Assessment of ecological risk for ecosystems caused by dredged materials in freshwater environments

Abstract

Several chemical substances are released into the environment, and many of them accumulate in the silt or sludge constituting sediments, at the bottom of rivers and lakes as well as in estuaries and seabeds. The ecological and health damage caused by the contamination of sediments by these chemical substances can have serious consequences on ecosystems by reducing the diversity of communities, particularly invertebrates, with indirect consequences on fish populations, loss of edibility of fish or shellfish, recreational uses affected or impossible, ecological risk assessment can be used prospectively or retrospectively. The general outline of the evaluation includes three stages: the formulation of the problem, which aims to develop an analysis plan and define the means to be implemented to characterize the risk, the analysis itself, where we collect the data necessary for the assessment of effects and exposure, and risk characterization, where the risk(s) and, as far as possible, the associated uncertainties are estimated. The application of this approach to dredged materials is proposed in the form of two successive stages: the first consists of a simplified risk analysis, from which we can decide to initiate a second stage of detailed evaluation. The review evaluates the ecological risk associated with the disposal of dredged materials in freshwater environments. It examines the impact of dredged materials on biodiversity and ecosystem health, focusing on assessing the extent of ecological damage, identifying influential factors, and proposing mitigation strategies.