Ecological effects of mine effluents on the South Esk River, north-eastern Tasmania. II. Trace metals

Abstract

Concentrations of manganese, iron. cadmium, zinc, copper and lead in sediments and in the water column of the South Esk River, Tasmania, were measured. Manganese and iron concentrations were shown to be independent of the mine effluents. The natural background levels of cadmium. zinc, copper and lead were found to be very low or below detection limits. In the stretch of river up to 130 km below a source of contamination, the concentrations of these four metals in the sediments, associated with the non-filterable residue, and in solution were all well above the natural background leveis. The facrors controlling the concentrations of cadmium, zinc, copper and lead in the sediments are not clear; however, sediment type appears to be important. The concentrations of cadmium and zinc in solution were inversely related to the distance from the source ofcontamination, whereas the concentrations of copper and lead in solution and of all four metals associated with the non-filterable residue did not vary significantly. Most of the metal-load carried to the South Esk River by Storys Creek is probably in solution rather than in other fractions.