SEDIMENT-TRAP EVALUATION OF MINE TAILINGS TRANSPORT

Mine tailings from an open-pit molybdenum mine were discharged at 50 m depth to Alice Arm, B.C., Canada, during 1981-1982. We report here th e results of a sediment-trap survey to determine the scale of transpor t of suspended tailings within the fjord. Tailings clearly affect the particle fluxes in the deeper water of Alice Arm out to a distance of about 12-14 km, as demonstrated by increased particle fluxes and enric hment of these particles in heavy metals (Cd, Zn, Pb). However the dis posal strategy appears to have been effective in trapping suspended ta ilings within Alice Arm; there was no evidence of tailings entering su rface water or escaping the inlet Three months after the mine closed p article fluxes in Alice Arm dropped to natural or near-natural levels Natural inorganic particle delivery is also recorded in the traps as s easonal pulses from rivers draining into the head and sides of the arm .