Ref ID : 6828
Paul J. Van Den Brink, Ellen Van Donk, Ronald Gylstra, Steven J.H. Crum, and Theo C.M. Brock; Effects of chronic low concentrations of the pesticides Chlorpyrifos and Atrazine in indoor freshwater microcosms. Chemosphere 31(5):3181-3200, 1995
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Effects of chronic low concentrations of chlorpyrifos (0.1 µg L-1) and atrazine (5 µg L-1) were studied in indoor freshwater microcosms. Test concentrations were based on a factor of 0.1 multiplied by the lowest available L(E)C50 of standard aquatic test organisms. We tested whether this safety factor was sufficient to protect aquatic communities in the microcosms in the case of a chronic exposure regime. Effects on plankton, macro-invertebrates and physico-chemical parameters during the seven weeks of treatment are summarized in this paper. Chlorpyrifos treatment resulted in primary effects on the zoolankton taxa Cyclopoida and Daphnia galeata and the macro-invertebrate Gammarus pulex, and secondary effects on the rotifer Keratella quadrata. No effects of chlorpyrifos on phytoplankton or on physico-chemical parameters were found. Atrazine exposure caused a slight shift in the functional parameters: DO, pH, alkalinity and conductivity, indicating a small decrease in photosynthetic activity. No effects of atrazine on the species composition of the ecosystem were found. In case of a chronic exposure to chlorpyrifos, a safety factor of 0.1 appeared to be insufficient to protect the aquatic community.