Potential Source Apportionment and Meteorological Conditions Involved in Airborne ¹³¹I Detections in January/February...

Area of Science:

• Environmental Science
• Nuclear Chemistry
• Atmospheric Monitoring

Background:

• Particulate radioactive iodine-131 (131I) was detected in the European atmosphere over an 8-week period in January/February 2017.
• Concentrations were generally low (0.1–10 μBq m⁻³), with a notable exception in Western Russia (several mBq m⁻³).
• Detections were reported by approximately 30 monitoring stations across Europe.

Purpose of the Study:

• To investigate the sources and pathways of 131I detected in the European atmosphere.
• To apportion potential emission sources based on their expected contributions.
• To analyze the impact of meteorological conditions on 131I dispersion.

Main Methods:

• Analysis of 131I concentrations from multiple monitoring stations.
• Ranking of potential emission sources: radiopharmaceutical production, sewage sludge incinerators, nuclear power plants, and spontaneous uranium fission.
• Inverse modeling simulations to identify likely source locations and terms.
• Evaluation of meteorological data, focusing on temperature inversions and dispersion conditions.

Main Results:

• Widespread 131I detections were attributed to a combination of multiple source releases.
• Radiopharmaceutical production units were identified as the most probable primary source.
• A facility in Western Russia was a likely contributor, with its estimated source term within authorized limits.
• Local detections could be explained by other 131I uses, such as medical applications or sewage sludge incineration.
• Poor atmospheric dispersion due to winter temperature inversions enhanced observed concentrations.

Conclusions:

• Radiopharmaceutical production is the most likely source of widespread 131I atmospheric detections in Europe.
• Meteorological conditions significantly influenced the observed 131I concentrations.
• Existing monitoring networks and inverse modeling are effective tools for source apportionment of atmospheric radionuclides.