Anomalous behavior of thorium and uranium isotopes in the marine environment of the West Coast of India
Geochemical behavior of thorium and uranium isotopes and their activity ratios have been studied in the coastal marine sediments of the West Coast region of the Indian sub-continent. Results of this study can be correlated with the transport and deposition of artificially introduced radioactivity or any run-off terrestrial pollutants in the region. In the southern part of the West Coast there are extensive placer deposits containing thorium- and uranium-bearing minerals (monazite) whereas the northern part is relatively free of such deposits. The surface layers of the coastal sediments are leached with 5 percent EDTA for the extraction of thorium and the saturated solution of ammonium carbonate for the extraction of uranium. The leaching agents are so chosen that they have high efficiency for leaching thorium and uranium and at the same time do not in any way attack the mineral core of the sediment particles. The thorium and uranium isotopic activities and the ratios $sup 228$Th/$sup 232$Th, $sup 230$Th/$sup 232$Th, $sup 234$U/$sup 238$U, and $sup 235$U/$sup 238$U are calculated. The $sup 228$Th/$sup 232$Th activity ratios in the Bombay region and in the Monazite areas are in the range 0.55 to 0.67 while the ratios in the region between Ratnagiri and Honawar are in the range 2.00 to 2.19. The $sup 230$Th/$sup 232$Th activity ratios are in the range 0.13 to 0.15 in the Bombay region, 0.95 to 1.07 in the region between Ratnagiri and Honawar and 0.23 to 0.25 in the monazite areas. However, such large variations are not observed in $sup 234$U/$sup 238$U activity ratios. The $sup 234$U/$sup 238$U activity ratios are in the range 1.12 to 1.14 in the coastal sediments from the regions between Bombay and Kottilppad. The activity ratios $sup 234$U/$sup 238$U in coastal sea-water are in the range 1.15 to 1.16. The $sup 235$U/$sup 238$U activity ratios in sediments and sea- water are 0.046, which is the same as that of natural uranium. (auth)
- Research Organization:
- Bhabha Atomic Research Centre, Trombay, India
- NSA Number:
- NSA-33-007302
- OSTI ID:
- 4151416
- Country of Publication:
- IAEA
- Language:
- English
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THORIUM ISOTOPES METHOD FOR DATING MARINE SEDIMENTS (thesis)
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*THORIUM 228-- ISOTOPE RATIO
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*URANIUM 238-- ISOTOPE RATIO
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Aquatic--Radioactive Materials Monitoring & Transport--Water
DEPOSITS
GEOCHEMISTRY
INDIA
N44330* --Environmental & Earth Sciences--Radioactivity Monitoring & Transport--Water
RADIOACTIVITY