Bioaccumulation and enatioselective trophic transfer of polychlorinated biphenyls in a benthic food chain

Abstract

Numerous anthropogenic pollutants are chiral in nature. It is known that chiral molecules which are released to the environment as a racemic degrade and metabolize enantioselectively, and sequentially changed their chirality. Since enantiomers of chiral compounds exhibit different biological and toxicological properties, understanding the environmental behavior of the enantiomers in the environment is important for determining the hazards they pose. We conducted a study that assessed the trophic transfer of PCB congeners in a benthic food chain. Particular emphasis was placed on understanding the behavior of the enantiomers of PCBs in the food chain. Sediment, polychaeta and flatfish were collected from a semi-enclosed bay of Korea and analyzed for concentrations and enantiomeric fractions of PCB congeners. Stomach content and stable isotope of carbon and nitrogen were analyzed in samples and used to confirm the prey and predator relationship between them. The PCB concentrations in the samples clearly showed that PCB was biomagnified up the food chain. Additionally, congener pattern is similar to between the food chain members, implying that PCB pattern in each food source is reflected into its consumer. However, they had different chiral signatures, indicating that PCBs were accumulated enantioselectively through the food chain. Congeners in sediment were racemic or near racemic compared to biological samples. For CB 136 and CB 149, preferential enrichment of (-)-enantiomer relative to (+)-enantiomer was observed in ascending food chain. For CB 91 and CB95, E1 was enriched.