Environmental implications of cargo sweeping in the Great Lakes

"Cargo sweeping" is the practice of removing the residues of dry bulk cargoes, such as iron ore, coal, grain, and various rock materials, from the deck and holds of cargo vessels. Such residues occur after most loading or unloading operations. Cleanup is accomplished by washing the decks and cargo spaces with water, which is then discharged over the side, usually while underway. Coast Guard regulations proposed in 1989 would have made the discharge of cargo residues illegal on the Great Lakes, which would have disrupted the continued operations of the U.S. Great Lakes shipping industry. In September 1994 a workshop was held to identify the research needed to provide a scientific basis for regulatory decisions. Three separate work groups, Risk to Fisheries & Habitat, Sediment Accumulation & Toxicity, and Water Column Impacts, were convened. Each group was asked to consider and identify what we already know and what gaps there are in our knowledge and understanding related to cargo sweeping, what further information or studies are needed, and how best to obtain the requisite information. [1.] All three groups identified the need for comprehensive information on the composition of the commodities, especially relative to impurities and added chemicals that might prove environmentally harmful. Such information should be obtained by literature searches and direct analyses of the composition. [2.] Each group indicated the need for studies to determine the bioavailability and bioaccumulation of cargo components and impurities that may be toxic. [3.] Each group identified a series of other information gaps and questions in need of answers, and recommended various approaches to obtain needed information"--Executive summary, Overview, p. 4.

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