This report is the result of an examination of the feasibility of isolating contaminated dredged material on the abyssal seafloor. The focus is on the technical and environmental factors that constrain the considerations of feasibility. The sources of the materials are assumed to be in U.S. coastal waters. A thorough conceptual design of a dredging to abyssal deposition system is analyzed with regard to each subsystem and to the entire operational concept. These subsystems include: (1) a low leakage dredge, (2) equipment for material handling and loading into geosynthetic fabric containers (GFCs), (3) the barge for transport and navigation, and (4) the subsystem for releasing the GFCs to sink to the abyssal seafloor isolation site. Particular consideration is given to the exclusion of dredged material from the ocean's productive zone in the upper 1000 m; this exclusion requires highly stable, reliable navigation and seakeeping by the barge transporter and control of the configuration of GFCs within it. New theoretical models and previous empirical results are used to predict GFC motion through the water column and response to impact on the abyssal seafloor, including the case of potential release of contaminated, turbid water at impact. A geochemical model of the temporal and spatial evolution of the post-deposition geochemistry of the water column, the GFC contents and the sediments below is developed and analyzed; the results show that release of metals into the ocean waters would be insignificant. A model of the biological impacts of the introduction of dredged material in the abyssal environment is used to infer that: (1) biological diversity in the vicinity of the deposition site will be diminished, (2) biomass will be increased by dominance of a few fast growing, opportunistic benthic species, and (3) concentrations of trace elements and organic contgt\h1

This volume examines the deep sea ecosystem from a variety of perspectives. The initial chapters examine the deep-sea floor, the deep pelagic environment and the more specialised chemosynthetic environments of hydrothermal vents and cold seeps. These environments are examined from the perspective of the relationship of deep-sea animals to their physico-chemical environment.Later chapters examine the biogeography of the main deep oceans (Atlantic, Pacific and Indian) with particular attention to the downward flux of surface-derived organic matter and how this drives the processes within the deep-sea ecosystem. The peripheral deep seas including the polar seas and the marginal deep seas (inter alia the Mediterranean, Red, Caribbean and Okhotsk seas) are explored in the same context. The final chapters examine the processes occurring in the deep sea and include an analysis of why the deep sea has high species diversity, how the fauna respond to organic input and how species have adapted reproductive activity in the deep sea. The volume concludes with an analysis of the anthropogenic impact on the deep sea.