The primary goal for remediation of sediments contaminated with polychlorinated biphenyls (PCBs) is the reduction of bioaccumulation in the aquatic food web, particularly in fish that is the source of exposure to top level predators and humans. While empirical results are available in the literature on bioavailability reductions after amendment of PCB-contaminated sediment with a strong sorbent like activated carbon (AC) or biochar, there is a lack of quantitative understanding on how reductions in sediment porewater and food concentrations impact accumulation in fish. Although passive sampling can measure freely dissolved concentrations accurately, there is a major gap in the utilization of fate and biouptake models that can use such measurements. In addition, well-calibrated partitioning models based on accurate freely dissolved concentrations that can predict uptake by pelagic organisms are lacking. The primary objective of this research was to test the ability of frequently used bioaccumulation models to predict changes in fish uptake upon amendment of AC sediment and use passive sampling inputs and additional studies to refine the predictions made by these bioaccumulation models.
Results from laboratory exposure studies with pelagic and benthic feeding fish indicate that by incorporating changes in porewater and overlying freely dissolved PCB concentrations in kinetic bioaccumulation models and by taking into account changes in food concentration it is possible to predict effectiveness of sediment remediation in reducing PCB uptake in fish. Assimilation efficiency of PCBs in the sediment were independently measured in a separate study and incorporated into the model. The modified model led to reasonable estimations of PCB uptake in the benthic feeding fish and was capable of predicting the dominant exposure pathways in the benthic and pelagic feeding fish as a result of their different feeding behaviour. Additionally, passive sampling measurements were linked to PCB accumulation in algae and zooplankton and resulted in refined models. Lastly, several scenarios were simulated to show the potential of a linked fate and biouptake model to capture the effect of different inputs.
This research presents a robust modeling framework that is able to predict uptake in fish after in situ remediation that alters bioavailability of PCBs in sediments with implications for risk assessment and management.
|Commitee:||Blaney, Lee, Hennigan, Christopher, Place, Allen, Welty, Claire|
|School:||University of Maryland, Baltimore County|
|Department:||Engineering, Civil and Environmental|
|School Location:||United States -- Maryland|
|Source:||DAI-B 79/04(E), Dissertation Abstracts International|
|Subjects:||Engineering, Environmental science, Environmental engineering|
|Keywords:||Activated carbon, Bioaccumulation, Bioavailability, Fish, Passive sampling, Polychlorinated biphenyls|
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