Trophodynamics and parabolic behaviors of polycyclic aromatic hydrocarbons in an urbanized lake food web, Shanghai

Understanding the trophic movement and trophic magnification factor (TMF) of polycyclic aromatic hydrocarbons (PAHs) is an important criterion to assess their fate and potential effects in an aquatic ecosystem. This study investigated concentrations and trophodynamics of 16 priority PAHs in food web _wb (food web comprising whole bodies) and food web _m (food web containing only muscles) of total 14 species ((including plankton, shrimp, whitebait, mussels, snails, red-eared terrapin and seven other fish species) from the Dianshan Lake. Values of δ ¹³ C and δ ¹⁵ N were determined to assign trophic levels to organisms. In general, there was no evidence of biomagnification because of biological degradation of PAHs compounds, but only 9 PAH compounds in food web _m showed a statistically significant negative relationship between trophic level and lipid normalized concentration compared to the 6 PAHs congeners in food web _wb . However, TMF values of PAHs in food web _m ranged from 0.32 for pyrene to 0.68 for phenanthrene compared to TMF values of food web _wb ranged from 0.34 for pyrene to 0.74 for fluorene. Because of two opposing scientific views for biomagnification and biodilution of PAHs in the food web, albeit based on a rather limited number of studies, our study investigated that there is parabolic behavior of most of the PAHs. Concentrations of PAHs in the red-eared terrapin (Trachemys scripta elegans) were biodiluted which showed that this species metabolises such compounds. There was no particular relationship between K _ow and TMFs of PAHs in the Dianshan Lake. Hepatobiliary system (such as gall bladder and liver) in the whole body considered to have higher bioaccumulation potential of organic compounds than extrahepatic tissue (muscles).