Water Quality Impacts of Aquatic Dredged Material Disposal (Laboratory Investigations).
ARMY ENGINEER WATERWAYS EXPERIMENT STATION VICKSBURG MISS
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Natural processes in aquatic ecosystmes tend to concentrate heavy metals, chlorinated hydrocarbons, pesticides, nutrients, and oil and grease compounds in bottom sediments. These contaminants are not very soluble in water under the conidtions that normally occur in oxygenated uncontaminated surface waters. Therefore, introducing high concentrations of these contaminants into aquatic ecosystems will generally result in an equilibrium condition where most of the contaminant will be sorbed adsorbed and absorbed by suspended particulate material and then deposited on the bottom when the suspended material settles. The time necessary to achieve the equilibrium condition depends upon the physicochemical conditions in the aquatic system and the quantity and duration of the contaminant introduction. Dredged Material Research Program DMRP reports and other literature indicate that dredging operations have the potential to temporarily mobilize or release some contaminants from the sediments. During disposal operations, the anaerobic sediments are mixed with aerated surface water, and a complex chemical interaction occurs. Heavy metals, such as cadmium, copper, chromium, lead, and zinc, are stabilized in the oxygen-free sediments as insoluble sulfides.
- Water Pollution and Control