Fingerprint Characteristics Of Petroleum Hydrocarbons In Sediments From Dalian Bay

The marine sediments were collected from Dalian Xingang port, in which catastrophic oil spill accident was happened on July 16,2010. The accelerated solvent extraction method was firstly applied, and subsequently gas chromatography (GC) adopted to determine the residue and component characteristics of n-alkanes and polycyclic aromatic hydrocarbons (PAHs) from the sediments samples. Source apportionment was preliminary analyzed according to their characteristic index. Finally, the potential ecological risk of PAHs was assessed. The main conclusions are as followed:(1)The average recovery of n-alkanes and isoprenoid is 60.07～118.99%, the RSD value is 1.58～14.27%, and the detection limit is 13.75～45.33 ng·g-1; the average recovery of PAHs is 78.39-117.46%, the RSD value is 4.13-12.80%, and the detection limit is 5.76～19.00 ng·g-1.(2) Concentrations of n-alkanes (C12-C40) are from 1.72 to 5.59 μg·g-1 in the Dalian Bay sediments, the total content of 3# and 5# stations is higher, which may be related to poor water exchange ability of these regional and frequent human activities. The ratios of Pr/Ph、C17/Pr and C18/Ph indicate that the study area may have been subjected to different degrees of pollution by oil, and petroleum hydrocarbons produced certain degradation and weathering. Concentrations of n-alkanes in the study areas are at the low to moderate levels of the global range.(3) The total content of PAHs in Dalian Bay are in the range of 1.16～2.63 μg·g-1, the total content of 5# station is the highest, followed by 3# station.4 ringed PAHs are the major components in each station, followed by 5 ringed PAHs. The content of low molecular weight PAHs accounts for 20 percent of total content, which indicates the pollution of petroleum. The indexes of characteristic compounds show that the PAHs in sediments are mainly derived from combustion sources, and mainly petroleum combustion, but we don’t rule out the possibility that the local area has the oil source input. The results are consistent with the analysis result of n-alkanes. Concentrations of PAHs in the study areas are at the low to moderate levels of the global range.(4) Risk assessment results show that concentrations of PAHs in the study area are much lower than effects range median (ERM) and the sediment have a low probability of ecological risk. However, contents of acenaphthene, fluoren, dibenzo[a,h]anthracene exceed the effect range low (ERL) value in many stations. Study areas exists potential ecological risk, which may pose harm to marine benthos.