Distributions and effects of existing and proposed wastes dumped into the deep ocean

Abstract

Except for containerized low-level radioactive waste having been dropped from vessels, all deep ocean waste disposal under United States permit has been and is surface discharged from barges of industrial and some municipal wastes. Two deep ocean sites have been used, one off the east coast in over 2000m of water the other north of Puerto Rico in over 8000m. This disposal method exploits the large initial dilution which is achievable with slow release from moving vessels and dispersion in the wind mixed upper ocean. Neither attribute is unique to the deep ocean, both are available with coastal discharges. The deep ocean is used because its surface waters are less productive and necessary to valued fisheries than the coastal ocean. Benthic effects from deep ocean disposal will be a function of the setting rate of waste particles or biogenic particles with incorporated waste components. For some wastes, proposed for extensive deep ocean dumping, such as fly ash from electric power plants, settling is rapid and distinct layers will be created on the seafloor. For others, such as sewage sludge, the benthic flux may be undetectable in sediment samples until decades of dumping have passed. Knowledge gained from studies of disposal and its effects at the two existing deep ocean sites will be reviewed and used to hypothesize the distribution and effects of proposed new wastes being considered for ocean disposal.