Atmospheric 210Pb activity concentrations in Stepnogorsk city, North Kazakhstan uranium province area

Lead-210 ( 210 Pb), a decay product of 222 Rn in the 238 U decay series, is associated with aerosol particles in the atmosphere and is therefore widely used as a tracer of atmospheric processes and aerosol dynamics. This study focused on airborne 210 Pb levels to evaluate the radiological influence of nearby uranium processing and waste storage facilities in North Kazakhstan uranium province. Collection of aerosol particles was conducted in Stepnogorsk city during 2020–2022 with the exception of the winter months. Activity of 210 Pb and major ion concentrations in seven size-fractionated aerosol particles were determined by high-purity germanium (HPGe) detector and ion chromatography, respectively. The observed 210 Pb activity concentrations in aerosol samples varied between 0.46±0.01 mBq/m 3 and 2.60±0.03 mBq/m 3 , with an arithmetic mean of 0.86 mBq/m 3 . The radiation dosimetry of daily inhalation of 210 Pb through exposure to outdoor air was estimated to be from 0.9 to 2.5 μSv/y. Although this level is low compared to global mean exposures, the long term presence of inhaled 210 Pb in the body constitutes a persistent radiation risk. The negative correlation (r=-0.60) was observed between total activity and average temperature indicating an increase in concentration with decreasing temperature. The dominant fraction of atmospheric 210 Pb predominantly was found in fine aerosol particles smaller than 2.1 μm, and accounted for 95.3±12.0% of the total. The linear correlation of 210 Pb with sulfate, nitrate, and chloride suggests that human activities, including coal combustion, are possible contributors to atmospheric 210 Pb in this study area. This highlights the importance of considering local anthropogenic emissions when interpreting the atmospheric 210 Pb levels. • Atmospheric size-fractionated 210 Pb measured in North Kazakhstan uranium region. • Higher 210 Pb levels were observed under lower ambient temperatures. • Fine aerosol particles were the dominant carriers of atmospheric 210 Pb. • 210 Pb levels correlate with suggesting human activity sources.