Assimilation efficiency of sediment-bound PCBs ingested by fish impacted by strong sorption

Area of Science:

• Environmental Toxicology
• Aquatic Toxicology
• Environmental Chemistry

Background:

• Fish bioaccumulation of polychlorinated biphenyls (PCBs) is modeled using gut uptake and gill transfer, but incidental sediment ingestion is often overlooked.
• Existing models lack data on PCB assimilation efficiency from sediments and the impact of mitigation strategies on this route.

Purpose of the Study:

• To investigate the bioavailability of PCBs from treated and untreated sediments in fish.
• To quantify dietary assimilation efficiencies of various PCB congeners associated with different sediment matrices and activated carbon treatments.

Main Methods:

• Measured assimilation efficiencies of 16 PCB congeners in mummichogs (Fundulus heteroclitus) using four experimental diets.
• Diets included PCB-spiked earthworms, untreated sediment with earthworms, activated carbon-treated sediment with earthworms, and activated carbon with earthworms.
• Assimilation efficiency was calculated as the ratio of PCB mass in fish tissue to PCB mass in the ingested food.

Main Results:

• PCB assimilation efficiencies from earthworm diets matched literature values.
• Fish fed untreated sediment showed high PCB assimilation, while those fed activated carbon showed the lowest assimilation.
• Activated carbon treatment significantly reduced sediment-bound PCB assimilation by 31-93% across congeners.

Conclusions:

• Sorption to activated carbon effectively reduces PCB assimilation in fish.
• Findings highlight the importance of considering sediment ingestion and the efficacy of activated carbon in mitigating PCB bioaccumulation.
• Results inform bioaccumulation models and contaminant management strategies in aquatic ecosystems.