Assessment of environmental risk related to the polycyclic aromatic hydrocarbons (PAH) in the sediments along the eastern Adriatic coast

Polycyclic aromatic hydrocarbons (PAH) were investigated in the sediments at 24 locations in the coastal area of Adriatic Sea. Total PAH concentrations ranged from 14,98 to 26145,62 µg kg-1, with the highest levels determined in the sediments of Šibenik Bay and the lowest in the sediment near Island of Pag. Unsubstituted PAH were prevailing PAH group in the sediments from the Šibenik Bay and in the Coastal area, while methyl-substituted PAH were dominant group in the sediments of the Kaštela Bay. In order to estimate the possible toxicological significance of PAH concentrations, Sediment Quality Assessment was done according to three different sets of sediment quality guidelines. A high environmental risk was calculated for each station in Šibenik Bay; for the station in vicinity of the Industrial port of Split and for the two stations in Coastal zone. Low environmental risk was determined in less urbanised areas such as Island of Pag. Sediment extracts were further analysed for acute toxicity by measurements of decrease in bioluminescence upon exposure to sediment extracts. Obtained results show disagreement between sediment toxicity predicted upon PAH levels in sediment and experimentally obtained sediment toxicity. Sediment extracts in which low PAH levels were measured showed high acute toxicity indicating that concentrations of PAH alone are a poor indicator of sediment toxicity. Correlation analysis between concentrations of specific PAH compounds and toxicity revealed the strongest association between acute sediment toxicity and sulphur-containing PAH suggesting the S-PAH should be considered in sediment toxicity assessment.