Stone-built heritage as a proxy archive for long-term historical air quality: A study of weathering crusts on three generations of stone sculptures on Broad Street, Oxford

Wilhelm, Katrin, Longman, Jack, Orr, Scott Allan and Viles, Heather (2021) Stone-built heritage as a proxy archive for long-term historical air quality: A study of weathering crusts on three generations of stone sculptures on Broad Street, Oxford. Science of the Total Environment, 759. p. 143916. ISSN 0048-9697

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Black crusts on historic buildings are mainly known for their aesthetic and deteriorative impacts, yet they also can advance air pollution research. Past air pollutants accumulate in distinct layers of weathering crusts. Recent studies have used these crusts to reconstruct pollution to improve our understanding of its effects on stone-built heritage. However, the majority of the studies provide only coarse resolution reconstruction of pollution, able to distinguish between ‘inner = old’ and ‘outer = modern’ crust layers. In contrast, very few studies have linked distinct periods of exposure to pollution variations in the composition of these crusts. Here we address this research gap by developing a finer-scale resolution pollution record. Our study explored the unique configuration of limestone sculptures in central Oxford, which have been exposed over the last 350 years to three different periods of atmospheric pollution; the early Industrial Revolution, the Victorian period and the 20th century. When the first two generations of sculptures were moved to less polluted areas, their ‘pollution clocks’ were stopped. Here we discuss the potential of investigating the ‘pollution clock’ recorded in the geochemical makeup of each sculpture generation's weathering crust layers. We found the analysed crusts record clear changes related to the evolution of modes of transport and industrial and technological development in Oxford. Higher levels of Arsenic (As), Selenium (Se) are linked to pollution from coal burning during Victorian times and Lead (Pb) indicated leaded petrol use in modern times. Our work shows that stone-built heritage with a known history of air pollution exposure allows improving the pollution reconstruction resolution of these weathering crusts. The results provide the basis for calibrating long-term geochemical archives. This approach may be used to reconstruct past air quality and has the potential to inform stone weathering research and conservation, in addition to improving the reconstruction of historical pollution.

Item Type: Article
Additional Information: Funding Information: The research team would like to express thanks to Lisa Brionne-Gray, Operations Manager at the Sheldonian Theatre, Oxford), Danielle Battigelli (EA, History of Science Museum), the joiners team from the Estate Services (University of Oxford), Emilia McDonald (Head of Conservation and Buildings at Estates Services), Sir Jonathan Bate (Provost, Worcester College, Oxford), Simon Bragnall (Head of Gardens, Worcester College, Oxford), Sophie (Fe) Torrance (Harcourt Arboretum, University of Oxford), Ella Quincy (The Old Country House, Malvern) for allowing and helping us to take samples. We are grateful to Martin Coombes for useful discussions and general support of the project. The authors are very grateful to the support given by the School of Geography and the Environment, University of Oxford, through a small grant from its ‘Inspiration Fund’.
Uncontrolled Keywords: Black crusts, Coal burning, Environmental pollution, Geochemical archives, Heavy metals, Palaeopollution
Subjects: F800 Physical and Terrestrial Geographical and Environmental Sciences
Department: Faculties > Engineering and Environment > Geography and Environmental Sciences
Depositing User: Rachel Branson
Date Deposited: 17 Feb 2023 11:46
Last Modified: 17 Feb 2023 12:00

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