Sulfur-isotope anomalies recorded in Antarctic ice cores as a potential proxy for tracing past ozone layer depletion events

• Published in: PNAS Nexus
• Main Authors: Dasari, Sanjeev, Paris, Guillaume, Charreau, Julien, Savarino, Joel
• Other Authors: Institut des Géosciences de l’Environnement (IGE), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP ), Université Grenoble Alpes (UGA), Centre de Recherches Pétrographiques et Géochimiques (CRPG), Institut national des sciences de l'Univers (INSU - CNRS)-Université de Lorraine (UL)-Centre National de la Recherche Scientifique (CNRS), This study was supported by the Marie Skłodowska-Curie Action Grant number 1010180
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2022
• Subjects: Major Category: Physical Sciences Minor Category: Earth; Atmospheric; and Planetary Sciences Cosmic-ray background; UV Radiation; Sulfur Mass-Independent Fractionation (S-MIF); Δ 33 S; [SDU.OCEAN]Sciences of the Universe [physics]/Ocean; Atmosphere; [SDU.STU.GC]Sciences of the Universe [physics]/Earth Sciences/Geochemistry; Antarctic; Antarc*; ice core
• Online Access: https://hal.science/hal-03775537; https://hal.science/hal-03775537/document; https://hal.science/hal-03775537/file/pgac170.pdf; https://doi.org/10.1093/pnasnexus/pgac170

International audience Abstract Changes in the cosmic-ray background of the Earth can impact the ozone layer. High-energy cosmic events (e.g., Supernova, SN) or rapid changes in the Earth's magnetic field (e.g., Geomagnetic Excursion, GE) can lead to a cascade of cosmic rays. Ensuing chemical reactions can then cause thinning/destruction of the ozone layer — leading to enhanced penetration of harmful UV radiation towards the Earth's surface. However, observational evidence for such UV ‘windows’ is still lacking. Here, we conduct a pilot study and investigate this notion during two well-known events: the multiple SN event (≈10 kBP) and the Laschamp GE event (≈41 kBP). We hypothesize that ice-core-Δ33S records—originally used as volcanic fingerprints—can reveal UV-induced background-tropospheric- photochemical imprints during such events. Indeed, we find non-volcanic S-isotopic anomalies (Δ33S≠0 ‰) in background Antarctic-ice-core sulfate during GE/SN periods, thereby confirming our hypothesis. This suggests that ice-core-Δ33S records can serve as a proxy for past ozone-layer-depletion events.