Investigations of sediments of backwater of river Drau for heavy metals

9 samples of sediments which were taken in August 1978 from reservoir of river Drau were analysed for zinc, manganese, arsenic by neutron activation analyses and for mercury, cadmium and lead by atomic absorption spectrometry. The concentration values found for Zn ranged between 157,2 to 7424, 2 ppm, for Mn between 230 to 527,5 ppm, for As between 6 to 96 ppm, for Hg between 0,05 to 0,35 ppm, for Cd between 1 to 21 ppm and for Pb between 69 to 1180,5 ppm. A comparison of the results with tolerance limits in the literature show, that Zn values at two points along the river (Highwaybridge Villach, right side of river and at the railwaybridge St. Ulrich) as well as Pb in the Area of Rosegger reservoir and Ferlacher reservoir are critical. (author)