A river runs through it: impact of acid mine drainage on the geochemistry of West Little Sugar Creek pre- and post-reclamation at the Green Valley coal mine, Indiana, USA

Acid mine drainage (AMD) associated with coal waste material at the abandoned Green Valley mine in Indiana discharges into West Little Sugar Creek, a nearby steam. The acidic effluent and mixed stream water carry elevated SO4, Fe3+, Al, Fe2+, Ca, Mg, Na, Cl, Mn, K, Si, Zn, Ni, Pb, Cd, V, Be, and Cr, with several of these contaminants exceeding local and/or national surface water quality standards. Iron- and aluminum-dominated precipitates form on site and in the mixing zone and contain high concentrations of major and trace elements, suggesting that many of these constituents partition into the solid phase. Phase stability relationships indicate ferrous iron sulfate aqueous species are in equilibrium with melanterite and goethite. Despite past reclamation efforts, as well as natural metal removal associated with formation of AMD-related precipitates, poor stream water quality persists and presents an ongoing threat to the aquatic ecosystem.