Ecological risk assessment appears as an useful approach for dredged materials. It is often proposed in the form of a tiered approach, the first tier relying upon a chemical characterisation of sediments, and a simplified risk assessment based on sediment quality guidelines. A recently proposed tiered framework, relying upon published sediment quality guidelines and a mean quotient approach at the first tier, is tested against two databases: one including bioassays results and chemicals concentrations of contaminated and non-contaminated sediments; and the second chemical concentrations in sediments from two French regions. The selected sediment quality guidelines seem reliable, as the incidence of type I and type II errors remain in accordance with their definitions. However, the relevance of this statement is somewhat limited by the size of the database used. Moreover, geochemistry may play a confusing role for some metals like Ni and Cr. The cut-off values initially proposed for the first tier appear questionable: the lower boundary allows discarding of a low proportion of sediment samples in the chemicals only database, and toxicity may be observed below this value. Conversely, the upper boundary value may be considered as too low, as a significant proportion of non-toxic samples may be observed above this value, and as a large number of sites in the chemicals only database would enter higher tiers of the framework. Further tests and development are needed with an extended database.
Use of sediment quality guidelines in ecological risk assessment of dredged materials: Preliminary reflections
M. P. Babut, J. Garric, M. Camusso, P. J. den Besten; Use of sediment quality guidelines in ecological risk assessment of dredged materials: Preliminary reflections. Aquatic Ecosystem Health & Management 1 December 2003; 6 (4): 359–367. doi: https://doi.org/10.1080/714044165
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