Variability of pesticide exposure in a stream mesocosm system: macrophyte-dominated vs. non-vegetated sections |
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Authors: | Beketov Mikhail A Liess Matthias |
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Institution: | UFZ-Helmholtz Centre for Environmental Research, Department of System Ecotoxicology, Permoserstrasse 15, D-04318 Leipzig, Germany. mikhail.beketov@ufz.de |
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Abstract: | For flowing water bodies no information is available about patterns of contaminant distribution in flowing water compared to macrophyte-dominated structures. The aim of the study was to examine temporal dynamic and spatial cross-channel variability of pulse exposure of the insecticide thiacloprid in outdoor stream mesocosms. Two distinct cross-channel sections have been considered: macrophyte-dominated littoral and non-vegetated midstream. Median disappearance time ranged from 17 to 43 h (water phase, midstream). We showed that during the exposure pulse (10h) thiacloprid concentrations in the macrophyte-dominated section were 20-60% lower than those in the non-vegetated section. This suggests that spatial variability in contaminant concentrations, particularly in streams containing macrophytes, should be taken into account to enable a more realistic assessment of (i) exposure and associated effects and (ii) mass transport of pesticides and other chemicals into river systems (e.g. losses with surface runoff). |
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