Distribution of natural radionuclide40K in biotic and abiotic components of the Cauvery river system,Tiruchirapalli, India

Abiotic components like water and sediment, and biotic components such as mussels, fish and grass collected from Cauvery river at Tiruchirapalli were analysed for⁴⁰K activity. The highest level of⁴⁰K activity was found in the sediment (342 mBq g^-1 dry weight) and the lowest activity was found in water (2·209 mBq ml⁻¹). In the freshwater musselParreysia favidens (Benson)⁴⁰K activity was estimated in the total soft tissues and shells of mussels belonging to three different size groups. In all the size groups⁴⁰K activity was two times higher in shells (68–39 mBq g^-1 fresh weight) than in the total soft tissues (25–17 mBq g^-1 fresh weight). The results indicate that the younger mussels accumulated more⁴⁰K than the older ones. The ability of internal organs of mussels belonging to group III to accumulate⁴⁰K was in the following order: gills > digestive gland > foot > mantle. The values ranged from 47 to 18 mBq g⁻¹ fresh weight in the various organs. Concentration of⁴⁰K in the mussel was distinctly higher than in the grassEchinochloa colonum (J Koenig) (95 mBq g⁻¹ fresh weight), and the concentration of⁴⁰K in the bone of the fishCirrhina cirrhosa (Bloch) (126 mBq g⁻¹ fresh weight) was higher than to that of muscle (113 mBq g⁻¹ fresh weight)