Assessment of PAH contamination in estuarine sediments using the equilibrium partitioning–toxic unit approach

Estimates of the potential acute toxicity of PAH residues to aquatic organisms in UK estuarine sediments using the equilibrium partitioning–toxic unit (EqP-TU) approach indicate that sediments from the Clyde and Mersey estuaries and Southampton Water will have the highest mean toxicities. The PAH residues probably originate from a combination of specific industrial sources and inputs from surrounding conurbations via combustion and run-off. Maximum sediment toxicities were evident at specific locations in Southampton Water near a chemical plant outfall and in sediments in docks on the Wear and Clyde. The limitations of the EqP-TU approach, particularly with regard to the potential for the over estimation of toxicity due to high levels of non-bioavailable high molecular weight PAHs occluded in combustion particles are discussed.