Analytical method, pattern and sources of polycyclic aromatic hydrocarbons (PAHs) in the stone of the Temples of Agrigento (Italy).

This study shows the extraction and analytical conditions for the determination of polycyclic aromatic hydrocarbons (PAHs) in the stone of archaeological and historical interest. The aim of this research was to determine the concentrations, distribution and the main sources of PAHs present in the surface layer of stone of the Temples of Agrigento. Together with PAHs, we analyzed sulphates and nitrates since it has been demonstrated that these are very destructive salts that play an important role in the deterioration of stones. Total PAHs at different sites of the Valley of Temples at Agrigento varied from 18 to 84 microg/kg. Analyses were performed by GC-MS. The relative abundance of molecular weight PAHs, together with the PAHs compound ratios and supported by the total index (by us proposed), demonstrate that the most samples in Hellenistic Agrigento historical buildings owe their PAHs to a predominant single mode of origin, i.e. anthropogenic combustion processes. The same origin of PAHs pollution was confirmed by the good correlations existing between total PAHs concentrations and the content of sulphates and nitrates of the analyzed samples.