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In the context of a changing environment, the preservation of outdoor built heritage is increasingly threatened. Furthermore the application of conservation products does not always achieve the expected results. Furthermore, preliminary tests aimed at evaluating the performance of new products often show them to be inappropriate. In such situations, the paper reports the outcomes of an innovative methodology adopted to assess the efficiency and durability of nano-based consolidating products utilized for the conservation of carbonate artworks, carrying out field exposure tests on Carrara Marble model samples in different sites. Surface properties, superficial cohesion, distribution and penetration of the conservation products and their interactions with substrates and environmental conditions were examined and compared with the features of undamaged samples and of artificially damaged samples.

The EC TeACH project (Technologies and tools to prioritize assessment and diagnosis of air pollution impact on immovable and movable cultural heritage) sets out to understand the different types of damage on cultural heritage in different sites: Oslo (Norway), Florence (Italy), Salè (Marocco), Cologne (Germany). There was performed the characterization of damage layer including the ion compounds performed by ion chromatography (IC) and elemental composition, carried out by coupled plasma-optical emission spectrometer (ICP-OES). To understand the origin of the ions and elements detected in the black crust specimens, the data obtained during analysis were analyzed statistically using the R Project for Statistical Computing. The results achieved shows that in all cases the SO2 has been proved to have among the pollutants the priority role in damage layer formation. Moreover, there has been reflected the impact of local pollutant sources on damage processes occurring, e.g. coal combustion and emission from railway transport in case of Cologne Cathedral, the marine aerosol in case of coastal sites Sale and Oslo.

The available scenarios of multi-pollutants trends in Europe indicate a shift in modern urban atmospheres from and SO2 dominated situation to a multi-pollutant situation, linked to the driven role played by traffic in determining the overall pollution in urban centres. In view of the proven overwhelming influence of mobile combustion sources in determining the future urban atmosphere, “modern’’ soiling on built heritage will be likely to contain primarily organic carbon (OC). This will imply a change in composition of damage layers, which will presumably assume a yellow-brown coloration. The EC TeACH project (Technologies and tools to prioritize assessment and diagnosis of air pollution impact on immovable and movable cultural heritage) sets out to understand the different types of damage on cultural heritage that can be expected in the future, due to changes in pollutants, both in terms of typology and concentration. To accomplish this goal, from the technological point of view the project aims to develop a non invasive device for the continuous monitoring of the damage caused on monuments located outdoor by changing pollution impact, based on the change of colour of the architectural surface. A prototype is currently under testing at 5 monuments located in urban sites in Europe and one in the Mediterranean area, characterized by different environmental and climate conditions: Cologne Cathedral (Germany), S. Maria del Fiore Cathedral in Florence (Italy), the National Gallery in Oslo (Norway), the Arriaga Theatre in Bilbao (Spain), the National Museum in Cracow (Poland), the historic walls of Salè (Morocco). Colorimetric analyses directly at the building surface for blackening/colour change characterisation using a portable spectrophotometer. Results achieved within this still running project on the composition of damage layers will be presented and discussed. Elaboration of carbon fractions data will be liked in particular to colorimetric parameters (L*a*b*), with the aim of exploring the application of monitoring of color change of architectural surfaces as potential strategy for preventive conservation.

In order to asses the environmental impact on the Baptistery, situated in the urban centre of Florence, a continuous monitoring of physical, chemical and biological agents was performed. The intent is to study the alteration produced by the action of atmospheric contaminants on works of art, acquire data on their state of conservation and draw up a risk map relating to chemical pollutants.

In order to evidence both the products of damage reactions and the components due to atmospheric deposition, and to identify the pollutant sources, specimens of damaged stone, consisting of surface black crusts with underlying unaltered material, were sampled on the blackened façade of the Corner Palace on the Canal Grande in Venice and submitted to a combination of physico-chemical analytical techniques. The samples were observed in thin section under optical microscope, and the damaged surface was investigated using a scanning electron microscope. X-ray diffractometric analyses, gravimetric and differential thermal analyses, and ion chromatographic analyses were performed in order to identify the main crystalline species, quantify gypsum and carbonate, and measure the anion concentrations, respectively. Finally, the carbon fractions were discriminated and measured following a chemical-thermal methodology specifically developed for damage layer specimens. The data obtained indicate gypsum as the main product of damage processes occurring due to wet and dry SO2 deposition. The burning of fossil fuels produces gases, smoke and particulate carbonaceous matter that deposit on building surfaces and react with the underlying calcareous materials forming the damage layer. Carbonaceous particles have a catalytic effect on CaSO4·2H2O formation and the ensuing surface blackening on building exteriors.

