Influence of soil physicochemical properties on the distribution and variability of 137Cs activity concentrations in urban soils of Ózd, Hungary

Abstract Urban soils exhibit substantial heterogeneity in their physicochemical properties influencing the sequestration of 137 Cs. This study investigates the distribution of 137 Cs in urban soils from Ózd, Hungary, and its relationship with soil properties using multivariate statistical analysis. The activity concentrations of 137 Cs were measured by gamma-ray spectrometry with well-type HPGe detector and ranged from below detection limit (DL = 0.3 Bq kg⁻ 1 ) to 19.3 ± 0.5 Bq kg⁻ 1 , indicating distinct spatial variability. Ammonium and silt content of the studied urban soils were identified as the primary variables, together explaining 45% of 137 Cs variability. These results demonstrate that the interplay between ionic exchange and sorption onto fine-grained soil fractions controls 137 Cs retention, providing a framework for understanding radionuclide fate in disturbed urban soils.