DISTRIBUTION AND TRANSPORT OF RADIUM IN A TROPICAL RIVER

The nuclides, **2**2**8Ra and **2**2**6Ra, distributed into the soluble, suspended and sediment fractions in the river have differential inputs, both fluvial and technological. The high background contribution, enhancement due to industrial activities, and changes at the backwaters are highlighted. The solubilization-precipitation cycle at the backwater is discussed in relation to the seasonal inputs of fresh and saline waters, respectively, into the estuary. Sediment shift and subsequent solubilization of Ra from sediments during monsoon are the major geological phenomena responsible for its transport from the river to the coastal marine environment.