Occurrence and concentration of PAHs in clams and sediments of the marine coastal lagoon of Ganzirri (Italy). Extraction, GC-MS analysis, distribution and sources

Abstract

The distribution of selected Polycyclic Aromatic Hydrocarbons (PAHs) in surface sediments and clams of marine coastal lagoons, called Ganzirri, located at the Sicilian coast of the, Messina's strait, has been investigated by GC/MS analysis with Selected Ion Monitoring (SIM) mode. The lagoon is characterized by abundant organic detritus, deriving from aquagenic and anthropogenic inputs. Anoxic/reduced conditions of sediments make them a preferential site for uptake and preservation of PAHs. From an eco-toxicological point of view, the aquatic ecosystem investigated appears to be moderately polluted. The investigations have been performed on the 16 PAHs recommended by US-EPA as priority pollutants to be monitored in the framework of environmental quality control. The sediment PAH concentrations ranged from 135 to 1650 mu g/kg dry matrix. The total concentrations of PAHs in clams ranged from 60 to 1427 mu g/kg d.w. The relative standard deviation (RSD) for all samples of the concentration replicates of individual compounds ranged from 10% to 25%. The resulting distributions and ratios of specific compounds have been discussed in terms of sampling location and origin of contaminants. The results obtained show that levels of contamination are not homogeneous throughout the stations. In the Ganzirri Lagoon, the bioavailability of hydrophobic organic compounds, such as PAHs, seems to be mainly governed by chemical characteristics of the contaminants. Pyrolytic compounds (penta- and hexa-aromatics) are not readily available. In contrast, petroleum hydrocarbons (some tetra-aromatics) are accumulated by clams to a great extent.