2026/01/12 by Dídac Navarro-Ciurana, Laura Culí, Clara Torrentó +3 · 1 voice
Environmental Science · Engineering · #Mine drainage and remediation techniques #Tailings Management and Properties #Mining and Resource Management
paper · doi:10.1016/j.gsd.2026.101581
openalex publication_date 2026/01/12 · openalex created_date 2026/01/13 · openalex updated_date 2026/08/01
Sustainable water management in porphyry copper tailings storage facilities (TSFs) is essential for environmental protection and regulatory compliance, particularly in Chile, which ranks third globally in TSF numbers. This study applies a multi-isotope framework ( δ 2 H-H 2 O, δ 18 O-H 2 O , δ 34 S-SO 4 2− and δ 18 O-SO 4 2− ) to trace the fate of tailings seepage towards groundwater and to evaluate hydraulic barriers effectiveness in porphyry Cu TSFs, demonstrating its applicability to systems characterized by complex mixing of multiple water sources with contrasting recharge conditions. Unlike previous studies where water sources shared similar recharge altitudes, this work addresses an “altitude-offset” scenario in which tailings water originates from high-altitude recharge zones while downstream aquifers are located at much lower elevations, creating additional isotopic end-members. To illustrate the usefulness of this approach, the Carén TSF (Chile) serves as case study. Isotopic data indicate that tailings waters are strongly evaporated, enriched in elevated SO 4 2− concentrations on the order of thousands of mg L −1 (≈2,000 mg L −1 ), mainly derived from sulfide ore oxidation (60-80 %), and recharged at high altitude (∼2,000 masl). In contrast, surrounding freshwater is recharged at lower altitude (∼220 masl) and shows significantly lower SO 4 2− concentrations on the order of tens of mg L −1 (≈20 mg L −1 ). Groundwater downstream of the TSF reflects variable mixing between these sources. Using Cl - /SO 4 2- , δ 2 H-H 2 O/ δ 18 O-H 2 O, δ 34 S-SO 4 2- / δ 18 O-SO 4 2- , δ 34 S-SO 4 2- /ln(SO 4 2- ) mixing models, the contribution of mine tailing water was quantified to be generally lower than 20% but reaching 30-40% in some groundwater samples located close to the TSF. In addition, δ 34 S-SO 4 2- and δ 18 O-SO 4 2- results suggest that bacterial sulfate reduction may occur in deeper zones of the TSF, promoting natural attenuation of dissolved metals. These findings highlight the usefulness of stable isotopes for tracing water sources, assessing hydraulic barrier efficiency, and estimating the proportion of pumped water exempt from water rights in TSFs. • δ 2 H- δ 18 O-H 2 O and δ 34 S- δ 18 O-SO 4 2- are effective tools to trace mine tailings seepage. • Stable isotopes provide a tool to evaluate the effectiveness of hydraulic barriers. • Multi-isotope approaches support the quantification of groundwater rights. • Isotope tools support site-specific strategies for sustainable mine water management. • This new approach has been fruitfully applied in the Carén tailing dam (Chile).