Polycyclic aromatic hydrocarbons (PAHs) in marine sediments of the Hellenic coastal zone, eastern Mediterranean: levels, sources and toxicological significance

Abstract

Polycyclic aromatic hydrocarbons (PAHs) are widespread in sediments, particularly near areas of intense human activities. Due to their mutagenic and carcinogenic behaviour, PAHs are classified as priority contaminants to be monitored in environmental quality control schemes. The purpose of this study was to determine the levels of PAHs in major coastal areas of Greece that receive various pressures, investigate their sources and evaluate their potential toxicity by comparison against effects-based Sediment Quality Guidelines (SQG). Forty-one sediment samples were collected from four areas of the Hellenic coastline. PAH concentrations were determined by GC–MS, after Soxhlet extraction and fractionation by silica column chromatography. Source apportionment was conducted by isomeric ratio diagnostic criteria. The mean quotient Effects Range—Median (m-ERM) was used to evaluate the potential of adverse effects posed to benthic organisms. The levels of PAHs were found to vary widely from 100 to more than 26,000 ng g−1. The highest levels were found in the close vicinity of an alumina production plant in the Gulf of Corinth. High levels of PAHs were also found at a few sites in each of the areas studied, close to a nickel production plant (North Evoikos Gulf), at the rainwater and wastewater outfalls of the great urban areas of Athens and Thessaloniki and at the industrialized area of Elefsis Bay (Saronikos Gulf). At the most contaminated sites PAH had a pyrolytic origin. Comparison of PAH levels to the SQG indicated that less than 15% of the sites studied have an intermediate probability (24–49%) of being toxic. In general, discrete point sources were identified as the major contributors of PAH contamination in the Hellenic coastal zone. Therefore, source control measures should be considered for protecting, or restoring, sediment quality, particularly in areas that support a diversity of anthropogenic activities (e.g. fishing, tourism, industry).