Natural radioactivity levels in the soils and human risk assessment in Tiruchirappalli district (Tamil Nadu, India)

The activity concentrations of ²²⁶Ra, ²³²Th and ⁴⁰K in 91 soil samples collected from proposed housing sites in Tiruchirappalli district were measured using gamma ray spectrometer, ²²²Rn activity using SSNTD technique and ambient absorbed gamma dose employing hand held scintillometer. The mean activity concentrations of ²²⁶Ra, ²³²Th and ⁴⁰K were found to be 6.5, 61.7 and 379.8 Bq kg^-1, respectively. The mean ambient gamma dose rate was 66.7 nGy h^-1 and the mean radon activity 210.8 Bq m^-3. The study identified two stations in which Ra_eq levels exceeded the permissible limit (370 Bq kg^-1). (author)