Temporal Trends of Heavy Metals and Geochemical Parameters in Ramura 1, 2, 3 and 4 Petrila Tailings Dump

Abstract Mining activities in the Jiu Valley coal basin have generated substantial volumes of waste materials, and Ramura 1, 2, 3 and 4 tailings dump in the Petrila area represents a continuously evolving geochemical system. This study examines the temporal trends of heavy metals (Cr(total), Cu, Ni, Zn, Co, Pb) and associated geochemical parameters (pH, Eh, moisture, organic matter, electrical conductivity) over the 2022–2024 period, using standardised determinations and year-to-year comparative analysis. The results indicate progressive increases in Cr (total), Cu and Ni (3–7% annually), while Zn remains consistently elevated but relatively stable. Geochemical parameters reveal gradual acidification (pH 6.72 → 6.31) and increasingly oxidising conditions (Eh 312 → 342 mV), both favouring the mobilisation of redox-sensitive metals. Comparison with Romanian Regulation Order 756/1997 shows no exceedance of intervention thresholds; however, several metals surpass normal values or approach alert thresholds. Overall, the findings confirm the dynamic nature of Ramura 1–4 tailings dump and highlight the need for continued long-term monitoring to assess environmental risks and to support informed post-mining management strategies.