Evaluation of natural gamma radiation and absorbed gamma dose in soil and rocks of Perambalur district (Tamil Nadu, India)

摘要

The activity concentrations and absorbed gamma dose of primordial radionuclides ~(238)U, ~(232)Th and ~(40)K were determined employing γ-ray spectrometry in 31 soil samples from the land area earmarked for house construction in Perambalur district and 14 rock samples from quarries that supply stones for the entire district. The soil samples registered relatively a higher mean value of 13.2 Bq kg~(-1) for ~(238)U, 66 Bq kg~(-1) for ~(232)Th and 340.3 Bq kg~(-1) for ~(40)K as compared to mean values for rock samples (~(238)U—8.0 Bq kg~(-1); ~(232)Th—65.1 Bq kg~(-1); ~(40)K— 199.1 Bq kg~(-1)). The mean absorbed gamma dose rate for soil (61.4 nGy h~(-1)) marginally exceeded the prescribed limit of 55 nGy h-1 while, rocks registered the mean absorbed gamma dose rate of 10.4 nGy h~(-1). The mean radium equivalent activity was distinctly higher in soil (130.6 Bq kg~(-1)) than in rock (20.0 Bq kg~(-1)). However, these values were lower than the limit (370 Bq kg~(-1)) set by OECD for building materials. It is evident from the data that the soil and rocks do not pose any radiological risk for house constructions in Perambalur district.