Emission and transport of cesium‐137 from boreal biomass burning in the summer of 2010

Abstract

While atmospheric concentrations of cesium‐137 (137Cs) have decreased since the nuclear testing era, resuspension of 137Cs during biomass burning provides an ongoing emission source. The summer of 2010 was an intense biomass burning season in western Russia, with high levels of particulate matter impacting air quality and visibility. A radionuclide monitoring station in western Russia shows enhanced airborne 137Cs concentrations during the wildfire period. Since 137Cs binds to aerosols, satellite observations of aerosols and fire occurrences can provide a global‐scale context for 137Cs emissions and transport during biomass burning events. We demonstrate that high values of the Moderate Resolution Imaging Spectroradiometer aerosol optical depth coincide with detections of 137Cs, and use the relationship between 137Cs and aerosols to model 137Cs based on organic carbon emissions and transport with the Goddard Earth Observing System, version 5 model. The model's boreal biomass burning tracer explains approximately half of the daily variability in detected 137Cs concentrations at a monitoring station in western Russia. Constraining the model with the station observations, we calculate 137Cs emissions of 1.5 × 1012 Bq from biomass burning north of 40° in July and August 2010. The emissions and subsequent deposition lead to a small northward redistribution of 137Cs.