• S Krishnaswamy

      Articles written in Proceedings – Section A

    • Isotopes of uranium and radium in Indian rivers

      Suman G Bhat S Krishnaswamy

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      The concentrations of dissolved uranium and radium isotopes have been determined in the waters of several Indian rivers. The concentration of uranium (U-238) is found to vary between 0·01–7·0 micrograms/litre, depending primarily on the terrain through which the river flows. From the available data on the activity ratios, U-234/U-238, concentration of U-238 in rivers and the amount of uranium depositing on the ocean floor, a material balance calculation has been attempted. This shows that the supply of uranium to sea by rivers based on above measurements, is inadequate to explain the observed concentrations of U-238 and U-234 in the oceans.

      The Ra-226 concentration of river waters is found to be of the order of 0·1 dpm/litre (varying between 0·05–0·2 dpm/litre). The activity ratios, Ra-228/Ra-226, range between 1 and 4. This large variation is clearly related to the fact that the concentrations of the parent nuclides of Ra-226 and Ra-228 are different. The observed ratios are consistent with those expected from leaching of clays/soils; however, analogous to the situation in the case of uranium, the observed concentrations of radium isotopes in the oceans are too large to be explained by their influx by rivers.

    • U234/U238 activity ratios in South Pacific Ocean waters

      S Krishnaswamy D Lal B L K Somayajulu

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      Analyses of uranium extracted from South Pacific waters by thein-situ extraction method point to a uniform depth independent value of 1·14 ±0 02 for the U234/U238 activity ratio. This value is also the same, within one standard deviation, as that determined for the N. Pacific, S. Indian and Atlantic waters.

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