ABSTRACT
Studies on natural and anthropogenic radioactivity assume greater importance in the context of human health and development. Hence two species of seaweeds viz: Gracilaria edulis and Ulva lactuca, from three high background radiation areas (Arockiapuram, Kadiapattinam and Kurumpanai) on the southwest coast of Tamil Nadu, and Mandapam as low background radiation area of the southeast coast of Tamil Nadu were studied for variations in activity concentration of 228 Ra, 40 K, 238 U and 228 Th. Among these radionuclides, 40K recorded significant inter-species variation while 238 U and 228 Th showed significant association. The overall mean concentration of radionuclides was found high in G.edulis (5.31, 57.49, 36.05, 356.55 Bq kg-1 for 228 Ra, 40K, 238U, 228 Th respectively), while the mean concentrations for U.lactuca were 4.88, 42.35, 34.40, 347.70 Bqkg-1 for 228 Ra, 40K, 238U, 228 Th respectively. The mean concentration of radionuclides was uniformly found low during northeast monsoon season in both the seaweed species.