Fate of ~(14)C-17α-ethinyIestradiol in the aquatic system: the presence of sediment lowers its bioavailability for Chironomus riparius larvae

摘要

At present, knowledge about the partitioning of estrogens between water, solids, and biota is poor, although of utmost importance for the prediction of their fate, and the associated effects on organisms in the aquatic food web. Therefore, laboratory studies were performed to investigate the distribution pattern of ~(14)C-labelled 17α-ethinylestradiol (EE2) in a sediment-water system that functions as a habitat for sediment dwelling larvae of the midge Chironomus riparius. Larvae were exposed to EE2 in two different ways: through spiking overlying water or by sediment spiking, in order to compare both possible uptake routes. Distribution of EE2 was determined by analysing sediment constituents, pore water, suspended solids, overlying water, organisms and the glass wall surface at different time intervals. It was shown that the larvae reach their maximum internal concentration of ~(14)C-EE2 after a very short exposure period (within 24 h). The bioavailability of EE2 was highly reduced by sorption of EE2 to the sediment. 144 h after water spiking, 90% of the radioactivity in the sediment was associated with its organic fraction. Further experiments showing that dietary exposure of C. riparius leads to the most efficient uptake of EE2 will be presented at the conference.