Resuspension of mercury-contaminated sediments from an in-lake industrial waste deposit

The resuspension and transport of particulate mercury (HgP) from a nearshore industrial waste deposit to the pelagic zone of Onondaga Lake, N.Y., was investigated using an array of sediment traps radiating from the deposit, and quantified through application of a steady-state mass balance model. Time-averaged downward fluxes of suspended solids and HgP decreased in the offshore direction, indicating a nearshore source. Strong temporal variations in resuspension were documented and were linked to the dynamics of wind-driven wave action, as quantified by a validated surface wave model. A simple steady-state model of offshore transport from the resuspension zone, which assumes a balance between offshore transport and settling, was used to analyze sediment trap data. The resulting larger, and likely more accurate, estimate of HgP resuspension (∼60 g day-1) represents the dominant contemporary source to the water column. This result supports the planned remediation of this source as a part of a Superfund cleanup project.