Magnetism and environmental biomonitoring: application for the preventive conservation of Cultural Heritage
(1) University of Siena, Italy, (2) Istituto Nazionale di Geofisica e Vulcanologia, Rome, Italy, (3) Parco Archeologico del Colosseo, Rome, Italy, (4) CIFICEN-UNCPBA-CONICET, Tandil, Argentina, (5) Universidad Nacional San Martín, Buenos Aires, Argentina, (6) Peggy Guggenheim Collection, Venice, Italy, (7) Accademia dei Lincei, Rome, Italy
In urban contexts, Cultural Heritage (CH) is heavily threatened by particulate matter (PM), which acts on their surfaces creating functional and aesthetical losses. Magnetic and chemical biomonitoring has been applied as an innovative preventive strategy for evaluating the impact of PM and potentially toxic elements (PTEs) on CH. Lichens collected in remote areas are exposed for three months inside and outside CH sites. Plant leaves are collected for checking their role in the removal of airborne pollutants. The magnetic properties of lichens and leaves provide information about the composition, concentration and grain-size of the bioaccumulated magnetic fraction of PM, that is usually linked to anthropogenic, mainly vehicular, emissions. The first application was at Villa Farnesina, in Rome, Italy, where, despite the intense magnetic properties outdoors, the lichens showed a minor accumulation of metallic emissions indoor, due to the combined effects of the distance from the road and the retention properties of roadside Platanus leaves. At the Peggy Guggenheim Collection in Venice, Italy, lichen bags were exposed along a transect from the Grand Canal to the Museum’s Garden. In this lagoon context, the accumulation of magnetic PM was moderate outdoors and negligible inside the museum. The leaves of Pittosporum tobira were unsuitable for the removal of airborne particles. The bioaccumulation of PTEs was similar in indoor and outdoor lichens and the modest accumulation of magnetic particles outdoors was attributed to long-distance pollution. Further investigations are going on at the Parco Archeologico del Colosseo in Rome, and at two museums in Buenos Aires, Argentina, in busy urban sites where vehicular traffic is by far the main source of metallic emissions, The aim is to test these methods in various urban ecosystems, where the use of lichen transplants and the correct choice of leaves can substantially improve the provision of preventive conservation services.
Keywords: lichens, leaves, magnetic properties, PM, trace metals, cultural heritage
