CARATTERIZZAZIONE DELLA QUALITA’ DEI CORSI D’ACQUA SUPERFICIALI MEDIANTE SAGGI MULTISPECIE

Silvia Castiglioni*°, Elisa Di Gioia*, Corrado L. Galli°, Maria Rosa Lovati*° Università degli Studi di Milano, *Lab. Tossicologia Ambientale, via S. Francesco 13-26900 Lodi, °Dip. di Scienze Farmacologiche, via Balzaretti 9-20133 Milano

The ecotoxicological characterization of surface watercourses, using Daphnia magna crustacean, has been requested by the Italian D.Lgs 152/06 in order to evaluate the potential synergism between the different pollutants present in the aquatic environment, even if their concentrations do not individually exceed the surface water quality standards. In these terms, biological assays play an important role in the assessment of the real/potential impact of anthropogenic agents on the natural sphere, since they represent a powerful method that quickly supplies information on the global effect on a living being of pollutants present in the environment. For a better evaluation of the quality of some Po Valley rivers (water/sediment), a "battery of tests", using species belonging to different trophic level, was selected as below reported: 
- Non-pathogen bacteria Vibrio fischeri, end point: evaluation of spontaneous bioluminescence inhibition (acute test); 
- Planctonic crustacean Daphnia magna, end point: examination of motility inhibition (acute test); 
- Green alga Pseudokirchneriella subcapitata, end point: evaluation of growth inhibition (sub-chronic test). 
- Seeds of Lepidium sativum, Cucumis sativus and Sorghum saccharatum, end point: germination and radix extension inhibition (sub-chronic test); 
- Benthonic crustacean Heterocypris incongruens, end points: mortality and growth inhibition (chronic test). The data obtained pointed out the difficulty to find a condition of pollution in the surface water, except the case of abusive spill out, able to cause an effect detectable in a short time of contact with the biomarkers tested in the present study. On the other hand, these biological tests are an useful tool to detect the potential toxicity present in the sediments, since they represent the historical memory of the anthropogenic activities, acting as bio-accumulators of polluting substances.