Physicochemical Properties of Dredge Spoil

Physicochemical changes resulting from the subaerial exposure of dredge spoil during land disposal were investigated using five fine-grain bottom sediment samples from the lower Great Lakes. Air-drying of unoxidized postglacial sediments increased cation exchange capacity and decreased plasticity. Air-drying of a Pleistocene oxidized sediment did not affect these parameters appreciably. The difference is attributed to an irreversible collapse of weathered swelling minerals and the oxidation of ferrous and manganous ions in postglacial sediments. Mineralogical composition and changes caused by citrate-dithionite extraction were examined by X-ray diffraction, infrared absorption, electron-optical, and surface area measurements.