Cadmium,zinc, lead and copper inChironomus riparius (Meigen) larvae (Diptera,Chironomidae): uptake and effects |
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Authors: | Klaas R Timmermans Wilma Peeters Marcel Tonkes |
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Institution: | (1) Department of Aquatic Ecology, Section Aquatic Ecotoxicology, University of Amsterdam, 320, NL-1098 Kruislaan, SM Amsterdam, The Netherlands;(2) Present address: Department of Chemical Oceanography and Marine Pollution, Netherlands Institute for Sea Research, P.O. Box 59, NL-1790 AB Den Burg Texel, The Netherlands |
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Abstract: | Cadmium, Zn, Pb and Cu uptake and effects in larvae ofChironomus riparius (Meigen) were studied in an integrated laboratory investigation, in which metal analyses in different instar stages, uptake kinetics and effects on development and growth were considered in three separate experiments.In short-term experiments with fourth instar larvae, it was demonstrated that only a minor portion of metals was adsorbed on the larval exoskeletons. No conclusive evidence on the uptake mechanism was found, but active uptake of trace metals seemed highly unlikely.In partial life cycle experiments, all four metals studied were readily accumulated in chironomid larvae. Uptake could be described satisfactorily utilizing a first-order one-compartment uptake model which incorporated growth. In all cases steady state conditions were approached and high uptake and elimination rate constants were estimated. Distinct differences between essential (Zn and Cu) and non-essential (Cd and Pb) metals were noted. Larval growth was significantly impaired upon exposure.Finally, long-term exposure experiments with low Cd concentrations (0.010 and 0.025 mg 1–1) resulted initially in growth impairment and high mortality in first instar stages, but surviving larvae restored growth and adults emerged even before control adults. In similar experiments with Zn (0.1 and 1.0 mg 1–1), development of larvae was significantly retarded. High Zn concentrations in larvae were noted and almost no adult midges emerged. |
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Keywords: | trace metals uptake kinetics development growth adsorption Chironomus riparius |
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