METAL SPECIES INDICATE THE POTENTIAL OF CONSTRUCTED WETLANDS FOR LONG-TERM TREATMENT OF METAL MINE DRAINAGE

Experimental peat-based wetlands at the former Bell Copper Mine (Smith ers, B.C., Canada) removed copper from low strength (0.3-1.0 ppm, pH 6 -8) and high strength (35-50 ppm, pH 3) copper-contaminated mine drain age. Copper species retained in wetlands sediments were quantified as a means to assess the long-term potential of these wetlands for treati ng mine drainage. Previous microbial and chemical analyses had indicat ed that sulphide was biologically generated in these wetlands, and min eralogical analysis confirmed that copper sulphides were present in we tland sediments. However, sequential leaching of these sediments showe d that copper was predominantly in organically-bound and oxide-bound p hases, with a smaller proportion present as sulphides. The available d ata suggest that much of the copper was retained as sulphides when low strength mine drainage was applied to the wetlands.