Environmental radiation and potential ecological risk levels in the intertidal zone of southern region of Tamil Nadu coast (HBRAs), India

Highlights: • ²³²Th alone is higher than the world average value. • With regard to heavy metals pollution, "Moderate" pollution level is observed. • Environmental radiation level and ecological risk value are within the safe limits. - Abstract: Natural radioactivity content and heavy metal concentration in the intertidal zone sand samples from the southern region of Tamil Nadu coast, India, have been analyzed using gamma ray spectrometer and ICP-OES, respectively. From gamma spectral analysis, the average radioactivity contents of ²³⁸U, ²³²Th, and ⁴⁰K in the intertidal zone sand samples are 12.13 ± 4.21, 59.03 ± 4.26, and 197.03 ± 26.24 Bq/kg, respectively. The average radioactivity content of ²³²Th alone is higher than the world average value. From the heavy metal analysis, the average Cd, Cr, Cu, Ni, Pb, and Zn concentrations are 3.1, 80.24, 82.84, 23.66, 91.67, and 137.07 ppm, respectively. The average Cr and Ni concentrations are lower, whereas other four metal (Cd, Cu, Pb, and Zn) concentrations are higher than world surface rock average values. From pollution assessment parameter values, the pollution level is "uncontaminated to moderately contaminated" in the study area.