Distribution of natural radionuclide 40K in biotic and abiotic components of the Cauvery river system, Tiruchirapalli, India.

ABSTRACT

Abiotic components like water and sediment, and biotic components such as mussels, fish and grass collected from Cauvery river at Tiruchirapalli were analysed for 40K activity. The highest level of 40K 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 mussel Parreysia 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 groups 40K 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 more 40K than the older ones. The ability of internal organs of mussels belonging to group III to accumulate 40K 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 of 40K in the mussel was distinctly higher than in the grass Echinochloa colonum (J Koenig) (95 mBq g–1 fresh weight), and the concentration of 40K in the bone of the fish Cirrhina cirrhosa (Bloch) (126 mBq g–1 fresh weight) was higher than to that of muscle (113 mBq g–1 fresh weight)·