Trace Element Transfer and Distribution in the Rock-Soil-Plant System: La Oriental Mine, Uruguay

The study of systems associated with mining activities is essential to understand the transfer of trace elements from the lithosphere to the biota. This research evaluated the origin and availability of metals in the Mina La Oriental area, in Uruguay. Rock and soil samples were collected from waste rock dumps and control sites, alongside specimens of Plantago brasiliensis, Nierembergia ericoides, and Blepharocalyx salicifolius. Results suggest that the high concentration of trace elements in soils derives from materials accumulated due to base metal mining (Cu, Pb, Zn), showing a heterogeneous distribution where Pb exhibits a lithogenic dominance associated with these waste structures. Extreme enrichment factors (EF > 40) were recorded throughout the area, exceeding the natural geochemical baseline even in locations distant from the dumps. Regarding vegetation, metal transfer was regulated by species identity: P. brasiliensis acted as an Al and Pb accumulator, whereas B. salicifolius exhibited an excluder behavior driven by effective root barriers. Meanwhile, N. ericoides showed intermediate transfer levels dependent on soil availability. Finally, cation exchange capacity, pH, and organic matter content were determined to be the primary geochemical controls of metal mobility. These findings allow for the characterization of retention mechanisms in a mining-impacted system, providing key data for the management of environmental liabilities.