222Rn Exhalation Flux Rate and 226Ra in the Soils of a Copper-Mineralised Area

Uranium-series radionuclides exist in trace quantities in all soils and rocks on earth in variable concentrations. Among these, 222Rn gas exhaled by the soil of a geological location is the main contributor to the environmental radioactivity. A 222Rn exhalation flux study was carried out in the heavily mineralised area of the Singhbhum Copper Belt of Jharkhand, India. A significant seasonal variation in the soil gas exhalation was observed, which is attributable to the seasonal atmospheric parameters of the study area. The average 222Rn exhalation flux from the soil was estimated to be in the range of 4.5-$20.1\ \mathrm{Bq}\ {\mathrm{m}}^{-2}\ {\mathrm{s}}^{-1}$ with a mean of $10.1\pm 3.9\ \mathrm{mBq}\ {\mathrm{m}}^{-2}\ {\mathrm{s}}^{-1}$ and geometric mean (GM) of $9.5\ \mathrm{mBq}\ {\mathrm{m}}^{-2}\ {\mathrm{s}}^{-1}$. Also, 20 soil samples collected from the study area were analysed by the emanometric method, which estimated the 226Ra specific activity in the soils in the range of 9-$63\ \mathrm{Bq}\ \mathrm{k}{\mathrm{g}}^{-1}$ and a mean value of $39\pm 16\ \mathrm{Bq}\ \mathrm{k}{\mathrm{g}}^{-1}$.