Il monitoraggio del particolato atmosferico riveste fondamentale importanza nella protezione del patrimonio culturale in quanto, per garantirla, è indispensabile conoscerne la composizione, in particolare della frazione solubile. Attualmente pochi sono i dati disponibili relativi a misure effettuate in prossimità dei monumenti. Il dosaggio della componente carboniosa nel particolato atmosferico risulta poi estremamente problematica e complessa. Nel presente lavoro, che ha lo scopo di fornire indicazioni utili ai responsabili della protezione e conservazione dei beni culturali, agli urbanisti e gestori del traffico e ai legislatori responsabili delle direttive di qualità dell’aria, vengono riportati alcuni risultati preliminari relativi alle indagini analitiche effettuate sull’aerosol atmosferico presso le Porte Nord e Sud del Battistero di Firenze. Le misure effettuate interessano la componente ionica e il carbonio non carbonatico. Il campionamento è stato eseguito utilizzando filtri in policarbonato, per le analisi in cromatografia ionica, e filtri di quarzo per le analisi della componente carboniosa. Dalla elaborazione dei dati analitici ottenuti nel corso del primo anno di monitoraggio e dei parametri metereologici e microclimatici rilevati, sono emerse importanti indicazioni riguardo le sorgenti di emissione dei principali inquinanti atmosferici presenti nell’area circostante le due Porte oggetto di studio del Battistero di Firenze e correlati con il degrado del materiale lapideo del monumento.

The work aims to improve knowledge on the role of black crusts in stone decay, their relationship with the carbonaceous particle content of the atmosphere, and surface blackening rate. Because of the diversity of urban atmospheric pollution, different target sites have been selected among European cities, in order to investigate the formation of damage layers on monuments built in low porous carbonate stone. This report lists the results of an analysis of black crusts from the Vittoriano Monument in Rome, a crucial site for the study of cultural heritage protection in the Mediterranean basin.

It is generally agreed that the role played by aerosols in determining the air quality in urban areas is steadily increasing. As well as being among the main agents responsible for today’s atmospheric pollution, atmospheric particles are also recognized to participate actively in damage layer formation. In fact, recent years have witnessed a marked acceleration in surface soiling phenomena, as can be observed in the continual blackening of monument surfaces located in polluted areas. While numerous authors have performed detailed studies on the impact of the sulphation process in monument decay on a world-wide scale, surface blackening remains in need of in-depth investigation. The EC project CARAMEL (Carbon content and origin of damage layers in European monuments) has as one of its fundamental work steps the analytical study of black crusts collected at different monuments located in European urban sites. The aim is to create a data base of the carbon fraction concentrations present, and understand their relationship with the content of aerosol carbon components.

The principal aim of the present work is to analyse the alteration products due to reactions between atmospheric components and one of the most common limestone utilised to build the Tower of London, in order to identify the pollutant sources and the damage mechanisms affecting the masonry. The samples were characterized using classical analytical methodologies associated with new methodologies specifically set up during the CARAMEL Project to obtain quantitative data on crust compositions. Gypsum is the main constituent of the damage layers, originating from the sulphation process that occurs as a result of SO2 deposition. Moreover, black crusts reveal different physical and chemical features from those of thin grey-brownish damage layers, a finding that reflects the changes in the pollution sources contributing to crust formation.

The availability of a correct, accurate and reproducible analytical method for a complete carbon balance in black crusts is of major importance in understanding the effects of the interaction between atmospheric pollutants and the environment, particularly in the partitioning of pollutant sources, damage mechanism identification, and a sustainable protection of cultural heritage. The EC Project CARAMEL has among its primary goal the setting up of a suitable and reliable analytic technique able to distinguish and measure carbon fractions in damage layers, particularly elemental carbon. The presence of a significant amount of carbonate carbon and the removal of organic carbon are critical steps in the measurement of carbon compounds in black crusts. A chemical-thermal methodology for carbon analyses in black crusts was set up, whose specificity, accuracy and precision was tested on appropriate standard samples. The results obtained indicate that the methodology satisfactorily distinguishes among carbon species and allows a reliable evaluation of their quantities in damage layers.

Le patine di ossalato di calcio rappresentano una delle forme di alterazione più conosciuta dei monumenti lapidei. In questo lavoro, alle analisi di routine sulle patine di ossalato di calcio campionate alla superficie di murature storiche dell'isola di Torcello (VE), sono state associate analisi isotopiche.