Discriminating between historical sources of solutes in the Robinson Mining District, Ely, Nevada

To elucidate potential solute fate and transport along groundwater pathways resulting from historical mining practices in the Robinson Mining District, Nevada, discrimination between background waters and mine-affected waters (i.e., pit lakes, a tailings pond, and waste-rock seeps) was necessary. Standard approaches such as Piper diagrams failed to provide sufficient discriminatory power. Hence, selected pit-lake, waste-rock seep, surface-water, and groundwater samples were analyzed for major, minor, and trace elements, rare earth elements (REEs), precious metals, and stable isotopes ( 16 O/ 18 O and D/H). The latter distinguished three classes of water: background waters contained barium above 10 µg/L, waste-rock seeps contained high scandium contents, and pit lakes contained high rhenium and rubidium contents. Because these elements are conservative tracers in groundwater, they proved useful in discriminating between sources. A quaternary plot based on barium, scandium, rhenium, and rubidium proved effective at differentiating between background and potentially mine-affected waters.