Natural radioactivity and hazardous index of major South Indian river sediments

Abstract

The activity concentrations of 238U, 232Th and 40K have been determined by gamma ray spectrometry with an NaI(Tl) detector in sediments of Palar River, Tamil Nadu, India. The absorbed dose rate, radium equivalent concentration, external (Hex) and internal (Hin) hazardous indices are calculated from criteria formula and compared with the international recommended limits. The Radioactive Heat Production (RHP) rate and Excess Lifetime Cancer Risk (ELCR) are also calculated. The observed dose rate from ERDM (Environmental Radiation Dosimeter) at 1 m above the ground level at each site of the river is measured and correlated with calculated absorbed dose rate. The distribution of quartz, feldspar, magnetic susceptibility and weight of the magnetic minerals is correlated with radioactivity results. From the observations, the weight of the magnetic minerals is an index to identify the sediments of low or high radiological risk.