Through chemical and magnetic investigations on leaves and lichens, used as biological accumulators of polluting atmospheric particulates, the diffusion and type of vehicular dust emitted along Via dei Cerchi in the direction of the Schola Praeconum and on the archaeological areas of the Paedagogium and the Arcate Severiane was determined , on the southern slopes of the Palatine
A team of experts fromNational Institute of Geophysics and Volcanology (INGV), from the Archaeological Park of the Colosseum,University of Siena (UniSI) andNational Academy of the Lincei, characterized atmospheric metallic particulates due to vehicular traffic of Via dei Cerchi, studying its diffusion by sampling leaves of various tree and shrub species present in Via dei Cerchi and in the archaeological areas of the Palatine. The data on the leaves were integrated with those deriving from the exposure of lichen transplants placed at increasing distances from Via dei Cerchi up to the Schola Praeconum, in recent months the subject of an enhancement intervention as part of the National Recovery and Resilience Plan - Caput Mundi, and on the summit of the Palatine.
The study, entitled "", just published in the journal 'Science of the Total Environment', has shown that the concentration of metal particles bioaccumulated by lichens and leaves depends on the longitudinal distance from the road, with a modest influence of the height compared to the road surface. Therefore, to provide the best ecosystem services for preventive conservation of historical and cultural assets, trees must be positioned as close as possible to the road surface.
The research employed sophisticated multidisciplinary environmental techniques, aimed at determining the diffusion of the so-called "fine particles", PM, up to the archaeological area in question. PM notoriously creates dark layers, abrasion, and deterioration in cultural property, resulting in artistic loss and permanent damage.
The vehicular metal particles accumulated by leaves and lichens derive from a mixture of exhaust and braking emissions, dependent, in proportions, on the different types of traffic regime in Via dei Cerchi. The results indicated that leaves accumulate all components of PM, thus limiting the adverse effects of its fractions, whether atmospheric or linked to soil and resuspension, while lichens are the best bioindicators of only the airborne component of PM.
"Participation in this interesting and innovative project was also a unique experience for all of us, which enriched us both on a professional and human level. In addition to providing new data for scientific research, we were able to understand the levels and trends of atmospheric particulate pollution on our site, also analyzing the effectiveness of the shrub barriers planted on the Palatine in 2020 to contain polluting dust. I am really happy that so much work has then merged into an important scientific article, a truly significant result that I hope can continue thanks to interdisciplinary and shared research" he claims Alfonsina Russo, Director of the Colosseum Archaeological Park.
“This study was carried out as part of the CHIOMA (Cultural Heritage Investigations and Observations: a Multidisciplinary Approach) research project”, whose title is inspired by protective ecosystem services environmental provided by trees, declares Aldo Winkler, Head of the INGV Paleomagnetism Laboratory, who oversaw the magnetic investigations. “This project, in fact, introduces magnetic biomonitoring methodologies in an archaeological area of unique prestige in the world, providing precious indications on the ability of leaves, depending on the species and tree location, to accumulate polluting particulates, thus contributing to limiting their the diffusion and harmful effects on cultural heritage."
”The joint use of leaves and lichens, combined with chemical and magnetic analysis techniques, allows us to trace and quantify atmospheric pollutants, distinguishing anthropogenic emission sources from natural ones. Lichens, once again, have proven to be efficient bioindicators, especially when used as transplants, allowing the accumulation and type of polluting particulate to be delineated based on an experimental design with high spatial density and customizable depending on the investigation context. , stresses Stefano Loppi, professor of the Department of Life Sciences of UniSI, who oversaw the lichen exposure and chemical investigations, together with Lisa Grifoni, PhD student at UniSI and INGV.
“This study was born within the framework agreement of collaboration between the Colosseum Archaeological Park and the Accademia Nazionale dei Lincei, as institutions that share a common commitment to research and the diffusion of culture. In this sense, this work continues the studies originally undertaken at Villa Farnesina, representative seat of the Accademia Nazionale di Lincei, expanding the use of chemical and magnetic techniques to determine the anthropic urban impact on cultural heritage to an archaeological context", he adds Antonio Sgamellotti, Socio of the Accademia Nazionale dei Lincei and co-author of the study.
Further studies on the biomonitoring of air pollution in the Museums of Buenos Aires, Brunelleschi's dome of the Cathedral of Santa Maria del Fiore in Florence and at the Metropolitan Museum of Art (Met) in New York, to obtain, on different types of highly urbanized contexts, original data of great interest for the preventive conservation of cultural heritage.
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Photo 1: Shrubs sampled in the archaeological area of Paedagogium, southern slopes of the Palatine.
Photo 2: Lichen bag exposed on an oleander on the edge of the archaeological area of the Arcate Severiane, above Via dei Cerchi.
Photo 3: Lichen bag displayed inside the Schola Praeconum, Colosseum Archaeological Park
Photo 4: Traffic jam in Via dei Cerchi, near the entrance to the Schola Praeconum, with a view of the holm oaks.