Rapport in het kort
Contamination of aquatic sediments may cause toxic
effects on organisms. Sediment toxicity tests, especially those with
benthic organisms, have to be standardized. In this study (semi)-chronic
research were performed using Daphnia magna and larvae of Chironomus
riparius. The testorganisms were exposed to both sediments and extracted
pore waters. In order to compare the reproducibility of the testmethods,
work with D. magna was carried out in two different laboratories. Two
aquatic sediments were sampled in the river Rhine and one reference sample
was taken from a nature reservate. Based on classification according to the
Dutch interim procedure to classify sediments the contaminated sediments
belong to class 3 and the reference sediment to class 2. With D. magna
effects in pore-water were stronger than effects in sediment-water systems.
Results of the two laboratories were not identical, possibly due to
differences in practical handling and in sensitivity of the daphnias.
Effects on C. riparius were not clear. High contents of ammonium and salt
may have caused serious side-effects. Such effects were also noticed in
tests with the reference material. the use of this material has to be
reconsidered. A test with a recirculating-water system requires much labour
and gives no further information in (semi)-static tests.