low to consider these sediments ore deposits of the seven elements studied.