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(M/MF198) Ecotoxicity of suspended solids from polluted rivers. Weltens, Reinhilde1, Corbisier, P.1, Witters, H.1, 1 ABSTRACT- Earlier studies showed that artificially contaminated particular matter could be responsible for acute effects in Daphnids and fish. Physical/chemical measurements on suspended solids and river water collected in the field showed that these samples were often contaminated with mixtures of toxic molecules. The partition coefficients in situ were not simply related to either Kow of the contaminant, nor to total organic contents of the solids. A pilot study was started to investigate the possible ecotoxic impact of suspended solids collected in situ. Materials were collected from 22 locations of polluted rivers in the Flanders. Their toxicity was investigated in 3 test organisms of different trophic levels: Bacteria (BIOMET®), Filter feeder (Daphnia immobilisation) and fish (Trout or zebrafish mortality). In this exploring study the acute toxicity was measured in a worst case scenario using high concentrations of solids resuspended in standard medium and under standard conditions. Results indicated that the ecotoxic impact should be further investigated in realistic (non worst case) conditions, i.e. for chronic effects at field relevant concentrations. In the present study 5 samples of suspended solids collected in situ were investigated at low concentrations in chronic toxicity tests (Daphnia and zebrafish) and in bacteria (BIOMET®). Both the toxicity of desolved and adsorbed pollutants was evaluated. Understanding the impact of contaminated suspended solids on the ecosystem health might have consequences for environmental risk assessment protocols Key words: ecotoxicity, suspended solids, surface waters, bioavailability |
