Dredging operations technical support program. Transformation, fixation, and mobilization of arsenic and antimony in contaminated sediments.

The potential environmental impacts of arsenic (As) and antimony (Sb) contaminated sediments were studied with emphasis placed on short and long term leaching and sediment conditions that effect mobilization. Under anaerobic conditions, arsenate As(v) was reduced to arsenite As(iii) in a wide range of sediments. In anaerobic Texas City sediment slurries, 70% of added As(v) to anaerobic sediments was also demonstrated. Short-term leaching was conducted with anaerobically incubated unamended and As-amended sediments using either distilled or saline water. Aerobic species would be released, the duration of the releases, and the sediment factors affecting releases. Long-term aerobic leaching caused significant changes in both sedimentary Fe and As phases. Sediments containing native and added Sb were subjected to similar experimental incubation, extraction procedures, and short and long term leaching as in the As experiments. Speciation of Sb was not examined however, so that only total Sb concentration are available. Short-term releases of Sb were higher from amended than from unamended sediments.