Biota-sediment accumulation and trophic transfer factors for extremely hydrophobic polychlorinated biphenyls

Polychlorinated biphenyls (PCBs) in fish, invertebrates, and sediment from a contaminated tidal creek system in coastal Georgia (USA) were traced to Aroclor 1268, a mixture of hepta through decachlorinated homologs ((x) over bar(Cl) = 8.5) used at a former chlor/alkali plant adjacent to the study site. The base 10 logarithm of the octanol/water partition coefficient (K-ow) for the 15 most abundant Aroclor 1268 components in these samples ranged from 6.7 to >9. The composite mean biota-sediment accumulation factor (BSAF) for these congeners was 3.1, 0.81, and 0.28 for yearling striped mullet, spotted sea trout, and grass shrimp, respectively, species representing three trophic levels of the local food web. Individual congener BSAFs were negatively correlated (p less than or equal to 0.05) with log K-ow for all three species. The composite mean trophic transfer factor (TTFlip), defined as the ratio of lipid-normalized PCB concentrations in fish to grass shrimp, was higher for mullet (12) than for sea trout (2.9). Individual TTFlip values were two to three times higher for Cl-7 and Cl-8 homologs that were substituted at all four ortho positions, suggesting a difference in PCB retention based on chlorine substitution patterns. The relative magnitude of BSAFs and TTFlip values indicated that sediment-ingesting forage species like mullet efficiently accumulate PCBs and are an important link in the food web transfer of sediment-associated contaminants in this system. The negative linear relationships between BSAF and log K-ow established in this study are among the first to be reported in the field for extremely hydrophobic PCBs.