Radon (222Rn) level variations on a regional scale from the Singhbhum Shear Zone, India: A comparative evaluation between influence of basement U-activity and porosity

This paper is devoted to the comparative study of the radon flux vs. uranium content and radon flux vs. porosity for mineral samples from some typical Indian rocks (schists, quartzites, argillaceous quartzites, slates and granites) used as building materials, primarily around the Singhbhum Shear Zone, Jharkhand State.As the radon flux of any particular rock type was investigated with reference to its uranium activity and porosity, a good concordance of porosity on radon flux was observed. Such a significant influence of porosity on radon flux was also observed when different rock types were inter-compared. For example, granite that is commonly considered as typical source of indoor radon showed depleted level of radon flux when compared to most other rocks in the study area. In case of rocks such as slates and argillaceous quartzites, low porosity exhibited reduced radon flux in spite of their enhanced radioactive source content. It is concluded that it may not be advisable to utilize materials that are uranium depleted for construction purposes without giving importance to the materials' porosity.