An aerosol particle containing enriched uranium encountered in the remote upper troposphere

Area of Science:

• Atmospheric chemistry and physics
• Isotope analysis
• Aerosol science

Background:

• Submicron aerosol particles are crucial components of the atmosphere.
• Enriched uranium (specifically Uranium-235) is typically associated with anthropogenic activities.
• Previous atmospheric sampling has rarely identified particles with high Uranium-238 content, and never with enriched Uranium-235.

Purpose of the Study:

• To report the discovery and characterization of a unique submicron aerosol particle.
• To investigate the potential origin and implications of enriched uranium found in the atmosphere.
• To document an unusual atmospheric sample for future reference.

Main Methods:

• Aircraft-based sampling of atmospheric aerosols at high altitudes.
• Submicron particle characterization using advanced analytical techniques.
• Isotopic analysis to determine uranium isotope ratios (e.g., 235U/238U).
• Wind trajectory analysis and particle dispersion modeling to infer potential source regions.

Main Results:

• A submicron aerosol particle was collected at 7 km altitude near the Aleutian Islands.
• The particle contained a small percentage of enriched uranium oxide, with 235U comprising 3.1 ± 0.5% of 238U.
• The bulk of the particle's mass was consistent with heavy fuel oil combustion products.
• Source analysis suggested potential origins from various regions in Asia.

Conclusions:

• The presence of enriched uranium in an atmospheric particle is highly unusual and warrants further investigation.
• The particle's composition and isotopic signature suggest a potential, but currently unidentified, anthropogenic source.
• This finding may indicate a novel pathway for the dispersion of enriched uranium into the global atmosphere.