Characterizing the Influence of Metabolism on the Halogenated Organic Contaminant Biomagnification in Two Artificial Food Chains Using Compound- and Enantiomer-Specific Stable Carbon Isotope Analysis

Two artificial food chains, food tiger barb oscar fish and food tiger barb-redtail catfish, were established in the laboratory. The species-specific biotransformation of ortho,para'-dichlorodiphenyltrichloroethane, 12 polychlorinated biphenyl, and five polybrominated diphenyl ether congeners were characterized by measuring the compound-and enantiomer-specific stable carbon isotope composition (delta C-13), enantiomeric fraction of the chiral chemicals, and metabolites in the fish. Compound- and enantiomer-specific biotransformations were revealed by the alteration of delta C-13 and EF in both predator fish species. Significant correlations between the carbon stable isotope signatures and the depuration rates and biomagnification factors (BMF) were observed. Chemicals that exhibited changes in delta C-13 during the experiment have higher k(d) and lower BMF values than those with unchanged delta C-13. Specifically, the difference between the predicted BMF based on the log K-ow, and the measured BMF, Delta BMF, was significantly positively and linearly correlated to the change in the delta C-13 (expressed by Delta delta C-13/delta C-13(initial), the percentage of Delta delta C-13:delta(13)(ending)-delta C-13 to the initial delta C-13(initial)) in both food chains. These results indicated that the impact of metabolism on the bioaccumulation potential of organic contaminants can be predicted by the stable carbon isotope fractionation of chemicals in the fish