Abstract-A unique, holistic modeling approach, combining theoretical, empirical, and deterministic elements, was developed to define the ambient background transport of polychlorinated biphenyl (PCB) from New Bedford Harbor, to provide a baseline for remediation assessment of this Superfund site. Both empirical and deterministic elements characterized sediment processes. The deterministic section employed experimental data to describe flocculation through fluid shear, differential settling, and Brownian motion mechanisms, yielding a sediment settling velocity. The empirical portion of the model used this settling velocity, along with suspended solids, and flow field data to characterize sediment action. The remaining PCB transport mechanisms (volatilization and sorption) are theoretically considered to give a complete contaminant transport assessment. The PCBs in New Bedford Harbor tend to volatilize at the rate of 5.9 g/d; or sorb, with sorption coefficients increasing with percent chlorination from 10 Ϫ2.2 to 10 Ϫ0.4 m 3 /g for Aroclors 1016 and 1260, respectively, rather than stay in solution. The deterministic model showed that fluid shear was the most significant flocculation mass removal mechanism contributing to the settling velocity calculation. From the empirical model, the dominant sediment action mechanisms, resuspension and deposition, were driven by the change in suspended solids concentration and tides. The cycling of PCB-laden sediment, indicated by the PCB sorption tendency and the presence and dominance of resuspension, and subsequent transport from the site, can lead to PCB contamination of the water column, atmosphere, or downstream (marine) areas.
is a Senior Research Development Associate with the Texas Engineering Experiment Station Office of Strategic Research Development. She has B.S., M.E., and Ph.D. degrees in civil engineering (environmental) from Texas A&M University and was an engineering faculty member before joining TEES in 1999 where she started working on technical research project grants related to interdisciplinary environmental themes. Currently, she leads the TEES New Faculty Initiative targeting grants such as the NSF CAREER awards for untenured engineering faculty throughout the TEES divisions, conducting workshops, guiding faculty through the proposal development process, with an overall goal to increase technical research capacity throughout the state. She has also worked with multi-institutional center-level efforts, such as proposals to the NSF CREST program.
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