Assessment of the role of urban monumental surfaces as record of pollution: the case study of the fountain of Camerlata

Cultural Heritage suffers daily the damages of environmental pollution, especially in those areas interested by heavy traffic. Various degradation phenomena occur, being soiling, deposition and black crust formation the most diffused and outstanding ones. In particular, since stone monuments undergo only periodically conservation or maintenance works, they are actually passive sampler of particulate, whose content of metal species should carefully be evaluated for their catalytic role in decay reactions such as the sulphatation of carbonatic substrates, e.g. marbles and mortars. The monitoring of these metals on the surfaces could be a good practice of planned conservation in urban areas, as indicator of the effects of pollution on monuments. As a first case study, the presence of metal tracers of recent automobile emissions, i.e. platinum and rhodium, was determined on the surfaces of a XX Century monument in Como, the Fontana di Camerlata.