The damage induced by atmospheric pollution on stone surfaces: The chemical characterization of black crusts

Atmospheric pollution is one of the most important causes of monuments surfaces decay in highly polluted urban environments. The deterioration phenomenon known as black crusts formation is one of the most dangerous degradation processes due to airborne pollutants. An in depth study has been carried out on the carbonaceous fraction (organic and elemental carbon, i.e. OC and EC) in black crusts samples coming from different Italian Monuments stones, mortars or bricks specimens sampled from monuments of historical interests and analysed by a multi-analytical approach. In particular, the characterization of organic carbon and elemental carbon was performed using a new analytical approach. The study of black crusts degradation has been completed with the quantifications of main ions, present on the altered stones surfaces. These species are also ascribable to atmospheric pollution and are responsible of degradation phenomenon such as sulphation.