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(19-26) Biomonitoring of Rivers in Rural Regions of Northern Bavaria. Velasco, Cristina*,1, Frank, Hartmut1, 1 Environmental Chemistry and Ecotoxicology, University of Bayreuth;, Bayreuth, Germany ABSTRACT- Surface waters contain xenochemicals of industrial, agricultural or/and domestic origin. Concentrations are often below the acute toxicity level and many relevant components are actually unknown. Biossay-directed chromatography is an attempt to identify the ecotoxicologically most problematic constituents of complex mixtures in surface or waste water. In this work, rivers of two rural regions of Northern Bavaria were monitored by chromatographic analysis, especially LC-MS/MS. Water samples were taken along the rivers from the spring to their mouth, in order to determine whether there is a dependency of sampling site, season of the year, or concentrations of herbicides in relation to observed effects. The medium-polar to polar organic compounds were concentrated by solid phase extraction of neutral and acidified sample aliquots. Besides Atrazine and Desethylatrazine, Metolachlor, Metazachlor and Isoproturon could be detected by LC-MS/MS in the ng/L range. A miniaturized algal test and the MicrotoxTM-test were applied, especially the former allowing a high sample throughput. The two biotests were performed in parallel to give information about the toxic potential of the organic xenochemicals in the sample extracts. The effects were studied at 100-fold enrichment, resulting in high toxicity in some cases, especially of the acid fraction. It was observed that the acid fractions of the rivers from forrested regions had a particularly strong effect in the MicrotoxTM-test. However, a significant correlation to pesticide concentrations was not found, indicating that other unknown but toxic xenochemicals are carrying high relevance. Key words: surface waters, microtox test, herbicides, algal test |
