Identification of Polycyclic Aromatic Hydrocarbons (PAHs) in the black crusts of Sicilian stone monuments: distribution and sources

Polycyclic Aromatic Hydrocarbons are a family of compounds with known carcinogenic potential; their properties of lipophilicity, low water solubility and adsorption to particles and sediments make them a potentially dangerous group of chemicals and a threat to the environment and its bio-resources. The concentrations of total Polycyclic Aromatic Hydrocarbons (PAHs) and 19 individual compounds in 8 black crusts sampled from historical building of Palermo (Italy) were analyzed, by gas chromatography/mass spectrometry (GC/MS) in selected ion monitoring (SIM) mode. PAH concentrations ranged from 78 to 9798 g/Kg of dry matrix. The resulting distributions and molecular ratios of specific compounds have been discussed in terms of sample location and origin of organic matter. Data collected show that these black crusts are contaminated. The levels of contamination are not quite homogeneous throughout the sites, while relative distributions of PAHs are quite homogeneous in the most of the sampling points. The organic matter content, obtained by ignition analysis, and PAHs are correlated (r = 0.98). It is also shown that pyrolytic origin is the main source of these compounds in black crusts.