The Caribou gold-mining areas in Nova Scotia, Canada were in full production from 1869 to 1927. Abandoned waste rocks and fine-grained tailings from Hg-amalgamation processes have weathered into Long Lake, part of the Moose River system. Metal burdens in tailings and lake sediments, as well as the biological community structure above and below the processing site, were investigated. Surface tailings were found to contain (in μ g g−1): As (5000–28 000), Cd (0.1–0.6), Cu (6–37), Mn (50–600), Ni (600–2000), Hg (0.3–0.7), Pb (70–120), Tl (0.03–0.06), V (3–10) and Zn (20–100). Lake sediments below the tailing field were found to be highly enriched with As, Ni, Pb and, to a lesser extent, Hg, Cu and Mn. Air–surface exchange from tailings (preliminary results, 48 h cycle) exhibit Hg-flux rates from 20 to >100 times greater than those of natural soils in Nova Scotia. Stream water and sediments below the mine were toxic to the benthic community.
- © 2002 AAG/The Geological Society of London