Bioaccumulation and transfer of benzo(a)pyrene in a simplified marine food chain

We examined the toxicokinetics of benzo(a)pyrene (BaP) and the trophic transfer in a marine planktonic food chain comprising phytoplankton, copepods, and fish. Kinetic parameters including the uptake rate from the dissolved phase, the assimilation efficiency (AE ) from the ingested food, and the elimination rate were quantified. Influences of food quality and quantity and different routes of exposure (aqueous and food) on the biokinetics were also examined. The uptake rate constants were 390 to 1090 ml mg^-1 h^-1 in different species of phytoplankton, 1.2 ml mg^-1 h^-1 in the copepods, and 0.157 ml mg^-1 h^-1 in the fish, respectively. The assimilation efficiencies were 2 to 24 % in the copepods and 32 to 51 % in the fish ingesting different prey types. Increasing food concentration significantly reduced the AEs, whereas the AEs varied little among the different food diets tested at the same biomass. The elimination rate constants by the copepods were 0.8 to 1.7 d^-1, and comparable following uptake from the aqueous phase and the dietary phase. A kinetic modeling calculation suggests that more BaP accumulated in the copepods originates from the dietary intake than the aqueous intake. For fish, both trophic transfer and aqueous uptake are important in BaP bioaccumulation. Feeding rates contribute to the differences in the relative proportion of accumulated BaP in the fish. © Inter-Research 2006.