The early diagenesis of submerged sulphide-rich mine tailings in Anderson Lake, Manitoba
The oxidation of sulphide-rich mine tailings stored on land by acidophilic bacteria is frequently associated with severe environmental degradation, as metal-rich acid drainage from the tailings contaminates groundwater and surface runoff. Permanent storage of tailings underwater may prove to be more chemically benign if oxidation is inhibited sufficiently. To assess this possibility, the chemistry of interstitial waters and the associated solid phases in tailings and organic-rich (20–30 wt.% C) natural sediments in Anderson Lake, Manitoba, is examined. The lake has been used as a receiving basin for sulphide-rich tailings since 1979, and is contaminated with metals as a result of the input of acid mine drainage along the north shore and the discharge of mill process water with the tailings. Three cores were collected and processed under nitrogen to extract interstitial waters. At all sites, the occurrence of high concentrations of dissolved iron in shallow pore waters indicates that the deposits are anoxi...