Application and Interpretation of Bioassay and Biomonitoring: A Planning Document.

The need for long-term predictive capabilities regarding contamination in waterways, dredged material, sediments, and soils is well recognized and is international in scope. The Proceedings of the Fifth International Workshop on Contaminant Mobility focus on three critical areas: the fate and effect of contaminants in the environment; physical, biological, and chemical assessment procedures; and regulatory decisionmaking criteria. The prediction of the environmental effects and fate of contaminants in dredged material has been based primarily upon bulk chemical analyses and bioassays of sediments collected prior to dredging and disposal operations. Dredged material changes greatly with time through physicochemical weathering (i.e., aging) processes such as drying, oxidation, photodecomposition, and leaching, especially when placed into an upland disposal environment. These processes are influenced further by the activities (i.e., bioturbation) of microorganisms, plants, and animals. The fate and effects of contaminants in disposal sites are greatly influenced by these physicochemical and biological processes. The currently-used approaches (laboratory tests which do not allow for the effects of aging of dredged material following disposal) for evaluating sediments prior to dredging are inadequate for predicting the long-term fate and effects of contaminants in the disposal environment.