URANIUM ISOTOPES IN THE MAHANADI RIVER ESTUARINE SYSTEM, INDIA

Extensive measurements of uranium isotopes in dissolved form during di fferent seasons and in suspended form during the monsoon season are re ported for the Mahanadi river-estuarine system on the east coast of pe ninsular India. Beyond the very low chlorinity (0.2 g l(-1)) region, u ranium isotopes behave conservatively in the Mahanadi estuary. The dis charge weighted mean uranium input to the Bay of Bengal is 36 tons yea r(-1), out of which the dissolved uranium input is only 18.3%, that is , 6.6 tons year(-1). Of the dissolved flux, only 27% (i.e. 1.8 tons ye ar(-1)) occurs during the monsoon season whereas 99% of the input of u ranium in suspended form takes place during the same season.