Geochemical environment affected by acid mine drainage: a case study of trace and rare earth elements of Colorful Lakes in Wieściszowice (Western Sudetes Mts., Poland)
摘要
Acid mine drainage (AMD) is one of the most serious threats to aquatic environments in mining areas, leading to low pH, elevated SO42- and Fe concentrations, and enrichment in trace elements (TEs) and rare earth elements (REEs). This study investigates the geochemistry of TEs and REEs in one of the most AMD-impacted areas in Poland – the Colorful Lakes in Wieściszowice. These pit lakes, formed in abandoned pyrite open pits, include Blue, Yellow, Purple, and Green Lakes. Three lakes (Blue, Yellow, Purple) and the Rdzawy Potok stream feeding Blue Lake were examined. The results indicate that pH is the primary factor controlling the geochemistry of both TEs and REEs. Waters of Blue Lake and the Rdzawy Potok stream (pH > 5) show higher concentrations of TEs and REEs in bottom sediments and lower concentrations in the water column compared to Yellow and Purple Lakes (pH < 3). TEs such as As, Mo, Sb, Se, Li, and Tl are associated with the less acidic waters, whereas typical AMD-related elements (Cu, Zn, Ni, Cr, Co, Mn) dominate in highly acidic lakes. Maximum REE concentrations reached 382.0 µg/L in Purple Lake waters and 59.6 mg/kg in bottom sediments of the Rdzawy Potok stream. The Colorful Lakes are characterized by enrichment in HREEs and MREEs, positive Gd anomaly, and distinct Tb anomaly in bottom sediments, indicating fractionation processes. A positive Eu anomaly was observed in less acidic environments, whereas under acidic conditions they occurred in the sediments, suggesting relatively higher mobility of Eu in less acidic settings. These findings highlight the role of AMD-affected pit lakes as natural laboratories for understanding the geochemical behavior of TEs and REEs in water–sediment systems.