The distribution and ecological risk of polycyclic aromatic hydrocarbons of surface sediments in the intertidal zone of Bohai Bay, China

86 surface sediment samples were collected from the intertidal zone of Bohai Bay, adjacent main rivers and offshore area, and were analyzed for 16 priority polycyclic aromatic hydrocarbons (PAHs) by GC/MS. The average PAHs concentration of surface sediment samples in the intertidal zone of Bohai Bay was (140.0±84.1)ng/g (n=44), which was close to the value from offshore samples [(161.6±38.7)ng/g, n=26], but significantly lower than that in the samples from main rivers [(452.7±206.0)ng/g, n=13]. Distinct spatial pattern of PAHs concentrations could be seen with "higher in the north while lower in the south" (divided by Tianjin Port) in the intertidal zone, which significantly related to the sediment granularity and the concentrations of black carbon (BC) and total organic carbon (TOC). Variation of percentage of low-molecule-weight PAHs in the intertidal zone demonstrated its special sedimentary environment. Average of BaP-equivalent carcinogenic concentrations was (24.5±21.1)ng/g in the intertidal zone sediments. Risk assessment by the criteria for marine sediment quality of Quebec, Canada suggested that there have been some ecological risk in the intertidal zone of Bohai Bay based on PAHs concentration in the surface sediment samples.