Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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Record number 409731
Title Effects of time-variable exposure regimes of the insecticide chlorpyrifos on freshwater invertebrate communities in microcosms
Author(s) Zafar, M.I.; Wijngaarden, R. van; Roessink, I.; Brink, P.J. van den
Source Environmental Toxicology and Chemistry 30 (2011)6. - ISSN 0730-7268 - p. 1383 - 1394.
Department(s) Aquatic Ecology and Water Quality Management
CWC - Environmental Risk Assessment
Publication type Refereed Article in a scientific journal
Publication year 2011
Keyword(s) active ingredient chlorpyrifos - outdoor experimental ditches - ecological risk-assessment - dursban(r) 4e - model-ecosystems - aquatic ecosystems - pulsed exposure - pesticides - responses - field
Abstract The present study compared the effects of different time-variable exposure regimes having the same time-weighted average (TWA) concentration of the organophosphate insecticide chlorpyrifos on freshwater invertebrate communities to enable extrapolation of effects across exposure regimes. The experiment was performed in outdoor microcosms by introducing three different regimes: a single application of 0.9mg active ingredients (a.i.)/L; three applications of 0.3 mg a.i./L, with a time interval of 7 d; and continuous exposure to 0.1 mg a.i./L for 21 d. Measurements showed that the TWA21d concentration in the continuous-exposure treatment (0.098mg/L) was slightly lower than in the three-application (0.116 mg/L) and single-application (0.126 mg/L) treatments. The application of chlorpyrifos resulted in decreased abundances in the arthropod community, with the largest adverse effects reported for the mayfly Cloeon dipterum and cladocerans Daphnia gr. longispina and Alona sp., while smaller effects were observed for other insects, copepods, and amphipods. At the population level, however, the mayfly C. dipterum only responded to the single-application treatment, which could be explained by the toxicokinetics of chlorpyrifos in this species. At the end of the experimental period the invertebrate community showed approximately the same effect magnitude for all treatment regimes. These results suggest that for this combination of concentrations and duration of the TWA, the TWA concentration is more important for most species than the peak concentration for the assessment of long-term risks of chlorpyrifos.
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