Resuspension of bottom sediments in Lake Ontario during the unstratified period, 1992-1993

Time-series measurements of current velocity and water temperature made at a station in southwestern Lake Ontario between October 1992 and June 1993 are combined with analyses of material collected in a sequencing sediment trap moored at the same location. The results show that local resuspension of bottom material occurred several times during November and December. Analyses of total PCBs and Mirex concentrations were used to infer the origins of the material collected in the traps. Material collected during the fall has multiples sources; in addition to material already in suspension and bottom material resuspended from the immediate area, some material appears to be derived from the Niagara River delta. This is the first reported instance of bottom resuspension in the Great Lakes at depths below wave base during the unstratified period that has been confirmed by current velocity measurements.