Effects of Linuron to an Aquatic Plant in Sediment-dosed Test Systems

The availability of standardised methodologies to assess the environmental risks of pesticides to non-target plants is currently limited. Aquatic plant test guidelines are only available for algae and Lemna. These studies may not be sufficient especially in the case when contamination via sediment is an important exposure pathway. The present study was initiated to investigate the effects of exposure via the sediment on a sediment-rooted aquatic plant, i. e. Myriophyllum spicatum. Plants of Myriophyllum spicatum were cultivated in linuron spiked sediment under similar conditions for 21 days. At days 7, 14 and 21 of the test, various morphological endpoints were measured and dose-response relationships, EC50 values and NOECs were estimated. During the test period, linuron concentrations in sediment, water and plants were monitored to quantify exposure in the aquatic plant test and concentrations in the compartments. The results from these experiments were used to quantify risks of a herbicide to sedimentrooted aquatic plants and may lead to recommendations for improvement of test designs and risk assessment methods.