Characterizing the Risks to Aquatic Ecosystems: A Tentative Approach in the Context of Freshwater Dredged Material Disposal

Abstract

The development of relevant frameworks for assessing ecological risks posed by dredged material management does not only involve an appropriate selection of assessment and measurement endpoints but also requires a sound approach to both risk characterization and the associated uncertainty. A formal methodology addressing both aspects has been developed in France for freshwater sediment deposits in water. Both exposure and effects measurements are 1st transformed into scores or classes. As far as possible, class boundaries are based on existing knowledge or expertise. Benthic organism exposure is based on a ratio of the deposit area to the burrow pit area, whereas pelagic species exposure is based on the ratio of porewater volume to water column volume. The combination of exposure and effect scores yields risk scores, or classes, which are linked to management decisions. Uncertainty is assessed with respect to a set of 4 predetermined criteria for exposure (the strength of association with the assessment endpoint, spatial and temporal representativeness, and the use of standard methods) and 4 criteria for effects (strength of association, the distinction between effect and no effect, sensitivity, and the use of standard methods). This approach was applied to 8 sediments from French canals contaminated to varying degrees.

Sediment quality assessment and dredged material management in Spain: Part II, analysis of action levels for dredged material management and application to the bay of Cádiz

“…Only The Netherlands has established quality criteria for the interpretation of results, although this approach seems recommended when broad databases are available for its development and especially for screening methodologies. Otherwise, the use of the statistical difference from a control or reference sediment avoids arbitrary differences in the classification of dredged materials between countries while allowing us to determine between different intensities of responses to different statistical probabilities that may be used afterwards in ecological risk assessment frameworks (Babut et al 2006). Nevertheless, the selection of the reference sediment to which results are compared could introduce major differences in the final classification of the sediments, while offering the possibility to interpret the results in terms of site‐specific conditions.…”

Acute toxicity of monocalm 400sl (<i>monocrotophos</i>) and profenalm 720ec (<i>profenofos</i>) on <i>Oreochromis niloticus</i> (Linnaeus, 1758)

“…It was found that the paralysis appeared after two to three weeks of exposure (Dinham, 1993). In agricultural areas, huge amounts of pesticides can be drained by storm water and discharged into nearby rivers plantations, jeopardizing, not only the survival of exposed organisms, but also the quality of these waters (Marchand, 1989;Monkiedje et al, 2004;Babut et al, 2006). Tests performed in laboratory microcosm, had previously shown different levels of tolerance of aquatic organisms to pesticides exposure (Monod, 2001).…”

Efficiency of sediment quality guidelines for predicting toxicity: The case of the St. Lawrence river

“…Most industrialized countries regulate and manage contaminated sediments and dredged materials in their waterways. Consequently, various ecological risk assessment (ERA) approaches have been developed, and sediment quality guidelines (SQGs) were included in many cases (Babut et al 2005, 2006; Alvarez‐Guerra et al 2007; Apitz et al 2007). In Canada, Environment Canada regulates ocean and estuarine dredging operations and open‐water disposal through Environment Canada's Disposal at Sea Program (DAS) under the Canadian Environmental Protection Act, 1999 (CEPA 1999).…”

“…Most industrialized countries regulate and manage contaminated sediments and dredged materials in their waterways. Consequently, various ecological risk assessment (ERA) approaches have been developed, and sediment quality guidelines (SQGs) were included in many cases (Babut et al , 2006Alvarez-Guerra et al 2007;Apitz et al 2007). In Canada Act, 1999(CEPA 1999.…”