TY - JOUR
T1 - Quantifying the potential seepage from porphyry copper tailing impoundments using a multi-isotopic approach
AU - Navarro-Ciurana, Dídac
AU - Saleta-Daví, Agnés
AU - Otero, Neus
AU - Torrentó, Clara
AU - Quintana-Sotomayor, Carlos
AU - Miguel-Cornejo, Diego San
AU - Musalem-Jara, Mónica
AU - Novoa-Godoy, Gullibert
AU - Carrasco-Jaramillo, Cristóbal
AU - Aguirre-Dueñas, Evelyn
AU - Escudero-Vargas, Manuel A.
AU - Soler, Albert
N1 - Publisher Copyright:
© 2023 The Authors
PY - 2023/9/10
Y1 - 2023/9/10
N2 - Porphyry-style copper deposits are characterized by low Cu grades and high tonnages, resulting in large mine tailing volumes disposed in impoundments. Due to the mining tailing sizes, waterproofing techniques cannot be applied along the dam base. Therefore, to minimize seepage towards the aquifers, pumping wells are usually installed as hydraulic barriers. Currently, there is a controversy over whether or not the water extracted from hydraulic barriers should be counted as the use of new water rights. Consequently, a growing interest to develop tools to trace and quantify the tailing impacts in groundwater and to determine the water pumped amount subjected to water rights exist. In the present study, isotope data (δ2H-H2O, δ18O-H2O, δ34S-SO42− and δ18O-SO42−) are proposed as a tool to quantify tailings seepage towards groundwater and to assess hydraulic barriers effectiveness. To illustrate this approach usefulness, the Quillayes porphyry Cu tailing impoundment (Chile) case study is presented. The multi-isotopic approach revealed that tailing waters are highly evaporated showing high SO42− content (~1900 mg L−1) derived from primary sulfate ore dissolution, whereas freshwaters, derived from recharge water, have low SO42− contents (10–400 mg L−1) resulting from the interaction with geogenic sulfides from barren host rock. The δ2H and δ18O values of groundwater samples collected downstream from the impoundment suggest a mixing at different proportions of highly evaporated water from the mine tailing waters and non-evaporated regional fresh groundwater. Cl−/SO42−, δ34S-SO42−/δ18O-SO42−, δ34S-SO42−/ln(SO42−) and δ2H-H2O/δ18O-H2O mixing models allowed to determine that groundwater located closer to the impoundment had a mine tailing water contribution from 45 to 90 %, whereas those located farther away had lower contribution (5–25 %). Results confirmed the stable isotope usefulness to determine the water origin and to calculate the hydraulic barrier efficiencies and the pumped water proportions unrelated to the mining tailing subject to the water rights.
AB - Porphyry-style copper deposits are characterized by low Cu grades and high tonnages, resulting in large mine tailing volumes disposed in impoundments. Due to the mining tailing sizes, waterproofing techniques cannot be applied along the dam base. Therefore, to minimize seepage towards the aquifers, pumping wells are usually installed as hydraulic barriers. Currently, there is a controversy over whether or not the water extracted from hydraulic barriers should be counted as the use of new water rights. Consequently, a growing interest to develop tools to trace and quantify the tailing impacts in groundwater and to determine the water pumped amount subjected to water rights exist. In the present study, isotope data (δ2H-H2O, δ18O-H2O, δ34S-SO42− and δ18O-SO42−) are proposed as a tool to quantify tailings seepage towards groundwater and to assess hydraulic barriers effectiveness. To illustrate this approach usefulness, the Quillayes porphyry Cu tailing impoundment (Chile) case study is presented. The multi-isotopic approach revealed that tailing waters are highly evaporated showing high SO42− content (~1900 mg L−1) derived from primary sulfate ore dissolution, whereas freshwaters, derived from recharge water, have low SO42− contents (10–400 mg L−1) resulting from the interaction with geogenic sulfides from barren host rock. The δ2H and δ18O values of groundwater samples collected downstream from the impoundment suggest a mixing at different proportions of highly evaporated water from the mine tailing waters and non-evaporated regional fresh groundwater. Cl−/SO42−, δ34S-SO42−/δ18O-SO42−, δ34S-SO42−/ln(SO42−) and δ2H-H2O/δ18O-H2O mixing models allowed to determine that groundwater located closer to the impoundment had a mine tailing water contribution from 45 to 90 %, whereas those located farther away had lower contribution (5–25 %). Results confirmed the stable isotope usefulness to determine the water origin and to calculate the hydraulic barrier efficiencies and the pumped water proportions unrelated to the mining tailing subject to the water rights.
KW - Chilean mining tailings
KW - Hydraulic barrier effectiveness
KW - Multi-isotopic approach
KW - Tailing water quantification
KW - Water management tool
KW - Water rights
UR - http://www.scopus.com/inward/record.url?scp=85160412642&partnerID=8YFLogxK
U2 - 10.1016/j.scitotenv.2023.164446
DO - 10.1016/j.scitotenv.2023.164446
M3 - Article
C2 - 37236441
AN - SCOPUS:85160412642
SN - 0048-9697
VL - 890
JO - Science of the total environment
JF - Science of the total environment
M1 - 164446
ER -