Ecotoxicological Tests of Metal-Contaminated Soils

The raw steel production plays a key role in the economic development of Slovakia. Unfortunately, the technology of steel production, agricultural and industrial activities contribute to contamination of the soil in the region Eastern Slovakia. The purpose of this study was to investigate the effect of heavy metals in urban soils from the Košice area, using bioassays on earthworms and phytotoxicity. An earthworm avoidance test has potential advantages for use in evaluation of hazardous soils sites and proved as a quick approach to determining the presence of contaminants. The earthworm (Dendrobaena veneta) takes up and retains metals from soil containing of heavy metals. Assessment of soil phytotoxicity was based on germination and seedling growth of the terrestrial plant (mustard Sinapis alba). The level of Cr, Co, Cd and Hg were assessed in 8 industrial soils (4 agricultural areas and 4 grass-plot areas) from the area U.S. Steel Košice. The highest levels contaminations of chromium (278mg/kg), cobalt (39mg/kg), cadmium (21mg/kg) and mercury (0.80mg/kg) were determined for the grass-plot soils (main gate of the U. S. Steel-plant). Phytotoxkit results for the agricultural soils from around Košice showed that, the potential toxicity values are lowly, represented by a lower percentage of inhibition in germination range between 5 and 33 % and the average percentage of growth inhibition was 12-39 % for Sinapis alba. The results for the grass-plot areas soils from around Košice showed the percentage of inhibition in germination range between 13 and 47 % and the average percentage of growth inhibition was 19-49 % for Sinapis alba. Low mortality effects were recorded in the tests with Dendronaena veneta. The distribution of the worms found in the double control was within the range 10–100 % for all areas of the agricultural soils and grass-plot soils, for after 48h. The significant (P<0.05) avoidance by Dendronaena veneta were 100% in soils of areas Gomboš and from main gate of the U. S. Steel-plant, Košice. The above results reflect that not only may the worms be able to detect metals, but in fact they may also change their behavioural response over time.