Distribution, sources and ecological risk assessment of polycyclic aromatic hydrocarbons (PAHs) in coastal waters in oyster pond

We explored the distribution of PAHs in pond waters in the Changsha Bay and assessed their ecological risk to the cultured oyster. It is indicated that the range of the 16 USEPA priority PAHs in water, suspended solids, oysters and surficial sediment from the oyster ponds were 6.62~21.2 ng·L^-1 (average:9.87 ng·L^-1), 92.9~355 μg·kg^-1(average:198μg·kg^-1), 12.7~17.4 μg·kg^-1(average:15.5 μg·kg^-1)and 247~615 μg·kg^-1(average:322 μg·kg^-1), respectively. Compositional analysis of the PAHs reveals that 3-ring PAHs were dominated in the sediments, followed by 4-ring compounds. The isomeric ratios of the PAHs in sediment show that the source of the PAHs in the oyster ponds were originated predominantly from high temperature pyrolytic inputs, which may be related with the thermal power plants around the culture zone. The Effects Range Low (ERL) and Effects Range Median (ERM) were applied to assess the ecological risk. It is indicated that the PAHs in the sediment were lower than the ERL values, which was rarely associated with adverse effects on oysters cultured in the ponds. However, attention must be paid to the compounds such as fluorine and anthracene due to their contents between ERL and ERM, which will cause adverse effects on the oyster.