Estimation of 238U and 232Th in soil and water of prominent fault region of Mizoram

Abstract

The study investigates radon and thoron concentrations in soil and water at one of the most prominent faults in Mizoram state, India. The obtained isotope pair data were consequently used for estimating the uranium and thorium content of the region. An indigenously developed and calibrated ZnS(Ag) alpha based scintillation counter (Model: SMARTRnDuo, BARC, India) was deployed for assessing radon and thoron data. Thoron concentration was found to be higher than radon concentration in both soil and water. The isotope pair and their parent nuclei concentration in water were found to be higher than in soil. The uranium and thorium content in soil were estimated to be 17.5 and 22.6 Bqkg-1 respectively, but in water, they were estimated to be 41.6 and 124.8 Bqkg-1 respectively. Comparisons with global averages were also presented in detail and no radiological risk has been observed for the region. A continuous radon data was generated at Mizoram University, Aizawl, Mizoram (India) for cross-analysis with data at Mat fault. It was observed that radon data of the two locations behave similarly during geophysical phenomena, indicating that the region was seismically active. No geophysical properties of thoron were observed.