Variability of 137Cs and natural radionuclides accumulation in mosses relative to soil activity in Iğdır, Türkiye

Abstract

Introduction: This study investigates the activity concentrations of 232Th, 226Ra, 40K, and 137Cs in soil and moss samples collected from locations in Iğdır Province, Türkiye to evaluate spatial patterns and radionuclide accumulation behavior. Methods: High-purity germanium (HPGe) gamma spectrometry was used to quantify radionuclide activities. Results: Statistical analyses included Shapiro–Wilk normality testing, descriptive comparisons between soil and moss, and correlation assessments. Concentration ratios (CR = Amoss/Asoil) were calculated to evaluate radionuclide accumulation patterns across species and sites. Spatial variability and multivariate structure were examined using PCA and k-means clustering to identify site- and nuclide-driven grouping patterns. Key radiological parameters calculated for the health risk analysis included absorbed gamma dose rate, internal and external hazard indices, radium equivalent activity, and annual effective dose equivalent. In moss samples, the mean activity concentrations of 226Ra, 232Th, 40K and 137Cs were measured as 13.74 ± 0.83 Bq kg-1, 13.79 ± 1.1 Bq kg-1, 244.72 ± 7.6 Bq kg-1, 129.47 ± 1.74 Bq kg-1, respectively, and in soil samples, 23.74 ± 0.82 Bq kg-1, 22.53 ± 1.11 Bq kg-1, 427.01 ± 8.95 Bq kg-1, 215.74 ± 1.83 Bq kg-1, respectively. Discussion: All calculated radiological hazard indices, derived from natural radionuclide concentrations, were within permissible recommended limits. Slightly elevated annual effective dose values and absorbed gamma dose rates are observed for the total activity concentrations of both anthropogenic and natural radionuclides, exceeding world population-weighted outdoor averages.