Assessment of Beach sand using Gamma Ray Spectrometer in Thiruvanathapuram District, Kerala of South India

Abstract

It is well recognized fact that some areas of the world have anomalously high levels of natural background radiation referred to as high background radiation areas (HBRAs).  Typical examples include Yangjiang in China, Rasmar in Iran and In India, part of coastal areas of Kerala and Tamil Nadu fall in this category.  It has been established earlier that the cause for this high background is the presence of monazite (thorium). This study focuses on the estimation of the environmental radioactivity levels in the beach sands of Thiruvanathapuram district, Kerala.  

Using high resolution gamma ray spectroscopy activity concentrations of ⁴⁰K, ²³⁸U & ²³²Th were estimated. Activity concentrations ranged from 17-154 Bq/kg for ⁴⁰K, from 4 to 100 Bq/kg for ²³⁸U and from 6 to 296 Bq/kg for ²³²Th.The mean activity concentration values obtained for the radionuclide are below than the world average values reported by the UNSCEAR. Subsequently assessed radiological effects show that the mean radium equivalent activity is 65 Bq/kg. The range of the calculated air exposure rate was between 14.2 to 228.1 nGy/h in both 0 m from the Waves and 10 m from the Waves. The values of external and internal radiation hazard indices are found to be less than unity. Measured natural radioactivity, hazard indices and effective dose received by the population were found to within the recommended limits. This work provides a good baseline data of natural radioactive elements for the sand of the area and  its radiological significance.