Fingerprinting Acid Mine Drainage in Wet-dry Tropical Climates using Stable Isotope Approach: An Example from Queensland, Australia

摘要

Mine water fingerprinting and sulfate stable isotope geochemistry can provide strong support for acid mine drainage (AMD) management. This study was conducted at a mine site in a semi-arid tropical climate of North East Queensland region using various techniques including water geochemical fingerprinting and stable isotope geochemistry of waters and sulfate-sulfur. It aims to investigate the connectivity between surface and ground water, and between mine water and the local stream system. Mine water geochemical fingerprinting techniques have indicated that AMD-affected waters were locally found near waste rock dumps, heap leach stockpiles and mill rejects. The effects of AMD on creek waters were limited by neutralizing capacity. Stable isotope compositions of waters revealed that mine waters showed some degree of evaporation, particularly tailing sumps in dry season, compared to rainwater, stream and ground waters. Stable isotope geochemistry of sulfate-sulfur has identified two distinct sources of sulfate including i) upstream background sulfate and ii) mine-related sulfate from sulfide oxidation at the site that contributed to creeks flowing across the site. The characterization of water connectivity and sources of sulfate could therefore, give important information on localities of AMD occurrences and relative effects on natural stream systems for management purposes.