Radiation Protection and Environment (Jan 2018)
Enrichment pattern and depth profile of natural radionuclides in monazite areas of coastal Karnataka
Abstract
The activities of radionuclides 232Th, 226Ra, and 40K have been measured in sand samples of Ullal beach area, where presence of low-level monazite has been reported. The sand samples collected from the region, at different distances from sea waterline and at different depths, were analyzed for radionuclide activity by gamma spectrometry to study the distribution, enrichment pattern, and vertical profile of the radionuclides in the region. The study on the enrichment of radionuclides in different size fractions shows highest activity confined in <125 μm and lowest activity confined in 1000–500 μm particle size fractions. The minimum 232Th activity was 1.1 Bq/kg, found in Ombattu Kere beach at a depth of 10–20 cm, at waterline in 1000–500 μm particle size fraction and maximum activity of 6690.7 Bq/kg was found in Ombattu Kere beach at a depth of 10–20 cm, at 50 m away from waterline in grains of size 250–125 μm. The lowest 226Ra activity was 25.1 Bq/kg, found in Ombattu Kere beach at a depth of 10–20 cm, at waterline in grains of size 1000–500 μm and highest 226Ra activity was 1286.0 Bq/kg, found in Ombattu Kere beach in grains of size <125 μm for sample collected at a distance of 50 m away from waterline and at a depth of 10–20 cm. The minimum 40K activity was 130.5 Bq/kg, found in Ombattu Kere beach at a depth of 20–30 cm, at 50 m away from waterline in grains of size 500–250 μm and maximum activity of 40K was 5686.2 Bq/kg, found in Ombattu Kere beach for sample collected at waterline at a depth of 20–30 cm in <125 μm particle size fraction. The dose rate measured using plastic scintillometer at 1 m above the ground level at Ullal is having the range 39.4–459.9 nGy/h with a mean value of 193.2 nGy/h. The results of these investigations are presented and discussed in this article.
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