Determining the geochemical fingerprint of the lead fallout from the Notre-Dame de Paris fire: Lessons for a better discrimination of chemical signatures

• Published in: The Science of the total environment 2023-03, Vol.864, p.160676, Article 160676
• Main Authors: Briard, Justine, Ayrault, Sophie, Roy-Barman, Matthieu, Bordier, Louise, L'Héritier, Maxime, Azéma, Aurélia, Syvilay, Delphine, Baron, Sandrine
• Format: Article
• Language: English
• Subjects: Continental interfaces, environment; Environmental pollution; Historical monuments; Lead isotopes; Metals; Ocean, Atmosphere; Sciences of the Universe; Tracing pollution
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2022.160676

On 2019, the fire of Notre-Dame de Paris cathedral (“NDdP”) spread an unknown amount of lead (Pb) dust from the roof of the cathedral over Paris. No data describing the geochemical fingerprint of the roof lead, as well as no particle collected during the fire, were available: a post-hoc sampling was performed. To discriminate the potential environmental impact of the fire from multiple Pb sources in Paris, it was mandatory to define unequivocally the fire dust geochemical signature. A dedicated and in hindsight geochemistry-based strategy was developed to eliminate any source of potential contamination due to sampling substrates or previously deposited dust. Radiogenic Pb isotopic signatures (206Pb/207Pb and 208Pb/206Pb ratios) and elemental ratios were determined in 23 Pb-rich samples collected inside NDdP. We determined that the dust collected on wood substrates on the first floor was most representative of fire emissions. These samples were the analyzed for the 4 Pb isotopes (204, 206, 207, 208) and the fire dust signature is characterized by ratio values of 206Pb/207Pb: 1.1669–1.1685, 208Pb/206Pb: 2.0981–2.1095, 208Pb/204Pb: 38.307–38.342, 207Pb/204Pb: 15.633–15.639 and 206Pb/204Pb: 18.242–18.275. In addition, the fire dust presents typical element-to-Pb ratio. This fingerprint was compared to the signatures of the known local Pb sources. The geochemical fingerprint of the fire is significantly different from that of the dominant urban Pb source. This will allow future evaluation of the contribution of the fire to Paris Pb pollution and of the real extent of the area affected by the Pb-containing dust plume. Moreover, the geographical origin of Pb used for the roof restauration and the spire building was identified. These findings open new ways to study the Pb sources in historical monuments for environmental impacts evaluation, as well as for historical perspectives. [Display omitted] •The 2019 fire of Notre-Dame spreads an unknown amount of leaded dust over Paris.•An innovative strategy was developed to define the plume geochemical signature.•Lead isotope signature and elemental ratios were determined in indoor dust.•Comparison of the fire fingerprint with the different Pb sources in urban environment•The fire leaded inputs are distinct from the pre-existing urban contamination.