Ecological risk analysis of polycyclic aromatic hydrocarbons (PAHs) in surface sediments from Laizhou Bay

Concentrations of 16 polycyclic aromatic hydrocarbons (PAHs) in surface sediments collected from 17 stations in Laizhou Bay were measured by gas chromatography–mass spectrometry. The results showed that the total concentrations of PAHs varied from 23.3 to 292.65 ng/g with a mean value of 134.27 ng/g. The total PAHs concentrations were at lower level compared to other marine coastal areas. The proportion of two to four ring PAHs was quite high. Sediment quality guidelines (SQGs) were conducted to assess the toxicity posed to the benthic community by PAHs. It was showed that concentrations of PAHs were below their respective effects range-median (ERM) and probable effects level (PEL) values in 17 stations using effects range-low (ERL)/ERM values and threshold effects level (TEL)/PEL values. Acenaphthene concentrations in surface sediment exceed TEL only in station L14, the concentrations were at levels where adverse biological effects may occasionally occur (≥TEL and <PEL) in the station. Fluorene concentrations were in the intermediate range (≥ERL/TEL and <ERM/PEL) in stations L05, L07, L15, and L16, indicating that occasionally adverse biological effects were likely to occur for fluorene at the four stations. Acenaphthylene levels in all stations are lower than corresponding ERL values, while TEL level was exceeded in 59% of the stations. Naphthalene concentrations exceeded ERL only in station L05, while naphthalene levels in 59% of the stations were in the intermediate range (≥TEL and <PEL). It was implied that concentrations of acenaphthylene and naphthalene that exceed ERL/TEL have been found to be occasionally associated with adverse biological effects at 59% of the Laizhou Bay stations. It was found that four PAHs (benzo[b]fluroranthene, benzo[k]fluoranthene, benzo[g,h,i]perylene, and indeno[1,2,3-cd]pyrene) had probably certain risk in all stations. The mean PAH ERM-Qs for all stations in Laizhou Bay did not exceed the value of 0.1, indicating that the potential combined ecological risks of PAHs in surface sediments are generally low.