Woody plant willow function in river water protection

Abstract

The coastal area surrounding the Ibar river in the North of Kosovo and Metohija, in the region from Kosovska Mitrovica to Leposavić alone, is occupied with seven industrial waste dumps originated from the exploitation and flotation refinement of mineral raw materials, metallurgic refinement of concentrates, chemical industry, industrial refinement and energetic facilities of Trepča. The existing waste dumps, active and passive, are of heterogenic chemical composition. They show its impact onto the river water by the content of heavy metals found in it. Removal of lead, cadmium and zinc, regardless to the any known technology, would be economically unrewarding. The prevailing wooden plant in this area is the white willow. This work is focused on removal of heavy metals (Pb, Cd and Zn) from the water of river Ibar using the white willow. Roots of the willow are cultivated using the method of water cultures in individual solution of heavy metals and sample of the river water. The preparation of the samples for analysis was performed by burning the herbal material and dissolving the ash in the appropriate acids. The concentrations of metals were being determined by stripping analysis. In the investigated solutions of heavy metals, the increase of biomass was 25.6% in the lead solution, 27.3% in cadmium and 30.7% in the zinc solution. The increase of biomass in the nutritional solution, without heavy metals, was 32.4% and in sample river water 27.5%. Coefficient of bioaccumulation in solutions with heavy metals was: 1.6% in lead solution, 1.9% in cadmium and 2.2% in zinc solution. Accumulated amounts of the metals from the tested samples were: 18.74 μg of lead, 20.09 μg of cadmium and 22.89 μg of zinc. The coefficient of bioaccumulation of the water samples which contained 44.83 μg/dm3 of lead, 29.21 μg/dm3 of cadmium and 434.00 μg/dm3 of zinc, during 45 days period, was 30.3% for lead, 53.4% for cadmium and 3.9% for zinc. The concentrations of accumulated metals from the river water were 19.01 μg of lead, 21.85 μg of cadmium and 23.96 μg of zinc in grams dry matter. The obtained results indicate that the willow might contribute to the decontamination of moderately contaminated river water from Pb, Cd and Zn.