NATURAL RADIOACTIVITY MEASUREMENT AND DOSE ASSESSMENT OF BEACH PLACER SANDS IN THE COASTAL REGION OF TAMIL NADU (INDIA)

Assessment of radioactivity in sand samples from eastern Nepal in perspective of radiological hazards

This study was conducted to investigate the activity concentrations of 226Ra, 232Th and 40K in the sand samples and the health hazards associated with them utilizing a NaI (Tl) gamma spectrometer. The average activity concentrations of 226Ra, 232Th and 40K were found to be 24.8 ± 10.1, 39.8 ± 16.4 and 531.3 ± 52.8 Bq kg-1, respectively. The calculated radiological hazard parameters, including radium equivalent activity, absorbed gamma dose and effective dose rate, were found to be 122.7 ± 34.0 Bq kg-1, 57.7 ± 14.9 nGy h-1 and 0.3 ± 0.1 mSv y-1, respectively. Notably, these results were observed to be below the recommended thresholds. Other measured hazard indices were also lower than the prescribed values. From a radiological perspective, the present study concludes that the sand samples do not pose any threat to human health when utilized as a building material.

Spatial analysis of radionuclide concentration in the high background radiation regions of Kerala, India

Every creature on earth undergoes continuous exposure to natural background radiation. Hence, it is crucial to monitor systematically, the degree of radioactivity in the ecosystem and possible radiological health hazards. The present study attempt to investigate the dynamics of prominent radionuclides and various radiological parameters associated with terrestrial gamma radiations along the littoral regions of the Kollam district, a well-reported high background radiation area in India. The gamma radiation exposure rate along the coastal belt of Kollam was measured using a portable Micro-R-survey meter and associated radiological parameters have been calculated and compared with the global average values. The result indicates that the radiological parameters cross the safe limits recommended by the UNSCEAR 2000. A high value is found in the shoreline of Chavara, with a maximum absorbed dose rate of 11 945.1nGyh-1. The monazite-enriched black sand widely distributed all along the coast, which contains natural radioisotopes such as 40K, 226Ra and 232Th, has greatly contributed to the increase in radiation levels in the regions.

Distribution of naturally occurring radionuclides and gamma dose rate assessment in the soils of high background natural radiation area Odisha, India

A study on the activity concentration of primordial radionuclides 226Ra, 232Th and 40K was carried out on the surface soil samples collected from the coastal villages between Chhatrapur and Gopalpur regions of high background natural radiation area Odisha, India, using high purity germanium gamma spectroscopy. The mean activity concentrations of 226Ra, 232Th and 40K were found to be 231, 1692 and 250 Bq/kg, respectively. The total mean absorbed dose owing to the presence of 226Ra, 232Th and 40K was 1139 nGy/h. The mean annual effective dose was found to be 1397 μSv/y and higher than the UNSCEAR average value 70 μSv/y.

Assessment of a naturally occurring high background radiation area with elevated levels of thorium along coastal Odisha, India using radiometric methods

The present study evaluates the enrichment and distribution of radioelements along the eastern coast of India. India possesses the second largest reserve of thorium bearing monazite in the world, in terms of heavy minerals present primarily along its long coastline. Radioelement estimation of about 30 km long beach area along the eastern coast of India is reported and implications discussed. A total number of 822 data points were studied using a portable Geiger Muller counter, to estimate the variation of dose rates, due to the ambient radionuclides along two different trends. One was parallel (northeast-southwest) and the second one perpendicular to the coastline. Pre-selected samples from in-situ radiometric surveys on the heavy mineral placers were studied further, for quantitative estimation of the abundance of radioactive elements primarily uranium and thorium, using a High Purity Germanium detector. Radioelement concentration assessment of core samples (depth ~2 m), were studied from two different beaches. Radiological parameters like radium equivalent, annual effective doserate and absorbed dose rate has been calculated based on the ²³⁸U, ²³²Th and ⁴⁰K concentrations. Heavy mineral placers along the shoreline indicate a very high thorium (avg - 2990.22 Bq kg^-1) which is due to the extensive distribution indicative of monazite. The coastal area also exhibits relatively low uranium (avg - 319.1 Bq kg^-1). Based on its high thorium concentration, the area can be considered as a high natural background radiation area. Based on the concentrations of uranium and thorium, the weathering conditions and depositional environment prevalent along the beach areas have been discussed.

Geochemical behavior of uranium and thorium in sand and sandy soil samples from a natural high background radiation area of the Odisha coast, India

Owing to their natural radioactivity, uranium (U) and thorium (Th) play significant roles in environmental sciences for monitoring radiation dose and in geological sciences for understanding sedimentary processes. The Odisha coastal area, in eastern India, is a well-known high background radiation area that is rich in monazites and rutile. This area was selected to study geochemical characteristics of U and Th in sand and sandy soil samples. The concentrations of U and Th were measured using inductively coupled plasma mass spectrometry (ICP-MS). The median, geometric mean, and standard deviation for U were determined to be 6, 4.5, and 2.5 μg/g and for Th were 186, 123.3, and 3.1 μg/g, respectively. Major element concentrations were evaluated using X-ray fluorescence spectroscopy to get the mineralogical composition and state of chemical weathering. The ratios of Th/U and Th/K varied from 4 to 37 and from 13 to 1058, respectively. These results clearly indicate that the samples from the coastal region were formed in an oxidizing and intense chemical weathering terrestrial environment with an enrichment of radiogenic heavy minerals (monazites and zircon) and clay mineral association. Since the majority of the samples have undergone moderate to intense weathering in the oxidizing environment, U is leached from the soil and sand matrix. Eventually, Th resides in the matrix and becomes a major source for radiation exposure in the environment. The high ratios of Th/U, along with the strong positive correlation between Th and P2O5, evidence the enrichment of the Th-bearing radioactive mineral, monazite, in these samples.