Radioactivity concentrations in Soils in Beijing, China from 2019 to 2025

<title>Abstract</title> <p> This study evaluated the activity concentrations of ²²⁶Ra, ²³²Th, ⁴⁰K and ¹³⁷Cs in soil samples collected from Beijing, China. Soil sampling was across all 16 administrative districts of Beijing annually from 2019 to 2025 and 137 soil samples were collected. The annual mean activity concentrations ranged from 23.2 to 27.6 Bq/kg for ²²⁶Ra, 29.2 to 32.4 Bq/kg for ²³²Th, 563 to 621 Bq/kg for ⁴⁰K and 0.72–1.06 Bq/kg for ¹³⁷ Cs. No significant differences in the activity concentrations of ²²⁶Ra, ²³²Th, ⁴⁰K and ¹³⁷Cs across different years from 2019 to 2025 ( <italic>P</italic>  &gt; 0.05). For ²²⁶Ra, ²³²Th and ¹³⁷ Cs, the radioactivity concentrations in samples collected from mountains were significant higher than those from plains( <italic>P</italic>  &lt; 0.05t). No significant differences were observed in the ⁴⁰K radioactivity concentration in soils of different land types ( <italic>P</italic>  &gt; 0.05). The data from this study support the conclusion that there were no significant industrial releases of naturally occurring radionuclides or detectable releases of the artificial radionuclide ¹³⁷Cs in Beijing's soils between 2019 and 2025. The average values of ²²⁶Ra, ²³²Th, and ⁴⁰K activity concentration fall within the range of the world. </p>