Radionuclide ratios of cesium and strontium in Tarapur marine environment,west coast of India

Marine environment of Tarapur located 100 km north of Bombay on the west co ast, receives low level liquid waste from Tarapur Atomic Power Station (TAP S) and Fuel Reprocessing Plant(FRP). Radionuclide ratios of cesium and stro ntium were obtained in source term (the quantum of radioactive liquid waste available for discharge) and different marine samples viz, seawater, sedim ent, seaweed and marine organisms. A constant ratio of Cs-137:Cs-134 was ob served in seawater and source term. But the ratio of Cs-137:Sr-90 had wide variation due to selective scavenging of Cs-137 by sedimentary particles at the discharge location. Among the other matrices, sediment showed a higher value of Cs-137:Cs-134 and Cs-137:Sr-90 reflecting the cumulative effects of releases from TAPS and FRP and higher distribution coefficient of radioc esium from seawater to sediment. Marine algae indicate a discrimination aga inst sorption of Sr-90 due to the isotopic dilution by stable strontium pre sent in seawater (8mg/l). The marine organisms preying on sediment containi ng microflora and fauna exhibited radionuclide ratios similar to seawater a s the sediment sorbed cesium is not available for assimilation due to the m ineral nature of the sediment. The matrices other than sediment indicated t he equilibrated activity ratio of radionuclides in seawater which is the re cipient medium and reflected the influence of continuous discharge. The sed imentary radionuclide ratio is largely dependent on sorption characteristic s of radionuclides and their retention.