THE EFFECT OF SUB-AQUEOUS DISPOSAL OF MINE TAILINGS IN STANDING WATERS

Field observations provided the basis for a numerical model designed t o quantify the vertical mass flux of material initially injected at th e base of the water column in a small lake; a process called sub-aqueo us disposal. Eddy diffusion estimation largely controlled the transpor t behaviour, highlighting the need for measurements of diffusion in de ep strongly stratified environments. The model followed the contaminan t development over 40 years and showed that (i) it is unlikely that an y material can ever be completely disposed of over realistic scales an d (ii) within the bounds limited by uncertainty in eddy diffusivity, t urnover penetration and surface layer precipitation-driven flushing ar e the mechanisms most likely to have bearing on the contaminant distri bution.