| As with all the Great Lakes, Lake Michigan is affected by the continuing input of persistent organic pollutants (POPs). Contaminated sediment resuspension is a major source of these potentially toxic compounds to the Lakes. However, controlling sediment sources is a near intractable task that is further aggravated by the poor understanding of the magnitude of this source. Fortunately, sediment resuspension may also be a major mechanism by which the Lakes are cleansed. The processes associated with sediment resuspension are heavily influenced by meteorological and limnological conditions. The primary purpose of the work described in this thesis was to assess the magnitude and variability of this mechanism for elimination and uptake of POPs in Lake Michigan. This work evaluates the sediment resuspension processes that control the short- and long-term cycling of POPs in the Lake Michigan.; In this thesis, sediment resuspension as a source to and a sink from Lake Michigan of PCBs was evaluated. Since large-scale sediment resuspension disrupts the overall distribution of PCBs between air, water, and suspended sediment, the magnitude of this disruption was evaluated. A three-year field sampling effort to study large-scale episodic sediment resuspension in southern Lake Michigan is reported on in this thesis and includes discussion of (a) the concentration of POPs in air, water, and suspended sediment before, during, and after major sediment resuspension events; (b) the fate and bioavailability by using changes in partitioning of POPs between air, water, and suspended sediment; and (c) short-term fate by using the unique chemical characteristics and patterns of POPs to trace the sources of resuspended sediment. The following major conclusions are reported. First, both dissolved-phase and suspended sediment SigmaPCB, SigmaPAH, or trans-nonachlor concentrations do not predictably vary with sediment resuspension event. These concentrations agree with previously reported data. Second, the partitioning of PCBs between the dissolved-phase and suspended sediment (Koc) changes as a function of sediment resuspension. Values of Koc vary spatially, corresponding with proximity to potential sources. Third, contaminant signals indicate strong source-receptor relationships between open water sampling stations and their proximity to the tributaries that discharge into southern Lake Michigan. |
