Prediction of a modern gold mine's contaminant dispersion and deposition in a river mixing zone

Abstract

Study site: Placer Dome Canada's Musselwhite Mine near Pickle Lake Ontario.

A predictive spatial model of contaminant dispersion and deposition was produced for the river mixing zone of Placer Dome Canada’s Musselwhite Mine. Discriminant analysis classified water and sediment quality into three groups based upon seven parameters; total aluminum, total zinc, total copper, total iron, nitrate, sulphate, and pH at three depths. The first group consisted of three sites situated immediately outside of the mine’s outfall, and was characterized by high mean discriminant function scores used to describe both water and sediment. The second and third groups consisted of the remainder of sites downstream and the control sites respectively, and were characterized by relatively lower scores in the water and sediment. Spatial predictions of contaminant dispersion and deposition, based upon the regression of discriminant function score to effluent tracer measurements taken at sampling sites, delineated an area of lower water and sediment quality within the vicinity of outfall. The effluent-receiving water body, within a minimum mixing length of 300 m, was found to be capable of diluting all parameters identified as being significantly higher at point of outfall to concentrations that were not significantly different from those found upstream of discharge. Parameters of current or potential environmental concern in the mine’s effluent mixing zone were also identified in this study.