Trophic transfer of polycyclic aromatic hydrocarbons (PAHs) in aquatic ecosystems
is an important criterion for assessing their ecological risk. This study analyzed
18 PAHs in phytoplankton/seston, zooplankton, five invertebrate species, five fish
species, and one seabird species collected from Bohai Bay, and trophic transfer of
the PAHs was determined in the food web, of which the length was approximately 4 on
the basis of stable nitrogen isotope values. The concentrations of PAHs (2-64.5 ng/g
wet weight) in the marine ecosystem were moderate compared with other marine organisms
worldwide, and the PAH compositions exhibited species-specific profiles that were
related to trophic levels in some organisms. Significant negative relationships were
also found between trophic levels and lipid-normalized concentrations for 10 PAH compounds
(acenaphthylene, anthracene, fluoranthene, pyrene, chrysene, benz[a]anthracene, benzo[b]fluoranthene
+ benzo[k]fluoranthene, benzo[e]pyrene, benzo[a]pyrene, and perylene), and their trophic
magnification factors (TMFs) ranged from 0.11 for fluoranthene to 0.45 for acenaphthylene.
These results confirm that PAHs undergo trophic dilution in the marine food web, which
is likely to be the combined results of low assimilation efficiencies and efficient
metabolic transformation at higher trophic levels.