Geological evidence of extensive N-fixation by volcanic lightning during very large explosive eruptions - Archive ouverte HAL Accéder directement au contenu
Article Dans Une Revue Proceedings of the National Academy of Sciences of the United States of America Année : 2024

Geological evidence of extensive N-fixation by volcanic lightning during very large explosive eruptions

Slimane Bekki
Jean-Luc Le Pennec
Marco Rivera

Résumé

Most of the nitrogen (N) accessible for life is trapped in dinitrogen (N 2 ), the most stable atmospheric molecule. In order to be metabolized by living organisms, N 2 has to be converted into biologically assimilable forms, so-called fixed N. Nowadays, nearly all the N-fixation is achieved through biological and anthropogenic processes. However, in early prebiotic environments of the Earth, N-fixation must have occurred via natural abiotic processes. One of the most invoked processes is electrical discharges, including from thunderstorms and lightning associated with volcanic eruptions. Despite the frequent occurrence of volcanic lightning during explosive eruptions and convincing laboratory experimentation, no evidence of substantial N-fixation has been found in any geological archive. Here, we report on the discovery of a significant amount of nitrate in volcanic deposits from Neogene caldera-forming eruptions, which are well correlated with the concentrations of species directly emitted by volcanoes (sulfur, chlorine). The multi-isotopic composition (δ 18 O, Δ 17 O) of the nitrates reveals that they originate from the atmospheric oxidation of nitrogen oxides formed by volcanic lightning. According to these first geological volcanic nitrate archive, we estimate that, on average, about 60 Tg of N can be fixed during a large explosive event. Our findings hint at a unique role potentially played by subaerial explosive eruptions in supplying essential ingredients for the emergence of life on Earth.
Fichier non déposé

Dates et versions

hal-04446185 , version 1 (08-02-2024)

Identifiants

Citer

Adeline Aroskay, Erwan Martin, Slimane Bekki, Jean-Luc Le Pennec, Joël Savarino, et al.. Geological evidence of extensive N-fixation by volcanic lightning during very large explosive eruptions. Proceedings of the National Academy of Sciences of the United States of America, 2024, 121 (7), pp.e2309131121. ⟨10.1073/pnas.2309131121⟩. ⟨hal-04446185⟩
28 Consultations
0 Téléchargements

Altmetric

Partager

Gmail Facebook X LinkedIn More