Nina D. Hirsch
Published: 1978
Total Pages: 52
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This report synthesizes data from the U.S. Army Corps of Engineers' Dredged Material Research Program, Task 1D. Task 1D consisted of six research projects (work units) that investigated the direct and indirect effects of dredging and disposal of dredged material on aquatic organisms. Determination of potential environmental effects of dredging and disposal, in spite of research conducted to date, is still in preliminary stages due to the multiplicity of variables involved. Bioavailability of sediment-sorbed heavy metals is low. Release of sediment-associated heavy metals and their uptake into organism tissues have been found to be the exception rather than the rule. Research results suggest that there is little or no correlation between the bulk sediment content of heavy metals and environmental impact. Oil and grease residues, like the heavy metals, seem tightly bound to sediment particles and accumulation of these residues by organisms is minimal. The diversity of variables that have the potential for direct and indirect effects on acquatic life argues for an integrated, whole-sediment bioassay, using sensitive test organisms. Such a procedure is currently under development by the Environmental Protection Agency and the Corps of Engineers and should uncover site-specific toxicity problems which can be addressed by appropriate chemical testing and biological evaluation of dredged material.