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.