Analysis of radionuclides and radiation hazards in soil, sediment, water, and rock in Sylhet, Bangladesh

The natural radioactivity level in soil, sediment, and water samples collected from the Bisnakandi region in Sylhet was measured using a high-purity germanium detector. The mean activity concentrations of radionuclides in samples from the Bisnakandi were: 232Th (surface soil: 28.60 ± 6.44 Bq/kg, depth soil: 34.97 ± 7.37 Bq/kg, sediment: 41.70 ± 8.22 Bq/kg, water: 16.37 ± 2.13 Bq/L), 226Ra (surface soil: 33.70 ± 6.85 Bq/kg, depth soil: 40.09 ± 8.06 Bq/kg, sediment: 47.60 ± 9.38 Bq/kg, water: 19.76 ± 3.16 Bq/L), and 40K (surface soil: 304.60 ± 20 Bq/kg, depth soil: 375 ± 23.10 Bq/kg, sediment: 455.80 ± 19.2 Bq/kg, water: 241 ± 19.70 Bq/L). The average activity concentrations in rock samples for 232Th, 226Ra, and 40K in (Jaflong, Bholagonj) were (45.69 ± 14.32 Bq/kg, 40.06 ± 12.71 Bq/kg), (36.27 ± 16.89 Bq/kg, 36.84 ± 13.02 Bq/kg), and (430.34 ± 36.82 Bq/kg, 426.7 ± 78.98 Bq/kg), respectively. All the hazard parameters, such as radium equivalent activity, absorbed dose, annual effective dose, and external hazard index, were found within the acceptable level recommended by international organizations.