An analysis of the black crusts from the Seville Cathedral: A challenge to deepen the understanding of the relationships among microstructure, microchemical features and pollution sources Silvestro A. Ruffolo a, ⁎, Valeria Comite a,b , Mauro F. La Russa a , Cristina M. Belfiore a,b , Donatella Barca a , Alessandra Bonazza c , Gino M. Crisci a , Antonino Pezzino b , Cristina Sabbioni c a Università della Calabria, Dipartimento di Biologia, Ecologia e Scienze della Terra (DiBEST), Via Pietro Bucci 87036, Arcavacata di Rende, CS, Italy b Dipartimento di Scienze Biologiche, Geologiche e Ambientali–Sezione di Scienze della Terra, Università di Catania, Corso Italia 57, 95129 Catania, Italy c Istituto di Scienze dell'Atmosfera e del Clima, ISAC-CNR, Via Gobetti 101, 40129 Bologna, Italy HIGHLIGHTS • Black crusts from the Cathedral of Seville have been studied. • The impact of the pollution on the Cathedral of Seville has been assessed. • A geochemical study has been performed on black crusts from Seville Cathedral. abstract article info Article history: Received 9 July 2014 Received in revised form 8 September 2014 Accepted 8 September 2014 Available online xxxx Editor: J. P. Bennett Keywords: Seville Cathedral Black crusts LA-ICP-MS analysis Heavy metals Environmental pollution The Cathedral of Seville is one of the most important buildings in the whole of southern Spain. It suffers, like most of the historical buildings located in urban environments, from several degradation phenomena related to the high pollution level. Undoubtedly, the formation of black crusts plays a crucial role in the decay of the stone ma- terials belonging to the church. Their formation occurs mainly on carbonate building materials, whose interaction with a sulfur oxide-enriched atmosphere leads to the transformation of calcium carbonate (calcite) into calcium sulfate dihydrate (gypsum) which, together with embedded carbonaceous particles, forms the black crusts on the stone surface. To better understand the composition and the formation dynamics of this degradation product and to identify the pollutant sources and evaluate their impact on the stone material, an analytical study was carried out on the black crust samples collected from different areas of the building. For a complete characterization of the black crusts, several techniques were used, including laser ablation inductively coupled plasma mass spectrometry, Fourier transform infrared spectroscopy, micro infrared spectroscopy, optical and scanning electron microscopy. This battery of tests provided information about the nature and distribution of the mineralogical phases and the elements within the crusts and the crust-substrate interface, contributing to the identification of the major pol- lution sources responsible for the deterioration of the monument over time. In addition, the results revealed a re- lation among the height of sampling, the surface exposure and the concentration of heavy metals. Finally, information has been provided about the origin of the concentration gradients of some metals. © 2014 Elsevier B.V. All rights reserved. 1. Introduction In recent decades, the architectural heritage has been degraded more than in the past, which suggests that air pollution is one of the most important causes of this process (Amoroso and Fassina, 1983; Bonazza et al., 2007; Brimblecombe, 1999, 2000; Del Monte et al., 1981; Turkington et al., 1997; Zappia et al., 1998). Over time, we have observed the consumption of wood, used for centuries, followed by coal in the nineteenth century (coinciding with the industrial revolu- tion) and petroleum in the twentieth century (fuels and fuel-oils). Cur- rently, emissions from mobile combustion sources are the main agents responsible for the pollution in European cities and the adverse effects of vehicular traffic are likely to continue to increase in the future. Scien- tific research has been carried out on the degradation of the architectur- al heritage (Amoroso and Fassina, 1983; Moropoulou et al., 1997; Antill and Viles, 1999; Smith et al., 2003), which is generated by the deposi- tion of air pollutants; both sulfur dioxide (SO 2 ) and particulate matter, Science of the Total Environment 502 (2015) 157–166 ⁎ Corresponding author. Tel.: +39 0984 493535; fax: +39 0984 493689. E-mail address: silvestro.ruffolo@unical.it (S.A. Ruffolo). http://dx.doi.org/10.1016/j.scitotenv.2014.09.023 0048-9697/© 2014 Elsevier B.V. All rights reserved. Contents lists available at ScienceDirect Science of the Total Environment journal homepage: www.elsevier.com/locate/scitotenv