Soil chemical analysis are not sufficient to assess environmental risk posed by contaminated soils and to verify the efficiency of clean up techniques. Ecotoxicological approach can help to overcome this problem. In this study the surface layer (30 cm) of a soil characterized by heavy metal and hydrocarbon contamination was collected in a disused industrial area near Naples (Italy). The soil sample was added with diesel oil and used for a micro-scale bioremediation experiment. Toxicity temporal modifications of the soil slurry, that is contaminated soil plus a mineral medium, were monitored. Toxicity test batteries based on organisms belonging to different trophic levels were performed to assess the effects due to total and soluble/insoluble soil pollutants. Toxicity tests with luminescent bacterium Vibrio fischeri and ostra-cod Heterocypris incongruens were carried on slurry solid phase. V. fischeri, green alga Selenastrum capricornutum and cladoceran Daphnia magna tests were carried on slurry liquid phase and organic extract. Test batteries were applied at zero, 14 and 42 days of the bioremediation process. The toxicity of slurry solid phase and organic extract decreased at the end of the experiment only for V. fischeri test, while for liquid phase a toxicity reduction was observed for all used organisms. The toxicity decrease of contaminated soil well matched with the bioremediation process operated by the selected bacterial consortium. © by PSP Volume 19 - No 8b. 2010.

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