Abstract_EANA2025-114

Abstract EANA2025-114

Modelling Global Abiotic Sulfur Cycling on Earth-like Terrestrial Planets

Rafael Rianço-Silva (1, 2, 3, 5) Javed Akhter Mondal (4, 5) Matthew A. Pasek (6), Henry Jurney (5), Marcos Jusino-Maldonado (5, 7) Henderson James Cleaves II (5, 8, 9, 10)

(1) - Instituto de Astrofísica e Ciências do Espaço, Observatório Astronómico de Lisboa, Ed. Leste, Tapada da Ajuda, 1349-018 Lisbon, Portugal (2) - Departamento de Física, Faculdade de Ciências, Universidade de Lisboa, 1749-016 Lisboa, Portugal (3) - Department of Physics and Astronomy, University College London, Gower Street, WC1E 6BT London, United Kingdom (4) - Deep Space Exploration Laboratory/CAS Key Laboratory of Crust-Mantle Materials and Environments, University of Science and Technology of China, Hefei, 230026, China (5) - Blue Marble Space Institute of Science, Seattle, USA (6) - Earth and Environmental Science, Rensselaer Polytechnic Institute, Troy, NY, USA (7) - Planetary Habitability Laboratory, University of Puerto Rico at Arecibo, Puerto Rico (8) - Earth-Life Science Institute, Tokyo Institute of Technology, Tokyo, Japan (9) - Earth and Planets Laboratory, Carnegie Institution of Washington, Washington DC, USA (10) - Department of Chemistry, Howard University, Washington DC, USA

Sulfur is a redox active element that may have helped mediate an electron flow that kickstarted life and which presently is an essential element for all life on Earth. Despite current uncertainties in global sulfur fluxes, modeling sulfur’s abiotic cycling through Earth’s deep history is important for understanding the impact of a planet-wide biosphere on sulfur’s geochemical cycling and availability and vice versa.

We present here an open-source, dynamical box model for estimating global sulfur fluxes and concentrations among surface and deep Earth reservoirs over Earth history, allowing tracking and estimation of the sulfur distribution in planetary reservoirs over deep time in the absence of life. While the main model presented here does not take into account the abrupt evolution of redox-shunting biosynthetic pathways such as oxygenic photosynthesis, we also modeled the abiotic sulfur cycle before and after a Great Oxidation Event (GOE)-like transition on Earth-like planets.

Our results suggest a considerably distinct chemical makeup of sulfur content in marine sediments in the absence of life on an Earth-like planet, leading to a marine sediment sulfate content two orders of magnitude larger than on present-day Earth and a marine sediment sulfide content 4 orders of magnitude lower than on present-day Earth, attributable to the lack of microbial sulfur metabolism. This model could be useful for understanding sulfur cycling on potentially habitable Earth-like exoplanets