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  • Author or Editor: M. Zingde x
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Abstract  

Nearshore surface sediments from various locations of the West Coast of India were leached by saturated ammonium carbonate solution for the extraction of uranium isotopes. The reagent chosen was found to have high efficiency for leaching uranium isotopes without attacking the mineral core of the sediment particle. The activity ratios of234U/238U are in the range of 1.11 to 1.14 and the activity ratios of235U/235U are in the range of 0.045 to 0.047. The respective activity ratios in leachates, and residues after removal of surface organic matter from the sediment particles by treatment with hydrogen peroxide and 0.05M HCl, revealed disequilibrium between238U and234U only in the surface organic matter. The activity ratios of234U/238U and235U/238U have also been determined in some seawater samples from the Arabian Sea.

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Abstract  

Measurements carried out recently with surface labile layers of the estuarine sediments have indicated remarkable dis-equilibrium between234U and238U activaties. The234U/238U activity ratios on the surface of the sediments collected from Mindola estuary of Gujarat State in India have been found to vary in the range of 1.12 to 1.43 while235U/238U activity ratios lie in the range of 0.045. On removing the labile layers and leaching uranium from the core of the sediment particles gave, an equilibrium ratio of 1.00 for234U/238U. There is however no change in the activity ratios of235U/238U.

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Abstract  

The measurements of natural radioactivity due to thorium isotopes have been carried out in estuarine sediments of Mandovi river (Goa). The geochemical behaviour of these sediments has been studied by leaching the samples with 5 % ethylenediaminetetraacetic acid at pH 3.0 in order to investigate the processes occurring on the surface of the sediment particles and the distribution of natural thorium in estuarine sediments. The228Th/232Th activity ratios have been found to be in the range of 2.00 to 2.12. This anomaly between232Th and228Th has been attributed to the preferential leaching of228Ra by water flowing over these sediments. The activities of228Ra on the surface labile layers of the sediments have also been determined. The230Th/232Th activity ratios have been found to be in the range of 0.94 to 1.04. These ratios are mainly dependent on the precipitation action of230Th on adjacent sediments.

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Abstract  

The surface leaching of the labile component of uranium has been carried out in estuarine sediments of Zuari river in Goa. The measurements of alpha activities of238U,235U and234U in the leachates indicated a remarkable anomaly between the activities of238U and234U. The activity ratios of234U/238U in these leachates have been found to be in the range of 1.10 to 1.14. However, the activity ratios of235U/238U have been found to be 0.045 which is close to that in natural uranium. It has also been observed that the anomaly between238U and234U exists only on the surface organic layers of the backwater sediments of the Zuari river.

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Abstract  

The sediment samples have been collected from estuarine regions of Mindola and Purna of Gujarat State. These samples are found to contain less than 3% of organic matter which scavange and carry most of the activity of226Ra, etc., to the sediment floor. The activities of226Ra are found to vary from 0.1 to 0.5 pCi/g, while210Pb activities lie in the range of 3 to 8 pCi/g. These activities find their way into the organisms present in sea water and then into fish which is finally consumed by humans. This paper gives in detail the sampling techniques, experimental procedures and the distribution of the isotopes of226Ra and210Pb in the estuarine regions and the concentration factors of226Ra in the region.

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