To assess this, we examine in this report the chemistry of interstitial waters and the associated solid phases in tailings and natural sediments in Anderson Lake, near Snow Lake, Manitoba. Anderson Lake has been used as a receiving basin for tailings since 1979.
Tailings are areally widespread in the lake, despite discharge being confined to the western side.
Three cores were collected in June 1990, and processed under nitrogen to extract interstitial waters. At all sites, dissolved iron measurements made on the pore water samples indicate that the deposits are anoxic at very shallow depths, within several millimetres of the sediment-water interface. High dissolved Zn, Cu and Pb concentrations in supernatant water confirm measurements made previously that Anderson Lake water is elevated with respect to these metals. The concentrations of all three elements decrease abruptly with depth in the cores at all three locations, however. Presumably, the metals are being precipitated as sulphide phases at shallow depths.