Meteoritic materials within sulfate aerosol particles in the troposphere are detected with transmission electron microscopy

Abstract

When meteorites impact the Earth’s atmosphere, they fractionalize and ablate, generating aerosol particles containing extraplanetary materials. Meteoritic materials have been identified among aerosol particles using elemental markers (iron and magnesium); however, their shapes and mixing states are largely unknown. Here we demonstrate the presence of meteoritic materials collected by a research aircraft from the troposphere over the western Pacific using transmission electron microscopy. The distribution of meteoritic elements within individual particles coincided with sulfur, indicating that they were in forms of sulfates, i.e., water-soluble. Enhanced number fractions of sulfate particles with meteoritic materials were observed during tropopause-folding events, suggesting that they originated from the stratosphere. We also estimated the potential contributions of the Chelyabinsk meteorite event, which occurred 5 months prior to the sampling and represents the largest meteorite event in the past century. This study provides unique observational evidence for the linkage between extraplanetary materials and tropospheric aerosols.