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Injection of meteoric phosphorus into planetary atmospheres

DOI: 10.1016/j.pss.2020.104926 DOI Help

Authors: Juan Diego Carrillo-sánchez (University of Leeds) , David L. Bones (University of Leeds) , Kevin M. Douglas (University of Leeds) , George J. Flynn (State University of New York at Plattsburgh) , Sue Wirick (Focused Beam Enterprises) , Bruce Fegley (Washington University) , Tohru Araki (Diamond Light Source) , Burkhard Kaulich (Diamond Light Source) , John M. C. Plane (University of Leeds)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Planetary And Space Science

State: Published (Approved)
Published: April 2020

Open Access Open Access

Abstract: This study explores the delivery of phosphorus to the upper atmospheres of Earth, Mars, and Venus via the ablation of cosmic dust particles. Micron-size meteoritic particles were flash heated to temperatures as high as 2900 K in a Meteor Ablation Simulator (MASI), and the ablation of PO and Ca recorded simultaneously by laser induced fluorescence. Apatite grains were also ablated as a reference. The speciation of P in anhydrous chondritic porous Interplanetary Dust Particles was made by K-edge X-ray absorption near edge structure (XANES) spectroscopy, demonstrating that P mainly occurs in phosphate-like domains. A thermodynamic model of P in a silicate melt was then developed for inclusion in the Leeds Chemical Ablation Model (CABMOD). A Regular Solution model used to describe the distribution of P between molten stainless steel and a multicomponent slag is shown to provide the most accurate solution for a chondritic-composition, and reproduces satisfactorily the PO ablation profiles observed in the MASI. Meteoritic P is moderately volatile and ablates before refractory metals such as Ca; its ablation efficiency in the upper atmosphere is similar to Ni and Fe. The speciation of evaporated P depends significantly on the oxygen fugacity, and P should mainly be injected into planetary upper atmospheres as PO2, which will then likely undergo dissociation to PO (and possibly P) through hyperthermal collisions with air molecules. The global P ablation rates are estimated to be 0.017 t d−1 (tonnes per Earth day), 1.15 × 10−3 t d−1 and 0.024 t d−1 for Earth, Mars and Venus, respectively.

Journal Keywords: Cosmic dust; Planetary atmospheres; Ablation; Phosphorus thermodynamics; Zodiacal cloud

Subject Areas: Earth Science, Chemistry

Instruments: I08-Scanning X-ray Microscopy beamline (SXM)