Effect of PCB Bioavailability Changes in Sediments on Bioaccumulation in Fish

Area of Science:

• Environmental Chemistry
• Aquatic Toxicology
• Ecotoxicology

Background:

• Sediment amendment using sorbents like activated carbon (AC) is a promising strategy for reducing hydrophobic organic chemical bioavailability.
• Polychlorinated biphenyls (PCBs) in aquatic ecosystems pose risks to humans and wildlife due to bioaccumulation in fish.
• Limited data exists on how sediment-bound PCB bioavailability affects fish bioaccumulation and associated risks.

Purpose of the Study:

• To experimentally and computationally assess the impact of PCB sorption in sediments on fish exposure pathways and bioaccumulation.
• To evaluate the effectiveness of AC amendment in reducing PCB bioavailability and uptake in fish.
• To validate bioaccumulation models using measured freely dissolved PCB concentrations.

Main Methods:

• Laboratory aquarium experiments involving in situ sediment amendment with fine granular activated carbon (AC).
• Passive sampling techniques to measure freely dissolved PCB concentrations in porewater and overlying water.
• Bioaccumulation studies in fish over 90 days, coupled with equilibrium and kinetic modeling of PCB uptake.

Main Results:

• AC amendment (4.5%) reduced freely dissolved PCBs in water by over 95%.
• PCB uptake in fish decreased by 87% after 90 days of exposure in amended sediments.
• Kinetic model predictions of fish PCB uptake were generally within a factor of 2 of measured values.

Conclusions:

• In situ AC amendment is effective in reducing PCB bioavailability and subsequent bioaccumulation in fish.
• Incorporating freely dissolved concentrations into bioaccumulation models accurately predicts the efficacy of sediment remediation.
• This approach aids in assessing and managing risks associated with PCB-contaminated sediments in aquatic environments.