Effectiveness of Capping in Isolating Contaminated Dredged Material from Biota and the Overlying Water

摘要

The effectiveness of capping in chemically and biologically isolating contaminated dredged material was investigated using large- (250 pound) and small- (22.6 pound) scale laboratory reactor units. The ability of various cap materials to isolate contaminated dredged material was assessed in the large reactor units by following the movement of chemical contaminants and microbial spores contained in the capped dredged material into the overlying water column and by monitoring the biological uptake of chemical contaminants by clams and polychaetes. The depth of cap material needed to chemically isolate contaminated dredged material was assessed in the small-scale reactor units. Changes in overlying water concentrations of dissolved oxygen (DO), ammonium nitrogen manganese, and orthophosphate were monitored following isolation of the water column from air by placing a 4-cm layer of mineral oil on the surface. The constituents analyzed were selected due to their mobility under anaerobic conditions, ease of measurement, and generally high concentrations in contaminated dredged material compared to clean cap materials.