Multi O- and S-isotopes as tracers of black crusts formation under volcanic and non-volcanic atmospheric conditions in Sicily (Italy)

• Published in: The Science of the total environment Vol. 750; p. 142283
• Main Authors: Aroskay, A., Martin, E., Bekki, S., Montana, G., Randazzo, L., Cartigny, P., Chabas, A., Verney-Carron, A.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.01.2021; Elsevier
• Subjects: Atmospheric and Oceanic Physics; Black crust; Oxygen isotope; Physics; Stone degradation; Sulphur isotope; Volcanic emissions; Δ17O anomaly; Oxygen isotope; Sulphur isotope; Volcanic emissions; Black crust; Δ17O anomaly; Stone degradation
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2020.142283

The deterioration of monument or building stone materials is mostly due to the growth of black crusts that cause blackening and disaggregation of the exposed surface. This study reports on new oxygen (δ17O, δ18O and Δ17O) and sulphur (δ33S, δ34S, δ36S, Δ33S and Δ36S) isotopic analyses of black crust sulphates formed on building stones in Sicily (Southern Italy). The measurements are used to identify the possible influence of volcanic emissions on black crust formation. Black crusts were mostly sampled on carbonate stone substrate in different locations subject to various sulphur emission sources (marine, anthropogenic and volcanic). Unlike atmospheric sulphate aerosols that mostly exhibit Δ33S > 0‰, here most of the analysed black crust sulphates show negative Δ33S. This confirms that black crust sulphates do not result from deposition of sulphate aerosols or of rainwater but mostly from the oxidation of dry deposited SO2 onto the stone substrate. The δ34S and δ18O values indicate that most of black crust sulphate originates from anthropogenic activities. Δ17O values are found to be related to the sampling location. The largest 17O-anomalies (up to ~4‰) are measured in black crust from areas highly influenced by volcanic emissions, which demonstrates the strong involvement of ozone in the formation of black crusts in volcanically influenced environments. [Display omitted] •Black crusts are mostly collected on carbonate building stones from different environments (coastal, rural, urban and volcanic environments).•δ34S and δ18O indicate that black crust sulphur is mostly derived from anthropogenic sources.•Δ33S and Δ36S of black crust sulphate are distinct from those of atmospheric sulphate aerosols.•The largest Δ17O anomalies are measured in black crust sampled in locations downwind of an active volcano (Mt Etna).