Assessment of air pollutant sources in the deposit on monuments by multivariate analysis

A proper recognition of the pollutant sources in atmospheric deposit is a key problem for any action aiming at reducing their emission, being this an important issue with implications both on human health safeguard and on the cultural heritage conservation in urban sites. This work presents the results of a statistical approach application for the identification of pollutant sources in deposits and damage layers on monuments located in different European sites: Santa Maria del Fiore, Florence (Italy), Cologne Cathedral, Cologne (Germany), Ancient ramparts, Sale (Morocco), National Museum, Cracow (Poland) and National Gallery, Oslo (Norway). For this aim, the surface damage layers on monuments and historical buildings of the selected sites were collected and analyzed, in terms of ionic and elemental composition, through application of ion chromatography and induced coupled plasma-optical emission spectroscopy. The achieved results were processed by multivariate analyses such as correlation matrix and principal component analysis in order to identify the possible origin of pollutants affecting the state of conservation of the monuments. This allowed us to assume that in all case studies the traffic emission is the main pollutant source. In the case of Ancient ramparts, Sale (Morocco), and National Gallery, Oslo (Norway), the surfaces are also under influence of marine aerosols. Moreover, concerning the Cologne Cathedral, the strong impact of the pollutants emitted by railway station was also revealed.