Analysis of PAHs content, source identification and ecological risk assessment in surface sediments from the Caspian Sea

The concentrations of Polycyclic Aromatic Hydrocarbons (PAHs) in surface sediments were investigated in the southern Caspian Sea. The results revealed that the total PAHs in sediments varied from 6.53 to 170.6 ng·g^{- 1}, with an average of 60.59 ng·g^{- 1}. The methods of diagnostic ratio and Principal Component Analysis (PCA) were applied to explore the sources of PAHs in the sediments and the results indicated that they had both petrogenic and pyrogenic origins. The ecological risk induced by PAHs in this area was evaluated using sediments quality guidelines (SQGs) criteria and Risk Quotient (RQ) index. SQG ranges for PAHs such as Acenaphthylene (Acy), Acenaphthene (Ace) and Fluorene (F) in the Lisar transect were found at a moderate toxicity level. The RQ∑PAHs index suggested a low ecological risk in the studied stations. Based on the results of the Toxic Equivalent (TEQ) approach, PAHs did not pose carcinogenic risks.